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-rw-r--r--refs/debug.c473
-rw-r--r--refs/files-backend.c3303
-rw-r--r--refs/iterator.c435
-rw-r--r--refs/packed-backend.c1615
-rw-r--r--refs/packed-backend.h39
-rw-r--r--refs/ref-cache.c504
-rw-r--r--refs/ref-cache.h220
-rw-r--r--refs/refs-internal.h737
8 files changed, 7326 insertions, 0 deletions
diff --git a/refs/debug.c b/refs/debug.c
new file mode 100644
index 0000000..eed8bc9
--- /dev/null
+++ b/refs/debug.c
@@ -0,0 +1,473 @@
+
+#include "refs-internal.h"
+#include "trace.h"
+
+static struct trace_key trace_refs = TRACE_KEY_INIT(REFS);
+
+struct debug_ref_store {
+ struct ref_store base;
+ struct ref_store *refs;
+};
+
+extern struct ref_storage_be refs_be_debug;
+
+struct ref_store *maybe_debug_wrap_ref_store(const char *gitdir, struct ref_store *store)
+{
+ struct debug_ref_store *res;
+ struct ref_storage_be *be_copy;
+
+ if (!trace_want(&trace_refs)) {
+ return store;
+ }
+ res = xmalloc(sizeof(struct debug_ref_store));
+ be_copy = xmalloc(sizeof(*be_copy));
+ *be_copy = refs_be_debug;
+ /* we never deallocate backends, so safe to copy the pointer. */
+ be_copy->name = store->be->name;
+ trace_printf_key(&trace_refs, "ref_store for %s\n", gitdir);
+ res->refs = store;
+ base_ref_store_init((struct ref_store *)res, store->repo, gitdir,
+ be_copy);
+ return (struct ref_store *)res;
+}
+
+static int debug_init_db(struct ref_store *refs, struct strbuf *err)
+{
+ struct debug_ref_store *drefs = (struct debug_ref_store *)refs;
+ int res = drefs->refs->be->init_db(drefs->refs, err);
+ trace_printf_key(&trace_refs, "init_db: %d\n", res);
+ return res;
+}
+
+static int debug_transaction_prepare(struct ref_store *refs,
+ struct ref_transaction *transaction,
+ struct strbuf *err)
+{
+ struct debug_ref_store *drefs = (struct debug_ref_store *)refs;
+ int res;
+ transaction->ref_store = drefs->refs;
+ res = drefs->refs->be->transaction_prepare(drefs->refs, transaction,
+ err);
+ trace_printf_key(&trace_refs, "transaction_prepare: %d \"%s\"\n", res,
+ err->buf);
+ return res;
+}
+
+static void print_update(int i, const char *refname,
+ const struct object_id *old_oid,
+ const struct object_id *new_oid, unsigned int flags,
+ unsigned int type, const char *msg)
+{
+ char o[GIT_MAX_HEXSZ + 1] = "null";
+ char n[GIT_MAX_HEXSZ + 1] = "null";
+ if (old_oid)
+ oid_to_hex_r(o, old_oid);
+ if (new_oid)
+ oid_to_hex_r(n, new_oid);
+
+ type &= 0xf; /* see refs.h REF_* */
+ flags &= REF_HAVE_NEW | REF_HAVE_OLD | REF_NO_DEREF |
+ REF_FORCE_CREATE_REFLOG;
+ trace_printf_key(&trace_refs, "%d: %s %s -> %s (F=0x%x, T=0x%x) \"%s\"\n", i, refname,
+ o, n, flags, type, msg);
+}
+
+static void print_transaction(struct ref_transaction *transaction)
+{
+ int i;
+ trace_printf_key(&trace_refs, "transaction {\n");
+ for (i = 0; i < transaction->nr; i++) {
+ struct ref_update *u = transaction->updates[i];
+ print_update(i, u->refname, &u->old_oid, &u->new_oid, u->flags,
+ u->type, u->msg);
+ }
+ trace_printf_key(&trace_refs, "}\n");
+}
+
+static int debug_transaction_finish(struct ref_store *refs,
+ struct ref_transaction *transaction,
+ struct strbuf *err)
+{
+ struct debug_ref_store *drefs = (struct debug_ref_store *)refs;
+ int res;
+ transaction->ref_store = drefs->refs;
+ res = drefs->refs->be->transaction_finish(drefs->refs, transaction,
+ err);
+ print_transaction(transaction);
+ trace_printf_key(&trace_refs, "finish: %d\n", res);
+ return res;
+}
+
+static int debug_transaction_abort(struct ref_store *refs,
+ struct ref_transaction *transaction,
+ struct strbuf *err)
+{
+ struct debug_ref_store *drefs = (struct debug_ref_store *)refs;
+ int res;
+ transaction->ref_store = drefs->refs;
+ res = drefs->refs->be->transaction_abort(drefs->refs, transaction, err);
+ return res;
+}
+
+static int debug_initial_transaction_commit(struct ref_store *refs,
+ struct ref_transaction *transaction,
+ struct strbuf *err)
+{
+ struct debug_ref_store *drefs = (struct debug_ref_store *)refs;
+ int res;
+ transaction->ref_store = drefs->refs;
+ res = drefs->refs->be->initial_transaction_commit(drefs->refs,
+ transaction, err);
+ return res;
+}
+
+static int debug_pack_refs(struct ref_store *ref_store, unsigned int flags)
+{
+ struct debug_ref_store *drefs = (struct debug_ref_store *)ref_store;
+ int res = drefs->refs->be->pack_refs(drefs->refs, flags);
+ trace_printf_key(&trace_refs, "pack_refs: %d\n", res);
+ return res;
+}
+
+static int debug_create_symref(struct ref_store *ref_store,
+ const char *ref_name, const char *target,
+ const char *logmsg)
+{
+ struct debug_ref_store *drefs = (struct debug_ref_store *)ref_store;
+ int res = drefs->refs->be->create_symref(drefs->refs, ref_name, target,
+ logmsg);
+ trace_printf_key(&trace_refs, "create_symref: %s -> %s \"%s\": %d\n", ref_name,
+ target, logmsg, res);
+ return res;
+}
+
+static int debug_delete_refs(struct ref_store *ref_store, const char *msg,
+ struct string_list *refnames, unsigned int flags)
+{
+ struct debug_ref_store *drefs = (struct debug_ref_store *)ref_store;
+ int res =
+ drefs->refs->be->delete_refs(drefs->refs, msg, refnames, flags);
+ int i;
+ trace_printf_key(&trace_refs, "delete_refs {\n");
+ for (i = 0; i < refnames->nr; i++)
+ trace_printf_key(&trace_refs, "%s\n", refnames->items[i].string);
+ trace_printf_key(&trace_refs, "}: %d\n", res);
+ return res;
+}
+
+static int debug_rename_ref(struct ref_store *ref_store, const char *oldref,
+ const char *newref, const char *logmsg)
+{
+ struct debug_ref_store *drefs = (struct debug_ref_store *)ref_store;
+ int res = drefs->refs->be->rename_ref(drefs->refs, oldref, newref,
+ logmsg);
+ trace_printf_key(&trace_refs, "rename_ref: %s -> %s \"%s\": %d\n", oldref, newref,
+ logmsg, res);
+ return res;
+}
+
+static int debug_copy_ref(struct ref_store *ref_store, const char *oldref,
+ const char *newref, const char *logmsg)
+{
+ struct debug_ref_store *drefs = (struct debug_ref_store *)ref_store;
+ int res =
+ drefs->refs->be->copy_ref(drefs->refs, oldref, newref, logmsg);
+ trace_printf_key(&trace_refs, "copy_ref: %s -> %s \"%s\": %d\n", oldref, newref,
+ logmsg, res);
+ return res;
+}
+
+struct debug_ref_iterator {
+ struct ref_iterator base;
+ struct ref_iterator *iter;
+};
+
+static int debug_ref_iterator_advance(struct ref_iterator *ref_iterator)
+{
+ struct debug_ref_iterator *diter =
+ (struct debug_ref_iterator *)ref_iterator;
+ int res = diter->iter->vtable->advance(diter->iter);
+ if (res)
+ trace_printf_key(&trace_refs, "iterator_advance: (%d)\n", res);
+ else
+ trace_printf_key(&trace_refs, "iterator_advance: %s (0)\n",
+ diter->iter->refname);
+
+ diter->base.ordered = diter->iter->ordered;
+ diter->base.refname = diter->iter->refname;
+ diter->base.oid = diter->iter->oid;
+ diter->base.flags = diter->iter->flags;
+ return res;
+}
+
+static int debug_ref_iterator_peel(struct ref_iterator *ref_iterator,
+ struct object_id *peeled)
+{
+ struct debug_ref_iterator *diter =
+ (struct debug_ref_iterator *)ref_iterator;
+ int res = diter->iter->vtable->peel(diter->iter, peeled);
+ trace_printf_key(&trace_refs, "iterator_peel: %s: %d\n", diter->iter->refname, res);
+ return res;
+}
+
+static int debug_ref_iterator_abort(struct ref_iterator *ref_iterator)
+{
+ struct debug_ref_iterator *diter =
+ (struct debug_ref_iterator *)ref_iterator;
+ int res = diter->iter->vtable->abort(diter->iter);
+ trace_printf_key(&trace_refs, "iterator_abort: %d\n", res);
+ return res;
+}
+
+static struct ref_iterator_vtable debug_ref_iterator_vtable = {
+ .advance = debug_ref_iterator_advance,
+ .peel = debug_ref_iterator_peel,
+ .abort = debug_ref_iterator_abort,
+};
+
+static struct ref_iterator *
+debug_ref_iterator_begin(struct ref_store *ref_store, const char *prefix,
+ unsigned int flags)
+{
+ struct debug_ref_store *drefs = (struct debug_ref_store *)ref_store;
+ struct ref_iterator *res =
+ drefs->refs->be->iterator_begin(drefs->refs, prefix, flags);
+ struct debug_ref_iterator *diter = xcalloc(1, sizeof(*diter));
+ base_ref_iterator_init(&diter->base, &debug_ref_iterator_vtable, 1);
+ diter->iter = res;
+ trace_printf_key(&trace_refs, "ref_iterator_begin: \"%s\" (0x%x)\n",
+ prefix, flags);
+ return &diter->base;
+}
+
+static int debug_read_raw_ref(struct ref_store *ref_store, const char *refname,
+ struct object_id *oid, struct strbuf *referent,
+ unsigned int *type, int *failure_errno)
+{
+ struct debug_ref_store *drefs = (struct debug_ref_store *)ref_store;
+ int res = 0;
+
+ oidcpy(oid, null_oid());
+ res = drefs->refs->be->read_raw_ref(drefs->refs, refname, oid, referent,
+ type, failure_errno);
+
+ if (res == 0) {
+ trace_printf_key(&trace_refs, "read_raw_ref: %s: %s (=> %s) type %x: %d\n",
+ refname, oid_to_hex(oid), referent->buf, *type, res);
+ } else {
+ trace_printf_key(&trace_refs,
+ "read_raw_ref: %s: %d (errno %d)\n", refname,
+ res, *failure_errno);
+ }
+ return res;
+}
+
+static int debug_read_symbolic_ref(struct ref_store *ref_store, const char *refname,
+ struct strbuf *referent)
+{
+ struct debug_ref_store *drefs = (struct debug_ref_store *)ref_store;
+ struct ref_store *refs = drefs->refs;
+ int res;
+
+ res = refs->be->read_symbolic_ref(refs, refname, referent);
+ if (!res)
+ trace_printf_key(&trace_refs, "read_symbolic_ref: %s: (%s)\n",
+ refname, referent->buf);
+ else
+ trace_printf_key(&trace_refs,
+ "read_symbolic_ref: %s: %d\n", refname, res);
+ return res;
+
+}
+
+static struct ref_iterator *
+debug_reflog_iterator_begin(struct ref_store *ref_store)
+{
+ struct debug_ref_store *drefs = (struct debug_ref_store *)ref_store;
+ struct ref_iterator *res =
+ drefs->refs->be->reflog_iterator_begin(drefs->refs);
+ trace_printf_key(&trace_refs, "for_each_reflog_iterator_begin\n");
+ return res;
+}
+
+struct debug_reflog {
+ const char *refname;
+ each_reflog_ent_fn *fn;
+ void *cb_data;
+};
+
+static int debug_print_reflog_ent(struct object_id *old_oid,
+ struct object_id *new_oid,
+ const char *committer, timestamp_t timestamp,
+ int tz, const char *msg, void *cb_data)
+{
+ struct debug_reflog *dbg = (struct debug_reflog *)cb_data;
+ int ret;
+ char o[GIT_MAX_HEXSZ + 1] = "null";
+ char n[GIT_MAX_HEXSZ + 1] = "null";
+ char *msgend = strchrnul(msg, '\n');
+ if (old_oid)
+ oid_to_hex_r(o, old_oid);
+ if (new_oid)
+ oid_to_hex_r(n, new_oid);
+
+ ret = dbg->fn(old_oid, new_oid, committer, timestamp, tz, msg,
+ dbg->cb_data);
+ trace_printf_key(&trace_refs,
+ "reflog_ent %s (ret %d): %s -> %s, %s %ld \"%.*s\"\n",
+ dbg->refname, ret, o, n, committer,
+ (long int)timestamp, (int)(msgend - msg), msg);
+ return ret;
+}
+
+static int debug_for_each_reflog_ent(struct ref_store *ref_store,
+ const char *refname, each_reflog_ent_fn fn,
+ void *cb_data)
+{
+ struct debug_ref_store *drefs = (struct debug_ref_store *)ref_store;
+ struct debug_reflog dbg = {
+ .refname = refname,
+ .fn = fn,
+ .cb_data = cb_data,
+ };
+
+ int res = drefs->refs->be->for_each_reflog_ent(
+ drefs->refs, refname, &debug_print_reflog_ent, &dbg);
+ trace_printf_key(&trace_refs, "for_each_reflog: %s: %d\n", refname, res);
+ return res;
+}
+
+static int debug_for_each_reflog_ent_reverse(struct ref_store *ref_store,
+ const char *refname,
+ each_reflog_ent_fn fn,
+ void *cb_data)
+{
+ struct debug_ref_store *drefs = (struct debug_ref_store *)ref_store;
+ struct debug_reflog dbg = {
+ .refname = refname,
+ .fn = fn,
+ .cb_data = cb_data,
+ };
+ int res = drefs->refs->be->for_each_reflog_ent_reverse(
+ drefs->refs, refname, &debug_print_reflog_ent, &dbg);
+ trace_printf_key(&trace_refs, "for_each_reflog_reverse: %s: %d\n", refname, res);
+ return res;
+}
+
+static int debug_reflog_exists(struct ref_store *ref_store, const char *refname)
+{
+ struct debug_ref_store *drefs = (struct debug_ref_store *)ref_store;
+ int res = drefs->refs->be->reflog_exists(drefs->refs, refname);
+ trace_printf_key(&trace_refs, "reflog_exists: %s: %d\n", refname, res);
+ return res;
+}
+
+static int debug_create_reflog(struct ref_store *ref_store, const char *refname,
+ struct strbuf *err)
+{
+ struct debug_ref_store *drefs = (struct debug_ref_store *)ref_store;
+ int res = drefs->refs->be->create_reflog(drefs->refs, refname, err);
+ trace_printf_key(&trace_refs, "create_reflog: %s: %d\n", refname, res);
+ return res;
+}
+
+static int debug_delete_reflog(struct ref_store *ref_store, const char *refname)
+{
+ struct debug_ref_store *drefs = (struct debug_ref_store *)ref_store;
+ int res = drefs->refs->be->delete_reflog(drefs->refs, refname);
+ trace_printf_key(&trace_refs, "delete_reflog: %s: %d\n", refname, res);
+ return res;
+}
+
+struct debug_reflog_expiry_should_prune {
+ reflog_expiry_prepare_fn *prepare;
+ reflog_expiry_should_prune_fn *should_prune;
+ reflog_expiry_cleanup_fn *cleanup;
+ void *cb_data;
+};
+
+static void debug_reflog_expiry_prepare(const char *refname,
+ const struct object_id *oid,
+ void *cb_data)
+{
+ struct debug_reflog_expiry_should_prune *prune = cb_data;
+ trace_printf_key(&trace_refs, "reflog_expire_prepare: %s\n", refname);
+ prune->prepare(refname, oid, prune->cb_data);
+}
+
+static int debug_reflog_expiry_should_prune_fn(struct object_id *ooid,
+ struct object_id *noid,
+ const char *email,
+ timestamp_t timestamp, int tz,
+ const char *message, void *cb_data) {
+ struct debug_reflog_expiry_should_prune *prune = cb_data;
+
+ int result = prune->should_prune(ooid, noid, email, timestamp, tz, message, prune->cb_data);
+ trace_printf_key(&trace_refs, "reflog_expire_should_prune: %s %ld: %d\n", message, (long int) timestamp, result);
+ return result;
+}
+
+static void debug_reflog_expiry_cleanup(void *cb_data)
+{
+ struct debug_reflog_expiry_should_prune *prune = cb_data;
+ prune->cleanup(prune->cb_data);
+}
+
+static int debug_reflog_expire(struct ref_store *ref_store, const char *refname,
+ unsigned int flags,
+ reflog_expiry_prepare_fn prepare_fn,
+ reflog_expiry_should_prune_fn should_prune_fn,
+ reflog_expiry_cleanup_fn cleanup_fn,
+ void *policy_cb_data)
+{
+ struct debug_ref_store *drefs = (struct debug_ref_store *)ref_store;
+ struct debug_reflog_expiry_should_prune prune = {
+ .prepare = prepare_fn,
+ .cleanup = cleanup_fn,
+ .should_prune = should_prune_fn,
+ .cb_data = policy_cb_data,
+ };
+ int res = drefs->refs->be->reflog_expire(drefs->refs, refname,
+ flags, &debug_reflog_expiry_prepare,
+ &debug_reflog_expiry_should_prune_fn,
+ &debug_reflog_expiry_cleanup,
+ &prune);
+ trace_printf_key(&trace_refs, "reflog_expire: %s: %d\n", refname, res);
+ return res;
+}
+
+struct ref_storage_be refs_be_debug = {
+ .next = NULL,
+ .name = "debug",
+ .init = NULL,
+ .init_db = debug_init_db,
+
+ /*
+ * None of these should be NULL. If the "files" backend (in
+ * "struct ref_storage_be refs_be_files" in files-backend.c)
+ * has a function we should also have a wrapper for it here.
+ * Test the output with "GIT_TRACE_REFS=1".
+ */
+ .transaction_prepare = debug_transaction_prepare,
+ .transaction_finish = debug_transaction_finish,
+ .transaction_abort = debug_transaction_abort,
+ .initial_transaction_commit = debug_initial_transaction_commit,
+
+ .pack_refs = debug_pack_refs,
+ .create_symref = debug_create_symref,
+ .delete_refs = debug_delete_refs,
+ .rename_ref = debug_rename_ref,
+ .copy_ref = debug_copy_ref,
+
+ .iterator_begin = debug_ref_iterator_begin,
+ .read_raw_ref = debug_read_raw_ref,
+ .read_symbolic_ref = debug_read_symbolic_ref,
+
+ .reflog_iterator_begin = debug_reflog_iterator_begin,
+ .for_each_reflog_ent = debug_for_each_reflog_ent,
+ .for_each_reflog_ent_reverse = debug_for_each_reflog_ent_reverse,
+ .reflog_exists = debug_reflog_exists,
+ .create_reflog = debug_create_reflog,
+ .delete_reflog = debug_delete_reflog,
+ .reflog_expire = debug_reflog_expire,
+};
diff --git a/refs/files-backend.c b/refs/files-backend.c
new file mode 100644
index 0000000..b899543
--- /dev/null
+++ b/refs/files-backend.c
@@ -0,0 +1,3303 @@
+#include "../cache.h"
+#include "../config.h"
+#include "../refs.h"
+#include "refs-internal.h"
+#include "ref-cache.h"
+#include "packed-backend.h"
+#include "../iterator.h"
+#include "../dir-iterator.h"
+#include "../lockfile.h"
+#include "../object.h"
+#include "../dir.h"
+#include "../chdir-notify.h"
+#include "worktree.h"
+
+/*
+ * This backend uses the following flags in `ref_update::flags` for
+ * internal bookkeeping purposes. Their numerical values must not
+ * conflict with REF_NO_DEREF, REF_FORCE_CREATE_REFLOG, REF_HAVE_NEW,
+ * or REF_HAVE_OLD, which are also stored in `ref_update::flags`.
+ */
+
+/*
+ * Used as a flag in ref_update::flags when a loose ref is being
+ * pruned. This flag must only be used when REF_NO_DEREF is set.
+ */
+#define REF_IS_PRUNING (1 << 4)
+
+/*
+ * Flag passed to lock_ref_sha1_basic() telling it to tolerate broken
+ * refs (i.e., because the reference is about to be deleted anyway).
+ */
+#define REF_DELETING (1 << 5)
+
+/*
+ * Used as a flag in ref_update::flags when the lockfile needs to be
+ * committed.
+ */
+#define REF_NEEDS_COMMIT (1 << 6)
+
+/*
+ * Used as a flag in ref_update::flags when the ref_update was via an
+ * update to HEAD.
+ */
+#define REF_UPDATE_VIA_HEAD (1 << 8)
+
+/*
+ * Used as a flag in ref_update::flags when a reference has been
+ * deleted and the ref's parent directories may need cleanup.
+ */
+#define REF_DELETED_RMDIR (1 << 9)
+
+struct ref_lock {
+ char *ref_name;
+ struct lock_file lk;
+ struct object_id old_oid;
+};
+
+struct files_ref_store {
+ struct ref_store base;
+ unsigned int store_flags;
+
+ char *gitcommondir;
+
+ struct ref_cache *loose;
+
+ struct ref_store *packed_ref_store;
+};
+
+static void clear_loose_ref_cache(struct files_ref_store *refs)
+{
+ if (refs->loose) {
+ free_ref_cache(refs->loose);
+ refs->loose = NULL;
+ }
+}
+
+/*
+ * Create a new submodule ref cache and add it to the internal
+ * set of caches.
+ */
+static struct ref_store *files_ref_store_create(struct repository *repo,
+ const char *gitdir,
+ unsigned int flags)
+{
+ struct files_ref_store *refs = xcalloc(1, sizeof(*refs));
+ struct ref_store *ref_store = (struct ref_store *)refs;
+ struct strbuf sb = STRBUF_INIT;
+
+ base_ref_store_init(ref_store, repo, gitdir, &refs_be_files);
+ refs->store_flags = flags;
+ get_common_dir_noenv(&sb, gitdir);
+ refs->gitcommondir = strbuf_detach(&sb, NULL);
+ refs->packed_ref_store =
+ packed_ref_store_create(repo, refs->gitcommondir, flags);
+
+ chdir_notify_reparent("files-backend $GIT_DIR", &refs->base.gitdir);
+ chdir_notify_reparent("files-backend $GIT_COMMONDIR",
+ &refs->gitcommondir);
+
+ return ref_store;
+}
+
+/*
+ * Die if refs is not the main ref store. caller is used in any
+ * necessary error messages.
+ */
+static void files_assert_main_repository(struct files_ref_store *refs,
+ const char *caller)
+{
+ if (refs->store_flags & REF_STORE_MAIN)
+ return;
+
+ BUG("operation %s only allowed for main ref store", caller);
+}
+
+/*
+ * Downcast ref_store to files_ref_store. Die if ref_store is not a
+ * files_ref_store. required_flags is compared with ref_store's
+ * store_flags to ensure the ref_store has all required capabilities.
+ * "caller" is used in any necessary error messages.
+ */
+static struct files_ref_store *files_downcast(struct ref_store *ref_store,
+ unsigned int required_flags,
+ const char *caller)
+{
+ struct files_ref_store *refs;
+
+ if (ref_store->be != &refs_be_files)
+ BUG("ref_store is type \"%s\" not \"files\" in %s",
+ ref_store->be->name, caller);
+
+ refs = (struct files_ref_store *)ref_store;
+
+ if ((refs->store_flags & required_flags) != required_flags)
+ BUG("operation %s requires abilities 0x%x, but only have 0x%x",
+ caller, required_flags, refs->store_flags);
+
+ return refs;
+}
+
+static void files_reflog_path(struct files_ref_store *refs,
+ struct strbuf *sb,
+ const char *refname)
+{
+ const char *bare_refname;
+ const char *wtname;
+ int wtname_len;
+ enum ref_worktree_type wt_type = parse_worktree_ref(
+ refname, &wtname, &wtname_len, &bare_refname);
+
+ switch (wt_type) {
+ case REF_WORKTREE_CURRENT:
+ strbuf_addf(sb, "%s/logs/%s", refs->base.gitdir, refname);
+ break;
+ case REF_WORKTREE_SHARED:
+ case REF_WORKTREE_MAIN:
+ strbuf_addf(sb, "%s/logs/%s", refs->gitcommondir, bare_refname);
+ break;
+ case REF_WORKTREE_OTHER:
+ strbuf_addf(sb, "%s/worktrees/%.*s/logs/%s", refs->gitcommondir,
+ wtname_len, wtname, bare_refname);
+ break;
+ default:
+ BUG("unknown ref type %d of ref %s", wt_type, refname);
+ }
+}
+
+static void files_ref_path(struct files_ref_store *refs,
+ struct strbuf *sb,
+ const char *refname)
+{
+ const char *bare_refname;
+ const char *wtname;
+ int wtname_len;
+ enum ref_worktree_type wt_type = parse_worktree_ref(
+ refname, &wtname, &wtname_len, &bare_refname);
+ switch (wt_type) {
+ case REF_WORKTREE_CURRENT:
+ strbuf_addf(sb, "%s/%s", refs->base.gitdir, refname);
+ break;
+ case REF_WORKTREE_OTHER:
+ strbuf_addf(sb, "%s/worktrees/%.*s/%s", refs->gitcommondir,
+ wtname_len, wtname, bare_refname);
+ break;
+ case REF_WORKTREE_SHARED:
+ case REF_WORKTREE_MAIN:
+ strbuf_addf(sb, "%s/%s", refs->gitcommondir, bare_refname);
+ break;
+ default:
+ BUG("unknown ref type %d of ref %s", wt_type, refname);
+ }
+}
+
+/*
+ * Manually add refs/bisect, refs/rewritten and refs/worktree, which, being
+ * per-worktree, might not appear in the directory listing for
+ * refs/ in the main repo.
+ */
+static void add_per_worktree_entries_to_dir(struct ref_dir *dir, const char *dirname)
+{
+ const char *prefixes[] = { "refs/bisect/", "refs/worktree/", "refs/rewritten/" };
+ int ip;
+
+ if (strcmp(dirname, "refs/"))
+ return;
+
+ for (ip = 0; ip < ARRAY_SIZE(prefixes); ip++) {
+ const char *prefix = prefixes[ip];
+ int prefix_len = strlen(prefix);
+ struct ref_entry *child_entry;
+ int pos;
+
+ pos = search_ref_dir(dir, prefix, prefix_len);
+ if (pos >= 0)
+ continue;
+ child_entry = create_dir_entry(dir->cache, prefix, prefix_len);
+ add_entry_to_dir(dir, child_entry);
+ }
+}
+
+/*
+ * Read the loose references from the namespace dirname into dir
+ * (without recursing). dirname must end with '/'. dir must be the
+ * directory entry corresponding to dirname.
+ */
+static void loose_fill_ref_dir(struct ref_store *ref_store,
+ struct ref_dir *dir, const char *dirname)
+{
+ struct files_ref_store *refs =
+ files_downcast(ref_store, REF_STORE_READ, "fill_ref_dir");
+ DIR *d;
+ struct dirent *de;
+ int dirnamelen = strlen(dirname);
+ struct strbuf refname;
+ struct strbuf path = STRBUF_INIT;
+ size_t path_baselen;
+
+ files_ref_path(refs, &path, dirname);
+ path_baselen = path.len;
+
+ d = opendir(path.buf);
+ if (!d) {
+ strbuf_release(&path);
+ return;
+ }
+
+ strbuf_init(&refname, dirnamelen + 257);
+ strbuf_add(&refname, dirname, dirnamelen);
+
+ while ((de = readdir(d)) != NULL) {
+ struct object_id oid;
+ struct stat st;
+ int flag;
+
+ if (de->d_name[0] == '.')
+ continue;
+ if (ends_with(de->d_name, ".lock"))
+ continue;
+ strbuf_addstr(&refname, de->d_name);
+ strbuf_addstr(&path, de->d_name);
+ if (stat(path.buf, &st) < 0) {
+ ; /* silently ignore */
+ } else if (S_ISDIR(st.st_mode)) {
+ strbuf_addch(&refname, '/');
+ add_entry_to_dir(dir,
+ create_dir_entry(dir->cache, refname.buf,
+ refname.len));
+ } else {
+ if (!refs_resolve_ref_unsafe(&refs->base,
+ refname.buf,
+ RESOLVE_REF_READING,
+ &oid, &flag)) {
+ oidclr(&oid);
+ flag |= REF_ISBROKEN;
+ } else if (is_null_oid(&oid)) {
+ /*
+ * It is so astronomically unlikely
+ * that null_oid is the OID of an
+ * actual object that we consider its
+ * appearance in a loose reference
+ * file to be repo corruption
+ * (probably due to a software bug).
+ */
+ flag |= REF_ISBROKEN;
+ }
+
+ if (check_refname_format(refname.buf,
+ REFNAME_ALLOW_ONELEVEL)) {
+ if (!refname_is_safe(refname.buf))
+ die("loose refname is dangerous: %s", refname.buf);
+ oidclr(&oid);
+ flag |= REF_BAD_NAME | REF_ISBROKEN;
+ }
+ add_entry_to_dir(dir,
+ create_ref_entry(refname.buf, &oid, flag));
+ }
+ strbuf_setlen(&refname, dirnamelen);
+ strbuf_setlen(&path, path_baselen);
+ }
+ strbuf_release(&refname);
+ strbuf_release(&path);
+ closedir(d);
+
+ add_per_worktree_entries_to_dir(dir, dirname);
+}
+
+static struct ref_cache *get_loose_ref_cache(struct files_ref_store *refs)
+{
+ if (!refs->loose) {
+ /*
+ * Mark the top-level directory complete because we
+ * are about to read the only subdirectory that can
+ * hold references:
+ */
+ refs->loose = create_ref_cache(&refs->base, loose_fill_ref_dir);
+
+ /* We're going to fill the top level ourselves: */
+ refs->loose->root->flag &= ~REF_INCOMPLETE;
+
+ /*
+ * Add an incomplete entry for "refs/" (to be filled
+ * lazily):
+ */
+ add_entry_to_dir(get_ref_dir(refs->loose->root),
+ create_dir_entry(refs->loose, "refs/", 5));
+ }
+ return refs->loose;
+}
+
+static int read_ref_internal(struct ref_store *ref_store, const char *refname,
+ struct object_id *oid, struct strbuf *referent,
+ unsigned int *type, int *failure_errno, int skip_packed_refs)
+{
+ struct files_ref_store *refs =
+ files_downcast(ref_store, REF_STORE_READ, "read_raw_ref");
+ struct strbuf sb_contents = STRBUF_INIT;
+ struct strbuf sb_path = STRBUF_INIT;
+ const char *path;
+ const char *buf;
+ struct stat st;
+ int fd;
+ int ret = -1;
+ int remaining_retries = 3;
+ int myerr = 0;
+
+ *type = 0;
+ strbuf_reset(&sb_path);
+
+ files_ref_path(refs, &sb_path, refname);
+
+ path = sb_path.buf;
+
+stat_ref:
+ /*
+ * We might have to loop back here to avoid a race
+ * condition: first we lstat() the file, then we try
+ * to read it as a link or as a file. But if somebody
+ * changes the type of the file (file <-> directory
+ * <-> symlink) between the lstat() and reading, then
+ * we don't want to report that as an error but rather
+ * try again starting with the lstat().
