text: /*
   * 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.h"
  
  #include "commit.h"
  #include "git2/repository.h"
  #include "git2/object.h"
  #include "fileops.h"
  #include "tree-cache.h"
  #include "index.h"
  
  #define DEFAULT_TREE_SIZE 16
  #define MAX_FILEMODE_BYTES 6
  
  #define TREE_ENTRY_CHECK_NAMELEN(n) \
  	if (n > UINT16_MAX) { giterr_set(GITERR_INVALID, "tree entry path too long"); }
  
  static bool valid_filemode(const int filemode)
  {
  	return (filemode == GIT_FILEMODE_TREE
  		|| filemode == GIT_FILEMODE_BLOB
  		|| filemode == GIT_FILEMODE_BLOB_EXECUTABLE
  		|| filemode == GIT_FILEMODE_LINK
  		|| filemode == GIT_FILEMODE_COMMIT);
  }
  
  GIT_INLINE(git_filemode_t) normalize_filemode(git_filemode_t filemode)
  {
  	/* Tree bits set, but it's not a commit */
  	if (GIT_MODE_TYPE(filemode) == GIT_FILEMODE_TREE)
  		return GIT_FILEMODE_TREE;
  
  	/* If any of the x bits are set */
  	if (GIT_PERMS_IS_EXEC(filemode))
  		return GIT_FILEMODE_BLOB_EXECUTABLE;
  
  	/* 16XXXX means commit */
  	if (GIT_MODE_TYPE(filemode) == GIT_FILEMODE_COMMIT)
  		return GIT_FILEMODE_COMMIT;
  
  	/* 12XXXX means symlink */
  	if (GIT_MODE_TYPE(filemode) == GIT_FILEMODE_LINK)
  		return GIT_FILEMODE_LINK;
  
  	/* Otherwise, return a blob */
  	return GIT_FILEMODE_BLOB;
  }
  
  static int valid_entry_name(git_repository *repo, const char *filename)
  {
  	return *filename != '\0' &&
  		git_path_isvalid(repo, filename, 0,
  		GIT_PATH_REJECT_TRAVERSAL | GIT_PATH_REJECT_DOT_GIT | GIT_PATH_REJECT_SLASH);
  }
  
  static int entry_sort_cmp(const void *a, const void *b)
  {
  	const git_tree_entry *e1 = (const git_tree_entry *)a;
  	const git_tree_entry *e2 = (const git_tree_entry *)b;
  
  	return git_path_cmp(
  		e1->filename, e1->filename_len, git_tree_entry__is_tree(e1),
  		e2->filename, e2->filename_len, git_tree_entry__is_tree(e2),
  		git__strncmp);
  }
  
  int git_tree_entry_cmp(const git_tree_entry *e1, const git_tree_entry *e2)
  {
  	return entry_sort_cmp(e1, e2);
  }
  
  int git_tree_entry_icmp(const git_tree_entry *e1, const git_tree_entry *e2)
  {
  	return git_path_cmp(
  		e1->filename, e1->filename_len, git_tree_entry__is_tree(e1),
  		e2->filename, e2->filename_len, git_tree_entry__is_tree(e2),
  		git__strncasecmp);
  }
  
  /**
   * Allocate a new self-contained entry, with enough space after it to
   * store the filename and the id.
   */
  static git_tree_entry *alloc_entry(const char *filename, size_t filename_len, const git_oid *id)
  {
  	git_tree_entry *entry = NULL;
  	size_t tree_len;
  
  	TREE_ENTRY_CHECK_NAMELEN(filename_len);
  
  	if (GIT_ADD_SIZET_OVERFLOW(&tree_len, sizeof(git_tree_entry), filename_len) ||
  	    GIT_ADD_SIZET_OVERFLOW(&tree_len, tree_len, 1) ||
  	    GIT_ADD_SIZET_OVERFLOW(&tree_len, tree_len, GIT_OID_RAWSZ))
  		return NULL;
  
  	entry = git__calloc(1, tree_len);
  	if (!entry)
  		return NULL;
  
  	{
  		char *filename_ptr;
  		void *id_ptr;
  
  		filename_ptr = ((char *) entry) + sizeof(git_tree_entry);
  		memcpy(filename_ptr, filename, filename_len);
  		entry->filename = filename_ptr;
  
  		id_ptr = filename_ptr + filename_len + 1;
  		git_oid_cpy(id_ptr, id);
  		entry->oid = id_ptr;
  	}
  
  	entry->filename_len = (uint16_t)filename_len;
  
  	return entry;
  }
  
  struct tree_key_search {
  	const char *filename;
  	uint16_t filename_len;
  };
  
  static int homing_search_cmp(const void *key, const void *array_member)
  {
  	const struct tree_key_search *ksearch = key;
  	const git_tree_entry *entry = array_member;
  
  	const uint16_t len1 = ksearch->filename_len;
  	const uint16_t len2 = entry->filename_len;
  
  	return memcmp(
  		ksearch->filename,
  		entry->filename,
  		len1 < len2 ? len1 : len2
  	);
  }
  
