Adding upstream version 1:2.39.2.upstream/1%2.39.2upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 975 insertions, 0 deletions

diff --git a/cache-tree.c b/cache-tree.c
new file mode 100644
index 0000000..c97111c
--- /dev/null
+++ b/cache-tree.c
@@ -0,0 +1,975 @@
+#include "cache.h"
+#include "lockfile.h"
+#include "tree.h"
+#include "tree-walk.h"
+#include "cache-tree.h"
+#include "bulk-checkin.h"
+#include "object-store.h"
+#include "replace-object.h"
+#include "promisor-remote.h"
+#include "sparse-index.h"
+
+#ifndef DEBUG_CACHE_TREE
+#define DEBUG_CACHE_TREE 0
+#endif
+
+struct cache_tree *cache_tree(void)
+{
+	struct cache_tree *it = xcalloc(1, sizeof(struct cache_tree));
+	it->entry_count = -1;
+	return it;
+}
+
+void cache_tree_free(struct cache_tree **it_p)
+{
+	int i;
+	struct cache_tree *it = *it_p;
+
+	if (!it)
+		return;
+	for (i = 0; i < it->subtree_nr; i++)
+		if (it->down[i]) {
+			cache_tree_free(&it->down[i]->cache_tree);
+			free(it->down[i]);
+		}
+	free(it->down);
+	free(it);
+	*it_p = NULL;
+}
+
+static int subtree_name_cmp(const char *one, int onelen,
+			    const char *two, int twolen)
+{
+	if (onelen < twolen)
+		return -1;
+	if (twolen < onelen)
+		return 1;
+	return memcmp(one, two, onelen);
+}
+
+int cache_tree_subtree_pos(struct cache_tree *it, const char *path, int pathlen)
+{
+	struct cache_tree_sub **down = it->down;
+	int lo, hi;
+	lo = 0;
+	hi = it->subtree_nr;
+	while (lo < hi) {
+		int mi = lo + (hi - lo) / 2;
+		struct cache_tree_sub *mdl = down[mi];
+		int cmp = subtree_name_cmp(path, pathlen,
+					   mdl->name, mdl->namelen);
+		if (!cmp)
+			return mi;
+		if (cmp < 0)
+			hi = mi;
+		else
+			lo = mi + 1;
+	}
+	return -lo-1;
+}
+
+static struct cache_tree_sub *find_subtree(struct cache_tree *it,
+					   const char *path,
+					   int pathlen,
+					   int create)
+{
+	struct cache_tree_sub *down;
+	int pos = cache_tree_subtree_pos(it, path, pathlen);
+	if (0 <= pos)
+		return it->down[pos];
+	if (!create)
+		return NULL;
+
+	pos = -pos-1;
+	ALLOC_GROW(it->down, it->subtree_nr + 1, it->subtree_alloc);
+	it->subtree_nr++;
+
+	FLEX_ALLOC_MEM(down, name, path, pathlen);
+	down->cache_tree = NULL;
+	down->namelen = pathlen;
+
+	if (pos < it->subtree_nr)
+		MOVE_ARRAY(it->down + pos + 1, it->down + pos,
+			   it->subtree_nr - pos - 1);
+	it->down[pos] = down;
+	return down;
+}
+
+struct cache_tree_sub *cache_tree_sub(struct cache_tree *it, const char *path)
+{
+	int pathlen = strlen(path);
+	return find_subtree(it, path, pathlen, 1);
+}
+
+static int do_invalidate_path(struct cache_tree *it, const char *path)
+{
+	/* a/b/c
+	 * ==> invalidate self
+	 * ==> find "a", have it invalidate "b/c"
+	 * a
+	 * ==> invalidate self
+	 * ==> if "a" exists as a subtree, remove it.