+ *
+ * We'll keep a count of the retries, though, just to avoid
+ * any confusing situation sending us into an infinite loop.
+ */
+
+ if (remaining_retries-- <= 0)
+ goto out;
+
+ if (lstat(path, &st) < 0) {
+ int ignore_errno;
+ myerr = errno;
+ if (myerr != ENOENT || skip_packed_refs)
+ goto out;
+ if (refs_read_raw_ref(refs->packed_ref_store, refname, oid,
+ referent, type, &ignore_errno)) {
+ myerr = ENOENT;
+ goto out;
+ }
+ ret = 0;
+ goto out;
+ }
+
+ /* Follow "normalized" - ie "refs/.." symlinks by hand */
+ if (S_ISLNK(st.st_mode)) {
+ strbuf_reset(&sb_contents);
+ if (strbuf_readlink(&sb_contents, path, st.st_size) < 0) {
+ myerr = errno;
+ if (myerr == ENOENT || myerr == EINVAL)
+ /* inconsistent with lstat; retry */
+ goto stat_ref;
+ else
+ goto out;
+ }
+ if (starts_with(sb_contents.buf, "refs/") &&
+ !check_refname_format(sb_contents.buf, 0)) {
+ strbuf_swap(&sb_contents, referent);
+ *type |= REF_ISSYMREF;
+ ret = 0;
+ goto out;
+ }
+ /*
+ * It doesn't look like a refname; fall through to just
+ * treating it like a non-symlink, and reading whatever it
+ * points to.
+ */
+ }
+
+ /* Is it a directory? */
+ if (S_ISDIR(st.st_mode)) {
+ int ignore_errno;
+ /*
+ * Even though there is a directory where the loose
+ * ref is supposed to be, there could still be a
+ * packed ref:
+ */
+ if (skip_packed_refs ||
+ refs_read_raw_ref(refs->packed_ref_store, refname, oid,
+ referent, type, &ignore_errno)) {
+ myerr = EISDIR;
+ goto out;
+ }
+ ret = 0;
+ goto out;
+ }
+
+ /*
+ * Anything else, just open it and try to use it as
+ * a ref
+ */
+ fd = open(path, O_RDONLY);
+ if (fd < 0) {
+ myerr = errno;
+ if (myerr == ENOENT && !S_ISLNK(st.st_mode))
+ /* inconsistent with lstat; retry */
+ goto stat_ref;
+ else
+ goto out;
+ }
+ strbuf_reset(&sb_contents);
+ if (strbuf_read(&sb_contents, fd, 256) < 0) {
+ myerr = errno;
+ close(fd);
+ goto out;
+ }
+ close(fd);
+ strbuf_rtrim(&sb_contents);
+ buf = sb_contents.buf;
+
+ ret = parse_loose_ref_contents(buf, oid, referent, type, &myerr);
+
+out:
+ if (ret && !myerr)
+ BUG("returning non-zero %d, should have set myerr!", ret);
+ *failure_errno = myerr;
+
+ strbuf_release(&sb_path);
+ strbuf_release(&sb_contents);
+ errno = 0;
+ return ret;
+}
+
+static int files_read_raw_ref(struct ref_store *ref_store, const char *refname,
+ struct object_id *oid, struct strbuf *referent,
+ unsigned int *type, int *failure_errno)
+{
+ return read_ref_internal(ref_store, refname, oid, referent, type, failure_errno, 0);
+}
+
+static int files_read_symbolic_ref(struct ref_store *ref_store, const char *refname,
+ struct strbuf *referent)
+{
+ struct object_id oid;
+ int failure_errno, ret;
+ unsigned int type;
+
+ ret = read_ref_internal(ref_store, refname, &oid, referent, &type, &failure_errno, 1);
+ if (ret)
+ return ret;
+
+ return !(type & REF_ISSYMREF);
+}
+
+int parse_loose_ref_contents(const char *buf, struct object_id *oid,
+ struct strbuf *referent, unsigned int *type,
+ int *failure_errno)
+{
+ const char *p;
+ if (skip_prefix(buf, "ref:", &buf)) {
+ while (isspace(*buf))
+ buf++;
+
+ strbuf_reset(referent);
+ strbuf_addstr(referent, buf);
+ *type |= REF_ISSYMREF;
+ return 0;
+ }
+
+ /*
+ * FETCH_HEAD has additional data after the sha.
+ */
+ if (parse_oid_hex(buf, oid, &p) ||
+ (*p != '\0' && !isspace(*p))) {
+ *type |= REF_ISBROKEN;
+ *failure_errno = EINVAL;
+ return -1;
+ }
+ return 0;
+}
+
+static void unlock_ref(struct ref_lock *lock)
+{
+ rollback_lock_file(&lock->lk);
+ free(lock->ref_name);
+ free(lock);
+}
+
+/*
+ * Lock refname, without following symrefs, and set *lock_p to point
+ * at a newly-allocated lock object. Fill in lock->old_oid, referent,
+ * and type similarly to read_raw_ref().
+ *
+ * The caller must verify that refname is a "safe" reference name (in
+ * the sense of refname_is_safe()) before calling this function.
+ *
+ * If the reference doesn't already exist, verify that refname doesn't
+ * have a D/F conflict with any existing references. extras and skip
+ * are passed to refs_verify_refname_available() for this check.
+ *
+ * If mustexist is not set and the reference is not found or is
+ * broken, lock the reference anyway but clear old_oid.
+ *
+ * Return 0 on success. On failure, write an error message to err and
+ * return TRANSACTION_NAME_CONFLICT or TRANSACTION_GENERIC_ERROR.
+ *
+ * Implementation note: This function is basically
+ *
+ * lock reference
+ * read_raw_ref()
+ *
+ * but it includes a lot more code to
+ * - Deal with possible races with other processes
+ * - Avoid calling refs_verify_refname_available() when it can be
+ * avoided, namely if we were successfully able to read the ref
+ * - Generate informative error messages in the case of failure
+ */
+static int lock_raw_ref(struct files_ref_store *refs,
+ const char *refname, int mustexist,
+ const struct string_list *extras,
+ struct ref_lock **lock_p,
+ struct strbuf *referent,
+ unsigned int *type,
+ struct strbuf *err)
+{
+ struct ref_lock *lock;
+ struct strbuf ref_file = STRBUF_INIT;
+ int attempts_remaining = 3;
+ int ret = TRANSACTION_GENERIC_ERROR;
+ int failure_errno;
+
+ assert(err);
+ files_assert_main_repository(refs, "lock_raw_ref");
+
+ *type = 0;
+
+ /* First lock the file so it can't change out from under us. */
+
+ *lock_p = CALLOC_ARRAY(lock, 1);
+
+ lock->ref_name = xstrdup(refname);
+ files_ref_path(refs, &ref_file, refname);
+
+retry:
+ switch (safe_create_leading_directories(ref_file.buf)) {
+ case SCLD_OK:
+ break; /* success */
+ case SCLD_EXISTS:
+ /*
+ * Suppose refname is "refs/foo/bar". We just failed
+ * to create the containing directory, "refs/foo",
+ * because there was a non-directory in the way. This
+ * indicates a D/F conflict, probably because of
+ * another reference such as "refs/foo". There is no
+ * reason to expect this error to be transitory.
+ */
+ if (refs_verify_refname_available(&refs->base, refname,
+ extras, NULL, err)) {
+ if (mustexist) {
+ /*
+ * To the user the relevant error is
+ * that the "mustexist" reference is
+ * missing:
+ */
+ strbuf_reset(err);
+ strbuf_addf(err, "unable to resolve reference '%s'",
+ refname);
+ } else {
+ /*
+ * The error message set by
+ * refs_verify_refname_available() is
+ * OK.
+ */
+ ret = TRANSACTION_NAME_CONFLICT;
+ }
+ } else {
+ /*
+ * The file that is in the way isn't a loose
+ * reference. Report it as a low-level
+ * failure.
+ */
+ strbuf_addf(err, "unable to create lock file %s.lock; "
+ "non-directory in the way",
+ ref_file.buf);
+ }
+ goto error_return;
+ case SCLD_VANISHED:
+ /* Maybe another process was tidying up. Try again. */
+ if (--attempts_remaining > 0)
+ goto retry;
+ /* fall through */
+ default:
+ strbuf_addf(err, "unable to create directory for %s",
+ ref_file.buf);
+ goto error_return;
+ }
+
+ if (hold_lock_file_for_update_timeout(
+ &lock->lk, ref_file.buf, LOCK_NO_DEREF,
+ get_files_ref_lock_timeout_ms()) < 0) {
+ int myerr = errno;
+ errno = 0;
+ if (myerr == ENOENT && --attempts_remaining > 0) {
+ /*
+ * Maybe somebody just deleted one of the
+ * directories leading to ref_file. Try
+ * again:
+ */
+ goto retry;
+ } else {
+ unable_to_lock_message(ref_file.buf, myerr, err);
+ goto error_return;
+ }
+ }
+
+ /*
+ * Now we hold the lock and can read the reference without
+ * fear that its value will change.
+ */
+
+ if (files_read_raw_ref(&refs->base, refname, &lock->old_oid, referent,
+ type, &failure_errno)) {
+ if (failure_errno == ENOENT) {
+ if (mustexist) {
+ /* Garden variety missing reference. */
+ strbuf_addf(err, "unable to resolve reference '%s'",
+ refname);
+ goto error_return;
+ } else {
+ /*
+ * Reference is missing, but that's OK. We
+ * know that there is not a conflict with
+ * another loose reference because
+ * (supposing that we are trying to lock
+ * reference "refs/foo/bar"):
+ *
+ * - We were successfully able to create
+ * the lockfile refs/foo/bar.lock, so we
+ * know there cannot be a loose reference
+ * named "refs/foo".
+ *
+ * - We got ENOENT and not EISDIR, so we
+ * know that there cannot be a loose
+ * reference named "refs/foo/bar/baz".
+ */
+ }
+ } else if (failure_errno == EISDIR) {
+ /*
+ * There is a directory in the way. It might have
+ * contained references that have been deleted. If
+ * we don't require that the reference already
+ * exists, try to remove the directory so that it
+ * doesn't cause trouble when we want to rename the
+ * lockfile into place later.
+ */
+ if (mustexist) {
+ /* Garden variety missing reference. */
+ strbuf_addf(err, "unable to resolve reference '%s'",
+ refname);
+ goto error_return;
+ } else if (remove_dir_recursively(&ref_file,
+ REMOVE_DIR_EMPTY_ONLY)) {
+ if (refs_verify_refname_available(
+ &refs->base, refname,
+ extras, NULL, err)) {
+ /*
+ * The error message set by
+ * verify_refname_available() is OK.
+ */
+ ret = TRANSACTION_NAME_CONFLICT;
+ goto error_return;
+ } else {
+ /*
+ * We can't delete the directory,
+ * but we also don't know of any
+ * references that it should
+ * contain.
+ */
+ strbuf_addf(err, "there is a non-empty directory '%s' "
+ "blocking reference '%s'",
+ ref_file.buf, refname);
+ goto error_return;
+ }
+ }
+ } else if (failure_errno == EINVAL && (*type & REF_ISBROKEN)) {
+ strbuf_addf(err, "unable to resolve reference '%s': "
+ "reference broken", refname);
+ goto error_return;
+ } else {
+ strbuf_addf(err, "unable to resolve reference '%s': %s",
+ refname, strerror(failure_errno));
+ goto error_return;
+ }
+
+ /*
+ * If the ref did not exist and we are creating it,
+ * make sure there is no existing packed ref that
+ * conflicts with refname:
+ */
+ if (refs_verify_refname_available(
+ refs->packed_ref_store, refname,
+ extras, NULL, err))
+ goto error_return;
+ }
+
+ ret = 0;
+ goto out;
+
+error_return:
+ unlock_ref(lock);
+ *lock_p = NULL;
+
+out:
+ strbuf_release(&ref_file);
+ return ret;
+}
+
+struct files_ref_iterator {
+ struct ref_iterator base;
+
+ struct ref_iterator *iter0;
+ struct repository *repo;
+ unsigned int flags;
+};
+
+static int files_ref_iterator_advance(struct ref_iterator *ref_iterator)
+{
+ struct files_ref_iterator *iter =
+ (struct files_ref_iterator *)ref_iterator;
+ int ok;
+
+ while ((ok = ref_iterator_advance(iter->iter0)) == ITER_OK) {
+ if (iter->flags & DO_FOR_EACH_PER_WORKTREE_ONLY &&
+ parse_worktree_ref(iter->iter0->refname, NULL, NULL,
+ NULL) != REF_WORKTREE_CURRENT)
+ continue;
+
+ if ((iter->flags & DO_FOR_EACH_OMIT_DANGLING_SYMREFS) &&
+ (iter->iter0->flags & REF_ISSYMREF) &&
+ (iter->iter0->flags & REF_ISBROKEN))
+ continue;
+
+ if (!(iter->flags & DO_FOR_EACH_INCLUDE_BROKEN) &&
+ !ref_resolves_to_object(iter->iter0->refname,
+ iter->repo,
+ iter->iter0->oid,
+ iter->iter0->flags))
+ continue;
+
+ iter->base.refname = iter->iter0->refname;
+ iter->base.oid = iter->iter0->oid;
+ iter->base.flags = iter->iter0->flags;
+ return ITER_OK;
+ }
+
+ iter->iter0 = NULL;
+ if (ref_iterator_abort(ref_iterator) != ITER_DONE)
+ ok = ITER_ERROR;
+
+ return ok;
+}
+
+static int files_ref_iterator_peel(struct ref_iterator *ref_iterator,
+ struct object_id *peeled)
+{
+ struct files_ref_iterator *iter =
+ (struct files_ref_iterator *)ref_iterator;
+
+ return ref_iterator_peel(iter->iter0, peeled);
+}
+
+static int files_ref_iterator_abort(struct ref_iterator *ref_iterator)
+{
+ struct files_ref_iterator *iter =
+ (struct files_ref_iterator *)ref_iterator;
+ int ok = ITER_DONE;
+
+ if (iter->iter0)
+ ok = ref_iterator_abort(iter->iter0);
+
+ base_ref_iterator_free(ref_iterator);
+ return ok;
+}
+
+static struct ref_iterator_vtable files_ref_iterator_vtable = {
+ .advance = files_ref_iterator_advance,
+ .peel = files_ref_iterator_peel,
+ .abort = files_ref_iterator_abort,
+};
+
+static struct ref_iterator *files_ref_iterator_begin(
+ struct ref_store *ref_store,
+ const char *prefix, unsigned int flags)
+{
+ struct files_ref_store *refs;
+ struct ref_iterator *loose_iter, *packed_iter, *overlay_iter;
+ struct files_ref_iterator *iter;
+ struct ref_iterator *ref_iterator;
+ unsigned int required_flags = REF_STORE_READ;
+
+ if (!(flags & DO_FOR_EACH_INCLUDE_BROKEN))
+ required_flags |= REF_STORE_ODB;
+
+ refs = files_downcast(ref_store, required_flags, "ref_iterator_begin");
+
+ /*
+ * We must make sure that all loose refs are read before
+ * accessing the packed-refs file; this avoids a race
+ * condition if loose refs are migrated to the packed-refs
+ * file by a simultaneous process, but our in-memory view is
+ * from before the migration. We ensure this as follows:
+ * First, we call start the loose refs iteration with its
+ * `prime_ref` argument set to true. This causes the loose
+ * references in the subtree to be pre-read into the cache.
+ * (If they've already been read, that's OK; we only need to
+ * guarantee that they're read before the packed refs, not
+ * *how much* before.) After that, we call
+ * packed_ref_iterator_begin(), which internally checks
+ * whether the packed-ref cache is up to date with what is on
+ * disk, and re-reads it if not.
+ */
+
+ loose_iter = cache_ref_iterator_begin(get_loose_ref_cache(refs),
+ prefix, ref_store->repo, 1);
+
+ /*
+ * The packed-refs file might contain broken references, for
+ * example an old version of a reference that points at an
+ * object that has since been garbage-collected. This is OK as
+ * long as there is a corresponding loose reference that
+ * overrides it, and we don't want to emit an error message in
+ * this case. So ask the packed_ref_store for all of its
+ * references, and (if needed) do our own check for broken
+ * ones in files_ref_iterator_advance(), after we have merged
+ * the packed and loose references.
+ */
+ packed_iter = refs_ref_iterator_begin(
+ refs->packed_ref_store, prefix, 0,
+ DO_FOR_EACH_INCLUDE_BROKEN);
+
+ overlay_iter = overlay_ref_iterator_begin(loose_iter, packed_iter);
+
+ CALLOC_ARRAY(iter, 1);
+ ref_iterator = &iter->base;
+ base_ref_iterator_init(ref_iterator, &files_ref_iterator_vtable,
+ overlay_iter->ordered);
+ iter->iter0 = overlay_iter;
+ iter->repo = ref_store->repo;
+ iter->flags = flags;
+
+ return ref_iterator;
+}
+
+/*
+ * Callback function for raceproof_create_file(). This function is
+ * expected to do something that makes dirname(path) permanent despite
+ * the fact that other processes might be cleaning up empty
+ * directories at the same time. Usually it will create a file named
+ * path, but alternatively it could create another file in that
+ * directory, or even chdir() into that directory. The function should
+ * return 0 if the action was completed successfully. On error, it
+ * should return a nonzero result and set errno.
+ * raceproof_create_file() treats two errno values specially:
+ *
+ * - ENOENT -- dirname(path) does not exist. In this case,
+ * raceproof_create_file() tries creating dirname(path)
+ * (and any parent directories, if necessary) and calls
+ * the function again.
+ *
+ * - EISDIR -- the file already exists and is a directory. In this
+ * case, raceproof_create_file() removes the directory if
+ * it is empty (and recursively any empty directories that
+ * it contains) and calls the function again.
+ *
+ * Any other errno causes raceproof_create_file() to fail with the
+ * callback's return value and errno.
+ *
+ * Obviously, this function should be OK with being called again if it
+ * fails with ENOENT or EISDIR. In other scenarios it will not be
+ * called again.
+ */
+typedef int create_file_fn(const char *path, void *cb);
+
+/*
+ * Create a file in dirname(path) by calling fn, creating leading
+ * directories if necessary. Retry a few times in case we are racing
+ * with another process that is trying to clean up the directory that
+ * contains path. See the documentation for create_file_fn for more
+ * details.
+ *
+ * Return the value and set the errno that resulted from the most
+ * recent call of fn. fn is always called at least once, and will be
+ * called more than once if it returns ENOENT or EISDIR.
+ */
+static int raceproof_create_file(const char *path, create_file_fn fn, void *cb)
+{
+ /*
+ * The number of times we will try to remove empty directories
+ * in the way of path. This is only 1 because if another
+ * process is racily creating directories that conflict with
+ * us, we don't want to fight against them.
+ */
+ int remove_directories_remaining = 1;
+
+ /*
+ * The number of times that we will try to create the
+ * directories containing path. We are willing to attempt this
+ * more than once, because another process could be trying to
+ * clean up empty directories at the same time as we are
+ * trying to create them.
+ */
+ int create_directories_remaining = 3;
+
+ /* A scratch copy of path, filled lazily if we need it: */
+ struct strbuf path_copy = STRBUF_INIT;
+
+ int ret, save_errno;
+
+ /* Sanity check: */
+ assert(*path);
+
+retry_fn:
+ ret = fn(path, cb);
+ save_errno = errno;
+ if (!ret)
+ goto out;
+
+ if (errno == EISDIR && remove_directories_remaining-- > 0) {
+ /*
+ * A directory is in the way. Maybe it is empty; try
+ * to remove it:
+ */
+ if (!path_copy.len)
+ strbuf_addstr(&path_copy, path);
+
+ if (!remove_dir_recursively(&path_copy, REMOVE_DIR_EMPTY_ONLY))
+ goto retry_fn;
+ } else if (errno == ENOENT && create_directories_remaining-- > 0) {
+ /*
+ * Maybe the containing directory didn't exist, or
+ * maybe it was just deleted by a process that is
+ * racing with us to clean up empty directories. Try
+ * to create it:
+ */
+ enum scld_error scld_result;
+
+ if (!path_copy.len)
+ strbuf_addstr(&path_copy, path);
+
+ do {
+ scld_result = safe_create_leading_directories(path_copy.buf);
+ if (scld_result == SCLD_OK)
+ goto retry_fn;
+ } while (scld_result == SCLD_VANISHED && create_directories_remaining-- > 0);
+ }
+
+out:
+ strbuf_release(&path_copy);
+ errno = save_errno;
+ return ret;
+}
+
+static int remove_empty_directories(struct strbuf *path)
+{
+ /*
+ * we want to create a file but there is a directory there;
+ * if that is an empty directory (or a directory that contains
+ * only empty directories), remove them.
+ */
+ return remove_dir_recursively(path, REMOVE_DIR_EMPTY_ONLY);
+}
+
+static int create_reflock(const char *path, void *cb)
+{
+ struct lock_file *lk = cb;
+
+ return hold_lock_file_for_update_timeout(
+ lk, path, LOCK_NO_DEREF,
+ get_files_ref_lock_timeout_ms()) < 0 ? -1 : 0;
+}
+
+/*
+ * Locks a ref returning the lock on success and NULL on failure.
+ */
+static struct ref_lock *lock_ref_oid_basic(struct files_ref_store *refs,
+ const char *refname,
+ struct strbuf *err)
+{
+ struct strbuf ref_file = STRBUF_INIT;
+ struct ref_lock *lock;
+
+ files_assert_main_repository(refs, "lock_ref_oid_basic");
+ assert(err);
+
+ CALLOC_ARRAY(lock, 1);
+
+ files_ref_path(refs, &ref_file, refname);
+
+ /*
+ * If the ref did not exist and we are creating it, make sure
+ * there is no existing packed ref whose name begins with our
+ * refname, nor a packed ref whose name is a proper prefix of
+ * our refname.
+ */
+ if (is_null_oid(&lock->old_oid) &&
+ refs_verify_refname_available(refs->packed_ref_store, refname,
+ NULL, NULL, err))
+ goto error_return;
+
+ lock->ref_name = xstrdup(refname);
+
+ if (raceproof_create_file(ref_file.buf, create_reflock, &lock->lk)) {
+ unable_to_lock_message(ref_file.buf, errno, err);
+ goto error_return;
+ }
+
+ if (!refs_resolve_ref_unsafe(&refs->base, lock->ref_name, 0,
+ &lock->old_oid, NULL))
+ oidclr(&lock->old_oid);
+ goto out;
+
+ error_return:
+ unlock_ref(lock);
+ lock = NULL;
+
+ out:
+ strbuf_release(&ref_file);
+ return lock;
+}
+
+struct ref_to_prune {
+ struct ref_to_prune *next;
+ struct object_id oid;
+ char name[FLEX_ARRAY];
+};
+
+enum {
+ REMOVE_EMPTY_PARENTS_REF = 0x01,
+ REMOVE_EMPTY_PARENTS_REFLOG = 0x02
+};
+
+/*
+ * Remove empty parent directories associated with the specified
+ * reference and/or its reflog, but spare [logs/]refs/ and immediate
+ * subdirs. flags is a combination of REMOVE_EMPTY_PARENTS_REF and/or
+ * REMOVE_EMPTY_PARENTS_REFLOG.
+ */
+static void try_remove_empty_parents(struct files_ref_store *refs,
+ const char *refname,
+ unsigned int flags)
+{
+ struct strbuf buf = STRBUF_INIT;
+ struct strbuf sb = STRBUF_INIT;
+ char *p, *q;
+ int i;
+
+ strbuf_addstr(&buf, refname);
+ p = buf.buf;
+ for (i = 0; i < 2; i++) { /* refs/{heads,tags,...}/ */
+ while (*p && *p != '/')
+ p++;
+ /* tolerate duplicate slashes; see check_refname_format() */
+ while (*p == '/')
+ p++;
+ }
+ q = buf.buf + buf.len;
+ while (flags & (REMOVE_EMPTY_PARENTS_REF | REMOVE_EMPTY_PARENTS_REFLOG)) {
+ while (q > p && *q != '/')
+ q--;
+ while (q > p && *(q-1) == '/')
+ q--;
+ if (q == p)
+ break;
+ strbuf_setlen(&buf, q - buf.buf);
+
+ strbuf_reset(&sb);
+ files_ref_path(refs, &sb, buf.buf);
+ if ((flags & REMOVE_EMPTY_PARENTS_REF) && rmdir(sb.buf))
+ flags &= ~REMOVE_EMPTY_PARENTS_REF;
+
+ strbuf_reset(&sb);
+ files_reflog_path(refs, &sb, buf.buf);
+ if ((flags & REMOVE_EMPTY_PARENTS_REFLOG) && rmdir(sb.buf))
+ flags &= ~REMOVE_EMPTY_PARENTS_REFLOG;
+ }
+ strbuf_release(&buf);
+ strbuf_release(&sb);
+}
+
+/* make sure nobody touched the ref, and unlink */
+static void prune_ref(struct files_ref_store *refs, struct ref_to_prune *r)
+{
+ struct ref_transaction *transaction;
+ struct strbuf err = STRBUF_INIT;
+ int ret = -1;
+
+ if (check_refname_format(r->name, 0))
+ return;
+
+ transaction = ref_store_transaction_begin(&refs->base, &err);
+ if (!transaction)
+ goto cleanup;
+ ref_transaction_add_update(
+ transaction, r->name,
+ REF_NO_DEREF | REF_HAVE_NEW | REF_HAVE_OLD | REF_IS_PRUNING,
+ null_oid(), &r->oid, NULL);
+ if (ref_transaction_commit(transaction, &err))
+ goto cleanup;
+
+ ret = 0;
+
+cleanup:
+ if (ret)
+ error("%s", err.buf);
+ strbuf_release(&err);
+ ref_transaction_free(transaction);
+ return;
+}
+
+/*
+ * Prune the loose versions of the references in the linked list
+ * `*refs_to_prune`, freeing the entries in the list as we go.
+ */
+static void prune_refs(struct files_ref_store *refs, struct ref_to_prune **refs_to_prune)
+{
+ while (*refs_to_prune) {
+ struct ref_to_prune *r = *refs_to_prune;
+ *refs_to_prune = r->next;
+ prune_ref(refs, r);
+ free(r);
+ }
+}
+
+/*
+ * Return true if the specified reference should be packed.
+ */
+static int should_pack_ref(const char *refname,
+ const struct object_id *oid, unsigned int ref_flags,
+ unsigned int pack_flags)
+{
+ /* Do not pack per-worktree refs: */
+ if (parse_worktree_ref(refname, NULL, NULL, NULL) !=
+ REF_WORKTREE_SHARED)
+ return 0;
+
+ /* Do not pack non-tags unless PACK_REFS_ALL is set: */
+ if (!(pack_flags & PACK_REFS_ALL) && !starts_with(refname, "refs/tags/"))
+ return 0;
+
+ /* Do not pack symbolic refs: */
+ if (ref_flags & REF_ISSYMREF)
+ return 0;
+
+ /* Do not pack broken refs: */
+ if (!ref_resolves_to_object(refname, the_repository, oid, ref_flags))
+ return 0;
+
+ return 1;
+}
+
+static int files_pack_refs(struct ref_store *ref_store, unsigned int flags)
+{
+ struct files_ref_store *refs =
+ files_downcast(ref_store, REF_STORE_WRITE | REF_STORE_ODB,
+ "pack_refs");
+ struct ref_iterator *iter;
+ int ok;
+ struct ref_to_prune *refs_to_prune = NULL;
+ struct strbuf err = STRBUF_INIT;
+ struct ref_transaction *transaction;
+
+ transaction = ref_store_transaction_begin(refs->packed_ref_store, &err);
+ if (!transaction)
+ return -1;
+
+ packed_refs_lock(refs->packed_ref_store, LOCK_DIE_ON_ERROR, &err);
+
+ iter = cache_ref_iterator_begin(get_loose_ref_cache(refs), NULL,
+ the_repository, 0);
+ while ((ok = ref_iterator_advance(iter)) == ITER_OK) {
+ /*
+ * If the loose reference can be packed, add an entry
+ * in the packed ref cache. If the reference should be
+ * pruned, also add it to refs_to_prune.
+ */
+ if (!should_pack_ref(iter->refname, iter->oid, iter->flags,
+ flags))
+ continue;
+
+ /*
+ * Add a reference creation for this reference to the
+ * packed-refs transaction:
+ */
+ if (ref_transaction_update(transaction, iter->refname,
+ iter->oid, NULL,
+ REF_NO_DEREF, NULL, &err))
+ die("failure preparing to create packed reference %s: %s",
+ iter->refname, err.buf);
+
+ /* Schedule the loose reference for pruning if requested. */
+ if ((flags & PACK_REFS_PRUNE)) {
+ struct ref_to_prune *n;
+ FLEX_ALLOC_STR(n, name, iter->refname);
+ oidcpy(&n->oid, iter->oid);
+ n->next = refs_to_prune;
+ refs_to_prune = n;
+ }
+ }
+ if (ok != ITER_DONE)
+ die("error while iterating over references");
+
+ if (ref_transaction_commit(transaction, &err))
+ die("unable to write new packed-refs: %s", err.buf);
+
+ ref_transaction_free(transaction);
+
+ packed_refs_unlock(refs->packed_ref_store);
+
+ prune_refs(refs, &refs_to_prune);
+ strbuf_release(&err);
+ return 0;
+}
+
+static int files_delete_refs(struct ref_store *ref_store, const char *msg,
+ struct string_list *refnames, unsigned int flags)
+{
+ struct files_ref_store *refs =
+ files_downcast(ref_store, REF_STORE_WRITE, "delete_refs");
+ struct strbuf err = STRBUF_INIT;
+ int i, result = 0;
+
+ if (!refnames->nr)
+ return 0;
+
+ if (packed_refs_lock(refs->packed_ref_store, 0, &err))
+ goto error;
+
+ if (refs_delete_refs(refs->packed_ref_store, msg, refnames, flags)) {
+ packed_refs_unlock(refs->packed_ref_store);
+ goto error;
+ }
+
+ packed_refs_unlock(refs->packed_ref_store);
+
+ for (i = 0; i < refnames->nr; i++) {
+ const char *refname = refnames->items[i].string;
+
+ if (refs_delete_ref(&refs->base, msg, refname, NULL, flags))
+ result |= error(_("could not remove reference %s"), refname);
+ }
+
+ strbuf_release(&err);
+ return result;
+
+error:
+ /*
+ * If we failed to rewrite the packed-refs file, then it is
+ * unsafe to try to remove loose refs, because doing so might
+ * expose an obsolete packed value for a reference that might
+ * even point at an object that has been garbage collected.
+ */
+ if (refnames->nr == 1)
+ error(_("could not delete reference %s: %s"),
+ refnames->items[0].string, err.buf);
+ else
+ error(_("could not delete references: %s"), err.buf);
+
+ strbuf_release(&err);
+ return -1;
+}
+
+/*
+ * People using contrib's git-new-workdir have .git/logs/refs ->
+ * /some/other/path/.git/logs/refs, and that may live on another device.