  /*
   * Search for an entry in a given tree.
   *
   * Note that this search is performed in two steps because
   * of the way tree entries are sorted internally in git:
   *
   * Entries in a tree are not sorted alphabetically; two entries
   * with the same root prefix will have different positions
   * depending on whether they are folders (subtrees) or normal files.
   *
   * Consequently, it is not possible to find an entry on the tree
   * with a binary search if you don't know whether the filename
   * you're looking for is a folder or a normal file.
   *
   * To work around this, we first perform a homing binary search
   * on the tree, using the minimal length root prefix of our filename.
   * Once the comparisons for this homing search start becoming
   * ambiguous because of folder vs file sorting, we look linearly
   * around the area for our target file.
   */
  static int tree_key_search(
  	size_t *at_pos,
  	const git_tree *tree,
  	const char *filename,
  	size_t filename_len)
  {
  	struct tree_key_search ksearch;
  	const git_tree_entry *entry;
  	size_t homing, i;
  
  	TREE_ENTRY_CHECK_NAMELEN(filename_len);
  
  	ksearch.filename = filename;
  	ksearch.filename_len = (uint16_t)filename_len;
  
  	/* Initial homing search; find an entry on the tree with
  	 * the same prefix as the filename we're looking for */
  
  	if (git_array_search(&homing,
  		tree->entries, &homing_search_cmp, &ksearch) < 0)
  		return GIT_ENOTFOUND; /* just a signal error; not passed back to user */
  
  	/* We found a common prefix. Look forward as long as
  	 * there are entries that share the common prefix */
  	for (i = homing; i < tree->entries.size; ++i) {
  		entry = git_array_get(tree->entries, i);
  
  		if (homing_search_cmp(&ksearch, entry) < 0)
  			break;
  
  		if (entry->filename_len == filename_len &&
  			memcmp(filename, entry->filename, filename_len) == 0) {
  			if (at_pos)
  				*at_pos = i;
  
  			return 0;
  		}
  	}
  
  	/* If we haven't found our filename yet, look backwards
  	 * too as long as we have entries with the same prefix */
  	if (homing > 0) {
  		i = homing - 1;
  
  		do {
  			entry = git_array_get(tree->entries, i);
  
  			if (homing_search_cmp(&ksearch, entry) > 0)
  				break;
  
  			if (entry->filename_len == filename_len &&
  				memcmp(filename, entry->filename, filename_len) == 0) {
  				if (at_pos)
  					*at_pos = i;
  
  				return 0;
  			}
  		} while (i-- > 0);
  	}
  
  	/* The filename doesn't exist at all */
  	return GIT_ENOTFOUND;
  }
  
  void git_tree_entry_free(git_tree_entry *entry)
  {
  	if (entry == NULL)
  		return;
  
  	git__free(entry);
  }
  
  int git_tree_entry_dup(git_tree_entry **dest, const git_tree_entry *source)
  {
  	git_tree_entry *cpy;
  
  	assert(source);
  
  	cpy = alloc_entry(source->filename, source->filename_len, source->oid);
  	if (cpy == NULL)
  		return -1;
  
  	cpy->attr = source->attr;
  
  	*dest = cpy;
  	return 0;
  }
  
  void git_tree__free(void *_tree)
  {
  	git_tree *tree = _tree;
  
  	git_odb_object_free(tree->odb_obj);
  	git_array_clear(tree->entries);
  	git__free(tree);
  }
  
  git_filemode_t git_tree_entry_filemode(const git_tree_entry *entry)
  {
  	return normalize_filemode(entry->attr);
  }
  
  git_filemode_t git_tree_entry_filemode_raw(const git_tree_entry *entry)
  {
  	return entry->attr;
  }
  
  const char *git_tree_entry_name(const git_tree_entry *entry)
  {
  	assert(entry);
  	return entry->filename;
  }
  
  const git_oid *git_tree_entry_id(const git_tree_entry *entry)
  {
  	assert(entry);
  	return entry->oid;
  }
  
  git_otype git_tree_entry_type(const git_tree_entry *entry)
  {
  	assert(entry);
  
  	if (S_ISGITLINK(entry->attr))
  		return GIT_OBJ_COMMIT;
  	else if (S_ISDIR(entry->attr))
  		return GIT_OBJ_TREE;
  	else
  		return GIT_OBJ_BLOB;
  }
  
  int git_tree_entry_to_object(
  	git_object **object_out,
  	git_repository *repo,
  	const git_tree_entry *entry)
  {
  	assert(entry && object_out);
  	return git_object_lookup(object_out, repo, entry->oid, GIT_OBJ_ANY);
  }
  
  static const git_tree_entry *entry_fromname(
  	const git_tree *tree, const char *name, size_t name_len)
  {
  	size_t idx;
  
  	if (tree_key_search(&idx, tree, name, name_len) < 0)
  		return NULL;
  
  	return git_array_get(tree->entries, idx);
  }
  
  const git_tree_entry *git_tree_entry_byname(
  	const git_tree *tree, const char *filename)
  {
  	assert(tree && filename);
  
  	return entry_fromname(tree, filename, strlen(filename));
  }
  
  const git_tree_entry *git_tree_entry_byindex(
  	const git_tree *tree, size_t idx)
  {
  	assert(tree);
  	return git_array_get(tree->entries, idx);
  }
  
  const git_tree_entry *git_tree_entry_byid(
  	const git_tree *tree, const git_oid *id)
  {
  	size_t i;
  	const git_tree_entry *e;
  
  	assert(tree);
  
  	git_array_foreach(tree->entries, i, e) {
  		if (memcmp(&e->oid->id, &id->id, sizeof(id->id)) == 0)
  			return e;
  	}
  
  	return NULL;
  }
  
  int git_tree__prefix_position(const git_tree *tree, const char *path)
  {
  	struct tree_key_search ksearch;
  	size_t at_pos, path_len;
  
  	if (!path)
  		return 0;
  
  	path_len = strlen(path);
  	TREE_ENTRY_CHECK_NAMELEN(path_len);
  
  	ksearch.filename = path;
  	ksearch.filename_len = (uint16_t)path_len;
  