+	 */
+	const char *slash;
+	int namelen;
+	struct cache_tree_sub *down;
+
+#if DEBUG_CACHE_TREE
+	fprintf(stderr, "cache-tree invalidate <%s>\n", path);
+#endif
+
+	if (!it)
+		return 0;
+	slash = strchrnul(path, '/');
+	namelen = slash - path;
+	it->entry_count = -1;
+	if (!*slash) {
+		int pos;
+		pos = cache_tree_subtree_pos(it, path, namelen);
+		if (0 <= pos) {
+			cache_tree_free(&it->down[pos]->cache_tree);
+			free(it->down[pos]);
+			/* 0 1 2 3 4 5
+			 *       ^     ^subtree_nr = 6
+			 *       pos
+			 * move 4 and 5 up one place (2 entries)
+			 * 2 = 6 - 3 - 1 = subtree_nr - pos - 1
+			 */
+			MOVE_ARRAY(it->down + pos, it->down + pos + 1,
+				   it->subtree_nr - pos - 1);
+			it->subtree_nr--;
+		}
+		return 1;
+	}
+	down = find_subtree(it, path, namelen, 0);
+	if (down)
+		do_invalidate_path(down->cache_tree, slash + 1);
+	return 1;
+}
+
+void cache_tree_invalidate_path(struct index_state *istate, const char *path)
+{
+	if (do_invalidate_path(istate->cache_tree, path))
+		istate->cache_changed |= CACHE_TREE_CHANGED;
+}
+
+static int verify_cache(struct index_state *istate, int flags)
+{
+	unsigned i, funny;
+	int silent = flags & WRITE_TREE_SILENT;
+
+	/* Verify that the tree is merged */
+	funny = 0;
+	for (i = 0; i < istate->cache_nr; i++) {
+		const struct cache_entry *ce = istate->cache[i];
+		if (ce_stage(ce)) {
+			if (silent)
+				return -1;
+			if (10 < ++funny) {
+				fprintf(stderr, "...\n");
+				break;
+			}
+			fprintf(stderr, "%s: unmerged (%s)\n",
+				ce->name, oid_to_hex(&ce->oid));
+		}
+	}
+	if (funny)
+		return -1;
+
+	/* Also verify that the cache does not have path and path/file
+	 * at the same time.  At this point we know the cache has only
+	 * stage 0 entries.
+	 */
+	funny = 0;
+	for (i = 0; i + 1 < istate->cache_nr; i++) {
+		/* path/file always comes after path because of the way
+		 * the cache is sorted.  Also path can appear only once,
+		 * which means conflicting one would immediately follow.
+		 */
+		const struct cache_entry *this_ce = istate->cache[i];
+		const struct cache_entry *next_ce = istate->cache[i + 1];
+		const char *this_name = this_ce->name;
+		const char *next_name = next_ce->name;
+		int this_len = ce_namelen(this_ce);
+		if (this_len < ce_namelen(next_ce) &&
+		    next_name[this_len] == '/' &&
+		    strncmp(this_name, next_name, this_len) == 0) {
+			if (10 < ++funny) {
+				fprintf(stderr, "...\n");
+				break;
+			}
+			fprintf(stderr, "You have both %s and %s\n",
+				this_name, next_name);
+		}
+	}
+	if (funny)
+		return -1;
+	return 0;
+}
+
+static void discard_unused_subtrees(struct cache_tree *it)
+{
+	struct cache_tree_sub **down = it->down;
+	int nr = it->subtree_nr;
+	int dst, src;
+	for (dst = src = 0; src < nr; src++) {
+		struct cache_tree_sub *s = down[src];
+		if (s->used)
+			down[dst++] = s;
+		else {
+			cache_tree_free(&s->cache_tree);
+			free(s);
+			it->subtree_nr--;
+		}
+	}
+}
+
+int cache_tree_fully_valid(struct cache_tree *it)
+{
+	int i;
+	if (!it)
+		return 0;
+	if (it->entry_count < 0 || !has_object_file(&it->oid))
+		return 0;
+	for (i = 0; i < it->subtree_nr; i++) {
+		if (!cache_tree_fully_valid(it->down[i]->cache_tree))
+			return 0;
+	}
+	return 1;
+}
+
+static int must_check_existence(const struct cache_entry *ce)
+{
+	return !(has_promisor_remote() && ce_skip_worktree(ce));
+}
+
+static int update_one(struct cache_tree *it,
+		      struct cache_entry **cache,
+		      int entries,
+		      const char *base,
+		      int baselen,
+		      int *skip_count,
+		      int flags)
+{
+	struct strbuf buffer;
+	int missing_ok = flags & WRITE_TREE_MISSING_OK;
+	int dryrun = flags & WRITE_TREE_DRY_RUN;
+	int repair = flags & WRITE_TREE_REPAIR;
+	int to_invalidate = 0;
+	int i;
+
+	assert(!(dryrun && repair));
+
+	*skip_count = 0;
+
+	/*
+	 * If the first entry of this region is a sparse directory
+	 * entry corresponding exactly to 'base', then this cache_tree
+	 * struct is a "leaf" in the data structure, pointing to the
+	 * tree OID specified in the entry.