+ *
+ * IOW, to avoid cross device rename errors, the temporary renamed log must
+ * live into logs/refs.
+ */
+#define TMP_RENAMED_LOG "refs/.tmp-renamed-log"
+
+struct rename_cb {
+ const char *tmp_renamed_log;
+ int true_errno;
+};
+
+static int rename_tmp_log_callback(const char *path, void *cb_data)
+{
+ struct rename_cb *cb = cb_data;
+
+ if (rename(cb->tmp_renamed_log, path)) {
+ /*
+ * rename(a, b) when b is an existing directory ought
+ * to result in ISDIR, but Solaris 5.8 gives ENOTDIR.
+ * Sheesh. Record the true errno for error reporting,
+ * but report EISDIR to raceproof_create_file() so
+ * that it knows to retry.
+ */
+ cb->true_errno = errno;
+ if (errno == ENOTDIR)
+ errno = EISDIR;
+ return -1;
+ } else {
+ return 0;
+ }
+}
+
+static int rename_tmp_log(struct files_ref_store *refs, const char *newrefname)
+{
+ struct strbuf path = STRBUF_INIT;
+ struct strbuf tmp = STRBUF_INIT;
+ struct rename_cb cb;
+ int ret;
+
+ files_reflog_path(refs, &path, newrefname);
+ files_reflog_path(refs, &tmp, TMP_RENAMED_LOG);
+ cb.tmp_renamed_log = tmp.buf;
+ ret = raceproof_create_file(path.buf, rename_tmp_log_callback, &cb);
+ if (ret) {
+ if (errno == EISDIR)
+ error("directory not empty: %s", path.buf);
+ else
+ error("unable to move logfile %s to %s: %s",
+ tmp.buf, path.buf,
+ strerror(cb.true_errno));
+ }
+
+ strbuf_release(&path);
+ strbuf_release(&tmp);
+ return ret;
+}
+
+static int write_ref_to_lockfile(struct ref_lock *lock,
+ const struct object_id *oid,
+ int skip_oid_verification, struct strbuf *err);
+static int commit_ref_update(struct files_ref_store *refs,
+ struct ref_lock *lock,
+ const struct object_id *oid, const char *logmsg,
+ struct strbuf *err);
+
+/*
+ * Emit a better error message than lockfile.c's
+ * unable_to_lock_message() would in case there is a D/F conflict with
+ * another existing reference. If there would be a conflict, emit an error
+ * message and return false; otherwise, return true.
+ *
+ * Note that this function is not safe against all races with other
+ * processes, and that's not its job. We'll emit a more verbose error on D/f
+ * conflicts if we get past it into lock_ref_oid_basic().
+ */
+static int refs_rename_ref_available(struct ref_store *refs,
+ const char *old_refname,
+ const char *new_refname)
+{
+ struct string_list skip = STRING_LIST_INIT_NODUP;
+ struct strbuf err = STRBUF_INIT;
+ int ok;
+
+ string_list_insert(&skip, old_refname);
+ ok = !refs_verify_refname_available(refs, new_refname,
+ NULL, &skip, &err);
+ if (!ok)
+ error("%s", err.buf);
+
+ string_list_clear(&skip, 0);
+ strbuf_release(&err);
+ return ok;
+}
+
+static int files_copy_or_rename_ref(struct ref_store *ref_store,
+ const char *oldrefname, const char *newrefname,
+ const char *logmsg, int copy)
+{
+ struct files_ref_store *refs =
+ files_downcast(ref_store, REF_STORE_WRITE, "rename_ref");
+ struct object_id orig_oid;
+ int flag = 0, logmoved = 0;
+ struct ref_lock *lock;
+ struct stat loginfo;
+ struct strbuf sb_oldref = STRBUF_INIT;
+ struct strbuf sb_newref = STRBUF_INIT;
+ struct strbuf tmp_renamed_log = STRBUF_INIT;
+ int log, ret;
+ struct strbuf err = STRBUF_INIT;
+
+ files_reflog_path(refs, &sb_oldref, oldrefname);
+ files_reflog_path(refs, &sb_newref, newrefname);
+ files_reflog_path(refs, &tmp_renamed_log, TMP_RENAMED_LOG);
+
+ log = !lstat(sb_oldref.buf, &loginfo);
+ if (log && S_ISLNK(loginfo.st_mode)) {
+ ret = error("reflog for %s is a symlink", oldrefname);
+ goto out;
+ }
+
+ if (!refs_resolve_ref_unsafe(&refs->base, oldrefname,
+ RESOLVE_REF_READING | RESOLVE_REF_NO_RECURSE,
+ &orig_oid, &flag)) {
+ ret = error("refname %s not found", oldrefname);
+ goto out;
+ }
+
+ if (flag & REF_ISSYMREF) {
+ if (copy)
+ ret = error("refname %s is a symbolic ref, copying it is not supported",
+ oldrefname);
+ else
+ ret = error("refname %s is a symbolic ref, renaming it is not supported",
+ oldrefname);
+ goto out;
+ }
+ if (!refs_rename_ref_available(&refs->base, oldrefname, newrefname)) {
+ ret = 1;
+ goto out;
+ }
+
+ if (!copy && log && rename(sb_oldref.buf, tmp_renamed_log.buf)) {
+ ret = error("unable to move logfile logs/%s to logs/"TMP_RENAMED_LOG": %s",
+ oldrefname, strerror(errno));
+ goto out;
+ }
+
+ if (copy && log && copy_file(tmp_renamed_log.buf, sb_oldref.buf, 0644)) {
+ ret = error("unable to copy logfile logs/%s to logs/"TMP_RENAMED_LOG": %s",
+ oldrefname, strerror(errno));
+ goto out;
+ }
+
+ if (!copy && refs_delete_ref(&refs->base, logmsg, oldrefname,
+ &orig_oid, REF_NO_DEREF)) {
+ error("unable to delete old %s", oldrefname);
+ goto rollback;
+ }
+
+ /*
+ * Since we are doing a shallow lookup, oid is not the
+ * correct value to pass to delete_ref as old_oid. But that
+ * doesn't matter, because an old_oid check wouldn't add to
+ * the safety anyway; we want to delete the reference whatever
+ * its current value.
+ */
+ if (!copy && refs_resolve_ref_unsafe(&refs->base, newrefname,
+ RESOLVE_REF_READING | RESOLVE_REF_NO_RECURSE,
+ NULL, NULL) &&
+ refs_delete_ref(&refs->base, NULL, newrefname,
+ NULL, REF_NO_DEREF)) {
+ if (errno == EISDIR) {
+ struct strbuf path = STRBUF_INIT;
+ int result;
+
+ files_ref_path(refs, &path, newrefname);
+ result = remove_empty_directories(&path);
+ strbuf_release(&path);
+
+ if (result) {
+ error("Directory not empty: %s", newrefname);
+ goto rollback;
+ }
+ } else {
+ error("unable to delete existing %s", newrefname);
+ goto rollback;
+ }
+ }
+
+ if (log && rename_tmp_log(refs, newrefname))
+ goto rollback;
+
+ logmoved = log;
+
+ lock = lock_ref_oid_basic(refs, newrefname, &err);
+ if (!lock) {
+ if (copy)
+ error("unable to copy '%s' to '%s': %s", oldrefname, newrefname, err.buf);
+ else
+ error("unable to rename '%s' to '%s': %s", oldrefname, newrefname, err.buf);
+ strbuf_release(&err);
+ goto rollback;
+ }
+ oidcpy(&lock->old_oid, &orig_oid);
+
+ if (write_ref_to_lockfile(lock, &orig_oid, 0, &err) ||
+ commit_ref_update(refs, lock, &orig_oid, logmsg, &err)) {
+ error("unable to write current sha1 into %s: %s", newrefname, err.buf);
+ strbuf_release(&err);
+ goto rollback;
+ }
+
+ ret = 0;
+ goto out;
+
+ rollback:
+ lock = lock_ref_oid_basic(refs, oldrefname, &err);
+ if (!lock) {
+ error("unable to lock %s for rollback: %s", oldrefname, err.buf);
+ strbuf_release(&err);
+ goto rollbacklog;
+ }
+
+ flag = log_all_ref_updates;
+ log_all_ref_updates = LOG_REFS_NONE;
+ if (write_ref_to_lockfile(lock, &orig_oid, 0, &err) ||
+ commit_ref_update(refs, lock, &orig_oid, NULL, &err)) {
+ error("unable to write current sha1 into %s: %s", oldrefname, err.buf);
+ strbuf_release(&err);
+ }
+ log_all_ref_updates = flag;
+
+ rollbacklog:
+ if (logmoved && rename(sb_newref.buf, sb_oldref.buf))
+ error("unable to restore logfile %s from %s: %s",
+ oldrefname, newrefname, strerror(errno));
+ if (!logmoved && log &&
+ rename(tmp_renamed_log.buf, sb_oldref.buf))
+ error("unable to restore logfile %s from logs/"TMP_RENAMED_LOG": %s",
+ oldrefname, strerror(errno));
+ ret = 1;
+ out:
+ strbuf_release(&sb_newref);
+ strbuf_release(&sb_oldref);
+ strbuf_release(&tmp_renamed_log);
+
+ return ret;
+}
+
+static int files_rename_ref(struct ref_store *ref_store,
+ const char *oldrefname, const char *newrefname,
+ const char *logmsg)
+{
+ return files_copy_or_rename_ref(ref_store, oldrefname,
+ newrefname, logmsg, 0);
+}
+
+static int files_copy_ref(struct ref_store *ref_store,
+ const char *oldrefname, const char *newrefname,
+ const char *logmsg)
+{
+ return files_copy_or_rename_ref(ref_store, oldrefname,
+ newrefname, logmsg, 1);
+}
+
+static int close_ref_gently(struct ref_lock *lock)
+{
+ if (close_lock_file_gently(&lock->lk))
+ return -1;
+ return 0;
+}
+
+static int commit_ref(struct ref_lock *lock)
+{
+ char *path = get_locked_file_path(&lock->lk);
+ struct stat st;
+
+ if (!lstat(path, &st) && S_ISDIR(st.st_mode)) {
+ /*
+ * There is a directory at the path we want to rename
+ * the lockfile to. Hopefully it is empty; try to
+ * delete it.
+ */
+ size_t len = strlen(path);
+ struct strbuf sb_path = STRBUF_INIT;
+
+ strbuf_attach(&sb_path, path, len, len);
+
+ /*
+ * If this fails, commit_lock_file() will also fail
+ * and will report the problem.
+ */
+ remove_empty_directories(&sb_path);
+ strbuf_release(&sb_path);
+ } else {
+ free(path);
+ }
+
+ if (commit_lock_file(&lock->lk))
+ return -1;
+ return 0;
+}
+
+static int open_or_create_logfile(const char *path, void *cb)
+{
+ int *fd = cb;
+
+ *fd = open(path, O_APPEND | O_WRONLY | O_CREAT, 0666);
+ return (*fd < 0) ? -1 : 0;
+}
+
+/*
+ * Create a reflog for a ref. If force_create = 0, only create the
+ * reflog for certain refs (those for which should_autocreate_reflog
+ * returns non-zero). Otherwise, create it regardless of the reference
+ * name. If the logfile already existed or was created, return 0 and
+ * set *logfd to the file descriptor opened for appending to the file.
+ * If no logfile exists and we decided not to create one, return 0 and
+ * set *logfd to -1. On failure, fill in *err, set *logfd to -1, and
+ * return -1.
+ */
+static int log_ref_setup(struct files_ref_store *refs,
+ const char *refname, int force_create,
+ int *logfd, struct strbuf *err)
+{
+ struct strbuf logfile_sb = STRBUF_INIT;
+ char *logfile;
+
+ files_reflog_path(refs, &logfile_sb, refname);
+ logfile = strbuf_detach(&logfile_sb, NULL);
+
+ if (force_create || should_autocreate_reflog(refname)) {
+ if (raceproof_create_file(logfile, open_or_create_logfile, logfd)) {
+ if (errno == ENOENT)
+ strbuf_addf(err, "unable to create directory for '%s': "
+ "%s", logfile, strerror(errno));
+ else if (errno == EISDIR)
+ strbuf_addf(err, "there are still logs under '%s'",
+ logfile);
+ else
+ strbuf_addf(err, "unable to append to '%s': %s",
+ logfile, strerror(errno));
+
+ goto error;
+ }
+ } else {
+ *logfd = open(logfile, O_APPEND | O_WRONLY);
+ if (*logfd < 0) {
+ if (errno == ENOENT || errno == EISDIR) {
+ /*
+ * The logfile doesn't already exist,
+ * but that is not an error; it only
+ * means that we won't write log
+ * entries to it.
+ */
+ ;
+ } else {
+ strbuf_addf(err, "unable to append to '%s': %s",
+ logfile, strerror(errno));
+ goto error;
+ }
+ }
+ }
+
+ if (*logfd >= 0)
+ adjust_shared_perm(logfile);
+
+ free(logfile);
+ return 0;
+
+error:
+ free(logfile);
+ return -1;
+}
+
+static int files_create_reflog(struct ref_store *ref_store, const char *refname,
+ struct strbuf *err)
+{
+ struct files_ref_store *refs =
+ files_downcast(ref_store, REF_STORE_WRITE, "create_reflog");
+ int fd;
+
+ if (log_ref_setup(refs, refname, 1, &fd, err))
+ return -1;
+
+ if (fd >= 0)
+ close(fd);
+
+ return 0;
+}
+
+static int log_ref_write_fd(int fd, const struct object_id *old_oid,
+ const struct object_id *new_oid,
+ const char *committer, const char *msg)
+{
+ struct strbuf sb = STRBUF_INIT;
+ int ret = 0;
+
+ strbuf_addf(&sb, "%s %s %s", oid_to_hex(old_oid), oid_to_hex(new_oid), committer);
+ if (msg && *msg) {
+ strbuf_addch(&sb, '\t');
+ strbuf_addstr(&sb, msg);
+ }
+ strbuf_addch(&sb, '\n');
+ if (write_in_full(fd, sb.buf, sb.len) < 0)
+ ret = -1;
+ strbuf_release(&sb);
+ return ret;
+}
+
+static int files_log_ref_write(struct files_ref_store *refs,
+ const char *refname, const struct object_id *old_oid,
+ const struct object_id *new_oid, const char *msg,
+ int flags, struct strbuf *err)
+{
+ int logfd, result;
+
+ if (log_all_ref_updates == LOG_REFS_UNSET)
+ log_all_ref_updates = is_bare_repository() ? LOG_REFS_NONE : LOG_REFS_NORMAL;
+
+ result = log_ref_setup(refs, refname,
+ flags & REF_FORCE_CREATE_REFLOG,
+ &logfd, err);
+
+ if (result)
+ return result;
+
+ if (logfd < 0)
+ return 0;
+ result = log_ref_write_fd(logfd, old_oid, new_oid,
+ git_committer_info(0), msg);
+ if (result) {
+ struct strbuf sb = STRBUF_INIT;
+ int save_errno = errno;
+
+ files_reflog_path(refs, &sb, refname);
+ strbuf_addf(err, "unable to append to '%s': %s",
+ sb.buf, strerror(save_errno));
+ strbuf_release(&sb);
+ close(logfd);
+ return -1;
+ }
+ if (close(logfd)) {
+ struct strbuf sb = STRBUF_INIT;
+ int save_errno = errno;
+
+ files_reflog_path(refs, &sb, refname);
+ strbuf_addf(err, "unable to append to '%s': %s",
+ sb.buf, strerror(save_errno));
+ strbuf_release(&sb);
+ return -1;
+ }
+ return 0;
+}
+
+/*
+ * Write oid into the open lockfile, then close the lockfile. On
+ * errors, rollback the lockfile, fill in *err and return -1.
+ */
+static int write_ref_to_lockfile(struct ref_lock *lock,
+ const struct object_id *oid,
+ int skip_oid_verification, struct strbuf *err)
+{
+ static char term = '\n';
+ struct object *o;
+ int fd;
+
+ if (!skip_oid_verification) {
+ o = parse_object(the_repository, oid);
+ if (!o) {
+ strbuf_addf(
+ err,
+ "trying to write ref '%s' with nonexistent object %s",
+ lock->ref_name, oid_to_hex(oid));
+ unlock_ref(lock);
+ return -1;
+ }
+ if (o->type != OBJ_COMMIT && is_branch(lock->ref_name)) {
+ strbuf_addf(
+ err,
+ "trying to write non-commit object %s to branch '%s'",
+ oid_to_hex(oid), lock->ref_name);
+ unlock_ref(lock);
+ return -1;
+ }
+ }
+ fd = get_lock_file_fd(&lock->lk);
+ if (write_in_full(fd, oid_to_hex(oid), the_hash_algo->hexsz) < 0 ||
+ write_in_full(fd, &term, 1) < 0 ||
+ fsync_component(FSYNC_COMPONENT_REFERENCE, get_lock_file_fd(&lock->lk)) < 0 ||
+ close_ref_gently(lock) < 0) {
+ strbuf_addf(err,
+ "couldn't write '%s'", get_lock_file_path(&lock->lk));
+ unlock_ref(lock);
+ return -1;
+ }
+ return 0;
+}
+
+/*
+ * Commit a change to a loose reference that has already been written
+ * to the loose reference lockfile. Also update the reflogs if
+ * necessary, using the specified lockmsg (which can be NULL).
+ */
+static int commit_ref_update(struct files_ref_store *refs,
+ struct ref_lock *lock,
+ const struct object_id *oid, const char *logmsg,
+ struct strbuf *err)
+{
+ files_assert_main_repository(refs, "commit_ref_update");
+
+ clear_loose_ref_cache(refs);
+ if (files_log_ref_write(refs, lock->ref_name,
+ &lock->old_oid, oid,
+ logmsg, 0, err)) {
+ char *old_msg = strbuf_detach(err, NULL);
+ strbuf_addf(err, "cannot update the ref '%s': %s",
+ lock->ref_name, old_msg);
+ free(old_msg);
+ unlock_ref(lock);
+ return -1;
+ }
+
+ if (strcmp(lock->ref_name, "HEAD") != 0) {
+ /*
+ * Special hack: If a branch is updated directly and HEAD
+ * points to it (may happen on the remote side of a push
+ * for example) then logically the HEAD reflog should be
+ * updated too.
+ * A generic solution implies reverse symref information,
+ * but finding all symrefs pointing to the given branch
+ * would be rather costly for this rare event (the direct
+ * update of a branch) to be worth it. So let's cheat and
+ * check with HEAD only which should cover 99% of all usage
+ * scenarios (even 100% of the default ones).
+ */
+ int head_flag;
+ const char *head_ref;
+
+ head_ref = refs_resolve_ref_unsafe(&refs->base, "HEAD",
+ RESOLVE_REF_READING,
+ NULL, &head_flag);
+ if (head_ref && (head_flag & REF_ISSYMREF) &&
+ !strcmp(head_ref, lock->ref_name)) {
+ struct strbuf log_err = STRBUF_INIT;
+ if (files_log_ref_write(refs, "HEAD",
+ &lock->old_oid, oid,
+ logmsg, 0, &log_err)) {
+ error("%s", log_err.buf);
+ strbuf_release(&log_err);
+ }
+ }
+ }
+
+ if (commit_ref(lock)) {
+ strbuf_addf(err, "couldn't set '%s'", lock->ref_name);
+ unlock_ref(lock);
+ return -1;
+ }
+
+ unlock_ref(lock);
+ return 0;
+}
+
+static int create_ref_symlink(struct ref_lock *lock, const char *target)
+{
+ int ret = -1;
+#ifndef NO_SYMLINK_HEAD
+ char *ref_path = get_locked_file_path(&lock->lk);
+ unlink(ref_path);
+ ret = symlink(target, ref_path);
+ free(ref_path);
+
+ if (ret)
+ fprintf(stderr, "no symlink - falling back to symbolic ref\n");
+#endif
+ return ret;
+}
+
+static void update_symref_reflog(struct files_ref_store *refs,
+ struct ref_lock *lock, const char *refname,
+ const char *target, const char *logmsg)
+{
+ struct strbuf err = STRBUF_INIT;
+ struct object_id new_oid;
+
+ if (logmsg &&
+ refs_resolve_ref_unsafe(&refs->base, target,
+ RESOLVE_REF_READING, &new_oid, NULL) &&
+ files_log_ref_write(refs, refname, &lock->old_oid,
+ &new_oid, logmsg, 0, &err)) {
+ error("%s", err.buf);
+ strbuf_release(&err);
+ }
+}
+
+static int create_symref_locked(struct files_ref_store *refs,
+ struct ref_lock *lock, const char *refname,
+ const char *target, const char *logmsg)
+{
+ if (prefer_symlink_refs && !create_ref_symlink(lock, target)) {
+ update_symref_reflog(refs, lock, refname, target, logmsg);
+ return 0;
+ }
+
+ if (!fdopen_lock_file(&lock->lk, "w"))
+ return error("unable to fdopen %s: %s",
+ get_lock_file_path(&lock->lk), strerror(errno));
+
+ update_symref_reflog(refs, lock, refname, target, logmsg);
+
+ /* no error check; commit_ref will check ferror */
+ fprintf(get_lock_file_fp(&lock->lk), "ref: %s\n", target);
+ if (commit_ref(lock) < 0)
+ return error("unable to write symref for %s: %s", refname,
+ strerror(errno));
+ return 0;
+}
+
+static int files_create_symref(struct ref_store *ref_store,
+ const char *refname, const char *target,
+ const char *logmsg)
+{
+ struct files_ref_store *refs =
+ files_downcast(ref_store, REF_STORE_WRITE, "create_symref");
+ struct strbuf err = STRBUF_INIT;
+ struct ref_lock *lock;
+ int ret;
+
+ lock = lock_ref_oid_basic(refs, refname, &err);
+ if (!lock) {
+ error("%s", err.buf);
+ strbuf_release(&err);
+ return -1;
+ }
+
+ ret = create_symref_locked(refs, lock, refname, target, logmsg);
+ unlock_ref(lock);
+ return ret;
+}
+
+static int files_reflog_exists(struct ref_store *ref_store,
+ const char *refname)
+{
+ struct files_ref_store *refs =
+ files_downcast(ref_store, REF_STORE_READ, "reflog_exists");
+ struct strbuf sb = STRBUF_INIT;
+ struct stat st;
+ int ret;
+
+ files_reflog_path(refs, &sb, refname);
+ ret = !lstat(sb.buf, &st) && S_ISREG(st.st_mode);
+ strbuf_release(&sb);
+ return ret;
+}
+
+static int files_delete_reflog(struct ref_store *ref_store,
+ const char *refname)
+{
+ struct files_ref_store *refs =
+ files_downcast(ref_store, REF_STORE_WRITE, "delete_reflog");
+ struct strbuf sb = STRBUF_INIT;
+ int ret;
+
+ files_reflog_path(refs, &sb, refname);
+ ret = remove_path(sb.buf);
+ strbuf_release(&sb);
+ return ret;
+}
+
+static int show_one_reflog_ent(struct strbuf *sb, each_reflog_ent_fn fn, void *cb_data)
+{
+ struct object_id ooid, noid;
+ char *email_end, *message;
+ timestamp_t timestamp;
+ int tz;
+ const char *p = sb->buf;
+
+ /* old SP new SP name <email> SP time TAB msg LF */
+ if (!sb->len || sb->buf[sb->len - 1] != '\n' ||
+ parse_oid_hex(p, &ooid, &p) || *p++ != ' ' ||
+ parse_oid_hex(p, &noid, &p) || *p++ != ' ' ||
+ !(email_end = strchr(p, '>')) ||
+ email_end[1] != ' ' ||
+ !(timestamp = parse_timestamp(email_end + 2, &message, 10)) ||
+ !message || message[0] != ' ' ||
+ (message[1] != '+' && message[1] != '-') ||
+ !isdigit(message[2]) || !isdigit(message[3]) ||
+ !isdigit(message[4]) || !isdigit(message[5]))
+ return 0; /* corrupt? */
+ email_end[1] = '\0';
+ tz = strtol(message + 1, NULL, 10);
+ if (message[6] != '\t')
+ message += 6;
+ else
+ message += 7;
+ return fn(&ooid, &noid, p, timestamp, tz, message, cb_data);
+}
+
+static char *find_beginning_of_line(char *bob, char *scan)
+{
+ while (bob < scan && *(--scan) != '\n')
+ ; /* keep scanning backwards */
+ /*
+ * Return either beginning of the buffer, or LF at the end of
+ * the previous line.
+ */
+ return scan;
+}
+
+static int files_for_each_reflog_ent_reverse(struct ref_store *ref_store,
+ const char *refname,
+ each_reflog_ent_fn fn,
+ void *cb_data)
+{
+ struct files_ref_store *refs =
+ files_downcast(ref_store, REF_STORE_READ,
+ "for_each_reflog_ent_reverse");
+ struct strbuf sb = STRBUF_INIT;
+ FILE *logfp;
+ long pos;
+ int ret = 0, at_tail = 1;
+
+ files_reflog_path(refs, &sb, refname);
+ logfp = fopen(sb.buf, "r");
+ strbuf_release(&sb);
+ if (!logfp)
+ return -1;
+
+ /* Jump to the end */
+ if (fseek(logfp, 0, SEEK_END) < 0)
+ ret = error("cannot seek back reflog for %s: %s",
+ refname, strerror(errno));
+ pos = ftell(logfp);
+ while (!ret && 0 < pos) {
+ int cnt;
+ size_t nread;
+ char buf[BUFSIZ];
+ char *endp, *scanp;
+
+ /* Fill next block from the end */
+ cnt = (sizeof(buf) < pos) ? sizeof(buf) : pos;
+ if (fseek(logfp, pos - cnt, SEEK_SET)) {
+ ret = error("cannot seek back reflog for %s: %s",
+ refname, strerror(errno));
+ break;
+ }
+ nread = fread(buf, cnt, 1, logfp);
+ if (nread != 1) {
+ ret = error("cannot read %d bytes from reflog for %s: %s",
+ cnt, refname, strerror(errno));
+ break;
+ }
+ pos -= cnt;
+
+ scanp = endp = buf + cnt;
+ if (at_tail && scanp[-1] == '\n')
+ /* Looking at the final LF at the end of the file */
+ scanp--;
+ at_tail = 0;
+
+ while (buf < scanp) {
+ /*
+ * terminating LF of the previous line, or the beginning
+ * of the buffer.
+ */
+ char *bp;
+
+ bp = find_beginning_of_line(buf, scanp);
+
+ if (*bp == '\n') {
+ /*
+ * The newline is the end of the previous line,
+ * so we know we have complete line starting
+ * at (bp + 1). Prefix it onto any prior data
+ * we collected for the line and process it.
+ */
+ strbuf_splice(&sb, 0, 0, bp + 1, endp - (bp + 1));
+ scanp = bp;
+ endp = bp + 1;
+ ret = show_one_reflog_ent(&sb, fn, cb_data);
+ strbuf_reset(&sb);
+ if (ret)
+ break;
+ } else if (!pos) {
+ /*
+ * We are at the start of the buffer, and the
+ * start of the file; there is no previous
+ * line, and we have everything for this one.
+ * Process it, and we can end the loop.
+ */
+ strbuf_splice(&sb, 0, 0, buf, endp - buf);
+ ret = show_one_reflog_ent(&sb, fn, cb_data);
+ strbuf_reset(&sb);
+ break;
+ }
+
+ if (bp == buf) {
+ /*
+ * We are at the start of the buffer, and there
+ * is more file to read backwards. Which means
+ * we are in the middle of a line. Note that we
+ * may get here even if *bp was a newline; that
+ * just means we are at the exact end of the
+ * previous line, rather than some spot in the
+ * middle.
+ *
+ * Save away what we have to be combined with
+ * the data from the next read.
+ */
+ strbuf_splice(&sb, 0, 0, buf, endp - buf);
+ break;
+ }
+ }
+
+ }
+ if (!ret && sb.len)
+ BUG("reverse reflog parser had leftover data");
+
+ fclose(logfp);
+ strbuf_release(&sb);
+ return ret;
+}
+
+static int files_for_each_reflog_ent(struct ref_store *ref_store,
+ const char *refname,
+ each_reflog_ent_fn fn, void *cb_data)
+{
+ struct files_ref_store *refs =
+ files_downcast(ref_store, REF_STORE_READ,
+ "for_each_reflog_ent");
+ FILE *logfp;
+ struct strbuf sb = STRBUF_INIT;
+ int ret = 0;
+
+ files_reflog_path(refs, &sb, refname);
+ logfp = fopen(sb.buf, "r");
+ strbuf_release(&sb);
+ if (!logfp)
+ return -1;
+
+ while (!ret && !strbuf_getwholeline(&sb, logfp, '\n'))
+ ret = show_one_reflog_ent(&sb, fn, cb_data);
+ fclose(logfp);
+ strbuf_release(&sb);
+ return ret;
+}
+
+struct files_reflog_iterator {
+ struct ref_iterator base;
+
+ struct ref_store *ref_store;
+ struct dir_iterator *dir_iterator;
+ struct object_id oid;
+};
+
+static int files_reflog_iterator_advance(struct ref_iterator *ref_iterator)
+{
+ struct files_reflog_iterator *iter =
+ (struct files_reflog_iterator *)ref_iterator;
+ struct dir_iterator *diter = iter->dir_iterator;
+ int ok;
+
+ while ((ok = dir_iterator_advance(diter)) == ITER_OK) {
+ int flags;
+
+ if (!S_ISREG(diter->st.st_mode))
+ continue;
+ if (diter->basename[0] == '.')
+ continue;
+ if (ends_with(diter->basename, ".lock"))
+ continue;
+
+ if (!refs_resolve_ref_unsafe(iter->ref_store,
+ diter->relative_path, 0,
+ &iter->oid, &flags)) {
+ error("bad ref for %s", diter->path.buf);
+ continue;
+ }
+
+ iter->base.refname = diter->relative_path;
+ iter->base.oid = &iter->oid;
+ iter->base.flags = flags;
+ return ITER_OK;
+ }
+
+ iter->dir_iterator = NULL;
+ if (ref_iterator_abort(ref_iterator) == ITER_ERROR)
+ ok = ITER_ERROR;
+ return ok;
+}
+
+static int files_reflog_iterator_peel(struct ref_iterator *ref_iterator UNUSED,
+ struct object_id *peeled UNUSED)
+{
+ BUG("ref_iterator_peel() called for reflog_iterator");
+}
+
+static int files_reflog_iterator_abort(struct ref_iterator *ref_iterator)
+{
+ struct files_reflog_iterator *iter =
+ (struct files_reflog_iterator *)ref_iterator;
+ int ok = ITER_DONE;
+
+ if (iter->dir_iterator)
+ ok = dir_iterator_abort(iter->dir_iterator);
+
+ base_ref_iterator_free(ref_iterator);
+ return ok;
+}
+
+static struct ref_iterator_vtable files_reflog_iterator_vtable = {
+ .advance = files_reflog_iterator_advance,
+ .peel = files_reflog_iterator_peel,
+ .abort = files_reflog_iterator_abort,
+};
+
+static struct ref_iterator *reflog_iterator_begin(struct ref_store *ref_store,
+ const char *gitdir)
+{
+ struct dir_iterator *diter;
+ struct files_reflog_iterator *iter;
+ struct ref_iterator *ref_iterator;
+ struct strbuf sb = STRBUF_INIT;
+
+ strbuf_addf(&sb, "%s/logs", gitdir);
+
+ diter = dir_iterator_begin(sb.buf, 0);
+ if (!diter) {
+ strbuf_release(&sb);
+ return empty_ref_iterator_begin();
+ }
+
+ CALLOC_ARRAY(iter, 1);
+ ref_iterator = &iter->base;
+
+ base_ref_iterator_init(ref_iterator, &files_reflog_iterator_vtable, 0);
+ iter->dir_iterator = diter;
+ iter->ref_store = ref_store;
+ strbuf_release(&sb);
+
+ return ref_iterator;
+}
+
+static enum iterator_selection reflog_iterator_select(
+ struct ref_iterator *iter_worktree,
+ struct ref_iterator *iter_common,
+ void *cb_data UNUSED)
+{
+ if (iter_worktree) {
+ /*
+ * We're a bit loose here. We probably should ignore
+ * common refs if they are accidentally added as
+ * per-worktree refs.