  	/* Find tree entry with appropriate prefix */
  	git_array_search(
  		&at_pos, tree->entries, &homing_search_cmp, &ksearch);
  
  	for (; at_pos < tree->entries.size; ++at_pos) {
  		const git_tree_entry *entry = git_array_get(tree->entries, at_pos);
  		if (homing_search_cmp(&ksearch, entry) < 0)
  			break;
  	}
  
  	for (; at_pos > 0; --at_pos) {
  		const git_tree_entry *entry =
  			git_array_get(tree->entries, at_pos - 1);
  
  		if (homing_search_cmp(&ksearch, entry) > 0)
  			break;
  	}
  
  	return (int)at_pos;
  }
  
  size_t git_tree_entrycount(const git_tree *tree)
  {
  	assert(tree);
  	return tree->entries.size;
  }
  
  unsigned int git_treebuilder_entrycount(git_treebuilder *bld)
  {
  	assert(bld);
  
  	return git_strmap_num_entries(bld->map);
  }
  
  static int tree_error(const char *str, const char *path)
  {
  	if (path)
  		giterr_set(GITERR_TREE, "%s - %s", str, path);
  	else
  		giterr_set(GITERR_TREE, "%s", str);
  	return -1;
  }
  
  static int parse_mode(uint16_t *mode_out, const char *buffer, size_t buffer_len, const char **buffer_out)
  {
  	int32_t mode;
  	int error;
  
  	if (!buffer_len || git__isspace(*buffer))
  		return -1;
  
  	if ((error = git__strntol32(&mode, buffer, buffer_len, buffer_out, 8)) < 0)
  		return error;
  
  	if (mode < 0 || mode > UINT16_MAX)
  		return -1;
  
  	*mode_out = mode;
  
  	return 0;
  }
  
  int git_tree__parse(void *_tree, git_odb_object *odb_obj)
  {
  	git_tree *tree = _tree;
  	const char *buffer;
  	const char *buffer_end;
  
  	if (git_odb_object_dup(&tree->odb_obj, odb_obj) < 0)
  		return -1;
  
  	buffer = git_odb_object_data(tree->odb_obj);
  	buffer_end = buffer + git_odb_object_size(tree->odb_obj);
  
  	git_array_init_to_size(tree->entries, DEFAULT_TREE_SIZE);
  	GITERR_CHECK_ARRAY(tree->entries);
  
  	while (buffer < buffer_end) {
  		git_tree_entry *entry;
  		size_t filename_len;
  		const char *nul;
  		uint16_t attr;
  
  		if (parse_mode(&attr, buffer, buffer_end - buffer, &buffer) < 0 || !buffer)
  			return tree_error("failed to parse tree: can't parse filemode", NULL);
  
  		if (buffer >= buffer_end || (*buffer++) != ' ')
  			return tree_error("failed to parse tree: missing space after filemode", NULL);
  
  		if ((nul = memchr(buffer, 0, buffer_end - buffer)) == NULL)
  			return tree_error("failed to parse tree: object is corrupted", NULL);
  
  		if ((filename_len = nul - buffer) == 0)
  			return tree_error("failed to parse tree: can't parse filename", NULL);
  
  		if ((buffer_end - (nul + 1)) < GIT_OID_RAWSZ)
  			return tree_error("failed to parse tree: can't parse OID", NULL);
  
  		/* Allocate the entry */
  		{
  			entry = git_array_alloc(tree->entries);
  			GITERR_CHECK_ALLOC(entry);
  
  			entry->attr = attr;
  			entry->filename_len = filename_len;
  			entry->filename = buffer;
  			entry->oid = (git_oid *) ((char *) buffer + filename_len + 1);
  		}
  
  		buffer += filename_len + 1;
  		buffer += GIT_OID_RAWSZ;
  	}
  
  	return 0;
  }
  
  static size_t find_next_dir(const char *dirname, git_index *index, size_t start)
  {
  	size_t dirlen, i, entries = git_index_entrycount(index);
  
  	dirlen = strlen(dirname);
  	for (i = start; i < entries; ++i) {
  		const git_index_entry *entry = git_index_get_byindex(index, i);
  		if (strlen(entry->path) < dirlen ||
  		    memcmp(entry->path, dirname, dirlen) ||
  			(dirlen > 0 && entry->path[dirlen] != '/')) {
  			break;
  		}
  	}
  
  	return i;
  }
  
  static int append_entry(
  	git_treebuilder *bld,
  	const char *filename,
  	const git_oid *id,
  	git_filemode_t filemode,
  	bool validate)
  {
  	git_tree_entry *entry;
  	int error = 0;
  