+	 */
+	if (entries > 0) {
+		const struct cache_entry *ce = cache[0];
+
+		if (S_ISSPARSEDIR(ce->ce_mode) &&
+		    ce->ce_namelen == baselen &&
+		    !strncmp(ce->name, base, baselen)) {
+			it->entry_count = 1;
+			oidcpy(&it->oid, &ce->oid);
+			return 1;
+		}
+	}
+
+	if (0 <= it->entry_count && has_object_file(&it->oid))
+		return it->entry_count;
+
+	/*
+	 * We first scan for subtrees and update them; we start by
+	 * marking existing subtrees -- the ones that are unmarked
+	 * should not be in the result.
+	 */
+	for (i = 0; i < it->subtree_nr; i++)
+		it->down[i]->used = 0;
+
+	/*
+	 * Find the subtrees and update them.
+	 */
+	i = 0;
+	while (i < entries) {
+		const struct cache_entry *ce = cache[i];
+		struct cache_tree_sub *sub;
+		const char *path, *slash;
+		int pathlen, sublen, subcnt, subskip;
+
+		path = ce->name;
+		pathlen = ce_namelen(ce);
+		if (pathlen <= baselen || memcmp(base, path, baselen))
+			break; /* at the end of this level */
+
+		slash = strchr(path + baselen, '/');
+		if (!slash) {
+			i++;
+			continue;
+		}
+		/*
+		 * a/bbb/c (base = a/, slash = /c)
+		 * ==>
+		 * path+baselen = bbb/c, sublen = 3
+		 */
+		sublen = slash - (path + baselen);
+		sub = find_subtree(it, path + baselen, sublen, 1);
+		if (!sub->cache_tree)
+			sub->cache_tree = cache_tree();
+		subcnt = update_one(sub->cache_tree,
+				    cache + i, entries - i,
+				    path,
+				    baselen + sublen + 1,
+				    &subskip,
+				    flags);
+		if (subcnt < 0)
+			return subcnt;
+		if (!subcnt)
+			die("index cache-tree records empty sub-tree");
+		i += subcnt;
+		sub->count = subcnt; /* to be used in the next loop */
+		*skip_count += subskip;
+		sub->used = 1;
+	}
+
+	discard_unused_subtrees(it);
+
+	/*
+	 * Then write out the tree object for this level.
+	 */
+	strbuf_init(&buffer, 8192);
+
+	i = 0;
+	while (i < entries) {
+		const struct cache_entry *ce = cache[i];
+		struct cache_tree_sub *sub = NULL;
+		const char *path, *slash;
+		int pathlen, entlen;
+		const struct object_id *oid;
+		unsigned mode;
+		int expected_missing = 0;
+		int contains_ita = 0;
+		int ce_missing_ok;
+
+		path = ce->name;
+		pathlen = ce_namelen(ce);
+		if (pathlen <= baselen || memcmp(base, path, baselen))
+			break; /* at the end of this level */
+
+		slash = strchr(path + baselen, '/');
+		if (slash) {
+			entlen = slash - (path + baselen);
+			sub = find_subtree(it, path + baselen, entlen, 0);
+			if (!sub)
+				die("cache-tree.c: '%.*s' in '%s' not found",
+				    entlen, path + baselen, path);
+			i += sub->count;
+			oid = &sub->cache_tree->oid;
+			mode = S_IFDIR;
+			contains_ita = sub->cache_tree->entry_count < 0;
+			if (contains_ita) {
+				to_invalidate = 1;
+				expected_missing = 1;
+			}
+		}
+		else {
+			oid = &ce->oid;
+			mode = ce->ce_mode;
+			entlen = pathlen - baselen;
+			i++;
+		}
+
+		ce_missing_ok = mode == S_IFGITLINK || missing_ok ||
+			!must_check_existence(ce);
+		if (is_null_oid(oid) ||
+		    (!ce_missing_ok && !has_object_file(oid))) {
+			strbuf_release(&buffer);
+			if (expected_missing)
+				return -1;
+			return error("invalid object %06o %s for '%.*s'",
+				mode, oid_to_hex(oid), entlen+baselen, path);
+		}
+
+		/*
+		 * CE_REMOVE entries are removed before the index is
+		 * written to disk. Skip them to remain consistent
+		 * with the future on-disk index.