+ */
+ return ITER_SELECT_0;
+ } else if (iter_common) {
+ if (parse_worktree_ref(iter_common->refname, NULL, NULL,
+ NULL) == REF_WORKTREE_SHARED)
+ return ITER_SELECT_1;
+
+ /*
+ * The main ref store may contain main worktree's
+ * per-worktree refs, which should be ignored
+ */
+ return ITER_SKIP_1;
+ } else
+ return ITER_DONE;
+}
+
+static struct ref_iterator *files_reflog_iterator_begin(struct ref_store *ref_store)
+{
+ struct files_ref_store *refs =
+ files_downcast(ref_store, REF_STORE_READ,
+ "reflog_iterator_begin");
+
+ if (!strcmp(refs->base.gitdir, refs->gitcommondir)) {
+ return reflog_iterator_begin(ref_store, refs->gitcommondir);
+ } else {
+ return merge_ref_iterator_begin(
+ 0, reflog_iterator_begin(ref_store, refs->base.gitdir),
+ reflog_iterator_begin(ref_store, refs->gitcommondir),
+ reflog_iterator_select, refs);
+ }
+}
+
+/*
+ * If update is a direct update of head_ref (the reference pointed to
+ * by HEAD), then add an extra REF_LOG_ONLY update for HEAD.
+ */
+static int split_head_update(struct ref_update *update,
+ struct ref_transaction *transaction,
+ const char *head_ref,
+ struct string_list *affected_refnames,
+ struct strbuf *err)
+{
+ struct string_list_item *item;
+ struct ref_update *new_update;
+
+ if ((update->flags & REF_LOG_ONLY) ||
+ (update->flags & REF_IS_PRUNING) ||
+ (update->flags & REF_UPDATE_VIA_HEAD))
+ return 0;
+
+ if (strcmp(update->refname, head_ref))
+ return 0;
+
+ /*
+ * First make sure that HEAD is not already in the
+ * transaction. This check is O(lg N) in the transaction
+ * size, but it happens at most once per transaction.
+ */
+ if (string_list_has_string(affected_refnames, "HEAD")) {
+ /* An entry already existed */
+ strbuf_addf(err,
+ "multiple updates for 'HEAD' (including one "
+ "via its referent '%s') are not allowed",
+ update->refname);
+ return TRANSACTION_NAME_CONFLICT;
+ }
+
+ new_update = ref_transaction_add_update(
+ transaction, "HEAD",
+ update->flags | REF_LOG_ONLY | REF_NO_DEREF,
+ &update->new_oid, &update->old_oid,
+ update->msg);
+
+ /*
+ * Add "HEAD". This insertion is O(N) in the transaction
+ * size, but it happens at most once per transaction.
+ * Add new_update->refname instead of a literal "HEAD".
+ */
+ if (strcmp(new_update->refname, "HEAD"))
+ BUG("%s unexpectedly not 'HEAD'", new_update->refname);
+ item = string_list_insert(affected_refnames, new_update->refname);
+ item->util = new_update;
+
+ return 0;
+}
+
+/*
+ * update is for a symref that points at referent and doesn't have
+ * REF_NO_DEREF set. Split it into two updates:
+ * - The original update, but with REF_LOG_ONLY and REF_NO_DEREF set
+ * - A new, separate update for the referent reference
+ * Note that the new update will itself be subject to splitting when
+ * the iteration gets to it.
+ */
+static int split_symref_update(struct ref_update *update,
+ const char *referent,
+ struct ref_transaction *transaction,
+ struct string_list *affected_refnames,
+ struct strbuf *err)
+{
+ struct string_list_item *item;
+ struct ref_update *new_update;
+ unsigned int new_flags;
+
+ /*
+ * First make sure that referent is not already in the
+ * transaction. This check is O(lg N) in the transaction
+ * size, but it happens at most once per symref in a
+ * transaction.
+ */
+ if (string_list_has_string(affected_refnames, referent)) {
+ /* An entry already exists */
+ strbuf_addf(err,
+ "multiple updates for '%s' (including one "
+ "via symref '%s') are not allowed",
+ referent, update->refname);
+ return TRANSACTION_NAME_CONFLICT;
+ }
+
+ new_flags = update->flags;
+ if (!strcmp(update->refname, "HEAD")) {
+ /*
+ * Record that the new update came via HEAD, so that
+ * when we process it, split_head_update() doesn't try
+ * to add another reflog update for HEAD. Note that
+ * this bit will be propagated if the new_update
+ * itself needs to be split.
+ */
+ new_flags |= REF_UPDATE_VIA_HEAD;
+ }
+
+ new_update = ref_transaction_add_update(
+ transaction, referent, new_flags,
+ &update->new_oid, &update->old_oid,
+ update->msg);
+
+ new_update->parent_update = update;
+
+ /*
+ * Change the symbolic ref update to log only. Also, it
+ * doesn't need to check its old OID value, as that will be
+ * done when new_update is processed.
+ */
+ update->flags |= REF_LOG_ONLY | REF_NO_DEREF;
+ update->flags &= ~REF_HAVE_OLD;
+
+ /*
+ * Add the referent. This insertion is O(N) in the transaction
+ * size, but it happens at most once per symref in a
+ * transaction. Make sure to add new_update->refname, which will
+ * be valid as long as affected_refnames is in use, and NOT
+ * referent, which might soon be freed by our caller.
+ */
+ item = string_list_insert(affected_refnames, new_update->refname);
+ if (item->util)
+ BUG("%s unexpectedly found in affected_refnames",
+ new_update->refname);
+ item->util = new_update;
+
+ return 0;
+}
+
+/*
+ * Return the refname under which update was originally requested.
+ */
+static const char *original_update_refname(struct ref_update *update)
+{
+ while (update->parent_update)
+ update = update->parent_update;
+
+ return update->refname;
+}
+
+/*
+ * Check whether the REF_HAVE_OLD and old_oid values stored in update
+ * are consistent with oid, which is the reference's current value. If
+ * everything is OK, return 0; otherwise, write an error message to
+ * err and return -1.
+ */
+static int check_old_oid(struct ref_update *update, struct object_id *oid,
+ struct strbuf *err)
+{
+ if (!(update->flags & REF_HAVE_OLD) ||
+ oideq(oid, &update->old_oid))
+ return 0;
+
+ if (is_null_oid(&update->old_oid))
+ strbuf_addf(err, "cannot lock ref '%s': "
+ "reference already exists",
+ original_update_refname(update));
+ else if (is_null_oid(oid))
+ strbuf_addf(err, "cannot lock ref '%s': "
+ "reference is missing but expected %s",
+ original_update_refname(update),
+ oid_to_hex(&update->old_oid));
+ else
+ strbuf_addf(err, "cannot lock ref '%s': "
+ "is at %s but expected %s",
+ original_update_refname(update),
+ oid_to_hex(oid),
+ oid_to_hex(&update->old_oid));
+
+ return -1;
+}
+
+/*
+ * Prepare for carrying out update:
+ * - Lock the reference referred to by update.
+ * - Read the reference under lock.
+ * - Check that its old OID value (if specified) is correct, and in
+ * any case record it in update->lock->old_oid for later use when
+ * writing the reflog.
+ * - If it is a symref update without REF_NO_DEREF, split it up into a
+ * REF_LOG_ONLY update of the symref and add a separate update for
+ * the referent to transaction.
+ * - If it is an update of head_ref, add a corresponding REF_LOG_ONLY
+ * update of HEAD.
+ */
+static int lock_ref_for_update(struct files_ref_store *refs,
+ struct ref_update *update,
+ struct ref_transaction *transaction,
+ const char *head_ref,
+ struct string_list *affected_refnames,
+ struct strbuf *err)
+{
+ struct strbuf referent = STRBUF_INIT;
+ int mustexist = (update->flags & REF_HAVE_OLD) &&
+ !is_null_oid(&update->old_oid);
+ int ret = 0;
+ struct ref_lock *lock;
+
+ files_assert_main_repository(refs, "lock_ref_for_update");
+
+ if ((update->flags & REF_HAVE_NEW) && is_null_oid(&update->new_oid))
+ update->flags |= REF_DELETING;
+
+ if (head_ref) {
+ ret = split_head_update(update, transaction, head_ref,
+ affected_refnames, err);
+ if (ret)
+ goto out;
+ }
+
+ ret = lock_raw_ref(refs, update->refname, mustexist,
+ affected_refnames,
+ &lock, &referent,
+ &update->type, err);
+ if (ret) {
+ char *reason;
+
+ reason = strbuf_detach(err, NULL);
+ strbuf_addf(err, "cannot lock ref '%s': %s",
+ original_update_refname(update), reason);
+ free(reason);
+ goto out;
+ }
+
+ update->backend_data = lock;
+
+ if (update->type & REF_ISSYMREF) {
+ if (update->flags & REF_NO_DEREF) {
+ /*
+ * We won't be reading the referent as part of
+ * the transaction, so we have to read it here
+ * to record and possibly check old_oid:
+ */
+ if (!refs_resolve_ref_unsafe(&refs->base,
+ referent.buf, 0,
+ &lock->old_oid, NULL)) {
+ if (update->flags & REF_HAVE_OLD) {
+ strbuf_addf(err, "cannot lock ref '%s': "
+ "error reading reference",
+ original_update_refname(update));
+ ret = TRANSACTION_GENERIC_ERROR;
+ goto out;
+ }
+ } else if (check_old_oid(update, &lock->old_oid, err)) {
+ ret = TRANSACTION_GENERIC_ERROR;
+ goto out;
+ }
+ } else {
+ /*
+ * Create a new update for the reference this
+ * symref is pointing at. Also, we will record
+ * and verify old_oid for this update as part
+ * of processing the split-off update, so we
+ * don't have to do it here.
+ */
+ ret = split_symref_update(update,
+ referent.buf, transaction,
+ affected_refnames, err);
+ if (ret)
+ goto out;
+ }
+ } else {
+ struct ref_update *parent_update;
+
+ if (check_old_oid(update, &lock->old_oid, err)) {
+ ret = TRANSACTION_GENERIC_ERROR;
+ goto out;
+ }
+
+ /*
+ * If this update is happening indirectly because of a
+ * symref update, record the old OID in the parent
+ * update:
+ */
+ for (parent_update = update->parent_update;
+ parent_update;
+ parent_update = parent_update->parent_update) {
+ struct ref_lock *parent_lock = parent_update->backend_data;
+ oidcpy(&parent_lock->old_oid, &lock->old_oid);
+ }
+ }
+
+ if ((update->flags & REF_HAVE_NEW) &&
+ !(update->flags & REF_DELETING) &&
+ !(update->flags & REF_LOG_ONLY)) {
+ if (!(update->type & REF_ISSYMREF) &&
+ oideq(&lock->old_oid, &update->new_oid)) {
+ /*
+ * The reference already has the desired
+ * value, so we don't need to write it.
+ */
+ } else if (write_ref_to_lockfile(
+ lock, &update->new_oid,
+ update->flags & REF_SKIP_OID_VERIFICATION,
+ err)) {
+ char *write_err = strbuf_detach(err, NULL);
+
+ /*
+ * The lock was freed upon failure of
+ * write_ref_to_lockfile():
+ */
+ update->backend_data = NULL;
+ strbuf_addf(err,
+ "cannot update ref '%s': %s",
+ update->refname, write_err);
+ free(write_err);
+ ret = TRANSACTION_GENERIC_ERROR;
+ goto out;
+ } else {
+ update->flags |= REF_NEEDS_COMMIT;
+ }
+ }
+ if (!(update->flags & REF_NEEDS_COMMIT)) {
+ /*
+ * We didn't call write_ref_to_lockfile(), so
+ * the lockfile is still open. Close it to
+ * free up the file descriptor:
+ */
+ if (close_ref_gently(lock)) {
+ strbuf_addf(err, "couldn't close '%s.lock'",
+ update->refname);
+ ret = TRANSACTION_GENERIC_ERROR;
+ goto out;
+ }
+ }
+
+out:
+ strbuf_release(&referent);
+ return ret;
+}
+
+struct files_transaction_backend_data {
+ struct ref_transaction *packed_transaction;
+ int packed_refs_locked;
+};
+
+/*
+ * Unlock any references in `transaction` that are still locked, and
+ * mark the transaction closed.
+ */
+static void files_transaction_cleanup(struct files_ref_store *refs,
+ struct ref_transaction *transaction)
+{
+ size_t i;
+ struct files_transaction_backend_data *backend_data =
+ transaction->backend_data;
+ struct strbuf err = STRBUF_INIT;
+
+ for (i = 0; i < transaction->nr; i++) {
+ struct ref_update *update = transaction->updates[i];
+ struct ref_lock *lock = update->backend_data;
+
+ if (lock) {
+ unlock_ref(lock);
+ update->backend_data = NULL;
+ }
+ }
+
+ if (backend_data) {
+ if (backend_data->packed_transaction &&
+ ref_transaction_abort(backend_data->packed_transaction, &err)) {
+ error("error aborting transaction: %s", err.buf);
+ strbuf_release(&err);
+ }
+
+ if (backend_data->packed_refs_locked)
+ packed_refs_unlock(refs->packed_ref_store);
+
+ free(backend_data);
+ }
+
+ transaction->state = REF_TRANSACTION_CLOSED;
+}
+
+static int files_transaction_prepare(struct ref_store *ref_store,
+ struct ref_transaction *transaction,
+ struct strbuf *err)
+{
+ struct files_ref_store *refs =
+ files_downcast(ref_store, REF_STORE_WRITE,
+ "ref_transaction_prepare");
+ size_t i;
+ int ret = 0;
+ struct string_list affected_refnames = STRING_LIST_INIT_NODUP;
+ char *head_ref = NULL;
+ int head_type;
+ struct files_transaction_backend_data *backend_data;
+ struct ref_transaction *packed_transaction = NULL;
+
+ assert(err);
+
+ if (!transaction->nr)
+ goto cleanup;
+
+ CALLOC_ARRAY(backend_data, 1);
+ transaction->backend_data = backend_data;
+
+ /*
+ * Fail if a refname appears more than once in the
+ * transaction. (If we end up splitting up any updates using
+ * split_symref_update() or split_head_update(), those
+ * functions will check that the new updates don't have the
+ * same refname as any existing ones.) Also fail if any of the
+ * updates use REF_IS_PRUNING without REF_NO_DEREF.
+ */
+ for (i = 0; i < transaction->nr; i++) {
+ struct ref_update *update = transaction->updates[i];
+ struct string_list_item *item =
+ string_list_append(&affected_refnames, update->refname);
+
+ if ((update->flags & REF_IS_PRUNING) &&
+ !(update->flags & REF_NO_DEREF))
+ BUG("REF_IS_PRUNING set without REF_NO_DEREF");
+
+ /*
+ * We store a pointer to update in item->util, but at
+ * the moment we never use the value of this field
+ * except to check whether it is non-NULL.
+ */
+ item->util = update;
+ }
+ string_list_sort(&affected_refnames);
+ if (ref_update_reject_duplicates(&affected_refnames, err)) {
+ ret = TRANSACTION_GENERIC_ERROR;
+ goto cleanup;
+ }
+
+ /*
+ * Special hack: If a branch is updated directly and HEAD
+ * points to it (may happen on the remote side of a push
+ * for example) then logically the HEAD reflog should be
+ * updated too.
+ *
+ * A generic solution would require reverse symref lookups,
+ * but finding all symrefs pointing to a given branch would be
+ * rather costly for this rare event (the direct update of a
+ * branch) to be worth it. So let's cheat and check with HEAD
+ * only, which should cover 99% of all usage scenarios (even
+ * 100% of the default ones).
+ *
+ * So if HEAD is a symbolic reference, then record the name of
+ * the reference that it points to. If we see an update of
+ * head_ref within the transaction, then split_head_update()
+ * arranges for the reflog of HEAD to be updated, too.
+ */
+ head_ref = refs_resolve_refdup(ref_store, "HEAD",
+ RESOLVE_REF_NO_RECURSE,
+ NULL, &head_type);
+
+ if (head_ref && !(head_type & REF_ISSYMREF)) {
+ FREE_AND_NULL(head_ref);
+ }
+
+ /*
+ * Acquire all locks, verify old values if provided, check
+ * that new values are valid, and write new values to the
+ * lockfiles, ready to be activated. Only keep one lockfile
+ * open at a time to avoid running out of file descriptors.
+ * Note that lock_ref_for_update() might append more updates
+ * to the transaction.
+ */
+ for (i = 0; i < transaction->nr; i++) {
+ struct ref_update *update = transaction->updates[i];
+
+ ret = lock_ref_for_update(refs, update, transaction,
+ head_ref, &affected_refnames, err);
+ if (ret)
+ goto cleanup;
+
+ if (update->flags & REF_DELETING &&
+ !(update->flags & REF_LOG_ONLY) &&
+ !(update->flags & REF_IS_PRUNING)) {
+ /*
+ * This reference has to be deleted from
+ * packed-refs if it exists there.
+ */
+ if (!packed_transaction) {
+ packed_transaction = ref_store_transaction_begin(
+ refs->packed_ref_store, err);
+ if (!packed_transaction) {
+ ret = TRANSACTION_GENERIC_ERROR;
+ goto cleanup;
+ }
+
+ backend_data->packed_transaction =
+ packed_transaction;
+ }
+
+ ref_transaction_add_update(
+ packed_transaction, update->refname,
+ REF_HAVE_NEW | REF_NO_DEREF,
+ &update->new_oid, NULL,
+ NULL);
+ }
+ }
+
+ if (packed_transaction) {
+ if (packed_refs_lock(refs->packed_ref_store, 0, err)) {
+ ret = TRANSACTION_GENERIC_ERROR;
+ goto cleanup;
+ }
+ backend_data->packed_refs_locked = 1;
+
+ if (is_packed_transaction_needed(refs->packed_ref_store,
+ packed_transaction)) {
+ ret = ref_transaction_prepare(packed_transaction, err);
+ /*
+ * A failure during the prepare step will abort
+ * itself, but not free. Do that now, and disconnect
+ * from the files_transaction so it does not try to
+ * abort us when we hit the cleanup code below.
+ */
+ if (ret) {
+ ref_transaction_free(packed_transaction);
+ backend_data->packed_transaction = NULL;
+ }
+ } else {
+ /*
+ * We can skip rewriting the `packed-refs`
+ * file. But we do need to leave it locked, so
+ * that somebody else doesn't pack a reference
+ * that we are trying to delete.
+ *
+ * We need to disconnect our transaction from
+ * backend_data, since the abort (whether successful or
+ * not) will free it.
+ */
+ backend_data->packed_transaction = NULL;
+ if (ref_transaction_abort(packed_transaction, err)) {
+ ret = TRANSACTION_GENERIC_ERROR;
+ goto cleanup;
+ }
+ }
+ }
+
+cleanup:
+ free(head_ref);
+ string_list_clear(&affected_refnames, 0);
+
+ if (ret)
+ files_transaction_cleanup(refs, transaction);
+ else
+ transaction->state = REF_TRANSACTION_PREPARED;
+
+ return ret;
+}
+
+static int files_transaction_finish(struct ref_store *ref_store,
+ struct ref_transaction *transaction,
+ struct strbuf *err)
+{
+ struct files_ref_store *refs =
+ files_downcast(ref_store, 0, "ref_transaction_finish");
+ size_t i;
+ int ret = 0;
+ struct strbuf sb = STRBUF_INIT;
+ struct files_transaction_backend_data *backend_data;
+ struct ref_transaction *packed_transaction;
+
+
+ assert(err);
+
+ if (!transaction->nr) {
+ transaction->state = REF_TRANSACTION_CLOSED;
+ return 0;
+ }
+
+ backend_data = transaction->backend_data;
+ packed_transaction = backend_data->packed_transaction;
+
+ /* Perform updates first so live commits remain referenced */
+ for (i = 0; i < transaction->nr; i++) {
+ struct ref_update *update = transaction->updates[i];
+ struct ref_lock *lock = update->backend_data;
+
+ if (update->flags & REF_NEEDS_COMMIT ||
+ update->flags & REF_LOG_ONLY) {
+ if (files_log_ref_write(refs,
+ lock->ref_name,
+ &lock->old_oid,
+ &update->new_oid,
+ update->msg, update->flags,
+ err)) {
+ char *old_msg = strbuf_detach(err, NULL);
+
+ strbuf_addf(err, "cannot update the ref '%s': %s",
+ lock->ref_name, old_msg);
+ free(old_msg);
+ unlock_ref(lock);
+ update->backend_data = NULL;
+ ret = TRANSACTION_GENERIC_ERROR;
+ goto cleanup;
+ }
+ }
+ if (update->flags & REF_NEEDS_COMMIT) {
+ clear_loose_ref_cache(refs);
+ if (commit_ref(lock)) {
+ strbuf_addf(err, "couldn't set '%s'", lock->ref_name);
+ unlock_ref(lock);
+ update->backend_data = NULL;
+ ret = TRANSACTION_GENERIC_ERROR;
+ goto cleanup;
+ }
+ }
+ }
+
+ /*
+ * Now that updates are safely completed, we can perform
+ * deletes. First delete the reflogs of any references that
+ * will be deleted, since (in the unexpected event of an
+ * error) leaving a reference without a reflog is less bad
+ * than leaving a reflog without a reference (the latter is a
+ * mildly invalid repository state):
+ */
+ for (i = 0; i < transaction->nr; i++) {
+ struct ref_update *update = transaction->updates[i];
+ if (update->flags & REF_DELETING &&
+ !(update->flags & REF_LOG_ONLY) &&
+ !(update->flags & REF_IS_PRUNING)) {
+ strbuf_reset(&sb);
+ files_reflog_path(refs, &sb, update->refname);
+ if (!unlink_or_warn(sb.buf))
+ try_remove_empty_parents(refs, update->refname,
+ REMOVE_EMPTY_PARENTS_REFLOG);
+ }
+ }
+
+ /*
+ * Perform deletes now that updates are safely completed.
+ *
+ * First delete any packed versions of the references, while
+ * retaining the packed-refs lock:
+ */
+ if (packed_transaction) {
+ ret = ref_transaction_commit(packed_transaction, err);
+ ref_transaction_free(packed_transaction);
+ packed_transaction = NULL;
+ backend_data->packed_transaction = NULL;
+ if (ret)
+ goto cleanup;
+ }
+
+ /* Now delete the loose versions of the references: */
+ for (i = 0; i < transaction->nr; i++) {
+ struct ref_update *update = transaction->updates[i];
+ struct ref_lock *lock = update->backend_data;
+
+ if (update->flags & REF_DELETING &&
+ !(update->flags & REF_LOG_ONLY)) {
+ update->flags |= REF_DELETED_RMDIR;
+ if (!(update->type & REF_ISPACKED) ||
+ update->type & REF_ISSYMREF) {
+ /* It is a loose reference. */
+ strbuf_reset(&sb);
+ files_ref_path(refs, &sb, lock->ref_name);
+ if (unlink_or_msg(sb.buf, err)) {
+ ret = TRANSACTION_GENERIC_ERROR;
+ goto cleanup;
+ }
+ }
+ }
+ }
+
+ clear_loose_ref_cache(refs);
+
+cleanup:
+ files_transaction_cleanup(refs, transaction);
+
+ for (i = 0; i < transaction->nr; i++) {
+ struct ref_update *update = transaction->updates[i];
+
+ if (update->flags & REF_DELETED_RMDIR) {
+ /*
+ * The reference was deleted. Delete any
+ * empty parent directories. (Note that this
+ * can only work because we have already
+ * removed the lockfile.)
+ */
+ try_remove_empty_parents(refs, update->refname,
+ REMOVE_EMPTY_PARENTS_REF);
+ }
+ }
+
+ strbuf_release(&sb);
+ return ret;
+}
+
+static int files_transaction_abort(struct ref_store *ref_store,
+ struct ref_transaction *transaction,
+ struct strbuf *err UNUSED)
+{
+ struct files_ref_store *refs =
+ files_downcast(ref_store, 0, "ref_transaction_abort");
+
+ files_transaction_cleanup(refs, transaction);
+ return 0;
+}
+
+static int ref_present(const char *refname,
+ const struct object_id *oid UNUSED,
+ int flags UNUSED,
+ void *cb_data)
+{
+ struct string_list *affected_refnames = cb_data;
+
+ return string_list_has_string(affected_refnames, refname);
+}
+
+static int files_initial_transaction_commit(struct ref_store *ref_store,
+ struct ref_transaction *transaction,
+ struct strbuf *err)
+{
+ struct files_ref_store *refs =
+ files_downcast(ref_store, REF_STORE_WRITE,
+ "initial_ref_transaction_commit");
+ size_t i;
+ int ret = 0;
+ struct string_list affected_refnames = STRING_LIST_INIT_NODUP;
+ struct ref_transaction *packed_transaction = NULL;
+
+ assert(err);
+
+ if (transaction->state != REF_TRANSACTION_OPEN)
+ BUG("commit called for transaction that is not open");
+
+ /* Fail if a refname appears more than once in the transaction: */
+ for (i = 0; i < transaction->nr; i++)
+ string_list_append(&affected_refnames,
+ transaction->updates[i]->refname);
+ string_list_sort(&affected_refnames);
+ if (ref_update_reject_duplicates(&affected_refnames, err)) {
+ ret = TRANSACTION_GENERIC_ERROR;
+ goto cleanup;
+ }
+
+ /*
+ * It's really undefined to call this function in an active
+ * repository or when there are existing references: we are
+ * only locking and changing packed-refs, so (1) any
+ * simultaneous processes might try to change a reference at
+ * the same time we do, and (2) any existing loose versions of
+ * the references that we are setting would have precedence
+ * over our values. But some remote helpers create the remote
+ * "HEAD" and "master" branches before calling this function,
+ * so here we really only check that none of the references
+ * that we are creating already exists.
+ */
+ if (refs_for_each_rawref(&refs->base, ref_present,
+ &affected_refnames))
+ BUG("initial ref transaction called with existing refs");
+
+ packed_transaction = ref_store_transaction_begin(refs->packed_ref_store, err);
+ if (!packed_transaction) {
+ ret = TRANSACTION_GENERIC_ERROR;
+ goto cleanup;
+ }
+
+ for (i = 0; i < transaction->nr; i++) {
+ struct ref_update *update = transaction->updates[i];
+
+ if ((update->flags & REF_HAVE_OLD) &&
+ !is_null_oid(&update->old_oid))
+ BUG("initial ref transaction with old_sha1 set");
+ if (refs_verify_refname_available(&refs->base, update->refname,
+ &affected_refnames, NULL,
+ err)) {
+ ret = TRANSACTION_NAME_CONFLICT;
+ goto cleanup;
+ }
+
+ /*
+ * Add a reference creation for this reference to the
+ * packed-refs transaction:
+ */
+ ref_transaction_add_update(packed_transaction, update->refname,
+ update->flags & ~REF_HAVE_OLD,
+ &update->new_oid, &update->old_oid,
+ NULL);
+ }
+
+ if (packed_refs_lock(refs->packed_ref_store, 0, err)) {
+ ret = TRANSACTION_GENERIC_ERROR;
+ goto cleanup;
+ }
+
+ if (initial_ref_transaction_commit(packed_transaction, err)) {
+ ret = TRANSACTION_GENERIC_ERROR;
+ }
+
+ packed_refs_unlock(refs->packed_ref_store);
+cleanup:
+ if (packed_transaction)
+ ref_transaction_free(packed_transaction);
+ transaction->state = REF_TRANSACTION_CLOSED;
+ string_list_clear(&affected_refnames, 0);
+ return ret;
+}
+
+struct expire_reflog_cb {
+ reflog_expiry_should_prune_fn *should_prune_fn;
+ void *policy_cb;
+ FILE *newlog;
+ struct object_id last_kept_oid;
+ unsigned int rewrite:1,
+ dry_run:1;
+};
+
+static int expire_reflog_ent(struct object_id *ooid, struct object_id *noid,
+ const char *email, timestamp_t timestamp, int tz,
+ const char *message, void *cb_data)
+{
+ struct expire_reflog_cb *cb = cb_data;
+ reflog_expiry_should_prune_fn *fn = cb->should_prune_fn;
+
+ if (cb->rewrite)
+ ooid = &cb->last_kept_oid;
+
+ if (fn(ooid, noid, email, timestamp, tz, message, cb->policy_cb))
+ return 0;
+
+ if (cb->dry_run)
+ return 0; /* --dry-run */
+
+ fprintf(cb->newlog, "%s %s %s %"PRItime" %+05d\t%s", oid_to_hex(ooid),
+ oid_to_hex(noid), email, timestamp, tz, message);
+ oidcpy(&cb->last_kept_oid, noid);
+
+ return 0;
+}
+
+static int files_reflog_expire(struct ref_store *ref_store,
+ const char *refname,
+ unsigned int expire_flags,
+ reflog_expiry_prepare_fn prepare_fn,
+ reflog_expiry_should_prune_fn should_prune_fn,
+ reflog_expiry_cleanup_fn cleanup_fn,
+ void *policy_cb_data)
+{
+ struct files_ref_store *refs =
+ files_downcast(ref_store, REF_STORE_WRITE, "reflog_expire");
+ struct lock_file reflog_lock = LOCK_INIT;
+ struct expire_reflog_cb cb;
+ struct ref_lock *lock;
+ struct strbuf log_file_sb = STRBUF_INIT;
+ char *log_file;
+ int status = 0;
+ struct strbuf err = STRBUF_INIT;
+ const struct object_id *oid;
+
+ memset(&cb, 0, sizeof(cb));
+ cb.rewrite = !!(expire_flags & EXPIRE_REFLOGS_REWRITE);
+ cb.dry_run = !!(expire_flags & EXPIRE_REFLOGS_DRY_RUN);
+ cb.policy_cb = policy_cb_data;
+ cb.should_prune_fn = should_prune_fn;
+
+ /*
+ * The reflog file is locked by holding the lock on the
+ * reference itself, plus we might need to update the
+ * reference if --updateref was specified:
+ */
+ lock = lock_ref_oid_basic(refs, refname, &err);
+ if (!lock) {
+ error("cannot lock ref '%s': %s", refname, err.buf);
+ strbuf_release(&err);
+ return -1;
+ }
+ oid = &lock->old_oid;
+
+ /*
+ * When refs are deleted, their reflog is deleted before the
+ * ref itself is deleted. This is because there is no separate
+ * lock for reflog; instead we take a lock on the ref with
+ * lock_ref_oid_basic().
+ *
+ * If a race happens and the reflog doesn't exist after we've
+ * acquired the lock that's OK. We've got nothing more to do;
+ * We were asked to delete the reflog, but someone else
+ * deleted it! The caller doesn't care that we deleted it,
+ * just that it is deleted. So we can return successfully.
