1 files changed, 277 insertions, 0 deletions
diff --git a/src/libgit2/tree-cache.c b/src/libgit2/tree-cache.c
new file mode 100644
index 000000000..cd69e7bf8
--- /dev/null
+++ b/src/libgit2/tree-cache.c
@@ -0,0 +1,277 @@
+/*
+ * Copyright (C) the libgit2 contributors. All rights reserved.
+ *
+ * This file is part of libgit2, distributed under the GNU GPL v2 with
+ * a Linking Exception. For full terms see the included COPYING file.
+ */
+
+#include "tree-cache.h"
+
+#include "pool.h"
+#include "tree.h"
+
+static git_tree_cache *find_child(
+	const git_tree_cache *tree, const char *path, const char *end)
+{
+	size_t i, dirlen = end ? (size_t)(end - path) : strlen(path);
+
+	for (i = 0; i < tree->children_count; ++i) {
+		git_tree_cache *child = tree->children[i];
+
+		if (child->namelen == dirlen && !memcmp(path, child->name, dirlen))
+			return child;
+	}
+
+	return NULL;
+}
+
+void git_tree_cache_invalidate_path(git_tree_cache *tree, const char *path)
+{
+	const char *ptr = path, *end;
+
+	if (tree == NULL)
+		return;
+
+	tree->entry_count = -1;
+
+	while (ptr != NULL) {
+		end = strchr(ptr, '/');
+
+		if (end == NULL) /* End of path */
+			break;
+
+		tree = find_child(tree, ptr, end);
+		if (tree == NULL) /* We don't have that tree */
+			return;
+
+		tree->entry_count = -1;
+		ptr = end + 1;
+	}
+}
+
+const git_tree_cache *git_tree_cache_get(const git_tree_cache *tree, const char *path)
+{
+	const char *ptr = path, *end;
+
+	if (tree == NULL) {
+		return NULL;
+	}
+
+	while (1) {
+		end = strchr(ptr, '/');
+
+		tree = find_child(tree, ptr, end);
+		if (tree == NULL) /* Can't find it */
+			return NULL;
+
+		if (end == NULL || *end + 1 == '\0')
+			return tree;
+
+		ptr = end + 1;
+	}
+}
+
+static int read_tree_internal(git_tree_cache **out,
+			      const char **buffer_in, const char *buffer_end,
+			      git_pool *pool)
+{
+	git_tree_cache *tree = NULL;
+	const char *name_start, *buffer;
+	int count;
+
+	buffer = name_start = *buffer_in;
+
+	if ((buffer = memchr(buffer, '\0', buffer_end - buffer)) == NULL)
+		goto corrupted;
+
+	if (++buffer >= buffer_end)
+		goto corrupted;
+
+	if (git_tree_cache_new(&tree, name_start, pool) < 0)
+		return -1;
+
+	/* Blank-terminated ASCII decimal number of entries in this tree */
+	if (git__strntol32(&count, buffer, buffer_end - buffer, &buffer, 10) < 0)
+		goto corrupted;
+
+	tree->entry_count = count;
+
+	if (*buffer != ' ' || ++buffer >= buffer_end)
+		goto corrupted;
+
+	 /* Number of children of the tree, newline-terminated */
+	if (git__strntol32(&count, buffer, buffer_end - buffer, &buffer, 10) < 0 || count < 0)
+		goto corrupted;
+
+	tree->children_count = count;
+
+	if (*buffer != '\n' || ++buffer > buffer_end)
+		goto corrupted;
+
+	/* The SHA1 is only there if it's not invalidated */
+	if (tree->entry_count >= 0) {
+		/* 160-bit SHA-1 for this tree and it's children */
+		if (buffer + GIT_OID_RAWSZ > buffer_end)
+			goto corrupted;
+
+		git_oid_fromraw(&tree->oid, (const unsigned char *)buffer);
+		buffer += GIT_OID_RAWSZ;
+	}
+
+	/* Parse children: */
+	if (tree->children_count > 0) {
+		size_t i, bufsize;
+
+		GIT_ERROR_CHECK_ALLOC_MULTIPLY(&bufsize, tree->children_count, sizeof(git_tree_cache*));
+
+		tree->children = git_pool_malloc(pool, bufsize);
+		GIT_ERROR_CHECK_ALLOC(tree->children);
+
+		memset(tree->children, 0x0, bufsize);
+
+		for (i = 0; i < tree->children_count; ++i) {
+			if (read_tree_internal(&tree->children[i], &buffer, buffer_end, pool) < 0)
+				goto corrupted;
+		}
+	}
+
+	*buffer_in = buffer;
+	*out = tree;
+	return 0;
+
+ corrupted:
+	git_error_set(GIT_ERROR_INDEX, "corrupted TREE extension in index");
+	return -1;
+}
+
+int git_tree_cache_read(git_tree_cache **tree, const char *buffer, size_t buffer_size, git_pool *pool)
+{
+	const char *buffer_end = buffer + buffer_size;
+
+	if (read_tree_internal(tree, &buffer, buffer_end, pool) < 0)
+		return -1;
+
+	if (buffer < buffer_end) {
+		git_error_set(GIT_ERROR_INDEX, "corrupted TREE extension in index (unexpected trailing data)");
+		return -1;
+	}
+
+	return 0;
+}
+
+static int read_tree_recursive(git_tree_cache *cache, const git_tree *tree, git_pool *pool)
+{
+	git_repository *repo;
+	size_t i, j, nentries, ntrees, alloc_size;
+	int error;
+
+	repo = git_tree_owner(tree);
+
+	git_oid_cpy(&cache->oid, git_tree_id(tree));
+	nentries = git_tree_entrycount(tree);
+
+	/*
+	 * We make sure we know how many trees we need to allocate for
+	 * so we don't have to realloc and change the pointers for the
+	 * parents.