+		 */
+		if (ce->ce_flags & CE_REMOVE) {
+			*skip_count = *skip_count + 1;
+			continue;
+		}
+
+		/*
+		 * CE_INTENT_TO_ADD entries exist on on-disk index but
+		 * they are not part of generated trees. Invalidate up
+		 * to root to force cache-tree users to read elsewhere.
+		 */
+		if (!sub && ce_intent_to_add(ce)) {
+			to_invalidate = 1;
+			continue;
+		}
+
+		/*
+		 * "sub" can be an empty tree if all subentries are i-t-a.
+		 */
+		if (contains_ita && is_empty_tree_oid(oid))
+			continue;
+
+		strbuf_grow(&buffer, entlen + 100);
+		strbuf_addf(&buffer, "%o %.*s%c", mode, entlen, path + baselen, '\0');
+		strbuf_add(&buffer, oid->hash, the_hash_algo->rawsz);
+
+#if DEBUG_CACHE_TREE
+		fprintf(stderr, "cache-tree update-one %o %.*s\n",
+			mode, entlen, path + baselen);
+#endif
+	}
+
+	if (repair) {
+		struct object_id oid;
+		hash_object_file(the_hash_algo, buffer.buf, buffer.len,
+				 OBJ_TREE, &oid);
+		if (has_object_file_with_flags(&oid, OBJECT_INFO_SKIP_FETCH_OBJECT))
+			oidcpy(&it->oid, &oid);
+		else
+			to_invalidate = 1;
+	} else if (dryrun) {
+		hash_object_file(the_hash_algo, buffer.buf, buffer.len,
+				 OBJ_TREE, &it->oid);
+	} else if (write_object_file_flags(buffer.buf, buffer.len, OBJ_TREE,
+					   &it->oid, flags & WRITE_TREE_SILENT
+					   ? HASH_SILENT : 0)) {
+		strbuf_release(&buffer);
+		return -1;
+	}
+
+	strbuf_release(&buffer);
+	it->entry_count = to_invalidate ? -1 : i - *skip_count;
+#if DEBUG_CACHE_TREE
+	fprintf(stderr, "cache-tree update-one (%d ent, %d subtree) %s\n",
+		it->entry_count, it->subtree_nr,
+		oid_to_hex(&it->oid));
+#endif
+	return i;
+}
+
+int cache_tree_update(struct index_state *istate, int flags)
+{
+	int skip, i;
+
+	i = verify_cache(istate, flags);
+
+	if (i)
+		return i;
+
+	if (!istate->cache_tree)
+		istate->cache_tree = cache_tree();
+
+	if (!(flags & WRITE_TREE_MISSING_OK) && has_promisor_remote())
+		prefetch_cache_entries(istate, must_check_existence);
+
+	trace_performance_enter();
+	trace2_region_enter("cache_tree", "update", the_repository);
+	begin_odb_transaction();
+	i = update_one(istate->cache_tree, istate->cache, istate->cache_nr,
+		       "", 0, &skip, flags);
+	end_odb_transaction();
+	trace2_region_leave("cache_tree", "update", the_repository);
+	trace_performance_leave("cache_tree_update");
+	if (i < 0)
+		return i;
+	istate->cache_changed |= CACHE_TREE_CHANGED;
+	return 0;
+}
+
+static void write_one(struct strbuf *buffer, struct cache_tree *it,
+		      const char *path, int pathlen)
+{
+	int i;
+
+	/* One "cache-tree" entry consists of the following:
+	 * path (NUL terminated)
+	 * entry_count, subtree_nr ("%d %d\n")
+	 * tree-sha1 (missing if invalid)
+	 * subtree_nr "cache-tree" entries for subtrees.