+ */
+ if (!refs_reflog_exists(ref_store, refname)) {
+ unlock_ref(lock);
+ return 0;
+ }
+
+ files_reflog_path(refs, &log_file_sb, refname);
+ log_file = strbuf_detach(&log_file_sb, NULL);
+ if (!cb.dry_run) {
+ /*
+ * Even though holding $GIT_DIR/logs/$reflog.lock has
+ * no locking implications, we use the lock_file
+ * machinery here anyway because it does a lot of the
+ * work we need, including cleaning up if the program
+ * exits unexpectedly.
+ */
+ if (hold_lock_file_for_update(&reflog_lock, log_file, 0) < 0) {
+ struct strbuf err = STRBUF_INIT;
+ unable_to_lock_message(log_file, errno, &err);
+ error("%s", err.buf);
+ strbuf_release(&err);
+ goto failure;
+ }
+ cb.newlog = fdopen_lock_file(&reflog_lock, "w");
+ if (!cb.newlog) {
+ error("cannot fdopen %s (%s)",
+ get_lock_file_path(&reflog_lock), strerror(errno));
+ goto failure;
+ }
+ }
+
+ (*prepare_fn)(refname, oid, cb.policy_cb);
+ refs_for_each_reflog_ent(ref_store, refname, expire_reflog_ent, &cb);
+ (*cleanup_fn)(cb.policy_cb);
+
+ if (!cb.dry_run) {
+ /*
+ * It doesn't make sense to adjust a reference pointed
+ * to by a symbolic ref based on expiring entries in
+ * the symbolic reference's reflog. Nor can we update
+ * a reference if there are no remaining reflog
+ * entries.
+ */
+ int update = 0;
+
+ if ((expire_flags & EXPIRE_REFLOGS_UPDATE_REF) &&
+ !is_null_oid(&cb.last_kept_oid)) {
+ int type;
+ const char *ref;
+
+ ref = refs_resolve_ref_unsafe(&refs->base, refname,
+ RESOLVE_REF_NO_RECURSE,
+ NULL, &type);
+ update = !!(ref && !(type & REF_ISSYMREF));
+ }
+
+ if (close_lock_file_gently(&reflog_lock)) {
+ status |= error("couldn't write %s: %s", log_file,
+ strerror(errno));
+ rollback_lock_file(&reflog_lock);
+ } else if (update &&
+ (write_in_full(get_lock_file_fd(&lock->lk),
+ oid_to_hex(&cb.last_kept_oid), the_hash_algo->hexsz) < 0 ||
+ write_str_in_full(get_lock_file_fd(&lock->lk), "\n") < 0 ||
+ close_ref_gently(lock) < 0)) {
+ status |= error("couldn't write %s",
+ get_lock_file_path(&lock->lk));
+ rollback_lock_file(&reflog_lock);
+ } else if (commit_lock_file(&reflog_lock)) {
+ status |= error("unable to write reflog '%s' (%s)",
+ log_file, strerror(errno));
+ } else if (update && commit_ref(lock)) {
+ status |= error("couldn't set %s", lock->ref_name);
+ }
+ }
+ free(log_file);
+ unlock_ref(lock);
+ return status;
+
+ failure:
+ rollback_lock_file(&reflog_lock);
+ free(log_file);
+ unlock_ref(lock);
+ return -1;
+}
+
+static int files_init_db(struct ref_store *ref_store, struct strbuf *err UNUSED)
+{
+ struct files_ref_store *refs =
+ files_downcast(ref_store, REF_STORE_WRITE, "init_db");
+ struct strbuf sb = STRBUF_INIT;
+
+ /*
+ * Create .git/refs/{heads,tags}
+ */
+ files_ref_path(refs, &sb, "refs/heads");
+ safe_create_dir(sb.buf, 1);
+
+ strbuf_reset(&sb);
+ files_ref_path(refs, &sb, "refs/tags");
+ safe_create_dir(sb.buf, 1);
+
+ strbuf_release(&sb);
+ return 0;
+}
+
+struct ref_storage_be refs_be_files = {
+ .next = NULL,
+ .name = "files",
+ .init = files_ref_store_create,
+ .init_db = files_init_db,
+ .transaction_prepare = files_transaction_prepare,
+ .transaction_finish = files_transaction_finish,
+ .transaction_abort = files_transaction_abort,
+ .initial_transaction_commit = files_initial_transaction_commit,
+
+ .pack_refs = files_pack_refs,
+ .create_symref = files_create_symref,
+ .delete_refs = files_delete_refs,
+ .rename_ref = files_rename_ref,
+ .copy_ref = files_copy_ref,
+
+ .iterator_begin = files_ref_iterator_begin,
+ .read_raw_ref = files_read_raw_ref,
+ .read_symbolic_ref = files_read_symbolic_ref,
+
+ .reflog_iterator_begin = files_reflog_iterator_begin,
+ .for_each_reflog_ent = files_for_each_reflog_ent,
+ .for_each_reflog_ent_reverse = files_for_each_reflog_ent_reverse,
+ .reflog_exists = files_reflog_exists,
+ .create_reflog = files_create_reflog,
+ .delete_reflog = files_delete_reflog,
+ .reflog_expire = files_reflog_expire
+};
diff --git a/refs/iterator.c b/refs/iterator.c
new file mode 100644
index 0000000..c9fd0bc
--- /dev/null
+++ b/refs/iterator.c
@@ -0,0 +1,435 @@
+/*
+ * Generic reference iterator infrastructure. See refs-internal.h for
+ * documentation about the design and use of reference iterators.
+ */
+
+#include "cache.h"
+#include "refs.h"
+#include "refs/refs-internal.h"
+#include "iterator.h"
+
+int ref_iterator_advance(struct ref_iterator *ref_iterator)
+{
+ return ref_iterator->vtable->advance(ref_iterator);
+}
+
+int ref_iterator_peel(struct ref_iterator *ref_iterator,
+ struct object_id *peeled)
+{
+ return ref_iterator->vtable->peel(ref_iterator, peeled);
+}
+
+int ref_iterator_abort(struct ref_iterator *ref_iterator)
+{
+ return ref_iterator->vtable->abort(ref_iterator);
+}
+
+void base_ref_iterator_init(struct ref_iterator *iter,
+ struct ref_iterator_vtable *vtable,
+ int ordered)
+{
+ iter->vtable = vtable;
+ iter->ordered = !!ordered;
+ iter->refname = NULL;
+ iter->oid = NULL;
+ iter->flags = 0;
+}
+
+void base_ref_iterator_free(struct ref_iterator *iter)
+{
+ /* Help make use-after-free bugs fail quickly: */
+ iter->vtable = NULL;
+ free(iter);
+}
+
+struct empty_ref_iterator {
+ struct ref_iterator base;
+};
+
+static int empty_ref_iterator_advance(struct ref_iterator *ref_iterator)
+{
+ return ref_iterator_abort(ref_iterator);
+}
+
+static int empty_ref_iterator_peel(struct ref_iterator *ref_iterator UNUSED,
+ struct object_id *peeled UNUSED)
+{
+ BUG("peel called for empty iterator");
+}
+
+static int empty_ref_iterator_abort(struct ref_iterator *ref_iterator)
+{
+ base_ref_iterator_free(ref_iterator);
+ return ITER_DONE;
+}
+
+static struct ref_iterator_vtable empty_ref_iterator_vtable = {
+ .advance = empty_ref_iterator_advance,
+ .peel = empty_ref_iterator_peel,
+ .abort = empty_ref_iterator_abort,
+};
+
+struct ref_iterator *empty_ref_iterator_begin(void)
+{
+ struct empty_ref_iterator *iter = xcalloc(1, sizeof(*iter));
+ struct ref_iterator *ref_iterator = &iter->base;
+
+ base_ref_iterator_init(ref_iterator, &empty_ref_iterator_vtable, 1);
+ return ref_iterator;
+}
+
+int is_empty_ref_iterator(struct ref_iterator *ref_iterator)
+{
+ return ref_iterator->vtable == &empty_ref_iterator_vtable;
+}
+
+struct merge_ref_iterator {
+ struct ref_iterator base;
+
+ struct ref_iterator *iter0, *iter1;
+
+ ref_iterator_select_fn *select;
+ void *cb_data;
+
+ /*
+ * A pointer to iter0 or iter1 (whichever is supplying the
+ * current value), or NULL if advance has not yet been called.
+ */
+ struct ref_iterator **current;
+};
+
+static int merge_ref_iterator_advance(struct ref_iterator *ref_iterator)
+{
+ struct merge_ref_iterator *iter =
+ (struct merge_ref_iterator *)ref_iterator;
+ int ok;
+
+ if (!iter->current) {
+ /* Initialize: advance both iterators to their first entries */
+ if ((ok = ref_iterator_advance(iter->iter0)) != ITER_OK) {
+ iter->iter0 = NULL;
+ if (ok == ITER_ERROR)
+ goto error;
+ }
+ if ((ok = ref_iterator_advance(iter->iter1)) != ITER_OK) {
+ iter->iter1 = NULL;
+ if (ok == ITER_ERROR)
+ goto error;
+ }
+ } else {
+ /*
+ * Advance the current iterator past the just-used
+ * entry:
+ */
+ if ((ok = ref_iterator_advance(*iter->current)) != ITER_OK) {
+ *iter->current = NULL;
+ if (ok == ITER_ERROR)
+ goto error;
+ }
+ }
+
+ /* Loop until we find an entry that we can yield. */
+ while (1) {
+ struct ref_iterator **secondary;
+ enum iterator_selection selection =
+ iter->select(iter->iter0, iter->iter1, iter->cb_data);
+
+ if (selection == ITER_SELECT_DONE) {
+ return ref_iterator_abort(ref_iterator);
+ } else if (selection == ITER_SELECT_ERROR) {
+ ref_iterator_abort(ref_iterator);
+ return ITER_ERROR;
+ }
+
+ if ((selection & ITER_CURRENT_SELECTION_MASK) == 0) {
+ iter->current = &iter->iter0;
+ secondary = &iter->iter1;
+ } else {
+ iter->current = &iter->iter1;
+ secondary = &iter->iter0;
+ }
+
+ if (selection & ITER_SKIP_SECONDARY) {
+ if ((ok = ref_iterator_advance(*secondary)) != ITER_OK) {
+ *secondary = NULL;
+ if (ok == ITER_ERROR)
+ goto error;
+ }
+ }
+
+ if (selection & ITER_YIELD_CURRENT) {
+ iter->base.refname = (*iter->current)->refname;
+ iter->base.oid = (*iter->current)->oid;
+ iter->base.flags = (*iter->current)->flags;
+ return ITER_OK;
+ }
+ }
+
+error:
+ ref_iterator_abort(ref_iterator);
+ return ITER_ERROR;
+}
+
+static int merge_ref_iterator_peel(struct ref_iterator *ref_iterator,
+ struct object_id *peeled)
+{
+ struct merge_ref_iterator *iter =
+ (struct merge_ref_iterator *)ref_iterator;
+
+ if (!iter->current) {
+ BUG("peel called before advance for merge iterator");
+ }
+ return ref_iterator_peel(*iter->current, peeled);
+}
+
+static int merge_ref_iterator_abort(struct ref_iterator *ref_iterator)
+{
+ struct merge_ref_iterator *iter =
+ (struct merge_ref_iterator *)ref_iterator;
+ int ok = ITER_DONE;
+
+ if (iter->iter0) {
+ if (ref_iterator_abort(iter->iter0) != ITER_DONE)
+ ok = ITER_ERROR;
+ }
+ if (iter->iter1) {
+ if (ref_iterator_abort(iter->iter1) != ITER_DONE)
+ ok = ITER_ERROR;
+ }
+ base_ref_iterator_free(ref_iterator);
+ return ok;
+}
+
+static struct ref_iterator_vtable merge_ref_iterator_vtable = {
+ .advance = merge_ref_iterator_advance,
+ .peel = merge_ref_iterator_peel,
+ .abort = merge_ref_iterator_abort,
+};
+
+struct ref_iterator *merge_ref_iterator_begin(
+ int ordered,
+ struct ref_iterator *iter0, struct ref_iterator *iter1,
+ ref_iterator_select_fn *select, void *cb_data)
+{
+ struct merge_ref_iterator *iter = xcalloc(1, sizeof(*iter));
+ struct ref_iterator *ref_iterator = &iter->base;
+
+ /*
+ * We can't do the same kind of is_empty_ref_iterator()-style
+ * optimization here as overlay_ref_iterator_begin() does,
+ * because we don't know the semantics of the select function.
+ * It might, for example, implement "intersect" by passing
+ * references through only if they exist in both iterators.
+ */
+
+ base_ref_iterator_init(ref_iterator, &merge_ref_iterator_vtable, ordered);
+ iter->iter0 = iter0;
+ iter->iter1 = iter1;
+ iter->select = select;
+ iter->cb_data = cb_data;
+ iter->current = NULL;
+ return ref_iterator;
+}
+
+/*
+ * A ref_iterator_select_fn that overlays the items from front on top
+ * of those from back (like loose refs over packed refs). See
+ * overlay_ref_iterator_begin().
+ */
+static enum iterator_selection overlay_iterator_select(
+ struct ref_iterator *front, struct ref_iterator *back,
+ void *cb_data UNUSED)
+{
+ int cmp;
+
+ if (!back)
+ return front ? ITER_SELECT_0 : ITER_SELECT_DONE;
+ else if (!front)
+ return ITER_SELECT_1;
+
+ cmp = strcmp(front->refname, back->refname);
+
+ if (cmp < 0)
+ return ITER_SELECT_0;
+ else if (cmp > 0)
+ return ITER_SELECT_1;
+ else
+ return ITER_SELECT_0_SKIP_1;
+}
+
+struct ref_iterator *overlay_ref_iterator_begin(
+ struct ref_iterator *front, struct ref_iterator *back)
+{
+ /*
+ * Optimization: if one of the iterators is empty, return the
+ * other one rather than incurring the overhead of wrapping
+ * them.
+ */
+ if (is_empty_ref_iterator(front)) {
+ ref_iterator_abort(front);
+ return back;
+ } else if (is_empty_ref_iterator(back)) {
+ ref_iterator_abort(back);
+ return front;
+ } else if (!front->ordered || !back->ordered) {
+ BUG("overlay_ref_iterator requires ordered inputs");
+ }
+
+ return merge_ref_iterator_begin(1, front, back,
+ overlay_iterator_select, NULL);
+}
+
+struct prefix_ref_iterator {
+ struct ref_iterator base;
+
+ struct ref_iterator *iter0;
+ char *prefix;
+ int trim;
+};
+
+/* Return -1, 0, 1 if refname is before, inside, or after the prefix. */
+static int compare_prefix(const char *refname, const char *prefix)
+{
+ while (*prefix) {
+ if (*refname != *prefix)
+ return ((unsigned char)*refname < (unsigned char)*prefix) ? -1 : +1;
+
+ refname++;
+ prefix++;
+ }
+
+ return 0;
+}
+
+static int prefix_ref_iterator_advance(struct ref_iterator *ref_iterator)
+{
+ struct prefix_ref_iterator *iter =
+ (struct prefix_ref_iterator *)ref_iterator;
+ int ok;
+
+ while ((ok = ref_iterator_advance(iter->iter0)) == ITER_OK) {
+ int cmp = compare_prefix(iter->iter0->refname, iter->prefix);
+
+ if (cmp < 0)
+ continue;
+
+ if (cmp > 0) {
+ /*
+ * If the source iterator is ordered, then we
+ * can stop the iteration as soon as we see a
+ * refname that comes after the prefix:
+ */
+ if (iter->iter0->ordered) {
+ ok = ref_iterator_abort(iter->iter0);
+ break;
+ } else {
+ continue;
+ }
+ }
+
+ if (iter->trim) {
+ /*
+ * It is nonsense to trim off characters that
+ * you haven't already checked for via a
+ * prefix check, whether via this
+ * `prefix_ref_iterator` or upstream in
+ * `iter0`). So if there wouldn't be at least
+ * one character left in the refname after
+ * trimming, report it as a bug:
+ */
+ if (strlen(iter->iter0->refname) <= iter->trim)
+ BUG("attempt to trim too many characters");
+ iter->base.refname = iter->iter0->refname + iter->trim;
+ } else {
+ iter->base.refname = iter->iter0->refname;
+ }
+
+ iter->base.oid = iter->iter0->oid;
+ iter->base.flags = iter->iter0->flags;
+ return ITER_OK;
+ }
+
+ iter->iter0 = NULL;
+ if (ref_iterator_abort(ref_iterator) != ITER_DONE)
+ return ITER_ERROR;
+ return ok;
+}
+
+static int prefix_ref_iterator_peel(struct ref_iterator *ref_iterator,
+ struct object_id *peeled)
+{
+ struct prefix_ref_iterator *iter =
+ (struct prefix_ref_iterator *)ref_iterator;
+
+ return ref_iterator_peel(iter->iter0, peeled);
+}
+
+static int prefix_ref_iterator_abort(struct ref_iterator *ref_iterator)
+{
+ struct prefix_ref_iterator *iter =
+ (struct prefix_ref_iterator *)ref_iterator;
+ int ok = ITER_DONE;
+
+ if (iter->iter0)
+ ok = ref_iterator_abort(iter->iter0);
+ free(iter->prefix);
+ base_ref_iterator_free(ref_iterator);
+ return ok;
+}
+
+static struct ref_iterator_vtable prefix_ref_iterator_vtable = {
+ .advance = prefix_ref_iterator_advance,
+ .peel = prefix_ref_iterator_peel,
+ .abort = prefix_ref_iterator_abort,
+};
+
+struct ref_iterator *prefix_ref_iterator_begin(struct ref_iterator *iter0,
+ const char *prefix,
+ int trim)
+{
+ struct prefix_ref_iterator *iter;
+ struct ref_iterator *ref_iterator;
+
+ if (!*prefix && !trim)
+ return iter0; /* optimization: no need to wrap iterator */
+
+ CALLOC_ARRAY(iter, 1);
+ ref_iterator = &iter->base;
+
+ base_ref_iterator_init(ref_iterator, &prefix_ref_iterator_vtable, iter0->ordered);
+
+ iter->iter0 = iter0;
+ iter->prefix = xstrdup(prefix);
+ iter->trim = trim;
+
+ return ref_iterator;
+}
+
+struct ref_iterator *current_ref_iter = NULL;
+
+int do_for_each_repo_ref_iterator(struct repository *r, struct ref_iterator *iter,
+ each_repo_ref_fn fn, void *cb_data)
+{
+ int retval = 0, ok;
+ struct ref_iterator *old_ref_iter = current_ref_iter;
+
+ current_ref_iter = iter;
+ while ((ok = ref_iterator_advance(iter)) == ITER_OK) {
+ retval = fn(r, iter->refname, iter->oid, iter->flags, cb_data);
+ if (retval) {
+ /*
+ * If ref_iterator_abort() returns ITER_ERROR,
+ * we ignore that error in deference to the
+ * callback function's return value.
+ */
+ ref_iterator_abort(iter);
+ goto out;
+ }
+ }
+
+out:
+ current_ref_iter = old_ref_iter;
+ if (ok == ITER_ERROR)
+ return -1;
+ return retval;
+}
diff --git a/refs/packed-backend.c b/refs/packed-backend.c
new file mode 100644
index 0000000..c1c71d1
--- /dev/null
+++ b/refs/packed-backend.c
@@ -0,0 +1,1615 @@
+#include "../cache.h"
+#include "../config.h"
+#include "../refs.h"
+#include "refs-internal.h"
+#include "packed-backend.h"
+#include "../iterator.h"
+#include "../lockfile.h"
+#include "../chdir-notify.h"
+
+enum mmap_strategy {
+ /*
+ * Don't use mmap() at all for reading `packed-refs`.
+ */
+ MMAP_NONE,
+
+ /*
+ * Can use mmap() for reading `packed-refs`, but the file must
+ * not remain mmapped. This is the usual option on Windows,
+ * where you cannot rename a new version of a file onto a file
+ * that is currently mmapped.
+ */
+ MMAP_TEMPORARY,
+
+ /*
+ * It is OK to leave the `packed-refs` file mmapped while
+ * arbitrary other code is running.
+ */
+ MMAP_OK
+};
+
+#if defined(NO_MMAP)
+static enum mmap_strategy mmap_strategy = MMAP_NONE;
+#elif defined(MMAP_PREVENTS_DELETE)
+static enum mmap_strategy mmap_strategy = MMAP_TEMPORARY;
+#else
+static enum mmap_strategy mmap_strategy = MMAP_OK;
+#endif
+
+struct packed_ref_store;
+
+/*
+ * A `snapshot` represents one snapshot of a `packed-refs` file.
+ *
+ * Normally, this will be a mmapped view of the contents of the
+ * `packed-refs` file at the time the snapshot was created. However,
+ * if the `packed-refs` file was not sorted, this might point at heap
+ * memory holding the contents of the `packed-refs` file with its
+ * records sorted by refname.
+ *
+ * `snapshot` instances are reference counted (via
+ * `acquire_snapshot()` and `release_snapshot()`). This is to prevent
+ * an instance from disappearing while an iterator is still iterating
+ * over it. Instances are garbage collected when their `referrers`
+ * count goes to zero.
+ *
+ * The most recent `snapshot`, if available, is referenced by the
+ * `packed_ref_store`. Its freshness is checked whenever
+ * `get_snapshot()` is called; if the existing snapshot is obsolete, a
+ * new snapshot is taken.
+ */
+struct snapshot {
+ /*
+ * A back-pointer to the packed_ref_store with which this
+ * snapshot is associated:
+ */
+ struct packed_ref_store *refs;
+
+ /* Is the `packed-refs` file currently mmapped? */
+ int mmapped;
+
+ /*
+ * The contents of the `packed-refs` file:
+ *
+ * - buf -- a pointer to the start of the memory
+ * - start -- a pointer to the first byte of actual references
+ * (i.e., after the header line, if one is present)
+ * - eof -- a pointer just past the end of the reference
+ * contents
+ *
+ * If the `packed-refs` file was already sorted, `buf` points
+ * at the mmapped contents of the file. If not, it points at
+ * heap-allocated memory containing the contents, sorted. If
+ * there were no contents (e.g., because the file didn't
+ * exist), `buf`, `start`, and `eof` are all NULL.
+ */
+ char *buf, *start, *eof;
+
+ /*
+ * What is the peeled state of the `packed-refs` file that
+ * this snapshot represents? (This is usually determined from
+ * the file's header.)
+ */
+ enum { PEELED_NONE, PEELED_TAGS, PEELED_FULLY } peeled;
+
+ /*
+ * Count of references to this instance, including the pointer
+ * from `packed_ref_store::snapshot`, if any. The instance
+ * will not be freed as long as the reference count is
+ * nonzero.
+ */
+ unsigned int referrers;
+
+ /*
+ * The metadata of the `packed-refs` file from which this
+ * snapshot was created, used to tell if the file has been
+ * replaced since we read it.
+ */
+ struct stat_validity validity;
+};
+
+/*
+ * A `ref_store` representing references stored in a `packed-refs`
+ * file. It implements the `ref_store` interface, though it has some
+ * limitations:
+ *
+ * - It cannot store symbolic references.
+ *
+ * - It cannot store reflogs.
+ *
+ * - It does not support reference renaming (though it could).
+ *
+ * On the other hand, it can be locked outside of a reference
+ * transaction. In that case, it remains locked even after the
+ * transaction is done and the new `packed-refs` file is activated.
+ */
+struct packed_ref_store {
+ struct ref_store base;
+
+ unsigned int store_flags;
+
+ /* The path of the "packed-refs" file: */
+ char *path;
+
+ /*
+ * A snapshot of the values read from the `packed-refs` file,
+ * if it might still be current; otherwise, NULL.
+ */
+ struct snapshot *snapshot;
+
+ /*
+ * Lock used for the "packed-refs" file. Note that this (and
+ * thus the enclosing `packed_ref_store`) must not be freed.
+ */
+ struct lock_file lock;
+
+ /*
+ * Temporary file used when rewriting new contents to the
+ * "packed-refs" file. Note that this (and thus the enclosing
+ * `packed_ref_store`) must not be freed.
+ */
+ struct tempfile *tempfile;
+};
+
+/*
+ * Increment the reference count of `*snapshot`.
+ */
+static void acquire_snapshot(struct snapshot *snapshot)
+{
+ snapshot->referrers++;
+}
+
+/*
+ * If the buffer in `snapshot` is active, then either munmap the
+ * memory and close the file, or free the memory. Then set the buffer
+ * pointers to NULL.
+ */
+static void clear_snapshot_buffer(struct snapshot *snapshot)
+{
+ if (snapshot->mmapped) {
+ if (munmap(snapshot->buf, snapshot->eof - snapshot->buf))
+ die_errno("error ummapping packed-refs file %s",
+ snapshot->refs->path);
+ snapshot->mmapped = 0;
+ } else {
+ free(snapshot->buf);
+ }
+ snapshot->buf = snapshot->start = snapshot->eof = NULL;
+}
+
+/*
+ * Decrease the reference count of `*snapshot`. If it goes to zero,
+ * free `*snapshot` and return true; otherwise return false.
+ */
+static int release_snapshot(struct snapshot *snapshot)
+{
+ if (!--snapshot->referrers) {
+ stat_validity_clear(&snapshot->validity);
+ clear_snapshot_buffer(snapshot);
+ free(snapshot);
+ return 1;
+ } else {
+ return 0;
+ }
+}
+
+struct ref_store *packed_ref_store_create(struct repository *repo,
+ const char *gitdir,
+ unsigned int store_flags)
+{
+ struct packed_ref_store *refs = xcalloc(1, sizeof(*refs));
+ struct ref_store *ref_store = (struct ref_store *)refs;
+ struct strbuf sb = STRBUF_INIT;
+
+ base_ref_store_init(ref_store, repo, gitdir, &refs_be_packed);
+ refs->store_flags = store_flags;
+
+ strbuf_addf(&sb, "%s/packed-refs", gitdir);
+ refs->path = strbuf_detach(&sb, NULL);
+ chdir_notify_reparent("packed-refs", &refs->path);
+ return ref_store;
+}
+
+/*
+ * Downcast `ref_store` to `packed_ref_store`. Die if `ref_store` is
+ * not a `packed_ref_store`. Also die if `packed_ref_store` doesn't
+ * support at least the flags specified in `required_flags`. `caller`
+ * is used in any necessary error messages.
+ */
+static struct packed_ref_store *packed_downcast(struct ref_store *ref_store,
+ unsigned int required_flags,
+ const char *caller)
+{
+ struct packed_ref_store *refs;
+
+ if (ref_store->be != &refs_be_packed)
+ BUG("ref_store is type \"%s\" not \"packed\" in %s",
+ ref_store->be->name, caller);
+
+ refs = (struct packed_ref_store *)ref_store;
+
+ if ((refs->store_flags & required_flags) != required_flags)
+ BUG("unallowed operation (%s), requires %x, has %x\n",
+ caller, required_flags, refs->store_flags);
+
+ return refs;
+}
+
+static void clear_snapshot(struct packed_ref_store *refs)
+{
+ if (refs->snapshot) {
+ struct snapshot *snapshot = refs->snapshot;
+
+ refs->snapshot = NULL;
+ release_snapshot(snapshot);
+ }
+}
+
+static NORETURN void die_unterminated_line(const char *path,
+ const char *p, size_t len)
+{
+ if (len < 80)
+ die("unterminated line in %s: %.*s", path, (int)len, p);
+ else
+ die("unterminated line in %s: %.75s...", path, p);
+}
+
+static NORETURN void die_invalid_line(const char *path,
+ const char *p, size_t len)
+{
+ const char *eol = memchr(p, '\n', len);
+
+ if (!eol)
+ die_unterminated_line(path, p, len);
+ else if (eol - p < 80)
+ die("unexpected line in %s: %.*s", path, (int)(eol - p), p);
+ else
+ die("unexpected line in %s: %.75s...", path, p);
+
+}
+
+struct snapshot_record {
+ const char *start;
+ size_t len;
+};
+
+static int cmp_packed_ref_records(const void *v1, const void *v2)
+{
+ const struct snapshot_record *e1 = v1, *e2 = v2;
+ const char *r1 = e1->start + the_hash_algo->hexsz + 1;
+ const char *r2 = e2->start + the_hash_algo->hexsz + 1;
+
+ while (1) {
+ if (*r1 == '\n')
+ return *r2 == '\n' ? 0 : -1;
+ if (*r1 != *r2) {
+ if (*r2 == '\n')
+ return 1;
+ else
+ return (unsigned char)*r1 < (unsigned char)*r2 ? -1 : +1;
+ }
+ r1++;
+ r2++;
+ }
+}
+
+/*
+ * Compare a snapshot record at `rec` to the specified NUL-terminated
+ * refname.
+ */
+static int cmp_record_to_refname(const char *rec, const char *refname)
+{
+ const char *r1 = rec + the_hash_algo->hexsz + 1;
+ const char *r2 = refname;
+
+ while (1) {
+ if (*r1 == '\n')
+ return *r2 ? -1 : 0;
+ if (!*r2)
+ return 1;
+ if (*r1 != *r2)
+ return (unsigned char)*r1 < (unsigned char)*r2 ? -1 : +1;
+ r1++;
+ r2++;
+ }
+}
+
+/*
+ * `snapshot->buf` is not known to be sorted. Check whether it is, and
+ * if not, sort it into new memory and munmap/free the old storage.
+ */
+static void sort_snapshot(struct snapshot *snapshot)
+{
+ struct snapshot_record *records = NULL;
+ size_t alloc = 0, nr = 0;
+ int sorted = 1;
+ const char *pos, *eof, *eol;
+ size_t len, i;
+ char *new_buffer, *dst;
+
+ pos = snapshot->start;
+ eof = snapshot->eof;
+
+ if (pos == eof)
+ return;
+
+ len = eof - pos;
+
+ /*
+ * Initialize records based on a crude estimate of the number
+ * of references in the file (we'll grow it below if needed):
+ */
+ ALLOC_GROW(records, len / 80 + 20, alloc);
+
+ while (pos < eof) {
+ eol = memchr(pos, '\n', eof - pos);
+ if (!eol)
+ /* The safety check should prevent this. */
+ BUG("unterminated line found in packed-refs");
+ if (eol - pos < the_hash_algo->hexsz + 2)
+ die_invalid_line(snapshot->refs->path,
+ pos, eof - pos);
+ eol++;
+ if (eol < eof && *eol == '^') {
+ /*
+ * Keep any peeled line together with its
+ * reference:
+ */
+ const char *peeled_start = eol;
+
+ eol = memchr(peeled_start, '\n', eof - peeled_start);
+ if (!eol)
+ /* The safety check should prevent this. */
+ BUG("unterminated peeled line found in packed-refs");
+ eol++;
+ }
+
+ ALLOC_GROW(records, nr + 1, alloc);
+ records[nr].start = pos;
+ records[nr].len = eol - pos;
+ nr++;
+
+ if (sorted &&
+ nr > 1 &&
+ cmp_packed_ref_records(&records[nr - 2],
+ &records[nr - 1]) >= 0)
+ sorted = 0;
+
+ pos = eol;
+ }
+
+ if (sorted)
+ goto cleanup;
+
+ /* We need to sort the memory. First we sort the records array: */
+ QSORT(records, nr, cmp_packed_ref_records);
+
+ /*
+ * Allocate a new chunk of memory, and copy the old memory to
+ * the new in the order indicated by `records` (not bothering
+ * with the header line):
+ */
+ new_buffer = xmalloc(len);
+ for (dst = new_buffer, i = 0; i < nr; i++) {
+ memcpy(dst, records[i].start, records[i].len);
+ dst += records[i].len;
+ }
+
+ /*
+ * Now munmap the old buffer and use the sorted buffer in its
+ * place:
+ */
+ clear_snapshot_buffer(snapshot);
+ snapshot->buf = snapshot->start = new_buffer;
+ snapshot->eof = new_buffer + len;
+
+cleanup:
+ free(records);
+}
+
+/*
+ * Return a pointer to the start of the record that contains the
+ * character `*p` (which must be within the buffer). If no other
+ * record start is found, return `buf`.