  	if (validate && !valid_entry_name(bld->repo, filename))
  		return tree_error("failed to insert entry: invalid name for a tree entry", filename);
  
  	if (validate && git_oid_iszero(id))
  		return tree_error("failed to insert entry: invalid null OID for a tree entry", filename);
  
  	entry = alloc_entry(filename, strlen(filename), id);
  	GITERR_CHECK_ALLOC(entry);
  
  	entry->attr = (uint16_t)filemode;
  
  	git_strmap_insert(bld->map, entry->filename, entry, &error);
  	if (error < 0) {
  		git_tree_entry_free(entry);
  		giterr_set(GITERR_TREE, "failed to append entry %s to the tree builder", filename);
  		return -1;
  	}
  
  	return 0;
  }
  
  static int write_tree(
  	git_oid *oid,
  	git_repository *repo,
  	git_index *index,
  	const char *dirname,
  	size_t start,
  	git_buf *shared_buf)
  {
  	git_treebuilder *bld = NULL;
  	size_t i, entries = git_index_entrycount(index);
  	int error;
  	size_t dirname_len = strlen(dirname);
  	const git_tree_cache *cache;
  
  	cache = git_tree_cache_get(index->tree, dirname);
  	if (cache != NULL && cache->entry_count >= 0){
  		git_oid_cpy(oid, &cache->oid);
  		return (int)find_next_dir(dirname, index, start);
  	}
  
  	if ((error = git_treebuilder_new(&bld, repo, NULL)) < 0 || bld == NULL)
  		return -1;
  
  	/*
  	 * This loop is unfortunate, but necessary. The index doesn't have
  	 * any directores, so we need to handle that manually, and we
  	 * need to keep track of the current position.
  	 */
  	for (i = start; i < entries; ++i) {
  		const git_index_entry *entry = git_index_get_byindex(index, i);
  		const char *filename, *next_slash;
  
  	/*
  	 * If we've left our (sub)tree, exit the loop and return. The
  	 * first check is an early out (and security for the
  	 * third). The second check is a simple prefix comparison. The
  	 * third check catches situations where there is a directory
  	 * win32/sys and a file win32mmap.c. Without it, the following
  	 * code believes there is a file win32/mmap.c
  	 */
  		if (strlen(entry->path) < dirname_len ||
  		    memcmp(entry->path, dirname, dirname_len) ||
  		    (dirname_len > 0 && entry->path[dirname_len] != '/')) {
  			break;
  		}
  
  		filename = entry->path + dirname_len;
  		if (*filename == '/')
  			filename++;
  		next_slash = strchr(filename, '/');
  		if (next_slash) {
  			git_oid sub_oid;
  			int written;
  			char *subdir, *last_comp;
  
  			subdir = git__strndup(entry->path, next_slash - entry->path);
  			GITERR_CHECK_ALLOC(subdir);
  
  			/* Write out the subtree */
  			written = write_tree(&sub_oid, repo, index, subdir, i, shared_buf);
  			if (written < 0) {
  				git__free(subdir);
  				goto on_error;
  			} else {
  				i = written - 1; /* -1 because of the loop increment */
  			}
  
  			/*
  			 * We need to figure out what we want toinsert
  			 * into this tree. If we're traversing
  			 * deps/zlib/, then we only want to write
  			 * 'zlib' into the tree.
  			 */
  			last_comp = strrchr(subdir, '/');
  			if (last_comp) {
  				last_comp++; /* Get rid of the '/' */
  			} else {
  				last_comp = subdir;
  			}
  
  			error = append_entry(bld, last_comp, &sub_oid, S_IFDIR, true);
  			git__free(subdir);
  			if (error < 0)
  				goto on_error;
  		} else {
  			error = append_entry(bld, filename, &entry->id, entry->mode, true);
  			if (error < 0)
  				goto on_error;
  		}
  	}
  
  	if (git_treebuilder_write_with_buffer(oid, bld, shared_buf) < 0)
  		goto on_error;
  
  	git_treebuilder_free(bld);
  	return (int)i;
  
  on_error:
  	git_treebuilder_free(bld);
  	return -1;
  }
  
  int git_tree__write_index(
  	git_oid *oid, git_index *index, git_repository *repo)
  {
  	int ret;
  	git_tree *tree;
  	git_buf shared_buf = GIT_BUF_INIT;
  	bool old_ignore_case = false;
  
  	assert(oid && index && repo);
  
  	if (git_index_has_conflicts(index)) {
  		giterr_set(GITERR_INDEX,
  			"cannot create a tree from a not fully merged index.");
  		return GIT_EUNMERGED;
  	}
  
  	if (index->tree != NULL && index->tree->entry_count >= 0) {
  		git_oid_cpy(oid, &index->tree->oid);
  		return 0;
  	}
  
  	/* The tree cache didn't help us; we'll have to write
  	 * out a tree. If the index is ignore_case, we must
  	 * make it case-sensitive for the duration of the tree-write
  	 * operation. */
  
  	if (index->ignore_case) {
  		old_ignore_case = true;
  		git_index__set_ignore_case(index, false);
  	}
  
  	ret = write_tree(oid, repo, index, "", 0, &shared_buf);
  	git_buf_free(&shared_buf);
  
  	if (old_ignore_case)
  		git_index__set_ignore_case(index, true);
  
  	index->tree = NULL;
  
  	if (ret < 0)
  		return ret;
  
  	git_pool_clear(&index->tree_pool);
  
  	if ((ret = git_tree_lookup(&tree, repo, oid)) < 0)
  		return ret;
  