+	 */
+	strbuf_grow(buffer, pathlen + 100);
+	strbuf_add(buffer, path, pathlen);
+	strbuf_addf(buffer, "%c%d %d\n", 0, it->entry_count, it->subtree_nr);
+
+#if DEBUG_CACHE_TREE
+	if (0 <= it->entry_count)
+		fprintf(stderr, "cache-tree <%.*s> (%d ent, %d subtree) %s\n",
+			pathlen, path, it->entry_count, it->subtree_nr,
+			oid_to_hex(&it->oid));
+	else
+		fprintf(stderr, "cache-tree <%.*s> (%d subtree) invalid\n",
+			pathlen, path, it->subtree_nr);
+#endif
+
+	if (0 <= it->entry_count) {
+		strbuf_add(buffer, it->oid.hash, the_hash_algo->rawsz);
+	}
+	for (i = 0; i < it->subtree_nr; i++) {
+		struct cache_tree_sub *down = it->down[i];
+		if (i) {
+			struct cache_tree_sub *prev = it->down[i-1];
+			if (subtree_name_cmp(down->name, down->namelen,
+					     prev->name, prev->namelen) <= 0)
+				die("fatal - unsorted cache subtree");
+		}
+		write_one(buffer, down->cache_tree, down->name, down->namelen);
+	}
+}
+
+void cache_tree_write(struct strbuf *sb, struct cache_tree *root)
+{
+	trace2_region_enter("cache_tree", "write", the_repository);
+	write_one(sb, root, "", 0);
+	trace2_region_leave("cache_tree", "write", the_repository);
+}
+
+static struct cache_tree *read_one(const char **buffer, unsigned long *size_p)
+{
+	const char *buf = *buffer;
+	unsigned long size = *size_p;
+	const char *cp;
+	char *ep;
+	struct cache_tree *it;
+	int i, subtree_nr;
+	const unsigned rawsz = the_hash_algo->rawsz;
+
+	it = NULL;
+	/* skip name, but make sure name exists */
+	while (size && *buf) {
+		size--;
+		buf++;
+	}
+	if (!size)
+		goto free_return;
+	buf++; size--;
+	it = cache_tree();
+
+	cp = buf;
+	it->entry_count = strtol(cp, &ep, 10);
+	if (cp == ep)
+		goto free_return;
+	cp = ep;
+	subtree_nr = strtol(cp, &ep, 10);
+	if (cp == ep)
+		goto free_return;
+	while (size && *buf && *buf != '\n') {
+		size--;
+		buf++;
+	}
+	if (!size)
+		goto free_return;
+	buf++; size--;
+	if (0 <= it->entry_count) {
+		if (size < rawsz)
+			goto free_return;
+		oidread(&it->oid, (const unsigned char *)buf);
+		buf += rawsz;
+		size -= rawsz;
+	}
+
+#if DEBUG_CACHE_TREE
+	if (0 <= it->entry_count)
+		fprintf(stderr, "cache-tree <%s> (%d ent, %d subtree) %s\n",
+			*buffer, it->entry_count, subtree_nr,
+			oid_to_hex(&it->oid));
+	else
+		fprintf(stderr, "cache-tree <%s> (%d subtrees) invalid\n",
+			*buffer, subtree_nr);
+#endif
+
+	/*
+	 * Just a heuristic -- we do not add directories that often but
+	 * we do not want to have to extend it immediately when we do,
+	 * hence +2.
+	 */
+	it->subtree_alloc = subtree_nr + 2;
+	CALLOC_ARRAY(it->down, it->subtree_alloc);
+	for (i = 0; i < subtree_nr; i++) {
+		/* read each subtree */
+		struct cache_tree *sub;
+		struct cache_tree_sub *subtree;
+		const char *name = buf;
+
+		sub = read_one(&buf, &size);
+		if (!sub)
+			goto free_return;
+		subtree = cache_tree_sub(it, name);
+		subtree->cache_tree = sub;
+	}
+	if (subtree_nr != it->subtree_nr)
+		die("cache-tree: internal error");
+	*buffer = buf;
+	*size_p = size;
+	return it;
+
+ free_return:
+	cache_tree_free(&it);
+	return NULL;
+}
+
+struct cache_tree *cache_tree_read(const char *buffer, unsigned long size)
+{
+	struct cache_tree *result;
+
+	if (buffer[0])
+		return NULL; /* not the whole tree */
+
+	trace2_region_enter("cache_tree", "read", the_repository);
+	result = read_one(&buffer, &size);
+	trace2_region_leave("cache_tree", "read", the_repository);
+
+	return result;
+}
+
+static struct cache_tree *cache_tree_find(struct cache_tree *it, const char *path)
+{
+	if (!it)
+		return NULL;
+	while (*path) {
+		const char *slash;
+		struct cache_tree_sub *sub;
+
+		slash = strchrnul(path, '/');
+		/*
+		 * Between path and slash is the name of the subtree
+		 * to look for.