+ */
+static const char *find_start_of_record(const char *buf, const char *p)
+{
+ while (p > buf && (p[-1] != '\n' || p[0] == '^'))
+ p--;
+ return p;
+}
+
+/*
+ * Return a pointer to the start of the record following the record
+ * that contains `*p`. If none is found before `end`, return `end`.
+ */
+static const char *find_end_of_record(const char *p, const char *end)
+{
+ while (++p < end && (p[-1] != '\n' || p[0] == '^'))
+ ;
+ return p;
+}
+
+/*
+ * We want to be able to compare mmapped reference records quickly,
+ * without totally parsing them. We can do so because the records are
+ * LF-terminated, and the refname should start exactly (GIT_SHA1_HEXSZ
+ * + 1) bytes past the beginning of the record.
+ *
+ * But what if the `packed-refs` file contains garbage? We're willing
+ * to tolerate not detecting the problem, as long as we don't produce
+ * totally garbled output (we can't afford to check the integrity of
+ * the whole file during every Git invocation). But we do want to be
+ * sure that we never read past the end of the buffer in memory and
+ * perform an illegal memory access.
+ *
+ * Guarantee that minimum level of safety by verifying that the last
+ * record in the file is LF-terminated, and that it has at least
+ * (GIT_SHA1_HEXSZ + 1) characters before the LF. Die if either of
+ * these checks fails.
+ */
+static void verify_buffer_safe(struct snapshot *snapshot)
+{
+ const char *start = snapshot->start;
+ const char *eof = snapshot->eof;
+ const char *last_line;
+
+ if (start == eof)
+ return;
+
+ last_line = find_start_of_record(start, eof - 1);
+ if (*(eof - 1) != '\n' || eof - last_line < the_hash_algo->hexsz + 2)
+ die_invalid_line(snapshot->refs->path,
+ last_line, eof - last_line);
+}
+
+#define SMALL_FILE_SIZE (32*1024)
+
+/*
+ * Depending on `mmap_strategy`, either mmap or read the contents of
+ * the `packed-refs` file into the snapshot. Return 1 if the file
+ * existed and was read, or 0 if the file was absent or empty. Die on
+ * errors.
+ */
+static int load_contents(struct snapshot *snapshot)
+{
+ int fd;
+ struct stat st;
+ size_t size;
+ ssize_t bytes_read;
+
+ fd = open(snapshot->refs->path, O_RDONLY);
+ if (fd < 0) {
+ if (errno == ENOENT) {
+ /*
+ * This is OK; it just means that no
+ * "packed-refs" file has been written yet,
+ * which is equivalent to it being empty,
+ * which is its state when initialized with
+ * zeros.
+ */
+ return 0;
+ } else {
+ die_errno("couldn't read %s", snapshot->refs->path);
+ }
+ }
+
+ stat_validity_update(&snapshot->validity, fd);
+
+ if (fstat(fd, &st) < 0)
+ die_errno("couldn't stat %s", snapshot->refs->path);
+ size = xsize_t(st.st_size);
+
+ if (!size) {
+ close(fd);
+ return 0;
+ } else if (mmap_strategy == MMAP_NONE || size <= SMALL_FILE_SIZE) {
+ snapshot->buf = xmalloc(size);
+ bytes_read = read_in_full(fd, snapshot->buf, size);
+ if (bytes_read < 0 || bytes_read != size)
+ die_errno("couldn't read %s", snapshot->refs->path);
+ snapshot->mmapped = 0;
+ } else {
+ snapshot->buf = xmmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
+ snapshot->mmapped = 1;
+ }
+ close(fd);
+
+ snapshot->start = snapshot->buf;
+ snapshot->eof = snapshot->buf + size;
+
+ return 1;
+}
+
+/*
+ * Find the place in `snapshot->buf` where the start of the record for
+ * `refname` starts. If `mustexist` is true and the reference doesn't
+ * exist, then return NULL. If `mustexist` is false and the reference
+ * doesn't exist, then return the point where that reference would be
+ * inserted, or `snapshot->eof` (which might be NULL) if it would be
+ * inserted at the end of the file. In the latter mode, `refname`
+ * doesn't have to be a proper reference name; for example, one could
+ * search for "refs/replace/" to find the start of any replace
+ * references.
+ *
+ * The record is sought using a binary search, so `snapshot->buf` must
+ * be sorted.
+ */
+static const char *find_reference_location(struct snapshot *snapshot,
+ const char *refname, int mustexist)
+{
+ /*
+ * This is not *quite* a garden-variety binary search, because
+ * the data we're searching is made up of records, and we
+ * always need to find the beginning of a record to do a
+ * comparison. A "record" here is one line for the reference
+ * itself and zero or one peel lines that start with '^'. Our
+ * loop invariant is described in the next two comments.
+ */
+
+ /*
+ * A pointer to the character at the start of a record whose
+ * preceding records all have reference names that come
+ * *before* `refname`.
+ */
+ const char *lo = snapshot->start;
+
+ /*
+ * A pointer to a the first character of a record whose
+ * reference name comes *after* `refname`.
+ */
+ const char *hi = snapshot->eof;
+
+ while (lo != hi) {
+ const char *mid, *rec;
+ int cmp;
+
+ mid = lo + (hi - lo) / 2;
+ rec = find_start_of_record(lo, mid);
+ cmp = cmp_record_to_refname(rec, refname);
+ if (cmp < 0) {
+ lo = find_end_of_record(mid, hi);
+ } else if (cmp > 0) {
+ hi = rec;
+ } else {
+ return rec;
+ }
+ }
+
+ if (mustexist)
+ return NULL;
+ else
+ return lo;
+}
+
+/*
+ * Create a newly-allocated `snapshot` of the `packed-refs` file in
+ * its current state and return it. The return value will already have
+ * its reference count incremented.
+ *
+ * A comment line of the form "# pack-refs with: " may contain zero or
+ * more traits. We interpret the traits as follows:
+ *
+ * Neither `peeled` nor `fully-peeled`:
+ *
+ * Probably no references are peeled. But if the file contains a
+ * peeled value for a reference, we will use it.
+ *
+ * `peeled`:
+ *
+ * References under "refs/tags/", if they *can* be peeled, *are*
+ * peeled in this file. References outside of "refs/tags/" are
+ * probably not peeled even if they could have been, but if we find
+ * a peeled value for such a reference we will use it.
+ *
+ * `fully-peeled`:
+ *
+ * All references in the file that can be peeled are peeled.
+ * Inversely (and this is more important), any references in the
+ * file for which no peeled value is recorded is not peelable. This
+ * trait should typically be written alongside "peeled" for
+ * compatibility with older clients, but we do not require it
+ * (i.e., "peeled" is a no-op if "fully-peeled" is set).
+ *
+ * `sorted`:
+ *
+ * The references in this file are known to be sorted by refname.
+ */
+static struct snapshot *create_snapshot(struct packed_ref_store *refs)
+{
+ struct snapshot *snapshot = xcalloc(1, sizeof(*snapshot));
+ int sorted = 0;
+
+ snapshot->refs = refs;
+ acquire_snapshot(snapshot);
+ snapshot->peeled = PEELED_NONE;
+
+ if (!load_contents(snapshot))
+ return snapshot;
+
+ /* If the file has a header line, process it: */
+ if (snapshot->buf < snapshot->eof && *snapshot->buf == '#') {
+ char *tmp, *p, *eol;
+ struct string_list traits = STRING_LIST_INIT_NODUP;
+
+ eol = memchr(snapshot->buf, '\n',
+ snapshot->eof - snapshot->buf);
+ if (!eol)
+ die_unterminated_line(refs->path,
+ snapshot->buf,
+ snapshot->eof - snapshot->buf);
+
+ tmp = xmemdupz(snapshot->buf, eol - snapshot->buf);
+
+ if (!skip_prefix(tmp, "# pack-refs with:", (const char **)&p))
+ die_invalid_line(refs->path,
+ snapshot->buf,
+ snapshot->eof - snapshot->buf);
+
+ string_list_split_in_place(&traits, p, ' ', -1);
+
+ if (unsorted_string_list_has_string(&traits, "fully-peeled"))
+ snapshot->peeled = PEELED_FULLY;
+ else if (unsorted_string_list_has_string(&traits, "peeled"))
+ snapshot->peeled = PEELED_TAGS;
+
+ sorted = unsorted_string_list_has_string(&traits, "sorted");
+
+ /* perhaps other traits later as well */
+
+ /* The "+ 1" is for the LF character. */
+ snapshot->start = eol + 1;
+
+ string_list_clear(&traits, 0);
+ free(tmp);
+ }
+
+ verify_buffer_safe(snapshot);
+
+ if (!sorted) {
+ sort_snapshot(snapshot);
+
+ /*
+ * Reordering the records might have moved a short one
+ * to the end of the buffer, so verify the buffer's
+ * safety again:
+ */
+ verify_buffer_safe(snapshot);
+ }
+
+ if (mmap_strategy != MMAP_OK && snapshot->mmapped) {
+ /*
+ * We don't want to leave the file mmapped, so we are
+ * forced to make a copy now:
+ */
+ size_t size = snapshot->eof - snapshot->start;
+ char *buf_copy = xmalloc(size);
+
+ memcpy(buf_copy, snapshot->start, size);
+ clear_snapshot_buffer(snapshot);
+ snapshot->buf = snapshot->start = buf_copy;
+ snapshot->eof = buf_copy + size;
+ }
+
+ return snapshot;
+}
+
+/*
+ * Check that `refs->snapshot` (if present) still reflects the
+ * contents of the `packed-refs` file. If not, clear the snapshot.
+ */
+static void validate_snapshot(struct packed_ref_store *refs)
+{
+ if (refs->snapshot &&
+ !stat_validity_check(&refs->snapshot->validity, refs->path))
+ clear_snapshot(refs);
+}
+
+/*
+ * Get the `snapshot` for the specified packed_ref_store, creating and
+ * populating it if it hasn't been read before or if the file has been
+ * changed (according to its `validity` field) since it was last read.
+ * On the other hand, if we hold the lock, then assume that the file
+ * hasn't been changed out from under us, so skip the extra `stat()`
+ * call in `stat_validity_check()`. This function does *not* increase
+ * the snapshot's reference count on behalf of the caller.
+ */
+static struct snapshot *get_snapshot(struct packed_ref_store *refs)
+{
+ if (!is_lock_file_locked(&refs->lock))
+ validate_snapshot(refs);
+
+ if (!refs->snapshot)
+ refs->snapshot = create_snapshot(refs);
+
+ return refs->snapshot;
+}
+
+static int packed_read_raw_ref(struct ref_store *ref_store, const char *refname,
+ struct object_id *oid, struct strbuf *referent UNUSED,
+ unsigned int *type, int *failure_errno)
+{
+ struct packed_ref_store *refs =
+ packed_downcast(ref_store, REF_STORE_READ, "read_raw_ref");
+ struct snapshot *snapshot = get_snapshot(refs);
+ const char *rec;
+
+ *type = 0;
+
+ rec = find_reference_location(snapshot, refname, 1);
+
+ if (!rec) {
+ /* refname is not a packed reference. */
+ *failure_errno = ENOENT;
+ return -1;
+ }
+
+ if (get_oid_hex(rec, oid))
+ die_invalid_line(refs->path, rec, snapshot->eof - rec);
+
+ *type = REF_ISPACKED;
+ return 0;
+}
+
+/*
+ * This value is set in `base.flags` if the peeled value of the
+ * current reference is known. In that case, `peeled` contains the
+ * correct peeled value for the reference, which might be `null_oid`
+ * if the reference is not a tag or if it is broken.
+ */
+#define REF_KNOWS_PEELED 0x40
+
+/*
+ * An iterator over a snapshot of a `packed-refs` file.
+ */
+struct packed_ref_iterator {
+ struct ref_iterator base;
+
+ struct snapshot *snapshot;
+
+ /* The current position in the snapshot's buffer: */
+ const char *pos;
+
+ /* The end of the part of the buffer that will be iterated over: */
+ const char *eof;
+
+ /* Scratch space for current values: */
+ struct object_id oid, peeled;
+ struct strbuf refname_buf;
+
+ struct repository *repo;
+ unsigned int flags;
+};
+
+/*
+ * Move the iterator to the next record in the snapshot, without
+ * respect for whether the record is actually required by the current
+ * iteration. Adjust the fields in `iter` and return `ITER_OK` or
+ * `ITER_DONE`. This function does not free the iterator in the case
+ * of `ITER_DONE`.
+ */
+static int next_record(struct packed_ref_iterator *iter)
+{
+ const char *p = iter->pos, *eol;
+
+ strbuf_reset(&iter->refname_buf);
+
+ if (iter->pos == iter->eof)
+ return ITER_DONE;
+
+ iter->base.flags = REF_ISPACKED;
+
+ if (iter->eof - p < the_hash_algo->hexsz + 2 ||
+ parse_oid_hex(p, &iter->oid, &p) ||
+ !isspace(*p++))
+ die_invalid_line(iter->snapshot->refs->path,
+ iter->pos, iter->eof - iter->pos);
+
+ eol = memchr(p, '\n', iter->eof - p);
+ if (!eol)
+ die_unterminated_line(iter->snapshot->refs->path,
+ iter->pos, iter->eof - iter->pos);
+
+ strbuf_add(&iter->refname_buf, p, eol - p);
+ iter->base.refname = iter->refname_buf.buf;
+
+ if (check_refname_format(iter->base.refname, REFNAME_ALLOW_ONELEVEL)) {
+ if (!refname_is_safe(iter->base.refname))
+ die("packed refname is dangerous: %s",
+ iter->base.refname);
+ oidclr(&iter->oid);
+ iter->base.flags |= REF_BAD_NAME | REF_ISBROKEN;
+ }
+ if (iter->snapshot->peeled == PEELED_FULLY ||
+ (iter->snapshot->peeled == PEELED_TAGS &&
+ starts_with(iter->base.refname, "refs/tags/")))
+ iter->base.flags |= REF_KNOWS_PEELED;
+
+ iter->pos = eol + 1;
+
+ if (iter->pos < iter->eof && *iter->pos == '^') {
+ p = iter->pos + 1;
+ if (iter->eof - p < the_hash_algo->hexsz + 1 ||
+ parse_oid_hex(p, &iter->peeled, &p) ||
+ *p++ != '\n')
+ die_invalid_line(iter->snapshot->refs->path,
+ iter->pos, iter->eof - iter->pos);
+ iter->pos = p;
+
+ /*
+ * Regardless of what the file header said, we
+ * definitely know the value of *this* reference. But
+ * we suppress it if the reference is broken:
+ */
+ if ((iter->base.flags & REF_ISBROKEN)) {
+ oidclr(&iter->peeled);
+ iter->base.flags &= ~REF_KNOWS_PEELED;
+ } else {
+ iter->base.flags |= REF_KNOWS_PEELED;
+ }
+ } else {
+ oidclr(&iter->peeled);
+ }
+
+ return ITER_OK;
+}
+
+static int packed_ref_iterator_advance(struct ref_iterator *ref_iterator)
+{
+ struct packed_ref_iterator *iter =
+ (struct packed_ref_iterator *)ref_iterator;
+ int ok;
+
+ while ((ok = next_record(iter)) == ITER_OK) {
+ if (iter->flags & DO_FOR_EACH_PER_WORKTREE_ONLY &&
+ !is_per_worktree_ref(iter->base.refname))
+ continue;
+
+ if (!(iter->flags & DO_FOR_EACH_INCLUDE_BROKEN) &&
+ !ref_resolves_to_object(iter->base.refname, iter->repo,
+ &iter->oid, iter->flags))
+ continue;
+
+ return ITER_OK;
+ }
+
+ if (ref_iterator_abort(ref_iterator) != ITER_DONE)
+ ok = ITER_ERROR;
+
+ return ok;
+}
+
+static int packed_ref_iterator_peel(struct ref_iterator *ref_iterator,
+ struct object_id *peeled)
+{
+ struct packed_ref_iterator *iter =
+ (struct packed_ref_iterator *)ref_iterator;
+
+ if (iter->repo != the_repository)
+ BUG("peeling for non-the_repository is not supported");
+
+ if ((iter->base.flags & REF_KNOWS_PEELED)) {
+ oidcpy(peeled, &iter->peeled);
+ return is_null_oid(&iter->peeled) ? -1 : 0;
+ } else if ((iter->base.flags & (REF_ISBROKEN | REF_ISSYMREF))) {
+ return -1;
+ } else {
+ return peel_object(&iter->oid, peeled) ? -1 : 0;
+ }
+}
+
+static int packed_ref_iterator_abort(struct ref_iterator *ref_iterator)
+{
+ struct packed_ref_iterator *iter =
+ (struct packed_ref_iterator *)ref_iterator;
+ int ok = ITER_DONE;
+
+ strbuf_release(&iter->refname_buf);
+ release_snapshot(iter->snapshot);
+ base_ref_iterator_free(ref_iterator);
+ return ok;
+}
+
+static struct ref_iterator_vtable packed_ref_iterator_vtable = {
+ .advance = packed_ref_iterator_advance,
+ .peel = packed_ref_iterator_peel,
+ .abort = packed_ref_iterator_abort
+};
+
+static struct ref_iterator *packed_ref_iterator_begin(
+ struct ref_store *ref_store,
+ const char *prefix, unsigned int flags)
+{
+ struct packed_ref_store *refs;
+ struct snapshot *snapshot;
+ const char *start;
+ struct packed_ref_iterator *iter;
+ struct ref_iterator *ref_iterator;
+ unsigned int required_flags = REF_STORE_READ;
+
+ if (!(flags & DO_FOR_EACH_INCLUDE_BROKEN))
+ required_flags |= REF_STORE_ODB;
+ refs = packed_downcast(ref_store, required_flags, "ref_iterator_begin");
+
+ /*
+ * Note that `get_snapshot()` internally checks whether the
+ * snapshot is up to date with what is on disk, and re-reads
+ * it if not.
+ */
+ snapshot = get_snapshot(refs);
+
+ if (prefix && *prefix)
+ start = find_reference_location(snapshot, prefix, 0);
+ else
+ start = snapshot->start;
+
+ if (start == snapshot->eof)
+ return empty_ref_iterator_begin();
+
+ CALLOC_ARRAY(iter, 1);
+ ref_iterator = &iter->base;
+ base_ref_iterator_init(ref_iterator, &packed_ref_iterator_vtable, 1);
+
+ iter->snapshot = snapshot;
+ acquire_snapshot(snapshot);
+
+ iter->pos = start;
+ iter->eof = snapshot->eof;
+ strbuf_init(&iter->refname_buf, 0);
+
+ iter->base.oid = &iter->oid;
+
+ iter->repo = ref_store->repo;
+ iter->flags = flags;
+
+ if (prefix && *prefix)
+ /* Stop iteration after we've gone *past* prefix: */
+ ref_iterator = prefix_ref_iterator_begin(ref_iterator, prefix, 0);
+
+ return ref_iterator;
+}
+
+/*
+ * Write an entry to the packed-refs file for the specified refname.
+ * If peeled is non-NULL, write it as the entry's peeled value. On
+ * error, return a nonzero value and leave errno set at the value left
+ * by the failing call to `fprintf()`.
+ */
+static int write_packed_entry(FILE *fh, const char *refname,
+ const struct object_id *oid,
+ const struct object_id *peeled)
+{
+ if (fprintf(fh, "%s %s\n", oid_to_hex(oid), refname) < 0 ||
+ (peeled && fprintf(fh, "^%s\n", oid_to_hex(peeled)) < 0))
+ return -1;
+
+ return 0;
+}
+
+int packed_refs_lock(struct ref_store *ref_store, int flags, struct strbuf *err)
+{
+ struct packed_ref_store *refs =
+ packed_downcast(ref_store, REF_STORE_WRITE | REF_STORE_MAIN,
+ "packed_refs_lock");
+ static int timeout_configured = 0;
+ static int timeout_value = 1000;
+
+ if (!timeout_configured) {
+ git_config_get_int("core.packedrefstimeout", &timeout_value);
+ timeout_configured = 1;
+ }
+
+ /*
+ * Note that we close the lockfile immediately because we
+ * don't write new content to it, but rather to a separate
+ * tempfile.
+ */
+ if (hold_lock_file_for_update_timeout(
+ &refs->lock,
+ refs->path,
+ flags, timeout_value) < 0) {
+ unable_to_lock_message(refs->path, errno, err);
+ return -1;
+ }
+
+ if (close_lock_file_gently(&refs->lock)) {
+ strbuf_addf(err, "unable to close %s: %s", refs->path, strerror(errno));
+ rollback_lock_file(&refs->lock);
+ return -1;
+ }
+
+ /*
+ * There is a stat-validity problem might cause `update-ref -d`
+ * lost the newly commit of a ref, because a new `packed-refs`
+ * file might has the same on-disk file attributes such as
+ * timestamp, file size and inode value, but has a changed
+ * ref value.
+ *
+ * This could happen with a very small chance when
+ * `update-ref -d` is called and at the same time another
+ * `pack-refs --all` process is running.
+ *
+ * Now that we hold the `packed-refs` lock, it is important
+ * to make sure we could read the latest version of
+ * `packed-refs` file no matter we have just mmap it or not.
+ * So what need to do is clear the snapshot if we hold it
+ * already.
+ */
+ clear_snapshot(refs);
+
+ /*
+ * Now make sure that the packed-refs file as it exists in the
+ * locked state is loaded into the snapshot:
+ */
+ get_snapshot(refs);
+ return 0;
+}
+
+void packed_refs_unlock(struct ref_store *ref_store)
+{
+ struct packed_ref_store *refs = packed_downcast(
+ ref_store,
+ REF_STORE_READ | REF_STORE_WRITE,
+ "packed_refs_unlock");
+
+ if (!is_lock_file_locked(&refs->lock))
+ BUG("packed_refs_unlock() called when not locked");
+ rollback_lock_file(&refs->lock);
+}
+
+int packed_refs_is_locked(struct ref_store *ref_store)
+{
+ struct packed_ref_store *refs = packed_downcast(
+ ref_store,
+ REF_STORE_READ | REF_STORE_WRITE,
+ "packed_refs_is_locked");
+
+ return is_lock_file_locked(&refs->lock);
+}
+
+/*
+ * The packed-refs header line that we write out. Perhaps other traits
+ * will be added later.
+ *
+ * Note that earlier versions of Git used to parse these traits by
+ * looking for " trait " in the line. For this reason, the space after
+ * the colon and the trailing space are required.
+ */
+static const char PACKED_REFS_HEADER[] =
+ "# pack-refs with: peeled fully-peeled sorted \n";
+
+static int packed_init_db(struct ref_store *ref_store UNUSED,
+ struct strbuf *err UNUSED)
+{
+ /* Nothing to do. */
+ return 0;
+}
+
+/*
+ * Write the packed refs from the current snapshot to the packed-refs
+ * tempfile, incorporating any changes from `updates`. `updates` must
+ * be a sorted string list whose keys are the refnames and whose util
+ * values are `struct ref_update *`. On error, rollback the tempfile,
+ * write an error message to `err`, and return a nonzero value.
+ *
+ * The packfile must be locked before calling this function and will
+ * remain locked when it is done.
+ */
+static int write_with_updates(struct packed_ref_store *refs,
+ struct string_list *updates,
+ struct strbuf *err)
+{
+ struct ref_iterator *iter = NULL;
+ size_t i;
+ int ok;
+ FILE *out;
+ struct strbuf sb = STRBUF_INIT;
+ char *packed_refs_path;
+
+ if (!is_lock_file_locked(&refs->lock))
+ BUG("write_with_updates() called while unlocked");
+
+ /*
+ * If packed-refs is a symlink, we want to overwrite the
+ * symlinked-to file, not the symlink itself. Also, put the
+ * staging file next to it:
+ */
+ packed_refs_path = get_locked_file_path(&refs->lock);
+ strbuf_addf(&sb, "%s.new", packed_refs_path);
+ free(packed_refs_path);
+ refs->tempfile = create_tempfile(sb.buf);
+ if (!refs->tempfile) {
+ strbuf_addf(err, "unable to create file %s: %s",
+ sb.buf, strerror(errno));
+ strbuf_release(&sb);
+ return -1;
+ }
+ strbuf_release(&sb);
+
+ out = fdopen_tempfile(refs->tempfile, "w");
+ if (!out) {
+ strbuf_addf(err, "unable to fdopen packed-refs tempfile: %s",
+ strerror(errno));
+ goto error;
+ }
+
+ if (fprintf(out, "%s", PACKED_REFS_HEADER) < 0)
+ goto write_error;
+
+ /*
+ * We iterate in parallel through the current list of refs and
+ * the list of updates, processing an entry from at least one
+ * of the lists each time through the loop. When the current
+ * list of refs is exhausted, set iter to NULL. When the list
+ * of updates is exhausted, leave i set to updates->nr.
+ */
+ iter = packed_ref_iterator_begin(&refs->base, "",
+ DO_FOR_EACH_INCLUDE_BROKEN);
+ if ((ok = ref_iterator_advance(iter)) != ITER_OK)
+ iter = NULL;
+
+ i = 0;
+
+ while (iter || i < updates->nr) {
+ struct ref_update *update = NULL;
+ int cmp;
+
+ if (i >= updates->nr) {
+ cmp = -1;
+ } else {
+ update = updates->items[i].util;
+
+ if (!iter)
+ cmp = +1;
+ else
+ cmp = strcmp(iter->refname, update->refname);
+ }
+
+ if (!cmp) {
+ /*
+ * There is both an old value and an update
+ * for this reference. Check the old value if
+ * necessary:
+ */
+ if ((update->flags & REF_HAVE_OLD)) {
+ if (is_null_oid(&update->old_oid)) {
+ strbuf_addf(err, "cannot update ref '%s': "
+ "reference already exists",
+ update->refname);
+ goto error;
+ } else if (!oideq(&update->old_oid, iter->oid)) {
+ strbuf_addf(err, "cannot update ref '%s': "
+ "is at %s but expected %s",
+ update->refname,
+ oid_to_hex(iter->oid),
+ oid_to_hex(&update->old_oid));
+ goto error;
+ }
+ }
+
+ /* Now figure out what to use for the new value: */
+ if ((update->flags & REF_HAVE_NEW)) {
+ /*
+ * The update takes precedence. Skip
+ * the iterator over the unneeded
+ * value.
+ */
+ if ((ok = ref_iterator_advance(iter)) != ITER_OK)
+ iter = NULL;
+ cmp = +1;
+ } else {
+ /*
+ * The update doesn't actually want to
+ * change anything. We're done with it.
+ */
+ i++;
+ cmp = -1;
+ }
+ } else if (cmp > 0) {
+ /*
+ * There is no old value but there is an
+ * update for this reference. Make sure that
+ * the update didn't expect an existing value:
+ */
+ if ((update->flags & REF_HAVE_OLD) &&
+ !is_null_oid(&update->old_oid)) {
+ strbuf_addf(err, "cannot update ref '%s': "
+ "reference is missing but expected %s",
+ update->refname,
+ oid_to_hex(&update->old_oid));
+ goto error;
+ }
+ }
+
+ if (cmp < 0) {
+ /* Pass the old reference through. */
+
+ struct object_id peeled;
+ int peel_error = ref_iterator_peel(iter, &peeled);
+
+ if (write_packed_entry(out, iter->refname,
+ iter->oid,
+ peel_error ? NULL : &peeled))
+ goto write_error;
+
+ if ((ok = ref_iterator_advance(iter)) != ITER_OK)
+ iter = NULL;
+ } else if (is_null_oid(&update->new_oid)) {
+ /*
+ * The update wants to delete the reference,
+ * and the reference either didn't exist or we
+ * have already skipped it. So we're done with
+ * the update (and don't have to write
+ * anything).
+ */
+ i++;
+ } else {
+ struct object_id peeled;
+ int peel_error = peel_object(&update->new_oid,
+ &peeled);
+
+ if (write_packed_entry(out, update->refname,
+ &update->new_oid,
+ peel_error ? NULL : &peeled))
+ goto write_error;
+
+ i++;
+ }
+ }
+
+ if (ok != ITER_DONE) {
+ strbuf_addstr(err, "unable to write packed-refs file: "
+ "error iterating over old contents");
+ goto error;
+ }
+
+ if (fsync_component(FSYNC_COMPONENT_REFERENCE, get_tempfile_fd(refs->tempfile)) ||
+ close_tempfile_gently(refs->tempfile)) {
+ strbuf_addf(err, "error closing file %s: %s",
+ get_tempfile_path(refs->tempfile),
+ strerror(errno));
+ strbuf_release(&sb);
+ delete_tempfile(&refs->tempfile);
+ return -1;
+ }
+
+ return 0;
+
+write_error:
+ strbuf_addf(err, "error writing to %s: %s",
+ get_tempfile_path(refs->tempfile), strerror(errno));
+
+error:
+ if (iter)
+ ref_iterator_abort(iter);
+
+ delete_tempfile(&refs->tempfile);
+ return -1;
+}
+
+int is_packed_transaction_needed(struct ref_store *ref_store,
+ struct ref_transaction *transaction)
+{
+ struct packed_ref_store *refs = packed_downcast(
+ ref_store,
+ REF_STORE_READ,
+ "is_packed_transaction_needed");
+ struct strbuf referent = STRBUF_INIT;
+ size_t i;
+ int ret;
+
+ if (!is_lock_file_locked(&refs->lock))
+ BUG("is_packed_transaction_needed() called while unlocked");
+
+ /*
+ * We're only going to bother returning false for the common,
+ * trivial case that references are only being deleted, their
+ * old values are not being checked, and the old `packed-refs`
+ * file doesn't contain any of those reference(s). This gives
+ * false positives for some other cases that could
+ * theoretically be optimized away:
+ *
+ * 1. It could be that the old value is being verified without
+ * setting a new value. In this case, we could verify the
+ * old value here and skip the update if it agrees. If it
+ * disagrees, we could either let the update go through
+ * (the actual commit would re-detect and report the
+ * problem), or come up with a way of reporting such an
+ * error to *our* caller.
+ *
+ * 2. It could be that a new value is being set, but that it
+ * is identical to the current packed value of the
+ * reference.
+ *
+ * Neither of these cases will come up in the current code,
+ * because the only caller of this function passes to it a
+ * transaction that only includes `delete` updates with no
+ * `old_id`. Even if that ever changes, false positives only
+ * cause an optimization to be missed; they do not affect
+ * correctness.