  	/* Read the tree cache into the index */
  	ret = git_tree_cache_read_tree(&index->tree, tree, &index->tree_pool);
  	git_tree_free(tree);
  
  	return ret;
  }
  
  int git_treebuilder_new(
  	git_treebuilder **builder_p,
  	git_repository *repo,
  	const git_tree *source)
  {
  	git_treebuilder *bld;
  	size_t i;
  
  	assert(builder_p && repo);
  
  	bld = git__calloc(1, sizeof(git_treebuilder));
  	GITERR_CHECK_ALLOC(bld);
  
  	bld->repo = repo;
  
  	if (git_strmap_alloc(&bld->map) < 0) {
  		git__free(bld);
  		return -1;
  	}
  
  	if (source != NULL) {
  		git_tree_entry *entry_src;
  
  		git_array_foreach(source->entries, i, entry_src) {
  			if (append_entry(
  				bld, entry_src->filename,
  				entry_src->oid,
  				entry_src->attr,
  				false) < 0)
  				goto on_error;
  		}
  	}
  
  	*builder_p = bld;
  	return 0;
  
  on_error:
  	git_treebuilder_free(bld);
  	return -1;
  }
  
  static git_otype otype_from_mode(git_filemode_t filemode)
  {
  	switch (filemode) {
  	case GIT_FILEMODE_TREE:
  		return GIT_OBJ_TREE;
  	case GIT_FILEMODE_COMMIT:
  		return GIT_OBJ_COMMIT;
  	default:
  		return GIT_OBJ_BLOB;
  	}
  }
  
  int git_treebuilder_insert(
  	const git_tree_entry **entry_out,
  	git_treebuilder *bld,
  	const char *filename,
  	const git_oid *id,
  	git_filemode_t filemode)
  {
  	git_tree_entry *entry;
  	int error;
  	git_strmap_iter pos;
  
  	assert(bld && id && filename);
  
  	if (!valid_filemode(filemode))
  		return tree_error("failed to insert entry: invalid filemode for file", filename);
  
  	if (!valid_entry_name(bld->repo, filename))
  		return tree_error("failed to insert entry: invalid name for a tree entry", filename);
  
  	if (git_oid_iszero(id))
  		return tree_error("failed to insert entry: invalid null OID", filename);
  
  	if (filemode != GIT_FILEMODE_COMMIT &&
  	    !git_object__is_valid(bld->repo, id, otype_from_mode(filemode)))
  		return tree_error("failed to insert entry: invalid object specified", filename);
  
  	pos = git_strmap_lookup_index(bld->map, filename);
  	if (git_strmap_valid_index(bld->map, pos)) {
  		entry = git_strmap_value_at(bld->map, pos);
  		git_oid_cpy((git_oid *) entry->oid, id);
  	} else {
  		entry = alloc_entry(filename, strlen(filename), id);
  		GITERR_CHECK_ALLOC(entry);
  
  		git_strmap_insert(bld->map, entry->filename, entry, &error);
  
  		if (error < 0) {
  			git_tree_entry_free(entry);
  			giterr_set(GITERR_TREE, "failed to insert %s", filename);
  			return -1;
  		}
  	}
  
  	entry->attr = filemode;
  
  	if (entry_out)
  		*entry_out = entry;
  
  	return 0;
  }
  
  static git_tree_entry *treebuilder_get(git_treebuilder *bld, const char *filename)
  {
  	git_tree_entry *entry = NULL;
  	git_strmap_iter pos;
  
  	assert(bld && filename);
  
  	pos = git_strmap_lookup_index(bld->map, filename);
  	if (git_strmap_valid_index(bld->map, pos))
  		entry = git_strmap_value_at(bld->map, pos);
  
  	return entry;
  }
  
  const git_tree_entry *git_treebuilder_get(git_treebuilder *bld, const char *filename)
  {
  	return treebuilder_get(bld, filename);
  }
  
  int git_treebuilder_remove(git_treebuilder *bld, const char *filename)
  {
  	git_tree_entry *entry = treebuilder_get(bld, filename);
  
  	if (entry == NULL)
  		return tree_error("failed to remove entry: file isn't in the tree", filename);
  
  	git_strmap_delete(bld->map, filename);
  	git_tree_entry_free(entry);
  
  	return 0;
  }
  
  int git_treebuilder_write(git_oid *oid, git_treebuilder *bld)
  {
  	int error;
  	git_buf buffer = GIT_BUF_INIT;
  
  	error = git_treebuilder_write_with_buffer(oid, bld, &buffer);
  
  	git_buf_free(&buffer);
  	return error;
  }
  
  int git_treebuilder_write_with_buffer(git_oid *oid, git_treebuilder *bld, git_buf *tree)
  {
  	int error = 0;
  	size_t i, entrycount;
  	git_odb *odb;
  	git_tree_entry *entry;
  	git_vector entries = GIT_VECTOR_INIT;
  
  	assert(bld);
  	assert(tree);
  