+		 */
+		sub = find_subtree(it, path, slash - path, 0);
+		if (!sub)
+			return NULL;
+		it = sub->cache_tree;
+
+		path = slash;
+		while (*path == '/')
+			path++;
+	}
+	return it;
+}
+
+static int write_index_as_tree_internal(struct object_id *oid,
+					struct index_state *index_state,
+					int cache_tree_valid,
+					int flags,
+					const char *prefix)
+{
+	if (flags & WRITE_TREE_IGNORE_CACHE_TREE) {
+		cache_tree_free(&index_state->cache_tree);
+		cache_tree_valid = 0;
+	}
+
+	if (!cache_tree_valid && cache_tree_update(index_state, flags) < 0)
+		return WRITE_TREE_UNMERGED_INDEX;
+
+	if (prefix) {
+		struct cache_tree *subtree;
+		subtree = cache_tree_find(index_state->cache_tree, prefix);
+		if (!subtree)
+			return WRITE_TREE_PREFIX_ERROR;
+		oidcpy(oid, &subtree->oid);
+	}
+	else
+		oidcpy(oid, &index_state->cache_tree->oid);
+
+	return 0;
+}
+
+struct tree* write_in_core_index_as_tree(struct repository *repo) {
+	struct object_id o;
+	int was_valid, ret;
+
+	struct index_state *index_state	= repo->index;
+	was_valid = index_state->cache_tree &&
+		    cache_tree_fully_valid(index_state->cache_tree);
+
+	ret = write_index_as_tree_internal(&o, index_state, was_valid, 0, NULL);
+	if (ret == WRITE_TREE_UNMERGED_INDEX) {
+		int i;
+		bug("there are unmerged index entries:");
+		for (i = 0; i < index_state->cache_nr; i++) {
+			const struct cache_entry *ce = index_state->cache[i];
+			if (ce_stage(ce))
+				bug("%d %.*s", ce_stage(ce),
+				    (int)ce_namelen(ce), ce->name);
+		}
+		BUG("unmerged index entries when writing in-core index");
+	}
+
+	return lookup_tree(repo, &index_state->cache_tree->oid);
+}
+
+
+int write_index_as_tree(struct object_id *oid, struct index_state *index_state, const char *index_path, int flags, const char *prefix)
+{
+	int entries, was_valid;
+	struct lock_file lock_file = LOCK_INIT;
+	int ret;
+
+	hold_lock_file_for_update(&lock_file, index_path, LOCK_DIE_ON_ERROR);
+
+	entries = read_index_from(index_state, index_path, get_git_dir());
+	if (entries < 0) {
+		ret = WRITE_TREE_UNREADABLE_INDEX;
+		goto out;
+	}
+
+	was_valid = !(flags & WRITE_TREE_IGNORE_CACHE_TREE) &&
+		    index_state->cache_tree &&
+		    cache_tree_fully_valid(index_state->cache_tree);
+
+	ret = write_index_as_tree_internal(oid, index_state, was_valid, flags,
+					   prefix);
+	if (!ret && !was_valid) {
+		write_locked_index(index_state, &lock_file, COMMIT_LOCK);
+		/* Not being able to write is fine -- we are only interested
+		 * in updating the cache-tree part, and if the next caller
+		 * ends up using the old index with unupdated cache-tree part
+		 * it misses the work we did here, but that is just a
+		 * performance penalty and not a big deal.