+ */
+
+ /*
+ * Start with the cheap checks that don't require old
+ * reference values to be read:
+ */
+ for (i = 0; i < transaction->nr; i++) {
+ struct ref_update *update = transaction->updates[i];
+
+ if (update->flags & REF_HAVE_OLD)
+ /* Have to check the old value -> needed. */
+ return 1;
+
+ if ((update->flags & REF_HAVE_NEW) && !is_null_oid(&update->new_oid))
+ /* Have to set a new value -> needed. */
+ return 1;
+ }
+
+ /*
+ * The transaction isn't checking any old values nor is it
+ * setting any nonzero new values, so it still might be able
+ * to be skipped. Now do the more expensive check: the update
+ * is needed if any of the updates is a delete, and the old
+ * `packed-refs` file contains a value for that reference.
+ */
+ ret = 0;
+ for (i = 0; i < transaction->nr; i++) {
+ struct ref_update *update = transaction->updates[i];
+ int failure_errno;
+ unsigned int type;
+ struct object_id oid;
+
+ if (!(update->flags & REF_HAVE_NEW))
+ /*
+ * This reference isn't being deleted -> not
+ * needed.
+ */
+ continue;
+
+ if (!refs_read_raw_ref(ref_store, update->refname, &oid,
+ &referent, &type, &failure_errno) ||
+ failure_errno != ENOENT) {
+ /*
+ * We have to actually delete that reference
+ * -> this transaction is needed.
+ */
+ ret = 1;
+ break;
+ }
+ }
+
+ strbuf_release(&referent);
+ return ret;
+}
+
+struct packed_transaction_backend_data {
+ /* True iff the transaction owns the packed-refs lock. */
+ int own_lock;
+
+ struct string_list updates;
+};
+
+static void packed_transaction_cleanup(struct packed_ref_store *refs,
+ struct ref_transaction *transaction)
+{
+ struct packed_transaction_backend_data *data = transaction->backend_data;
+
+ if (data) {
+ string_list_clear(&data->updates, 0);
+
+ if (is_tempfile_active(refs->tempfile))
+ delete_tempfile(&refs->tempfile);
+
+ if (data->own_lock && is_lock_file_locked(&refs->lock)) {
+ packed_refs_unlock(&refs->base);
+ data->own_lock = 0;
+ }
+
+ free(data);
+ transaction->backend_data = NULL;
+ }
+
+ transaction->state = REF_TRANSACTION_CLOSED;
+}
+
+static int packed_transaction_prepare(struct ref_store *ref_store,
+ struct ref_transaction *transaction,
+ struct strbuf *err)
+{
+ struct packed_ref_store *refs = packed_downcast(
+ ref_store,
+ REF_STORE_READ | REF_STORE_WRITE | REF_STORE_ODB,
+ "ref_transaction_prepare");
+ struct packed_transaction_backend_data *data;
+ size_t i;
+ int ret = TRANSACTION_GENERIC_ERROR;
+
+ /*
+ * Note that we *don't* skip transactions with zero updates,
+ * because such a transaction might be executed for the side
+ * effect of ensuring that all of the references are peeled or
+ * ensuring that the `packed-refs` file is sorted. If the
+ * caller wants to optimize away empty transactions, it should
+ * do so itself.
+ */
+
+ CALLOC_ARRAY(data, 1);
+ string_list_init_nodup(&data->updates);
+
+ transaction->backend_data = data;
+
+ /*
+ * Stick the updates in a string list by refname so that we
+ * can sort them:
+ */
+ for (i = 0; i < transaction->nr; i++) {
+ struct ref_update *update = transaction->updates[i];
+ struct string_list_item *item =
+ string_list_append(&data->updates, update->refname);
+
+ /* Store a pointer to update in item->util: */
+ item->util = update;
+ }
+ string_list_sort(&data->updates);
+
+ if (ref_update_reject_duplicates(&data->updates, err))
+ goto failure;
+
+ if (!is_lock_file_locked(&refs->lock)) {
+ if (packed_refs_lock(ref_store, 0, err))
+ goto failure;
+ data->own_lock = 1;
+ }
+
+ if (write_with_updates(refs, &data->updates, err))
+ goto failure;
+
+ transaction->state = REF_TRANSACTION_PREPARED;
+ return 0;
+
+failure:
+ packed_transaction_cleanup(refs, transaction);
+ return ret;
+}
+
+static int packed_transaction_abort(struct ref_store *ref_store,
+ struct ref_transaction *transaction,
+ struct strbuf *err UNUSED)
+{
+ struct packed_ref_store *refs = packed_downcast(
+ ref_store,
+ REF_STORE_READ | REF_STORE_WRITE | REF_STORE_ODB,
+ "ref_transaction_abort");
+
+ packed_transaction_cleanup(refs, transaction);
+ return 0;
+}
+
+static int packed_transaction_finish(struct ref_store *ref_store,
+ struct ref_transaction *transaction,
+ struct strbuf *err)
+{
+ struct packed_ref_store *refs = packed_downcast(
+ ref_store,
+ REF_STORE_READ | REF_STORE_WRITE | REF_STORE_ODB,
+ "ref_transaction_finish");
+ int ret = TRANSACTION_GENERIC_ERROR;
+ char *packed_refs_path;
+
+ clear_snapshot(refs);
+
+ packed_refs_path = get_locked_file_path(&refs->lock);
+ if (rename_tempfile(&refs->tempfile, packed_refs_path)) {
+ strbuf_addf(err, "error replacing %s: %s",
+ refs->path, strerror(errno));
+ goto cleanup;
+ }
+
+ ret = 0;
+
+cleanup:
+ free(packed_refs_path);
+ packed_transaction_cleanup(refs, transaction);
+ return ret;
+}
+
+static int packed_initial_transaction_commit(struct ref_store *ref_store UNUSED,
+ struct ref_transaction *transaction,
+ struct strbuf *err)
+{
+ return ref_transaction_commit(transaction, err);
+}
+
+static int packed_delete_refs(struct ref_store *ref_store, const char *msg,
+ struct string_list *refnames, unsigned int flags)
+{
+ struct packed_ref_store *refs =
+ packed_downcast(ref_store, REF_STORE_WRITE, "delete_refs");
+ struct strbuf err = STRBUF_INIT;
+ struct ref_transaction *transaction;
+ struct string_list_item *item;
+ int ret;
+
+ (void)refs; /* We need the check above, but don't use the variable */
+
+ if (!refnames->nr)
+ return 0;
+
+ /*
+ * Since we don't check the references' old_oids, the
+ * individual updates can't fail, so we can pack all of the
+ * updates into a single transaction.
+ */
+
+ transaction = ref_store_transaction_begin(ref_store, &err);
+ if (!transaction)
+ return -1;
+
+ for_each_string_list_item(item, refnames) {
+ if (ref_transaction_delete(transaction, item->string, NULL,
+ flags, msg, &err)) {
+ warning(_("could not delete reference %s: %s"),
+ item->string, err.buf);
+ strbuf_reset(&err);
+ }
+ }
+
+ ret = ref_transaction_commit(transaction, &err);
+
+ if (ret) {
+ if (refnames->nr == 1)
+ error(_("could not delete reference %s: %s"),
+ refnames->items[0].string, err.buf);
+ else
+ error(_("could not delete references: %s"), err.buf);
+ }
+
+ ref_transaction_free(transaction);
+ strbuf_release(&err);
+ return ret;
+}
+
+static int packed_pack_refs(struct ref_store *ref_store UNUSED,
+ unsigned int flags UNUSED)
+{
+ /*
+ * Packed refs are already packed. It might be that loose refs
+ * are packed *into* a packed refs store, but that is done by
+ * updating the packed references via a transaction.
+ */
+ return 0;
+}
+
+static struct ref_iterator *packed_reflog_iterator_begin(struct ref_store *ref_store UNUSED)
+{
+ return empty_ref_iterator_begin();
+}
+
+struct ref_storage_be refs_be_packed = {
+ .next = NULL,
+ .name = "packed",
+ .init = packed_ref_store_create,
+ .init_db = packed_init_db,
+ .transaction_prepare = packed_transaction_prepare,
+ .transaction_finish = packed_transaction_finish,
+ .transaction_abort = packed_transaction_abort,
+ .initial_transaction_commit = packed_initial_transaction_commit,
+
+ .pack_refs = packed_pack_refs,
+ .create_symref = NULL,
+ .delete_refs = packed_delete_refs,
+ .rename_ref = NULL,
+ .copy_ref = NULL,
+
+ .iterator_begin = packed_ref_iterator_begin,
+ .read_raw_ref = packed_read_raw_ref,
+ .read_symbolic_ref = NULL,
+
+ .reflog_iterator_begin = packed_reflog_iterator_begin,
+ .for_each_reflog_ent = NULL,
+ .for_each_reflog_ent_reverse = NULL,
+ .reflog_exists = NULL,
+ .create_reflog = NULL,
+ .delete_reflog = NULL,
+ .reflog_expire = NULL,
+};
diff --git a/refs/packed-backend.h b/refs/packed-backend.h
new file mode 100644
index 0000000..9dd8a34
--- /dev/null
+++ b/refs/packed-backend.h
@@ -0,0 +1,39 @@
+#ifndef REFS_PACKED_BACKEND_H
+#define REFS_PACKED_BACKEND_H
+
+struct repository;
+struct ref_transaction;
+
+/*
+ * Support for storing references in a `packed-refs` file.
+ *
+ * Note that this backend doesn't check for D/F conflicts, because it
+ * doesn't care about them. But usually it should be wrapped in a
+ * `files_ref_store` that prevents D/F conflicts from being created,
+ * even among packed refs.
+ */
+
+struct ref_store *packed_ref_store_create(struct repository *repo,
+ const char *gitdir,
+ unsigned int store_flags);
+
+/*
+ * Lock the packed-refs file for writing. Flags is passed to
+ * hold_lock_file_for_update(). Return 0 on success. On errors, write
+ * an error message to `err` and return a nonzero value.
+ */
+int packed_refs_lock(struct ref_store *ref_store, int flags, struct strbuf *err);
+
+void packed_refs_unlock(struct ref_store *ref_store);
+int packed_refs_is_locked(struct ref_store *ref_store);
+
+/*
+ * Return true if `transaction` really needs to be carried out against
+ * the specified packed_ref_store, or false if it can be skipped
+ * (i.e., because it is an obvious NOOP). `ref_store` must be locked
+ * before calling this function.
+ */
+int is_packed_transaction_needed(struct ref_store *ref_store,
+ struct ref_transaction *transaction);
+
+#endif /* REFS_PACKED_BACKEND_H */
diff --git a/refs/ref-cache.c b/refs/ref-cache.c
new file mode 100644
index 0000000..32afd8a
--- /dev/null
+++ b/refs/ref-cache.c
@@ -0,0 +1,504 @@
+#include "../cache.h"
+#include "../refs.h"
+#include "refs-internal.h"
+#include "ref-cache.h"
+#include "../iterator.h"
+
+void add_entry_to_dir(struct ref_dir *dir, struct ref_entry *entry)
+{
+ ALLOC_GROW(dir->entries, dir->nr + 1, dir->alloc);
+ dir->entries[dir->nr++] = entry;
+ /* optimize for the case that entries are added in order */
+ if (dir->nr == 1 ||
+ (dir->nr == dir->sorted + 1 &&
+ strcmp(dir->entries[dir->nr - 2]->name,
+ dir->entries[dir->nr - 1]->name) < 0))
+ dir->sorted = dir->nr;
+}
+
+struct ref_dir *get_ref_dir(struct ref_entry *entry)
+{
+ struct ref_dir *dir;
+ assert(entry->flag & REF_DIR);
+ dir = &entry->u.subdir;
+ if (entry->flag & REF_INCOMPLETE) {
+ if (!dir->cache->fill_ref_dir)
+ BUG("incomplete ref_store without fill_ref_dir function");
+
+ dir->cache->fill_ref_dir(dir->cache->ref_store, dir, entry->name);
+ entry->flag &= ~REF_INCOMPLETE;
+ }
+ return dir;
+}
+
+struct ref_entry *create_ref_entry(const char *refname,
+ const struct object_id *oid, int flag)
+{
+ struct ref_entry *ref;
+
+ FLEX_ALLOC_STR(ref, name, refname);
+ oidcpy(&ref->u.value.oid, oid);
+ ref->flag = flag;
+ return ref;
+}
+
+struct ref_cache *create_ref_cache(struct ref_store *refs,
+ fill_ref_dir_fn *fill_ref_dir)
+{
+ struct ref_cache *ret = xcalloc(1, sizeof(*ret));
+
+ ret->ref_store = refs;
+ ret->fill_ref_dir = fill_ref_dir;
+ ret->root = create_dir_entry(ret, "", 0);
+ return ret;
+}
+
+static void clear_ref_dir(struct ref_dir *dir);
+
+static void free_ref_entry(struct ref_entry *entry)
+{
+ if (entry->flag & REF_DIR) {
+ /*
+ * Do not use get_ref_dir() here, as that might
+ * trigger the reading of loose refs.
+ */
+ clear_ref_dir(&entry->u.subdir);
+ }
+ free(entry);
+}
+
+void free_ref_cache(struct ref_cache *cache)
+{
+ free_ref_entry(cache->root);
+ free(cache);
+}
+
+/*
+ * Clear and free all entries in dir, recursively.
+ */
+static void clear_ref_dir(struct ref_dir *dir)
+{
+ int i;
+ for (i = 0; i < dir->nr; i++)
+ free_ref_entry(dir->entries[i]);
+ FREE_AND_NULL(dir->entries);
+ dir->sorted = dir->nr = dir->alloc = 0;
+}
+
+struct ref_entry *create_dir_entry(struct ref_cache *cache,
+ const char *dirname, size_t len)
+{
+ struct ref_entry *direntry;
+
+ FLEX_ALLOC_MEM(direntry, name, dirname, len);
+ direntry->u.subdir.cache = cache;
+ direntry->flag = REF_DIR | REF_INCOMPLETE;
+ return direntry;
+}
+
+static int ref_entry_cmp(const void *a, const void *b)
+{
+ struct ref_entry *one = *(struct ref_entry **)a;
+ struct ref_entry *two = *(struct ref_entry **)b;
+ return strcmp(one->name, two->name);
+}
+
+static void sort_ref_dir(struct ref_dir *dir);
+
+struct string_slice {
+ size_t len;
+ const char *str;
+};
+
+static int ref_entry_cmp_sslice(const void *key_, const void *ent_)
+{
+ const struct string_slice *key = key_;
+ const struct ref_entry *ent = *(const struct ref_entry * const *)ent_;
+ int cmp = strncmp(key->str, ent->name, key->len);
+ if (cmp)
+ return cmp;
+ return '\0' - (unsigned char)ent->name[key->len];
+}
+
+int search_ref_dir(struct ref_dir *dir, const char *refname, size_t len)
+{
+ struct ref_entry **r;
+ struct string_slice key;
+
+ if (refname == NULL || !dir->nr)
+ return -1;
+
+ sort_ref_dir(dir);
+ key.len = len;
+ key.str = refname;
+ r = bsearch(&key, dir->entries, dir->nr, sizeof(*dir->entries),
+ ref_entry_cmp_sslice);
+
+ if (!r)
+ return -1;
+
+ return r - dir->entries;
+}
+
+/*
+ * Search for a directory entry directly within dir (without
+ * recursing). Sort dir if necessary. subdirname must be a directory
+ * name (i.e., end in '/'). Returns NULL if the desired
+ * directory cannot be found. dir must already be complete.
+ */
+static struct ref_dir *search_for_subdir(struct ref_dir *dir,
+ const char *subdirname, size_t len)
+{
+ int entry_index = search_ref_dir(dir, subdirname, len);
+ struct ref_entry *entry;
+
+ if (entry_index == -1)
+ return NULL;
+
+ entry = dir->entries[entry_index];
+ return get_ref_dir(entry);
+}
+
+/*
+ * If refname is a reference name, find the ref_dir within the dir
+ * tree that should hold refname. If refname is a directory name
+ * (i.e., it ends in '/'), then return that ref_dir itself. dir must
+ * represent the top-level directory and must already be complete.
+ * Sort ref_dirs and recurse into subdirectories as necessary. Will
+ * return NULL if the desired directory cannot be found.
+ */
+static struct ref_dir *find_containing_dir(struct ref_dir *dir,
+ const char *refname)
+{
+ const char *slash;
+ for (slash = strchr(refname, '/'); slash; slash = strchr(slash + 1, '/')) {
+ size_t dirnamelen = slash - refname + 1;
+ struct ref_dir *subdir;
+ subdir = search_for_subdir(dir, refname, dirnamelen);
+ if (!subdir) {
+ dir = NULL;
+ break;
+ }
+ dir = subdir;
+ }
+
+ return dir;
+}
+
+struct ref_entry *find_ref_entry(struct ref_dir *dir, const char *refname)
+{
+ int entry_index;
+ struct ref_entry *entry;
+ dir = find_containing_dir(dir, refname);
+ if (!dir)
+ return NULL;
+ entry_index = search_ref_dir(dir, refname, strlen(refname));
+ if (entry_index == -1)
+ return NULL;
+ entry = dir->entries[entry_index];
+ return (entry->flag & REF_DIR) ? NULL : entry;
+}
+
+/*
+ * Emit a warning and return true iff ref1 and ref2 have the same name
+ * and the same oid. Die if they have the same name but different
+ * oids.
+ */
+static int is_dup_ref(const struct ref_entry *ref1, const struct ref_entry *ref2)
+{
+ if (strcmp(ref1->name, ref2->name))
+ return 0;
+
+ /* Duplicate name; make sure that they don't conflict: */
+
+ if ((ref1->flag & REF_DIR) || (ref2->flag & REF_DIR))
+ /* This is impossible by construction */
+ die("Reference directory conflict: %s", ref1->name);
+
+ if (!oideq(&ref1->u.value.oid, &ref2->u.value.oid))
+ die("Duplicated ref, and SHA1s don't match: %s", ref1->name);
+
+ warning("Duplicated ref: %s", ref1->name);
+ return 1;
+}
+
+/*
+ * Sort the entries in dir non-recursively (if they are not already
+ * sorted) and remove any duplicate entries.
+ */
+static void sort_ref_dir(struct ref_dir *dir)
+{
+ int i, j;
+ struct ref_entry *last = NULL;
+
+ /*
+ * This check also prevents passing a zero-length array to qsort(),
+ * which is a problem on some platforms.
+ */
+ if (dir->sorted == dir->nr)
+ return;
+
+ QSORT(dir->entries, dir->nr, ref_entry_cmp);
+
+ /* Remove any duplicates: */
+ for (i = 0, j = 0; j < dir->nr; j++) {
+ struct ref_entry *entry = dir->entries[j];
+ if (last && is_dup_ref(last, entry))
+ free_ref_entry(entry);
+ else
+ last = dir->entries[i++] = entry;
+ }
+ dir->sorted = dir->nr = i;
+}
+
+enum prefix_state {
+ /* All refs within the directory would match prefix: */
+ PREFIX_CONTAINS_DIR,
+
+ /* Some, but not all, refs within the directory might match prefix: */
+ PREFIX_WITHIN_DIR,
+
+ /* No refs within the directory could possibly match prefix: */
+ PREFIX_EXCLUDES_DIR
+};
+
+/*
+ * Return a `prefix_state` constant describing the relationship
+ * between the directory with the specified `dirname` and `prefix`.
+ */
+static enum prefix_state overlaps_prefix(const char *dirname,
+ const char *prefix)
+{
+ while (*prefix && *dirname == *prefix) {
+ dirname++;
+ prefix++;
+ }
+ if (!*prefix)
+ return PREFIX_CONTAINS_DIR;
+ else if (!*dirname)
+ return PREFIX_WITHIN_DIR;
+ else
+ return PREFIX_EXCLUDES_DIR;
+}
+
+/*
+ * Load all of the refs from `dir` (recursively) that could possibly
+ * contain references matching `prefix` into our in-memory cache. If
+ * `prefix` is NULL, prime unconditionally.
+ */
+static void prime_ref_dir(struct ref_dir *dir, const char *prefix)
+{
+ /*
+ * The hard work of loading loose refs is done by get_ref_dir(), so we
+ * just need to recurse through all of the sub-directories. We do not
+ * even need to care about sorting, as traversal order does not matter
+ * to us.
+ */
+ int i;
+ for (i = 0; i < dir->nr; i++) {
+ struct ref_entry *entry = dir->entries[i];
+ if (!(entry->flag & REF_DIR)) {
+ /* Not a directory; no need to recurse. */
+ } else if (!prefix) {
+ /* Recurse in any case: */
+ prime_ref_dir(get_ref_dir(entry), NULL);
+ } else {
+ switch (overlaps_prefix(entry->name, prefix)) {
+ case PREFIX_CONTAINS_DIR:
+ /*
+ * Recurse, and from here down we
+ * don't have to check the prefix
+ * anymore:
+ */
+ prime_ref_dir(get_ref_dir(entry), NULL);
+ break;
+ case PREFIX_WITHIN_DIR:
+ prime_ref_dir(get_ref_dir(entry), prefix);
+ break;
+ case PREFIX_EXCLUDES_DIR:
+ /* No need to prime this directory. */
+ break;
+ }
+ }
+ }
+}
+
+/*
+ * A level in the reference hierarchy that is currently being iterated
+ * through.
+ */
+struct cache_ref_iterator_level {
+ /*
+ * The ref_dir being iterated over at this level. The ref_dir
+ * is sorted before being stored here.
+ */
+ struct ref_dir *dir;
+
+ enum prefix_state prefix_state;
+
+ /*
+ * The index of the current entry within dir (which might
+ * itself be a directory). If index == -1, then the iteration
+ * hasn't yet begun. If index == dir->nr, then the iteration
+ * through this level is over.
+ */
+ int index;
+};
+
+/*
+ * Represent an iteration through a ref_dir in the memory cache. The
+ * iteration recurses through subdirectories.
+ */
+struct cache_ref_iterator {
+ struct ref_iterator base;
+
+ /*
+ * The number of levels currently on the stack. This is always
+ * at least 1, because when it becomes zero the iteration is
+ * ended and this struct is freed.
+ */
+ size_t levels_nr;
+
+ /* The number of levels that have been allocated on the stack */
+ size_t levels_alloc;
+
+ /*
+ * Only include references with this prefix in the iteration.
+ * The prefix is matched textually, without regard for path
+ * component boundaries.
+ */
+ const char *prefix;
+
+ /*
+ * A stack of levels. levels[0] is the uppermost level that is
+ * being iterated over in this iteration. (This is not
+ * necessary the top level in the references hierarchy. If we
+ * are iterating through a subtree, then levels[0] will hold
+ * the ref_dir for that subtree, and subsequent levels will go
+ * on from there.)
+ */
+ struct cache_ref_iterator_level *levels;
+
+ struct repository *repo;
+};
+
+static int cache_ref_iterator_advance(struct ref_iterator *ref_iterator)
+{
+ struct cache_ref_iterator *iter =
+ (struct cache_ref_iterator *)ref_iterator;
+
+ while (1) {
+ struct cache_ref_iterator_level *level =
+ &iter->levels[iter->levels_nr - 1];
+ struct ref_dir *dir = level->dir;
+ struct ref_entry *entry;
+ enum prefix_state entry_prefix_state;
+
+ if (level->index == -1)
+ sort_ref_dir(dir);
+
+ if (++level->index == level->dir->nr) {
+ /* This level is exhausted; pop up a level */
+ if (--iter->levels_nr == 0)
+ return ref_iterator_abort(ref_iterator);
+
+ continue;
+ }
+
+ entry = dir->entries[level->index];
+
+ if (level->prefix_state == PREFIX_WITHIN_DIR) {
+ entry_prefix_state = overlaps_prefix(entry->name, iter->prefix);
+ if (entry_prefix_state == PREFIX_EXCLUDES_DIR)
+ continue;
+ } else {
+ entry_prefix_state = level->prefix_state;
+ }
+
+ if (entry->flag & REF_DIR) {
+ /* push down a level */
+ ALLOC_GROW(iter->levels, iter->levels_nr + 1,
+ iter->levels_alloc);
+
+ level = &iter->levels[iter->levels_nr++];
+ level->dir = get_ref_dir(entry);
+ level->prefix_state = entry_prefix_state;
+ level->index = -1;
+ } else {
+ iter->base.refname = entry->name;
+ iter->base.oid = &entry->u.value.oid;
+ iter->base.flags = entry->flag;
+ return ITER_OK;
+ }
+ }
+}
+
+static int cache_ref_iterator_peel(struct ref_iterator *ref_iterator,
+ struct object_id *peeled)
+{
+ struct cache_ref_iterator *iter =
+ (struct cache_ref_iterator *)ref_iterator;
+
+ if (iter->repo != the_repository)
+ BUG("peeling for non-the_repository is not supported");
+ return peel_object(ref_iterator->oid, peeled) ? -1 : 0;
+}
+
+static int cache_ref_iterator_abort(struct ref_iterator *ref_iterator)
+{
+ struct cache_ref_iterator *iter =
+ (struct cache_ref_iterator *)ref_iterator;
+
+ free((char *)iter->prefix);
+ free(iter->levels);
+ base_ref_iterator_free(ref_iterator);
+ return ITER_DONE;
+}
+
+static struct ref_iterator_vtable cache_ref_iterator_vtable = {
+ .advance = cache_ref_iterator_advance,
+ .peel = cache_ref_iterator_peel,
+ .abort = cache_ref_iterator_abort
+};
+
+struct ref_iterator *cache_ref_iterator_begin(struct ref_cache *cache,
+ const char *prefix,
+ struct repository *repo,
+ int prime_dir)
+{
+ struct ref_dir *dir;
+ struct cache_ref_iterator *iter;
+ struct ref_iterator *ref_iterator;
+ struct cache_ref_iterator_level *level;
+
+ dir = get_ref_dir(cache->root);
+ if (prefix && *prefix)
+ dir = find_containing_dir(dir, prefix);
+ if (!dir)
+ /* There's nothing to iterate over. */
+ return empty_ref_iterator_begin();
+
+ if (prime_dir)
+ prime_ref_dir(dir, prefix);
+
+ CALLOC_ARRAY(iter, 1);
+ ref_iterator = &iter->base;
+ base_ref_iterator_init(ref_iterator, &cache_ref_iterator_vtable, 1);
+ ALLOC_GROW(iter->levels, 10, iter->levels_alloc);
+
+ iter->levels_nr = 1;
+ level = &iter->levels[0];
+ level->index = -1;
+ level->dir = dir;
+
+ if (prefix && *prefix) {
+ iter->prefix = xstrdup(prefix);
+ level->prefix_state = PREFIX_WITHIN_DIR;
+ } else {
+ level->prefix_state = PREFIX_CONTAINS_DIR;
+ }
+
+ iter->repo = repo;
+
+ return ref_iterator;
+}
diff --git a/refs/ref-cache.h b/refs/ref-cache.h
new file mode 100644
index 0000000..850d9d3
--- /dev/null
+++ b/refs/ref-cache.h
@@ -0,0 +1,220 @@
+#ifndef REFS_REF_CACHE_H
+#define REFS_REF_CACHE_H
+
+#include "cache.h"
+
+struct ref_dir;
+struct ref_store;
+
+/*
+ * If this ref_cache is filled lazily, this function is used to load
+ * information into the specified ref_dir (shallow or deep, at the
+ * option of the ref_store). dirname includes a trailing slash.
+ */
+typedef void fill_ref_dir_fn(struct ref_store *ref_store,
+ struct ref_dir *dir, const char *dirname);
+
+struct ref_cache {
+ struct ref_entry *root;
+
+ /* A pointer to the ref_store whose cache this is: */
+ struct ref_store *ref_store;
+
+ /*
+ * Function used (if necessary) to lazily-fill cache. May be
+ * NULL.
+ */
+ fill_ref_dir_fn *fill_ref_dir;
+};
+
+/*
+ * Information used (along with the information in ref_entry) to
+ * describe a single cached reference. This data structure only
+ * occurs embedded in a union in struct ref_entry, and only when
+ * (ref_entry->flag & REF_DIR) is zero.
+ */
+struct ref_value {
+ /*
+ * The name of the object to which this reference resolves
+ * (which may be a tag object). If REF_ISBROKEN, this is
+ * null. If REF_ISSYMREF, then this is the name of the object
+ * referred to by the last reference in the symlink chain.
+ */
+ struct object_id oid;
+};
+
+/*
+ * Information used (along with the information in ref_entry) to
+ * describe a level in the hierarchy of references. This data
+ * structure only occurs embedded in a union in struct ref_entry, and
+ * only when (ref_entry.flag & REF_DIR) is set. In that case,
+ * (ref_entry.flag & REF_INCOMPLETE) determines whether the references
+ * in the directory have already been read:
+ *
+ * (ref_entry.flag & REF_INCOMPLETE) unset -- a directory of loose
+ * or packed references, already read.
+ *
+ * (ref_entry.flag & REF_INCOMPLETE) set -- a directory of loose
+ * references that hasn't been read yet (nor has any of its
+ * subdirectories).
+ *
+ * Entries within a directory are stored within a growable array of
+ * pointers to ref_entries (entries, nr, alloc). Entries 0 <= i <
+ * sorted are sorted by their component name in strcmp() order and the
+ * remaining entries are unsorted.
+ *
+ * Loose references are read lazily, one directory at a time. When a
+ * directory of loose references is read, then all of the references
+ * in that directory are stored, and REF_INCOMPLETE stubs are created
+ * for any subdirectories, but the subdirectories themselves are not
+ * read. The reading is triggered by get_ref_dir().
+ */
+struct ref_dir {
+ int nr, alloc;
+
+ /*
+ * Entries with index 0 <= i < sorted are sorted by name. New
+ * entries are appended to the list unsorted, and are sorted
+ * only when required; thus we avoid the need to sort the list
+ * after the addition of every reference.
+ */
+ int sorted;
+
+ /* The ref_cache containing this entry: */
+ struct ref_cache *cache;
+
+ struct ref_entry **entries;
+};
+
+/*
+ * Bit values for ref_entry::flag. REF_ISSYMREF=0x01,
+ * REF_ISPACKED=0x02, REF_ISBROKEN=0x04 and REF_BAD_NAME=0x08 are
+ * public values; see refs.h.
+ */
+
+/* ref_entry represents a directory of references */
+#define REF_DIR 0x10
+
+/*
+ * Entry has not yet been read from disk (used only for REF_DIR
+ * entries representing loose references)
+ */
+#define REF_INCOMPLETE 0x20
+
+/*
+ * A ref_entry represents either a reference or a "subdirectory" of
+ * references.
+ *
+ * Each directory in the reference namespace is represented by a
+ * ref_entry with (flags & REF_DIR) set and containing a subdir member
+ * that holds the entries in that directory that have been read so
+ * far. If (flags & REF_INCOMPLETE) is set, then the directory and
+ * its subdirectories haven't been read yet. REF_INCOMPLETE is only
+ * used for loose reference directories.
+ *
+ * References are represented by a ref_entry with (flags & REF_DIR)
+ * unset and a value member that describes the reference's value. The
+ * flag member is at the ref_entry level, but it is also needed to
+ * interpret the contents of the value field (in other words, a
+ * ref_value object is not very much use without the enclosing
+ * ref_entry).
+ *
+ * Reference names cannot end with slash and directories' names are
+ * always stored with a trailing slash (except for the top-level
+ * directory, which is always denoted by ""). This has two nice
+ * consequences: (1) when the entries in each subdir are sorted
+ * lexicographically by name (as they usually are), the references in
+ * a whole tree can be generated in lexicographic order by traversing
+ * the tree in left-to-right, depth-first order; (2) the names of
+ * references and subdirectories cannot conflict, and therefore the
+ * presence of an empty subdirectory does not block the creation of a
+ * similarly-named reference. (The fact that reference names with the
+ * same leading components can conflict *with each other* is a
+ * separate issue that is regulated by refs_verify_refname_available().)
