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-rw-r--r--object-file-convert.c277
1 files changed, 277 insertions, 0 deletions
diff --git a/object-file-convert.c b/object-file-convert.c
new file mode 100644
index 0000000..4f61890
--- /dev/null
+++ b/object-file-convert.c
@@ -0,0 +1,277 @@
+#include "git-compat-util.h"
+#include "gettext.h"
+#include "strbuf.h"
+#include "hex.h"
+#include "repository.h"
+#include "hash-ll.h"
+#include "hash.h"
+#include "object.h"
+#include "loose.h"
+#include "commit.h"
+#include "gpg-interface.h"
+#include "object-file-convert.h"
+
+int repo_oid_to_algop(struct repository *repo, const struct object_id *src,
+ const struct git_hash_algo *to, struct object_id *dest)
+{
+ /*
+ * If the source algorithm is not set, then we're using the
+ * default hash algorithm for that object.
+ */
+ const struct git_hash_algo *from =
+ src->algo ? &hash_algos[src->algo] : repo->hash_algo;
+
+ if (from == to) {
+ if (src != dest)
+ oidcpy(dest, src);
+ return 0;
+ }
+ if (repo_loose_object_map_oid(repo, src, to, dest)) {
+ /*
+ * We may have loaded the object map at repo initialization but
+ * another process (perhaps upstream of a pipe from us) may have
+ * written a new object into the map. If the object is missing,
+ * let's reload the map to see if the object has appeared.
+ */
+ repo_read_loose_object_map(repo);
+ if (repo_loose_object_map_oid(repo, src, to, dest))
+ return -1;
+ }
+ return 0;
+}
+
+static int decode_tree_entry_raw(struct object_id *oid, const char **path,
+ size_t *len, const struct git_hash_algo *algo,
+ const char *buf, unsigned long size)
+{
+ uint16_t mode;
+ const unsigned hashsz = algo->rawsz;
+
+ if (size < hashsz + 3 || buf[size - (hashsz + 1)]) {
+ return -1;
+ }
+
+ *path = parse_mode(buf, &mode);
+ if (!*path || !**path)
+ return -1;
+ *len = strlen(*path) + 1;
+
+ oidread_algop(oid, (const unsigned char *)*path + *len, algo);
+ return 0;
+}
+
+static int convert_tree_object(struct strbuf *out,
+ const struct git_hash_algo *from,
+ const struct git_hash_algo *to,
+ const char *buffer, size_t size)
+{
+ const char *p = buffer, *end = buffer + size;
+
+ while (p < end) {
+ struct object_id entry_oid, mapped_oid;
+ const char *path = NULL;
+ size_t pathlen;
+
+ if (decode_tree_entry_raw(&entry_oid, &path, &pathlen, from, p,
+ end - p))
+ return error(_("failed to decode tree entry"));
+ if (repo_oid_to_algop(the_repository, &entry_oid, to, &mapped_oid))
+ return error(_("failed to map tree entry for %s"), oid_to_hex(&entry_oid));
+ strbuf_add(out, p, path - p);
+ strbuf_add(out, path, pathlen);
+ strbuf_add(out, mapped_oid.hash, to->rawsz);
+ p = path + pathlen + from->rawsz;
+ }
+ return 0;
+}
+
+static int convert_tag_object(struct strbuf *out,
+ const struct git_hash_algo *from,
+ const struct git_hash_algo *to,
+ const char *buffer, size_t size)
+{
+ struct strbuf payload = STRBUF_INIT, oursig = STRBUF_INIT, othersig = STRBUF_INIT;
+ const int entry_len = from->hexsz + 7;
+ size_t payload_size;
+ struct object_id oid, mapped_oid;
+ const char *p;
+
+ /* Consume the object line */
+ if ((entry_len >= size) ||
+ memcmp(buffer, "object ", 7) || buffer[entry_len] != '\n')
+ return error("bogus tag object");
+ if (parse_oid_hex_algop(buffer + 7, &oid, &p, from) < 0)
+ return error("bad tag object ID");
+ if (repo_oid_to_algop(the_repository, &oid, to, &mapped_oid))
+ return error("unable to map tree %s in tag object",
+ oid_to_hex(&oid));
+ size -= ((p + 1) - buffer);
+ buffer = p + 1;
+
+ /* Is there a signature for our algorithm? */
+ payload_size = parse_signed_buffer(buffer, size);
+ if (payload_size != size) {
+ /* Yes, there is. */
+ strbuf_add(&oursig, buffer + payload_size, size - payload_size);
+ }
+
+ /* Now, is there a signature for the other algorithm? */
+ parse_buffer_signed_by_header(buffer, payload_size, &payload, &othersig, to);
+ /*
+ * Our payload is now in payload and we may have up to two signatrures
+ * in oursig and othersig.