+		 */
+	}
+
+out:
+	rollback_lock_file(&lock_file);
+	return ret;
+}
+
+static void prime_cache_tree_sparse_dir(struct cache_tree *it,
+					struct tree *tree)
+{
+
+	oidcpy(&it->oid, &tree->object.oid);
+	it->entry_count = 1;
+}
+
+static void prime_cache_tree_rec(struct repository *r,
+				 struct cache_tree *it,
+				 struct tree *tree,
+				 struct strbuf *tree_path)
+{
+	struct tree_desc desc;
+	struct name_entry entry;
+	int cnt;
+	int base_path_len = tree_path->len;
+
+	oidcpy(&it->oid, &tree->object.oid);
+
+	init_tree_desc(&desc, tree->buffer, tree->size);
+	cnt = 0;
+	while (tree_entry(&desc, &entry)) {
+		if (!S_ISDIR(entry.mode))
+			cnt++;
+		else {
+			struct cache_tree_sub *sub;
+			struct tree *subtree = lookup_tree(r, &entry.oid);
+
+			if (!subtree->object.parsed)
+				parse_tree(subtree);
+			sub = cache_tree_sub(it, entry.path);
+			sub->cache_tree = cache_tree();
+
+			/*
+			 * Recursively-constructed subtree path is only needed when working
+			 * in a sparse index (where it's used to determine whether the
+			 * subtree is a sparse directory in the index).
+			 */
+			if (r->index->sparse_index) {
+				strbuf_setlen(tree_path, base_path_len);
+				strbuf_grow(tree_path, base_path_len + entry.pathlen + 1);
+				strbuf_add(tree_path, entry.path, entry.pathlen);
+				strbuf_addch(tree_path, '/');
+			}
+
+			/*
+			 * If a sparse index is in use, the directory being processed may be
+			 * sparse. To confirm that, we can check whether an entry with that
+			 * exact name exists in the index. If it does, the created subtree
+			 * should be sparse. Otherwise, cache tree expansion should continue
+			 * as normal.
+			 */
+			if (r->index->sparse_index &&
+			    index_entry_exists(r->index, tree_path->buf, tree_path->len))
+				prime_cache_tree_sparse_dir(sub->cache_tree, subtree);
+			else
+				prime_cache_tree_rec(r, sub->cache_tree, subtree, tree_path);
+			cnt += sub->cache_tree->entry_count;
+		}
+	}
+
+	it->entry_count = cnt;
+}
+
+void prime_cache_tree(struct repository *r,
+		      struct index_state *istate,
+		      struct tree *tree)
+{
+	struct strbuf tree_path = STRBUF_INIT;
+
+	trace2_region_enter("cache-tree", "prime_cache_tree", the_repository);
+	cache_tree_free(&istate->cache_tree);
+	istate->cache_tree = cache_tree();
+
+	prime_cache_tree_rec(r, istate->cache_tree, tree, &tree_path);
+	strbuf_release(&tree_path);
+	istate->cache_changed |= CACHE_TREE_CHANGED;
+	trace2_region_leave("cache-tree", "prime_cache_tree", the_repository);
+}
+
+/*
+ * find the cache_tree that corresponds to the current level without
+ * exploding the full path into textual form.  The root of the
+ * cache tree is given as "root", and our current level is "info".
+ * (1) When at root level, info->prev is NULL, so it is "root" itself.
+ * (2) Otherwise, find the cache_tree that corresponds to one level
+ *     above us, and find ourselves in there.
+ */
+static struct cache_tree *find_cache_tree_from_traversal(struct cache_tree *root,
+							 struct traverse_info *info)
+{
+	struct cache_tree *our_parent;
+
+	if (!info->prev)
+		return root;
+	our_parent = find_cache_tree_from_traversal(root, info->prev);
+	return cache_tree_find(our_parent, info->name);
+}
+
+int cache_tree_matches_traversal(struct cache_tree *root,
+				 struct name_entry *ent,
+				 struct traverse_info *info)
+{
+	struct cache_tree *it;
+
+	it = find_cache_tree_from_traversal(root, info);
+	it = cache_tree_find(it, ent->path);
+	if (it && it->entry_count > 0 && oideq(&ent->oid, &it->oid))
+		return it->entry_count;
+	return 0;
+}
+
+static void verify_one_sparse(struct index_state *istate,
+			      struct strbuf *path,
+			      int pos)
+{
+	struct cache_entry *ce = istate->cache[pos];
+
+	if (!S_ISSPARSEDIR(ce->ce_mode))
+		BUG("directory '%s' is present in index, but not sparse",
+		    path->buf);
+}
+
+/*
+ * Returns:
+ *  0 - Verification completed.
