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-rw-r--r--refs/iterator.c435
1 files changed, 435 insertions, 0 deletions
diff --git a/refs/iterator.c b/refs/iterator.c
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--- /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;
+}