+	 */
+	ntrees = 0;
+	for (i = 0; i < nentries; i++) {
+		const git_tree_entry *entry;
+
+		entry = git_tree_entry_byindex(tree, i);
+		if (git_tree_entry_filemode(entry) == GIT_FILEMODE_TREE)
+			ntrees++;
+	}
+
+	GIT_ERROR_CHECK_ALLOC_MULTIPLY(&alloc_size, ntrees, sizeof(git_tree_cache *));
+
+	cache->children_count = ntrees;
+	cache->children = git_pool_mallocz(pool, alloc_size);
+	GIT_ERROR_CHECK_ALLOC(cache->children);
+
+	j = 0;
+	for (i = 0; i < nentries; i++) {
+		const git_tree_entry *entry;
+		git_tree *subtree;
+
+		entry = git_tree_entry_byindex(tree, i);
+		if (git_tree_entry_filemode(entry) != GIT_FILEMODE_TREE) {
+			cache->entry_count++;
+			continue;
+		}
+
+		if ((error = git_tree_cache_new(&cache->children[j], git_tree_entry_name(entry), pool)) < 0)
+			return error;
+
+		if ((error = git_tree_lookup(&subtree, repo, git_tree_entry_id(entry))) < 0)
+			return error;
+
+		error = read_tree_recursive(cache->children[j], subtree, pool);
+		git_tree_free(subtree);
+		cache->entry_count += cache->children[j]->entry_count;
+		j++;
+
+		if (error < 0)
+			return error;
+	}
+
+	return 0;
+}
+
+int git_tree_cache_read_tree(git_tree_cache **out, const git_tree *tree, git_pool *pool)
+{
+	int error;
+	git_tree_cache *cache;
+
+	if ((error = git_tree_cache_new(&cache, "", pool)) < 0)
+		return error;
+
+	if ((error = read_tree_recursive(cache, tree, pool)) < 0)
+		return error;
+
+	*out = cache;
+	return 0;
+}
+
+int git_tree_cache_new(git_tree_cache **out, const char *name, git_pool *pool)
+{
+	size_t name_len, alloc_size;
+	git_tree_cache *tree;
+
+	name_len = strlen(name);
+
+	GIT_ERROR_CHECK_ALLOC_ADD3(&alloc_size, sizeof(git_tree_cache), name_len, 1);
+
+	tree = git_pool_malloc(pool, alloc_size);
+	GIT_ERROR_CHECK_ALLOC(tree);
+
+	memset(tree, 0x0, sizeof(git_tree_cache));
+	/* NUL-terminated tree name */
+	tree->namelen = name_len;
+	memcpy(tree->name, name, name_len);
+	tree->name[name_len] = '\0';
+
+	*out = tree;
+	return 0;
+}
+
+static void write_tree(git_str *out, git_tree_cache *tree)
+{
+	size_t i;
+
+	git_str_printf(out, "%s%c%"PRIdZ" %"PRIuZ"\n", tree->name, 0, tree->entry_count, tree->children_count);
+
+	if (tree->entry_count != -1)
+		git_str_put(out, (char *)&tree->oid.id, GIT_OID_RAWSZ);
+
+	for (i = 0; i < tree->children_count; i++)
+		write_tree(out, tree->children[i]);
+}
+
+int git_tree_cache_write(git_str *out, git_tree_cache *tree)
+{
+	write_tree(out, tree);
+
+	return git_str_oom(out) ? -1 : 0;
+}