  	git_buf_clear(tree);
  
  	entrycount = git_strmap_num_entries(bld->map);
  	if ((error = git_vector_init(&entries, entrycount, entry_sort_cmp)) < 0)
  		goto out;
  
  	if (tree->asize == 0 &&
  	    (error = git_buf_grow(tree, entrycount * 72)) < 0)
  		goto out;
  
  	git_strmap_foreach_value(bld->map, entry, {
  		if ((error = git_vector_insert(&entries, entry)) < 0)
  			goto out;
  	});
  
  	git_vector_sort(&entries);
  
  	for (i = 0; i < entries.length && !error; ++i) {
  		entry = git_vector_get(&entries, i);
  
  		git_buf_printf(tree, "%o ", entry->attr);
  		git_buf_put(tree, entry->filename, entry->filename_len + 1);
  		git_buf_put(tree, (char *)entry->oid->id, GIT_OID_RAWSZ);
  
  		if (git_buf_oom(tree)) {
  			error = -1;
  			goto out;
  		}
  	}
  
  	if ((error = git_repository_odb__weakptr(&odb, bld->repo)) == 0)
  		error = git_odb_write(oid, odb, tree->ptr, tree->size, GIT_OBJ_TREE);
  
  out:
  	git_vector_free(&entries);
  
  	return error;
  }
  
  void git_treebuilder_filter(
  	git_treebuilder *bld,
  	git_treebuilder_filter_cb filter,
  	void *payload)
  {
  	const char *filename;
  	git_tree_entry *entry;
  
  	assert(bld && filter);
  
  	git_strmap_foreach(bld->map, filename, entry, {
  			if (filter(entry, payload)) {
  				git_strmap_delete(bld->map, filename);
  				git_tree_entry_free(entry);
  			}
  	});
  }
  
  void git_treebuilder_clear(git_treebuilder *bld)
  {
  	git_tree_entry *e;
  
  	assert(bld);
  
  	git_strmap_foreach_value(bld->map, e, git_tree_entry_free(e));
  	git_strmap_clear(bld->map);
  }
  
  void git_treebuilder_free(git_treebuilder *bld)
  {
  	if (bld == NULL)
  		return;
  
  	git_treebuilder_clear(bld);
  	git_strmap_free(bld->map);
  	git__free(bld);
  }
  
  static size_t subpath_len(const char *path)
  {
  	const char *slash_pos = strchr(path, '/');
  	if (slash_pos == NULL)
  		return strlen(path);
  
  	return slash_pos - path;
  }
  
  int git_tree_entry_bypath(
  	git_tree_entry **entry_out,
  	const git_tree *root,
  	const char *path)
  {
  	int error = 0;
  	git_tree *subtree;
  	const git_tree_entry *entry;
  	size_t filename_len;
  
  	/* Find how long is the current path component (i.e.
  	 * the filename between two slashes */
  	filename_len = subpath_len(path);
  
  	if (filename_len == 0) {
  		giterr_set(GITERR_TREE, "invalid tree path given");
  		return GIT_ENOTFOUND;
  	}
  
  	entry = entry_fromname(root, path, filename_len);
  
  	if (entry == NULL) {
  		giterr_set(GITERR_TREE,
  			   "the path '%.*s' does not exist in the given tree", (int) filename_len, path);
  		return GIT_ENOTFOUND;
  	}
  
  	switch (path[filename_len]) {
  	case '/':
  		/* If there are more components in the path...
  		 * then this entry *must* be a tree */
  		if (!git_tree_entry__is_tree(entry)) {
  			giterr_set(GITERR_TREE,
  				   "the path '%.*s' exists but is not a tree", (int) filename_len, path);
  			return GIT_ENOTFOUND;
  		}
  
  		/* If there's only a slash left in the path, we
  		 * return the current entry; otherwise, we keep
  		 * walking down the path */
  		if (path[filename_len + 1] != '\0')
  			break;
  		/* fall through */
  	case '\0':
  		/* If there are no more components in the path, return
  		 * this entry */
  		return git_tree_entry_dup(entry_out, entry);
  	}
  
  	if (git_tree_lookup(&subtree, root->object.repo, entry->oid) < 0)
  		return -1;
  
  	error = git_tree_entry_bypath(
  		entry_out,
  		subtree,
  		path + filename_len + 1
  	);
  
  	git_tree_free(subtree);
  	return error;
  }
  
  static int tree_walk(
  	const git_tree *tree,
  	git_treewalk_cb callback,
  	git_buf *path,
  	void *payload,
  	bool preorder)
  {
  	int error = 0;
  	size_t i;
  	const git_tree_entry *entry;
  
  	git_array_foreach(tree->entries, i, entry) {
  		if (preorder) {
  			error = callback(path->ptr, entry, payload);
  			if (error < 0) { /* negative value stops iteration */
  				giterr_set_after_callback_function(error, "git_tree_walk");
  				break;
  			}
  			if (error > 0) { /* positive value skips this entry */
  				error = 0;
  				continue;
  			}
  		}
  
  		if (git_tree_entry__is_tree(entry)) {
  			git_tree *subtree;
  			size_t path_len = git_buf_len(path);
  
  			error = git_tree_lookup(&subtree, tree->object.repo, entry->oid);
  			if (error < 0)
  				break;
  