+ *  1 - Restart verification - a call to ensure_full_index() freed the cache
+ *      tree that is being verified and verification needs to be restarted from
+ *      the new toplevel cache tree.
+ */
+static int verify_one(struct repository *r,
+		      struct index_state *istate,
+		      struct cache_tree *it,
+		      struct strbuf *path)
+{
+	int i, pos, len = path->len;
+	struct strbuf tree_buf = STRBUF_INIT;
+	struct object_id new_oid;
+
+	for (i = 0; i < it->subtree_nr; i++) {
+		strbuf_addf(path, "%s/", it->down[i]->name);
+		if (verify_one(r, istate, it->down[i]->cache_tree, path))
+			return 1;
+		strbuf_setlen(path, len);
+	}
+
+	if (it->entry_count < 0 ||
+	    /* no verification on tests (t7003) that replace trees */
+	    lookup_replace_object(r, &it->oid) != &it->oid)
+		return 0;
+
+	if (path->len) {
+		/*
+		 * If the index is sparse and the cache tree is not
+		 * index_name_pos() may trigger ensure_full_index() which will
+		 * free the tree that is being verified.
+		 */
+		int is_sparse = istate->sparse_index;
+		pos = index_name_pos(istate, path->buf, path->len);
+		if (is_sparse && !istate->sparse_index)
+			return 1;
+
+		if (pos >= 0) {
+			verify_one_sparse(istate, path, pos);
+			return 0;
+		}
+
+		pos = -pos - 1;
+	} else {
+		pos = 0;
+	}
+
+	i = 0;
+	while (i < it->entry_count) {
+		struct cache_entry *ce = istate->cache[pos + i];
+		const char *slash;
+		struct cache_tree_sub *sub = NULL;
+		const struct object_id *oid;
+		const char *name;
+		unsigned mode;
+		int entlen;
+
+		if (ce->ce_flags & (CE_STAGEMASK | CE_INTENT_TO_ADD | CE_REMOVE))
+			BUG("%s with flags 0x%x should not be in cache-tree",
+			    ce->name, ce->ce_flags);
+		name = ce->name + path->len;
+		slash = strchr(name, '/');
+		if (slash) {
+			entlen = slash - name;
+			sub = find_subtree(it, ce->name + path->len, entlen, 0);
+			if (!sub || sub->cache_tree->entry_count < 0)
+				BUG("bad subtree '%.*s'", entlen, name);
+			oid = &sub->cache_tree->oid;
+			mode = S_IFDIR;
+			i += sub->cache_tree->entry_count;
+		} else {
+			oid = &ce->oid;
+			mode = ce->ce_mode;
+			entlen = ce_namelen(ce) - path->len;
+			i++;
+		}
+		strbuf_addf(&tree_buf, "%o %.*s%c", mode, entlen, name, '\0');
+		strbuf_add(&tree_buf, oid->hash, r->hash_algo->rawsz);
+	}
+	hash_object_file(r->hash_algo, tree_buf.buf, tree_buf.len, OBJ_TREE,
+			 &new_oid);
+	if (!oideq(&new_oid, &it->oid))
+		BUG("cache-tree for path %.*s does not match. "
+		    "Expected %s got %s", len, path->buf,
+		    oid_to_hex(&new_oid), oid_to_hex(&it->oid));
+	strbuf_setlen(path, len);
+	strbuf_release(&tree_buf);
+	return 0;
+}
+
+void cache_tree_verify(struct repository *r, struct index_state *istate)
+{
+	struct strbuf path = STRBUF_INIT;
+
+	if (!istate->cache_tree)
+		return;
+	if (verify_one(r, istate, istate->cache_tree, &path)) {
+		strbuf_reset(&path);
+		if (verify_one(r, istate, istate->cache_tree, &path))
+			BUG("ensure_full_index() called twice while verifying cache tree");
+	}
+	strbuf_release(&path);
+}