+ */
+
+ /* Add some slop for longer signature header in the new algorithm. */
+ strbuf_grow(out, (7 + to->hexsz + 1) + size + 7);
+ strbuf_addf(out, "object %s\n", oid_to_hex(&mapped_oid));
+ strbuf_addbuf(out, &payload);
+ if (oursig.len)
+ add_header_signature(out, &oursig, from);
+ strbuf_addbuf(out, &othersig);
+
+ strbuf_release(&payload);
+ strbuf_release(&othersig);
+ strbuf_release(&oursig);
+ return 0;
+}
+
+static int convert_commit_object(struct strbuf *out,
+ const struct git_hash_algo *from,
+ const struct git_hash_algo *to,
+ const char *buffer, size_t size)
+{
+ const char *tail = buffer;
+ const char *bufptr = buffer;
+ const int tree_entry_len = from->hexsz + 5;
+ const int parent_entry_len = from->hexsz + 7;
+ struct object_id oid, mapped_oid;
+ const char *p, *eol;
+
+ tail += size;
+
+ while ((bufptr < tail) && (*bufptr != '\n')) {
+ eol = memchr(bufptr, '\n', tail - bufptr);
+ if (!eol)
+ return error(_("bad %s in commit"), "line");
+
+ if (((bufptr + 5) < eol) && !memcmp(bufptr, "tree ", 5))
+ {
+ if (((bufptr + tree_entry_len) != eol) ||
+ parse_oid_hex_algop(bufptr + 5, &oid, &p, from) ||
+ (p != eol))
+ return error(_("bad %s in commit"), "tree");
+
+ if (repo_oid_to_algop(the_repository, &oid, to, &mapped_oid))
+ return error(_("unable to map %s %s in commit object"),
+ "tree", oid_to_hex(&oid));
+ strbuf_addf(out, "tree %s\n", oid_to_hex(&mapped_oid));
+ }
+ else if (((bufptr + 7) < eol) && !memcmp(bufptr, "parent ", 7))
+ {
+ if (((bufptr + parent_entry_len) != eol) ||
+ parse_oid_hex_algop(bufptr + 7, &oid, &p, from) ||
+ (p != eol))
+ return error(_("bad %s in commit"), "parent");
+
+ if (repo_oid_to_algop(the_repository, &oid, to, &mapped_oid))
+ return error(_("unable to map %s %s in commit object"),
+ "parent", oid_to_hex(&oid));
+
+ strbuf_addf(out, "parent %s\n", oid_to_hex(&mapped_oid));
+ }
+ else if (((bufptr + 9) < eol) && !memcmp(bufptr, "mergetag ", 9))
+ {
+ struct strbuf tag = STRBUF_INIT, new_tag = STRBUF_INIT;
+
+ /* Recover the tag object from the mergetag */
+ strbuf_add(&tag, bufptr + 9, (eol - (bufptr + 9)) + 1);
+
+ bufptr = eol + 1;
+ while ((bufptr < tail) && (*bufptr == ' ')) {
+ eol = memchr(bufptr, '\n', tail - bufptr);
+ if (!eol) {
+ strbuf_release(&tag);
+ return error(_("bad %s in commit"), "mergetag continuation");
+ }
+ strbuf_add(&tag, bufptr + 1, (eol - (bufptr + 1)) + 1);
+ bufptr = eol + 1;
+ }
+
+ /* Compute the new tag object */
+ if (convert_tag_object(&new_tag, from, to, tag.buf, tag.len)) {
+ strbuf_release(&tag);
+ strbuf_release(&new_tag);
+ return -1;
+ }
+
+ /* Write the new mergetag */
+ strbuf_addstr(out, "mergetag");
+ strbuf_add_lines(out, " ", new_tag.buf, new_tag.len);
+ strbuf_release(&tag);
+ strbuf_release(&new_tag);
+ }
+ else if (((bufptr + 7) < tail) && !memcmp(bufptr, "author ", 7))
+ strbuf_add(out, bufptr, (eol - bufptr) + 1);
+ else if (((bufptr + 10) < tail) && !memcmp(bufptr, "committer ", 10))
+ strbuf_add(out, bufptr, (eol - bufptr) + 1);
+ else if (((bufptr + 9) < tail) && !memcmp(bufptr, "encoding ", 9))
+ strbuf_add(out, bufptr, (eol - bufptr) + 1);
+ else if (((bufptr + 6) < tail) && !memcmp(bufptr, "gpgsig", 6))
+ strbuf_add(out, bufptr, (eol - bufptr) + 1);
+ else {
+ /* Unknown line fail it might embed an oid */
+ return -1;
+ }
+ /* Consume any trailing continuation lines */
+ bufptr = eol + 1;
+ while ((bufptr < tail) && (*bufptr == ' ')) {
+ eol = memchr(bufptr, '\n', tail - bufptr);
+ if (!eol)
+ return error(_("bad %s in commit"), "continuation");
+ strbuf_add(out, bufptr, (eol - bufptr) + 1);
+ bufptr = eol + 1;
+ }
+ }
+ if (bufptr < tail)
+ strbuf_add(out, bufptr, tail - bufptr);
+ return 0;
+}
+
+int convert_object_file(struct strbuf *outbuf,
+ const struct git_hash_algo *from,
+ const struct git_hash_algo *to,
+ const void *buf, size_t len,
+ enum object_type type,
+ int gentle)
+{
+ int ret;
+
+ /* Don't call this function when no conversion is necessary */
+ if ((from == to) || (type == OBJ_BLOB))
+ BUG("Refusing noop object file conversion");
+
+ switch (type) {
+ case OBJ_COMMIT:
+ ret = convert_commit_object(outbuf, from, to, buf, len);
+ break;
+ case OBJ_TREE:
+ ret = convert_tree_object(outbuf, from, to, buf, len);
+ break;
+ case OBJ_TAG:
+ ret = convert_tag_object(outbuf, from, to, buf, len);
+ break;
+ default:
+ /* Not implemented yet, so fail. */
+ ret = -1;
+ break;
+ }
+ if (!ret)
+ return 0;
+ if (gentle) {
+ strbuf_release(outbuf);
+ return ret;
+ }
+ die(_("Failed to convert object from %s to %s"),
+ from->name, to->name);
+}