  			/* append the next entry to the path */
  			git_buf_puts(path, entry->filename);
  			git_buf_putc(path, '/');
  
  			if (git_buf_oom(path))
  				error = -1;
  			else
  				error = tree_walk(subtree, callback, path, payload, preorder);
  
  			git_tree_free(subtree);
  			if (error != 0)
  				break;
  
  			git_buf_truncate(path, path_len);
  		}
  
  		if (!preorder) {
  			error = callback(path->ptr, entry, payload);
  			if (error < 0) { /* negative value stops iteration */
  				giterr_set_after_callback_function(error, "git_tree_walk");
  				break;
  			}
  			error = 0;
  		}
  	}
  
  	return error;
  }
  
  int git_tree_walk(
  	const git_tree *tree,
  	git_treewalk_mode mode,
  	git_treewalk_cb callback,
  	void *payload)
  {
  	int error = 0;
  	git_buf root_path = GIT_BUF_INIT;
  
  	if (mode != GIT_TREEWALK_POST && mode != GIT_TREEWALK_PRE) {
  		giterr_set(GITERR_INVALID, "invalid walking mode for tree walk");
  		return -1;
  	}
  
  	error = tree_walk(
  		tree, callback, &root_path, payload, (mode == GIT_TREEWALK_PRE));
  
  	git_buf_free(&root_path);
  
  	return error;
  }
  
  static int compare_entries(const void *_a, const void *_b)
  {
  	const git_tree_update *a = (git_tree_update *) _a;
  	const git_tree_update *b = (git_tree_update *) _b;
  
  	return strcmp(a->path, b->path);
  }
  
  static int on_dup_entry(void **old, void *new)
  {
  	GIT_UNUSED(old); GIT_UNUSED(new);
  
  	giterr_set(GITERR_TREE, "duplicate entries given for update");
  	return -1;
  }
  
  /*
   * We keep the previous tree and the new one at each level of the
   * stack. When we leave a level we're done with that tree and we can
   * write it out to the odb.
   */
  typedef struct {
  	git_treebuilder *bld;
  	git_tree *tree;
  	char *name;
  } tree_stack_entry;
  
  /** Count how many slashes (i.e. path components) there are in this string */
  GIT_INLINE(size_t) count_slashes(const char *path)
  {
  	size_t count = 0;
  	const char *slash;
  
  	while ((slash = strchr(path, '/')) != NULL) {
  		count++;
  		path = slash + 1;
  	}
  
  	return count;
  }
  
  static bool next_component(git_buf *out, const char *in)
  {
  	const char *slash = strchr(in, '/');
  
  	git_buf_clear(out);
  
  	if (slash)
  		git_buf_put(out, in, slash - in);
  
  	return !!slash;
  }
  
  static int create_popped_tree(tree_stack_entry *current, tree_stack_entry *popped, git_buf *component)
  {
  	int error;
  	git_oid new_tree;
  
  	git_tree_free(popped->tree);
  
  	/* If the tree would be empty, remove it from the one higher up */
  	if (git_treebuilder_entrycount(popped->bld) == 0) {
  		git_treebuilder_free(popped->bld);
  		error = git_treebuilder_remove(current->bld, popped->name);
  		git__free(popped->name);
  		return error;
  	}
  
  	error = git_treebuilder_write(&new_tree, popped->bld);
  	git_treebuilder_free(popped->bld);
  
  	if (error < 0) {
  		git__free(popped->name);
  		return error;
  	}
  
  	/* We've written out the tree, now we have to put the new value into its parent */
  	git_buf_clear(component);
  	git_buf_puts(component, popped->name);
  	git__free(popped->name);
  
  	GITERR_CHECK_ALLOC(component->ptr);
  
  	/* Error out if this would create a D/F conflict in this update */
  	if (current->tree) {
  		const git_tree_entry *to_replace;
  		to_replace = git_tree_entry_byname(current->tree, component->ptr);
  		if (to_replace && git_tree_entry_type(to_replace) != GIT_OBJ_TREE) {
  			giterr_set(GITERR_TREE, "D/F conflict when updating tree");
  			return -1;
  		}
  	}
  
  	return git_treebuilder_insert(NULL, current->bld, component->ptr, &new_tree, GIT_FILEMODE_TREE);
  }
  
  int git_tree_create_updated(git_oid *out, git_repository *repo, git_tree *baseline, size_t nupdates, const git_tree_update *updates)
  {
  	git_array_t(tree_stack_entry) stack = GIT_ARRAY_INIT;
  	tree_stack_entry *root_elem;
  	git_vector entries;
  	int error;
  	size_t i;
  	git_buf component = GIT_BUF_INIT;
  
  	if ((error = git_vector_init(&entries, nupdates, compare_entries)) < 0)
  		return error;
  