+ *
+ * Please note that the name field contains the fully-qualified
+ * reference (or subdirectory) name. Space could be saved by only
+ * storing the relative names. But that would require the full names
+ * to be generated on the fly when iterating in do_for_each_ref(), and
+ * would break callback functions, who have always been able to assume
+ * that the name strings that they are passed will not be freed during
+ * the iteration.
+ */
+struct ref_entry {
+ unsigned char flag; /* ISSYMREF? ISPACKED? */
+ union {
+ struct ref_value value; /* if not (flags&REF_DIR) */
+ struct ref_dir subdir; /* if (flags&REF_DIR) */
+ } u;
+ /*
+ * The full name of the reference (e.g., "refs/heads/master")
+ * or the full name of the directory with a trailing slash
+ * (e.g., "refs/heads/"):
+ */
+ char name[FLEX_ARRAY];
+};
+
+/*
+ * Return the index of the entry with the given refname from the
+ * ref_dir (non-recursively), sorting dir if necessary. Return -1 if
+ * no such entry is found. dir must already be complete.
+ */
+int search_ref_dir(struct ref_dir *dir, const char *refname, size_t len);
+
+struct ref_dir *get_ref_dir(struct ref_entry *entry);
+
+/*
+ * Create a struct ref_entry object for the specified dirname.
+ * dirname is the name of the directory with a trailing slash (e.g.,
+ * "refs/heads/") or "" for the top-level directory.
+ */
+struct ref_entry *create_dir_entry(struct ref_cache *cache,
+ const char *dirname, size_t len);
+
+struct ref_entry *create_ref_entry(const char *refname,
+ const struct object_id *oid, int flag);
+
+/*
+ * Return a pointer to a new `ref_cache`. Its top-level starts out
+ * marked incomplete. If `fill_ref_dir` is non-NULL, it is the
+ * function called to fill in incomplete directories in the
+ * `ref_cache` when they are accessed. If it is NULL, then the whole
+ * `ref_cache` must be filled (including clearing its directories'
+ * `REF_INCOMPLETE` bits) before it is used, and `refs` can be NULL,
+ * too.
+ */
+struct ref_cache *create_ref_cache(struct ref_store *refs,
+ fill_ref_dir_fn *fill_ref_dir);
+
+/*
+ * Free the `ref_cache` and all of its associated data.
+ */
+void free_ref_cache(struct ref_cache *cache);
+
+/*
+ * Add a ref_entry to the end of dir (unsorted). Entry is always
+ * stored directly in dir; no recursion into subdirectories is
+ * done.
+ */
+void add_entry_to_dir(struct ref_dir *dir, struct ref_entry *entry);
+
+/*
+ * Find the value entry with the given name in dir, sorting ref_dirs
+ * and recursing into subdirectories as necessary. If the name is not
+ * found or it corresponds to a directory entry, return NULL.
+ */
+struct ref_entry *find_ref_entry(struct ref_dir *dir, const char *refname);
+
+/*
+ * Start iterating over references in `cache`. If `prefix` is
+ * specified, only include references whose names start with that
+ * prefix. If `prime_dir` is true, then fill any incomplete
+ * directories before beginning the iteration. The output is ordered
+ * by refname.
+ */
+struct ref_iterator *cache_ref_iterator_begin(struct ref_cache *cache,
+ const char *prefix,
+ struct repository *repo,
+ int prime_dir);
+
+#endif /* REFS_REF_CACHE_H */
diff --git a/refs/refs-internal.h b/refs/refs-internal.h
new file mode 100644
index 0000000..69f93b0
--- /dev/null
+++ b/refs/refs-internal.h
@@ -0,0 +1,737 @@
+#ifndef REFS_REFS_INTERNAL_H
+#define REFS_REFS_INTERNAL_H
+
+#include "cache.h"
+#include "refs.h"
+#include "iterator.h"
+
+struct ref_transaction;
+
+/*
+ * Data structures and functions for the internal use of the refs
+ * module. Code outside of the refs module should use only the public
+ * functions defined in "refs.h", and should *not* include this file.
+ */
+
+/*
+ * The following flags can appear in `ref_update::flags`. Their
+ * numerical values must not conflict with those of REF_NO_DEREF and
+ * REF_FORCE_CREATE_REFLOG, which are also stored in
+ * `ref_update::flags`.
+ */
+
+/*
+ * The reference should be updated to new_oid.
+ */
+#define REF_HAVE_NEW (1 << 2)
+
+/*
+ * The current reference's value should be checked to make sure that
+ * it agrees with old_oid.
+ */
+#define REF_HAVE_OLD (1 << 3)
+
+/*
+ * Used as a flag in ref_update::flags when we want to log a ref
+ * update but not actually perform it. This is used when a symbolic
+ * ref update is split up.
+ */
+#define REF_LOG_ONLY (1 << 7)
+
+/*
+ * Return the length of time to retry acquiring a loose reference lock
+ * before giving up, in milliseconds:
+ */
+long get_files_ref_lock_timeout_ms(void);
+
+/*
+ * Return true iff refname is minimally safe. "Safe" here means that
+ * deleting a loose reference by this name will not do any damage, for
+ * example by causing a file that is not a reference to be deleted.
+ * This function does not check that the reference name is legal; for
+ * that, use check_refname_format().
+ *
+ * A refname that starts with "refs/" is considered safe iff it
+ * doesn't contain any "." or ".." components or consecutive '/'
+ * characters, end with '/', or (on Windows) contain any '\'
+ * characters. Names that do not start with "refs/" are considered
+ * safe iff they consist entirely of upper case characters and '_'
+ * (like "HEAD" and "MERGE_HEAD" but not "config" or "FOO/BAR").
+ */
+int refname_is_safe(const char *refname);
+
+/*
+ * Helper function: return true if refname, which has the specified
+ * oid and flags, can be resolved to an object in the database. If the
+ * referred-to object does not exist, emit a warning and return false.
+ */
+int ref_resolves_to_object(const char *refname,
+ struct repository *repo,
+ const struct object_id *oid,
+ unsigned int flags);
+
+enum peel_status {
+ /* object was peeled successfully: */
+ PEEL_PEELED = 0,
+
+ /*
+ * object cannot be peeled because the named object (or an
+ * object referred to by a tag in the peel chain), does not
+ * exist.
+ */
+ PEEL_INVALID = -1,
+
+ /* object cannot be peeled because it is not a tag: */
+ PEEL_NON_TAG = -2,
+
+ /* ref_entry contains no peeled value because it is a symref: */
+ PEEL_IS_SYMREF = -3,
+
+ /*
+ * ref_entry cannot be peeled because it is broken (i.e., the
+ * symbolic reference cannot even be resolved to an object
+ * name):
+ */
+ PEEL_BROKEN = -4
+};
+
+/*
+ * Peel the named object; i.e., if the object is a tag, resolve the
+ * tag recursively until a non-tag is found. If successful, store the
+ * result to oid and return PEEL_PEELED. If the object is not a tag
+ * or is not valid, return PEEL_NON_TAG or PEEL_INVALID, respectively,
+ * and leave oid unchanged.
+ */
+enum peel_status peel_object(const struct object_id *name, struct object_id *oid);
+
+/**
+ * Information needed for a single ref update. Set new_oid to the new
+ * value or to null_oid to delete the ref. To check the old value
+ * while the ref is locked, set (flags & REF_HAVE_OLD) and set old_oid
+ * to the old value, or to null_oid to ensure the ref does not exist
+ * before update.
+ */
+struct ref_update {
+ /*
+ * If (flags & REF_HAVE_NEW), set the reference to this value
+ * (or delete it, if `new_oid` is `null_oid`).
+ */
+ struct object_id new_oid;
+
+ /*
+ * If (flags & REF_HAVE_OLD), check that the reference
+ * previously had this value (or didn't previously exist, if
+ * `old_oid` is `null_oid`).
+ */
+ struct object_id old_oid;
+
+ /*
+ * One or more of REF_NO_DEREF, REF_FORCE_CREATE_REFLOG,
+ * REF_HAVE_NEW, REF_HAVE_OLD, or backend-specific flags.
+ */
+ unsigned int flags;
+
+ void *backend_data;
+ unsigned int type;
+ char *msg;
+
+ /*
+ * If this ref_update was split off of a symref update via
+ * split_symref_update(), then this member points at that
+ * update. This is used for two purposes:
+ * 1. When reporting errors, we report the refname under which
+ * the update was originally requested.
+ * 2. When we read the old value of this reference, we
+ * propagate it back to its parent update for recording in
+ * the latter's reflog.
+ */
+ struct ref_update *parent_update;
+
+ const char refname[FLEX_ARRAY];
+};
+
+int refs_read_raw_ref(struct ref_store *ref_store, const char *refname,
+ struct object_id *oid, struct strbuf *referent,
+ unsigned int *type, int *failure_errno);
+
+/*
+ * Write an error to `err` and return a nonzero value iff the same
+ * refname appears multiple times in `refnames`. `refnames` must be
+ * sorted on entry to this function.
+ */
+int ref_update_reject_duplicates(struct string_list *refnames,
+ struct strbuf *err);
+
+/*
+ * Add a ref_update with the specified properties to transaction, and
+ * return a pointer to the new object. This function does not verify
+ * that refname is well-formed. new_oid and old_oid are only
+ * dereferenced if the REF_HAVE_NEW and REF_HAVE_OLD bits,
+ * respectively, are set in flags.
+ */
+struct ref_update *ref_transaction_add_update(
+ struct ref_transaction *transaction,
+ const char *refname, unsigned int flags,
+ const struct object_id *new_oid,
+ const struct object_id *old_oid,
+ const char *msg);
+
+/*
+ * Transaction states.
+ *
+ * OPEN: The transaction is initialized and new updates can still be
+ * added to it. An OPEN transaction can be prepared,
+ * committed, freed, or aborted (freeing and aborting an open
+ * transaction are equivalent).
+ *
+ * PREPARED: ref_transaction_prepare(), which locks all of the
+ * references involved in the update and checks that the
+ * update has no errors, has been called successfully for the
+ * transaction. A PREPARED transaction can be committed or
+ * aborted.
+ *
+ * CLOSED: The transaction is no longer active. A transaction becomes
+ * CLOSED if there is a failure while building the transaction
+ * or if a transaction is committed or aborted. A CLOSED
+ * transaction can only be freed.
+ */
+enum ref_transaction_state {
+ REF_TRANSACTION_OPEN = 0,
+ REF_TRANSACTION_PREPARED = 1,
+ REF_TRANSACTION_CLOSED = 2
+};
+
+/*
+ * Data structure for holding a reference transaction, which can
+ * consist of checks and updates to multiple references, carried out
+ * as atomically as possible. This structure is opaque to callers.
+ */
+struct ref_transaction {
+ struct ref_store *ref_store;
+ struct ref_update **updates;
+ size_t alloc;
+ size_t nr;
+ enum ref_transaction_state state;
+ void *backend_data;
+};
+
+/*
+ * Check for entries in extras that are within the specified
+ * directory, where dirname is a reference directory name including
+ * the trailing slash (e.g., "refs/heads/foo/"). Ignore any
+ * conflicting references that are found in skip. If there is a
+ * conflicting reference, return its name.
+ *
+ * extras and skip must be sorted lists of reference names. Either one
+ * can be NULL, signifying the empty list.
+ */
+const char *find_descendant_ref(const char *dirname,
+ const struct string_list *extras,
+ const struct string_list *skip);
+
+/* We allow "recursive" symbolic refs. Only within reason, though */
+#define SYMREF_MAXDEPTH 5
+
+/*
+ * These flags are passed to refs_ref_iterator_begin() (and do_for_each_ref(),
+ * which feeds it).
+ */
+enum do_for_each_ref_flags {
+ /*
+ * Include broken references in a do_for_each_ref*() iteration, which
+ * would normally be omitted. This includes both refs that point to
+ * missing objects (a true repository corruption), ones with illegal
+ * names (which we prefer not to expose to callers), as well as
+ * dangling symbolic refs (i.e., those that point to a non-existent
+ * ref; this is not a corruption, but as they have no valid oid, we
+ * omit them from normal iteration results).
+ */
+ DO_FOR_EACH_INCLUDE_BROKEN = (1 << 0),
+
+ /*
+ * Only include per-worktree refs in a do_for_each_ref*() iteration.
+ * Normally this will be used with a files ref_store, since that's
+ * where all reference backends will presumably store their
+ * per-worktree refs.
+ */
+ DO_FOR_EACH_PER_WORKTREE_ONLY = (1 << 1),
+
+ /*
+ * Omit dangling symrefs from output; this only has an effect with
+ * INCLUDE_BROKEN, since they are otherwise not included at all.
+ */
+ DO_FOR_EACH_OMIT_DANGLING_SYMREFS = (1 << 2),
+};
+
+/*
+ * Reference iterators
+ *
+ * A reference iterator encapsulates the state of an in-progress
+ * iteration over references. Create an instance of `struct
+ * ref_iterator` via one of the functions in this module.
+ *
+ * A freshly-created ref_iterator doesn't yet point at a reference. To
+ * advance the iterator, call ref_iterator_advance(). If successful,
+ * this sets the iterator's refname, oid, and flags fields to describe
+ * the next reference and returns ITER_OK. The data pointed at by
+ * refname and oid belong to the iterator; if you want to retain them
+ * after calling ref_iterator_advance() again or calling
+ * ref_iterator_abort(), you must make a copy. When the iteration has
+ * been exhausted, ref_iterator_advance() releases any resources
+ * associated with the iteration, frees the ref_iterator object, and
+ * returns ITER_DONE. If you want to abort the iteration early, call
+ * ref_iterator_abort(), which also frees the ref_iterator object and
+ * any associated resources. If there was an internal error advancing
+ * to the next entry, ref_iterator_advance() aborts the iteration,
+ * frees the ref_iterator, and returns ITER_ERROR.
+ *
+ * The reference currently being looked at can be peeled by calling
+ * ref_iterator_peel(). This function is often faster than peel_ref(),
+ * so it should be preferred when iterating over references.
+ *
+ * Putting it all together, a typical iteration looks like this:
+ *
+ * int ok;
+ * struct ref_iterator *iter = ...;
+ *
+ * while ((ok = ref_iterator_advance(iter)) == ITER_OK) {
+ * if (want_to_stop_iteration()) {
+ * ok = ref_iterator_abort(iter);
+ * break;
+ * }
+ *
+ * // Access information about the current reference:
+ * if (!(iter->flags & REF_ISSYMREF))
+ * printf("%s is %s\n", iter->refname, oid_to_hex(iter->oid));
+ *
+ * // If you need to peel the reference:
+ * ref_iterator_peel(iter, &oid);
+ * }
+ *
+ * if (ok != ITER_DONE)
+ * handle_error();
+ */
+struct ref_iterator {
+ struct ref_iterator_vtable *vtable;
+
+ /*
+ * Does this `ref_iterator` iterate over references in order
+ * by refname?
+ */
+ unsigned int ordered : 1;
+
+ const char *refname;
+ const struct object_id *oid;
+ unsigned int flags;
+};
+
+/*
+ * Advance the iterator to the first or next item and return ITER_OK.
+ * If the iteration is exhausted, free the resources associated with
+ * the ref_iterator and return ITER_DONE. On errors, free the iterator
+ * resources and return ITER_ERROR. It is a bug to use ref_iterator or
+ * call this function again after it has returned ITER_DONE or
+ * ITER_ERROR.
+ */
+int ref_iterator_advance(struct ref_iterator *ref_iterator);
+
+/*
+ * If possible, peel the reference currently being viewed by the
+ * iterator. Return 0 on success.
+ */
+int ref_iterator_peel(struct ref_iterator *ref_iterator,
+ struct object_id *peeled);
+
+/*
+ * End the iteration before it has been exhausted, freeing the
+ * reference iterator and any associated resources and returning
+ * ITER_DONE. If the abort itself failed, return ITER_ERROR.
+ */
+int ref_iterator_abort(struct ref_iterator *ref_iterator);
+
+/*
+ * An iterator over nothing (its first ref_iterator_advance() call
+ * returns ITER_DONE).
+ */
+struct ref_iterator *empty_ref_iterator_begin(void);
+
+/*
+ * Return true iff ref_iterator is an empty_ref_iterator.
+ */
+int is_empty_ref_iterator(struct ref_iterator *ref_iterator);
+
+/*
+ * Return an iterator that goes over each reference in `refs` for
+ * which the refname begins with prefix. If trim is non-zero, then
+ * trim that many characters off the beginning of each refname.
+ * The output is ordered by refname.
+ */
+struct ref_iterator *refs_ref_iterator_begin(
+ struct ref_store *refs,
+ const char *prefix, int trim,
+ enum do_for_each_ref_flags flags);
+
+/*
+ * A callback function used to instruct merge_ref_iterator how to
+ * interleave the entries from iter0 and iter1. The function should
+ * return one of the constants defined in enum iterator_selection. It
+ * must not advance either of the iterators itself.
+ *
+ * The function must be prepared to handle the case that iter0 and/or
+ * iter1 is NULL, which indicates that the corresponding sub-iterator
+ * has been exhausted. Its return value must be consistent with the
+ * current states of the iterators; e.g., it must not return
+ * ITER_SKIP_1 if iter1 has already been exhausted.
+ */
+typedef enum iterator_selection ref_iterator_select_fn(
+ struct ref_iterator *iter0, struct ref_iterator *iter1,
+ void *cb_data);
+
+/*
+ * Iterate over the entries from iter0 and iter1, with the values
+ * interleaved as directed by the select function. The iterator takes
+ * ownership of iter0 and iter1 and frees them when the iteration is
+ * over. A derived class should set `ordered` to 1 or 0 based on
+ * whether it generates its output in order by reference name.
+ */
+struct ref_iterator *merge_ref_iterator_begin(
+ int ordered,
+ struct ref_iterator *iter0, struct ref_iterator *iter1,
+ ref_iterator_select_fn *select, void *cb_data);
+
+/*
+ * An iterator consisting of the union of the entries from front and
+ * back. If there are entries common to the two sub-iterators, use the
+ * one from front. Each iterator must iterate over its entries in
+ * strcmp() order by refname for this to work.
+ *
+ * The new iterator takes ownership of its arguments and frees them
+ * when the iteration is over. As a convenience to callers, if front
+ * or back is an empty_ref_iterator, then abort that one immediately
+ * and return the other iterator directly, without wrapping it.
+ */
+struct ref_iterator *overlay_ref_iterator_begin(
+ struct ref_iterator *front, struct ref_iterator *back);
+
+/*
+ * Wrap iter0, only letting through the references whose names start
+ * with prefix. If trim is set, set iter->refname to the name of the
+ * reference with that many characters trimmed off the front;
+ * otherwise set it to the full refname. The new iterator takes over
+ * ownership of iter0 and frees it when iteration is over. It makes
+ * its own copy of prefix.
+ *
+ * As an convenience to callers, if prefix is the empty string and
+ * trim is zero, this function returns iter0 directly, without
+ * wrapping it.
+ *
+ * The resulting ref_iterator is ordered if iter0 is.
+ */
+struct ref_iterator *prefix_ref_iterator_begin(struct ref_iterator *iter0,
+ const char *prefix,
+ int trim);
+
+/* Internal implementation of reference iteration: */
+
+/*
+ * Base class constructor for ref_iterators. Initialize the
+ * ref_iterator part of iter, setting its vtable pointer as specified.
+ * `ordered` should be set to 1 if the iterator will iterate over
+ * references in order by refname; otherwise it should be set to 0.
+ * This is meant to be called only by the initializers of derived
+ * classes.
+ */
+void base_ref_iterator_init(struct ref_iterator *iter,
+ struct ref_iterator_vtable *vtable,
+ int ordered);
+
+/*
+ * Base class destructor for ref_iterators. Destroy the ref_iterator
+ * part of iter and shallow-free the object. This is meant to be
+ * called only by the destructors of derived classes.
+ */
+void base_ref_iterator_free(struct ref_iterator *iter);
+
+/* Virtual function declarations for ref_iterators: */
+
+/*
+ * backend-specific implementation of ref_iterator_advance. For symrefs, the
+ * function should set REF_ISSYMREF, and it should also dereference the symref
+ * to provide the OID referent. It should respect do_for_each_ref_flags
+ * that were passed to refs_ref_iterator_begin().
+ */
+typedef int ref_iterator_advance_fn(struct ref_iterator *ref_iterator);
+
+/*
+ * Peels the current ref, returning 0 for success or -1 for failure.
+ */
+typedef int ref_iterator_peel_fn(struct ref_iterator *ref_iterator,
+ struct object_id *peeled);
+
+/*
+ * Implementations of this function should free any resources specific
+ * to the derived class, then call base_ref_iterator_free() to clean
+ * up and free the ref_iterator object.
+ */
+typedef int ref_iterator_abort_fn(struct ref_iterator *ref_iterator);
+
+struct ref_iterator_vtable {
+ ref_iterator_advance_fn *advance;
+ ref_iterator_peel_fn *peel;
+ ref_iterator_abort_fn *abort;
+};
+
+/*
+ * current_ref_iter is a performance hack: when iterating over
+ * references using the for_each_ref*() functions, current_ref_iter is
+ * set to the reference iterator before calling the callback function.
+ * If the callback function calls peel_ref(), then peel_ref() first
+ * checks whether the reference to be peeled is the one referred to by
+ * the iterator (it usually is) and if so, asks the iterator for the
+ * peeled version of the reference if it is available. This avoids a
+ * refname lookup in a common case. current_ref_iter is set to NULL
+ * when the iteration is over.
+ */
+extern struct ref_iterator *current_ref_iter;
+
+/*
+ * The common backend for the for_each_*ref* functions. Call fn for
+ * each reference in iter. If the iterator itself ever returns
+ * ITER_ERROR, return -1. If fn ever returns a non-zero value, stop
+ * the iteration and return that value. Otherwise, return 0. In any
+ * case, free the iterator when done. This function is basically an
+ * adapter between the callback style of reference iteration and the
+ * iterator style.
+ */
+int do_for_each_repo_ref_iterator(struct repository *r,
+ struct ref_iterator *iter,
+ each_repo_ref_fn fn, void *cb_data);
+
+struct ref_store;
+
+/* refs backends */
+
+/* ref_store_init flags */
+#define REF_STORE_READ (1 << 0)
+#define REF_STORE_WRITE (1 << 1) /* can perform update operations */
+#define REF_STORE_ODB (1 << 2) /* has access to object database */
+#define REF_STORE_MAIN (1 << 3)
+#define REF_STORE_ALL_CAPS (REF_STORE_READ | \
+ REF_STORE_WRITE | \
+ REF_STORE_ODB | \
+ REF_STORE_MAIN)
+
+/*
+ * Initialize the ref_store for the specified gitdir. These functions
+ * should call base_ref_store_init() to initialize the shared part of
+ * the ref_store and to record the ref_store for later lookup.
+ */
+typedef struct ref_store *ref_store_init_fn(struct repository *repo,
+ const char *gitdir,
+ unsigned int flags);
+
+typedef int ref_init_db_fn(struct ref_store *refs, struct strbuf *err);
+
+typedef int ref_transaction_prepare_fn(struct ref_store *refs,
+ struct ref_transaction *transaction,
+ struct strbuf *err);
+
+typedef int ref_transaction_finish_fn(struct ref_store *refs,
+ struct ref_transaction *transaction,
+ struct strbuf *err);
+
+typedef int ref_transaction_abort_fn(struct ref_store *refs,
+ struct ref_transaction *transaction,
+ struct strbuf *err);
+
+typedef int ref_transaction_commit_fn(struct ref_store *refs,
+ struct ref_transaction *transaction,
+ struct strbuf *err);
+
+typedef int pack_refs_fn(struct ref_store *ref_store, unsigned int flags);
+typedef int create_symref_fn(struct ref_store *ref_store,
+ const char *ref_target,
+ const char *refs_heads_master,
+ const char *logmsg);
+typedef int delete_refs_fn(struct ref_store *ref_store, const char *msg,
+ struct string_list *refnames, unsigned int flags);
+typedef int rename_ref_fn(struct ref_store *ref_store,
+ const char *oldref, const char *newref,
+ const char *logmsg);
+typedef int copy_ref_fn(struct ref_store *ref_store,
+ const char *oldref, const char *newref,
+ const char *logmsg);
+
+/*
+ * Iterate over the references in `ref_store` whose names start with
+ * `prefix`. `prefix` is matched as a literal string, without regard
+ * for path separators. If prefix is NULL or the empty string, iterate
+ * over all references in `ref_store`. The output is ordered by
+ * refname.
+ */
+typedef struct ref_iterator *ref_iterator_begin_fn(
+ struct ref_store *ref_store,
+ const char *prefix, unsigned int flags);
+
+/* reflog functions */
+
+/*
+ * Iterate over the references in the specified ref_store that have a
+ * reflog. The refs are iterated over in arbitrary order.
+ */
+typedef struct ref_iterator *reflog_iterator_begin_fn(
+ struct ref_store *ref_store);
+
+typedef int for_each_reflog_ent_fn(struct ref_store *ref_store,
+ const char *refname,
+ each_reflog_ent_fn fn,
+ void *cb_data);
+typedef int for_each_reflog_ent_reverse_fn(struct ref_store *ref_store,
+ const char *refname,
+ each_reflog_ent_fn fn,
+ void *cb_data);
+typedef int reflog_exists_fn(struct ref_store *ref_store, const char *refname);
+typedef int create_reflog_fn(struct ref_store *ref_store, const char *refname,
+ struct strbuf *err);
+typedef int delete_reflog_fn(struct ref_store *ref_store, const char *refname);
+typedef int reflog_expire_fn(struct ref_store *ref_store,
+ const char *refname,
+ unsigned int flags,
+ reflog_expiry_prepare_fn prepare_fn,
+ reflog_expiry_should_prune_fn should_prune_fn,
+ reflog_expiry_cleanup_fn cleanup_fn,
+ void *policy_cb_data);
+
+/*
+ * Read a reference from the specified reference store, non-recursively.
+ * Set type to describe the reference, and:
+ *
+ * - If refname is the name of a normal reference, fill in oid
+ * (leaving referent unchanged).
+ *
+ * - If refname is the name of a symbolic reference, write the full
+ * name of the reference to which it refers (e.g.
+ * "refs/heads/master") to referent and set the REF_ISSYMREF bit in
+ * type (leaving oid unchanged). The caller is responsible for
+ * validating that referent is a valid reference name.
+ *
+ * WARNING: refname might be used as part of a filename, so it is
+ * important from a security standpoint that it be safe in the sense
+ * of refname_is_safe(). Moreover, for symrefs this function sets
+ * referent to whatever the repository says, which might not be a
+ * properly-formatted or even safe reference name. NEITHER INPUT NOR
+ * OUTPUT REFERENCE NAMES ARE VALIDATED WITHIN THIS FUNCTION.
+ *
+ * Return 0 on success, or -1 on failure. If the ref exists but is neither a
+ * symbolic ref nor an object ID, it is broken. In this case set REF_ISBROKEN in
+ * type, and return -1 (failure_errno should not be ENOENT)
+ *
+ * failure_errno provides errno codes that are interpreted beyond error
+ * reporting. The following error codes have special meaning:
+ * * ENOENT: the ref doesn't exist
+ * * EISDIR: ref name is a directory
+ * * ENOTDIR: ref prefix is not a directory
+ *
+ * Backend-specific flags might be set in type as well, regardless of
+ * outcome.
+ *
+ * It is OK for refname to point into referent. If so:
+ *
+ * - if the function succeeds with REF_ISSYMREF, referent will be
+ * overwritten and the memory formerly pointed to by it might be
+ * changed or even freed.
+ *
+ * - in all other cases, referent will be untouched, and therefore
+ * refname will still be valid and unchanged.
+ */
+typedef int read_raw_ref_fn(struct ref_store *ref_store, const char *refname,
+ struct object_id *oid, struct strbuf *referent,
+ unsigned int *type, int *failure_errno);
+
+/*
+ * Read a symbolic reference from the specified reference store. This function
+ * is optional: if not implemented by a backend, then `read_raw_ref_fn` is used
+ * to read the symbolcic reference instead. It is intended to be implemented
+ * only in case the backend can optimize the reading of symbolic references.
+ *
+ * Return 0 on success, or -1 on failure. `referent` will be set to the target
+ * of the symbolic reference on success. This function explicitly does not
+ * distinguish between error cases and the reference not being a symbolic
+ * reference to allow backends to optimize this operation in case symbolic and
+ * non-symbolic references are treated differently.
+ */
+typedef int read_symbolic_ref_fn(struct ref_store *ref_store, const char *refname,
+ struct strbuf *referent);
+
+struct ref_storage_be {
+ struct ref_storage_be *next;
+ const char *name;
+ ref_store_init_fn *init;
+ ref_init_db_fn *init_db;
+
+ ref_transaction_prepare_fn *transaction_prepare;
+ ref_transaction_finish_fn *transaction_finish;
+ ref_transaction_abort_fn *transaction_abort;
+ ref_transaction_commit_fn *initial_transaction_commit;
+
+ pack_refs_fn *pack_refs;
+ create_symref_fn *create_symref;
+ delete_refs_fn *delete_refs;
+ rename_ref_fn *rename_ref;
+ copy_ref_fn *copy_ref;
+
+ ref_iterator_begin_fn *iterator_begin;
+ read_raw_ref_fn *read_raw_ref;
+ read_symbolic_ref_fn *read_symbolic_ref;
+
+ reflog_iterator_begin_fn *reflog_iterator_begin;
+ for_each_reflog_ent_fn *for_each_reflog_ent;
+ for_each_reflog_ent_reverse_fn *for_each_reflog_ent_reverse;
+ reflog_exists_fn *reflog_exists;
+ create_reflog_fn *create_reflog;
+ delete_reflog_fn *delete_reflog;
+ reflog_expire_fn *reflog_expire;
+};
+
+extern struct ref_storage_be refs_be_files;
+extern struct ref_storage_be refs_be_packed;
+
+/*
+ * A representation of the reference store for the main repository or
+ * a submodule. The ref_store instances for submodules are kept in a
+ * hash map; see get_submodule_ref_store() for more info.
+ */
+struct ref_store {
+ /* The backend describing this ref_store's storage scheme: */
+ const struct ref_storage_be *be;
+
+ struct repository *repo;
+
+ /*
+ * The gitdir that this ref_store applies to. Note that this is not
+ * necessarily repo->gitdir if the repo has multiple worktrees.
+ */
+ char *gitdir;
+};
+
+/*
+ * Parse contents of a loose ref file. *failure_errno maybe be set to EINVAL for
+ * invalid contents.
+ */
+int parse_loose_ref_contents(const char *buf, struct object_id *oid,
+ struct strbuf *referent, unsigned int *type,
+ int *failure_errno);
+
+/*
+ * Fill in the generic part of refs and add it to our collection of
+ * reference stores.
+ */
+void base_ref_store_init(struct ref_store *refs, struct repository *repo,
+ const char *path, const struct ref_storage_be *be);
+
+/*
+ * Support GIT_TRACE_REFS by optionally wrapping the given ref_store instance.
+ */
+struct ref_store *maybe_debug_wrap_ref_store(const char *gitdir, struct ref_store *store);
+
+#endif /* REFS_REFS_INTERNAL_H */