  	/* Sort the entries for treversal */
  	for (i = 0 ; i < nupdates; i++)	{
  		if ((error = git_vector_insert_sorted(&entries, (void *) &updates[i], on_dup_entry)) < 0)
  			goto cleanup;
  	}
  
  	root_elem = git_array_alloc(stack);
  	GITERR_CHECK_ALLOC(root_elem);
  	memset(root_elem, 0, sizeof(*root_elem));
  
  	if (baseline && (error = git_tree_dup(&root_elem->tree, baseline)) < 0)
  		goto cleanup;
  
  	if ((error = git_treebuilder_new(&root_elem->bld, repo, root_elem->tree)) < 0)
  		goto cleanup;
  
  	for (i = 0; i < nupdates; i++) {
  		const git_tree_update *last_update = i == 0 ? NULL : git_vector_get(&entries, i-1);
  		const git_tree_update *update = git_vector_get(&entries, i);
  		size_t common_prefix = 0, steps_up, j;
  		const char *path;
  
  		/* Figure out how much we need to change from the previous tree */
  		if (last_update)
  			common_prefix = git_path_common_dirlen(last_update->path, update->path);
  
  		/*
  		 * The entries are sorted, so when we find we're no
  		 * longer in the same directory, we need to abandon
  		 * the old tree (steps up) and dive down to the next
  		 * one.
  		 */
  		steps_up = last_update == NULL ? 0 : count_slashes(&last_update->path[common_prefix]);
  
  		for (j = 0; j < steps_up; j++) {
  			tree_stack_entry *current, *popped = git_array_pop(stack);
  			assert(popped);
  
  			current = git_array_last(stack);
  			assert(current);
  
  			if ((error = create_popped_tree(current, popped, &component)) < 0)
  				goto cleanup;
  		}
  
  		/* Now that we've created the trees we popped from the stack, let's go back down */
  		path = &update->path[common_prefix];
  		while (next_component(&component, path)) {
  			tree_stack_entry *last, *new_entry;
  			const git_tree_entry *entry;
  
  			last = git_array_last(stack);
  			entry = last->tree ? git_tree_entry_byname(last->tree, component.ptr) : NULL;
  			if (!entry)
  				entry = treebuilder_get(last->bld, component.ptr);
  
  			if (entry && git_tree_entry_type(entry) != GIT_OBJ_TREE) {
  				giterr_set(GITERR_TREE, "D/F conflict when updating tree");
  				error = -1;
  				goto cleanup;
  			}
  
  			new_entry = git_array_alloc(stack);
  			GITERR_CHECK_ALLOC(new_entry);
  			memset(new_entry, 0, sizeof(*new_entry));
  
  			new_entry->tree = NULL;
  			if (entry && (error = git_tree_lookup(&new_entry->tree, repo, git_tree_entry_id(entry))) < 0)
  				goto cleanup;
  
  			if ((error = git_treebuilder_new(&new_entry->bld, repo, new_entry->tree)) < 0)
  				goto cleanup;
  
  			new_entry->name = git__strdup(component.ptr);
  			GITERR_CHECK_ALLOC(new_entry->name);
  
  			/* Get to the start of the next component */
  			path += component.size + 1;
  		}
  
  		/* After all that, we're finally at the place where we want to perform the update */
  		switch (update->action) {
  			case GIT_TREE_UPDATE_UPSERT:
  			{
  				/* Make sure we're replacing something of the same type */
  				tree_stack_entry *last = git_array_last(stack);
  				char *basename = git_path_basename(update->path);
  				const git_tree_entry *e = git_treebuilder_get(last->bld, basename);
  				if (e && git_tree_entry_type(e) != git_object__type_from_filemode(update->filemode)) {
  					git__free(basename);
  					giterr_set(GITERR_TREE, "cannot replace '%s' with '%s' at '%s'",
  						   git_object_type2string(git_tree_entry_type(e)),
  						   git_object_type2string(git_object__type_from_filemode(update->filemode)),
  						   update->path);
  					error = -1;
  					goto cleanup;
  				}
  
  				error = git_treebuilder_insert(NULL, last->bld, basename, &update->id, update->filemode);
  				git__free(basename);
  				break;
  			}
  			case GIT_TREE_UPDATE_REMOVE:
  			{
  				char *basename = git_path_basename(update->path);
  				error = git_treebuilder_remove(git_array_last(stack)->bld, basename);
  				git__free(basename);
  				break;
  			}
  			default:
  				giterr_set(GITERR_TREE, "unknown action for update");
  				error = -1;
  				goto cleanup;
  		}
  
  		if (error < 0)
  			goto cleanup;
  	}
  
  	/* We're done, go up the stack again and write out the tree */
  	{
  		tree_stack_entry *current = NULL, *popped = NULL;
  		while ((popped = git_array_pop(stack)) != NULL) {
  			current = git_array_last(stack);
  			/* We've reached the top, current is the root tree */
  			if (!current)
  				break;
  
  			if ((error = create_popped_tree(current, popped, &component)) < 0)
  				goto cleanup;
  		}
  
  		/* Write out the root tree */
  		git__free(popped->name);
  		git_tree_free(popped->tree);
  
  		error = git_treebuilder_write(out, popped->bld);
  		git_treebuilder_free(popped->bld);
  		if (error < 0)
  			goto cleanup;
  	}
  
  cleanup:
  	{
  		tree_stack_entry *e;
  		while ((e = git_array_pop(stack)) != NULL) {
  			git_treebuilder_free(e->bld);
  			git_tree_free(e->tree);
  			git__free(e->name);
  		}
  	}
  
  	git_buf_free(&component);
  	git_array_clear(stack);
  	git_vector_free(&entries);
  	return error;
  }
  