text: /*
   * Copyright (C) 2009-2012 the libgit2 contributors
   *
   * 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 "refs.h"
  #include "hash.h"
  #include "repository.h"
  #include "fileops.h"
  #include "pack.h"
  #include "reflog.h"
  
  #include <git2/tag.h>
  #include <git2/object.h>
  #include <git2/oid.h>
  #include <git2/branch.h>
  
  GIT__USE_STRMAP;
  
  #define DEFAULT_NESTING_LEVEL	5
  #define MAX_NESTING_LEVEL		10
  
  enum {
  	GIT_PACKREF_HAS_PEEL = 1,
  	GIT_PACKREF_WAS_LOOSE = 2
  };
  
  struct packref {
  	git_oid oid;
  	git_oid peel;
  	char flags;
  	char name[GIT_FLEX_ARRAY];
  };
  
  static int reference_read(
  	git_buf *file_content,
  	time_t *mtime,
  	const char *repo_path,
  	const char *ref_name,
  	int *updated);
  
  /* loose refs */
  static int loose_parse_symbolic(git_reference *ref, git_buf *file_content);
  static int loose_parse_oid(git_oid *ref, git_buf *file_content);
  static int loose_lookup(git_reference *ref);
  static int loose_lookup_to_packfile(struct packref **ref_out,
  	git_repository *repo, const char *name);
  static int loose_write(git_reference *ref);
  
  /* packed refs */
  static int packed_parse_peel(struct packref *tag_ref,
  	const char **buffer_out, const char *buffer_end);
  static int packed_parse_oid(struct packref **ref_out,
  	const char **buffer_out, const char *buffer_end);
  static int packed_load(git_repository *repo);
  static int packed_loadloose(git_repository *repository);
  static int packed_write_ref(struct packref *ref, git_filebuf *file);
  static int packed_find_peel(git_repository *repo, struct packref *ref);
  static int packed_remove_loose(git_repository *repo, git_vector *packing_list);
  static int packed_sort(const void *a, const void *b);
  static int packed_lookup(git_reference *ref);
  static int packed_write(git_repository *repo);
  
  /* internal helpers */
  static int reference_path_available(git_repository *repo,
  	const char *ref, const char *old_ref);
  static int reference_delete(git_reference *ref);
  static int reference_lookup(git_reference *ref);
  
  void git_reference_free(git_reference *reference)
  {
  	if (reference == NULL)
  		return;
  
  	git__free(reference->name);
  	reference->name = NULL;
  
  	if (reference->flags & GIT_REF_SYMBOLIC) {
  		git__free(reference->target.symbolic);
  		reference->target.symbolic = NULL;
  	}
  
  	git__free(reference);
  }
  
  static int reference_alloc(
  	git_reference **ref_out,
  	git_repository *repo,
  	const char *name)
  {
  	git_reference *reference = NULL;
  
  	assert(ref_out && repo && name);
  
  	reference = git__malloc(sizeof(git_reference));
  	GITERR_CHECK_ALLOC(reference);
  
  	memset(reference, 0x0, sizeof(git_reference));
  	reference->owner = repo;
  
  	reference->name = git__strdup(name);
  	GITERR_CHECK_ALLOC(reference->name);
  
  	*ref_out = reference;
  	return 0;
  }
  
  static int reference_read(
  	git_buf *file_content,
  	time_t *mtime,
  	const char *repo_path,
  	const char *ref_name,
  	int *updated)
  {
  	git_buf path = GIT_BUF_INIT;
  	int result;
  
  	assert(file_content && repo_path && ref_name);
  
  	/* Determine the full path of the file */
  	if (git_buf_joinpath(&path, repo_path, ref_name) < 0)
  		return -1;
  
  	result = git_futils_readbuffer_updated(
  		file_content, path.ptr, mtime, NULL, updated);
  	git_buf_free(&path);
  
  	return result;
  }
  
  static int loose_parse_symbolic(git_reference *ref, git_buf *file_content)
  {
  	const unsigned int header_len = (unsigned int)strlen(GIT_SYMREF);
  	const char *refname_start;
  
  	refname_start = (const char *)file_content->ptr;
  
  	if (git_buf_len(file_content) < header_len + 1) {
  		giterr_set(GITERR_REFERENCE, "Corrupted loose reference file");
  		return -1;
  	}
  
  	/*
  	 * Assume we have already checked for the header
  	 * before calling this function
  	 */
  	refname_start += header_len;
  
  	ref->target.symbolic = git__strdup(refname_start);
  	GITERR_CHECK_ALLOC(ref->target.symbolic);
  
  	return 0;
  }
  
  static int loose_parse_oid(git_oid *oid, git_buf *file_content)
  {
  	size_t len;
  	const char *str;
  
  	len = git_buf_len(file_content);
  	if (len < GIT_OID_HEXSZ)
  		goto corrupted;
  
  	/* str is guranteed to be zero-terminated */
  	str = git_buf_cstr(file_content);
  
  	/* we need to get 40 OID characters from the file */
  	if (git_oid_fromstr(oid, git_buf_cstr(file_content)) < 0)
  		goto corrupted;
  
  	/* If the file is longer than 40 chars, the 41st must be a space */
  	str += GIT_OID_HEXSZ;
  	if (*str == '\0' || git__isspace(*str))
  		return 0;
  
  corrupted:
  	giterr_set(GITERR_REFERENCE, "Corrupted loose reference file");
  	return -1;
  }
  
  static git_ref_t loose_guess_rtype(const git_buf *full_path)
  {
  	git_buf ref_file = GIT_BUF_INIT;
  	git_ref_t type;
  
  	type = GIT_REF_INVALID;
  
  	if (git_futils_readbuffer(&ref_file, full_path->ptr) == 0) {
  		if (git__prefixcmp((const char *)(ref_file.ptr), GIT_SYMREF) == 0)
  			type = GIT_REF_SYMBOLIC;
  		else
  			type = GIT_REF_OID;
  	}
  
  	git_buf_free(&ref_file);
  	return type;
  }
  
  static int loose_lookup(git_reference *ref)
  {
  	int result, updated;
  	git_buf ref_file = GIT_BUF_INIT;
  
  	result = reference_read(&ref_file, &ref->mtime,
  		ref->owner->path_repository, ref->name, &updated);
  
  	if (result < 0)
  		return result;
  
  	if (!updated)
  		return 0;
  
  	if (ref->flags & GIT_REF_SYMBOLIC) {
  		git__free(ref->target.symbolic);
  		ref->target.symbolic = NULL;
  	}
  
  	ref->flags = 0;
  
  	if (git__prefixcmp((const char *)(ref_file.ptr), GIT_SYMREF) == 0) {
  		ref->flags |= GIT_REF_SYMBOLIC;
  		git_buf_rtrim(&ref_file);
  		result = loose_parse_symbolic(ref, &ref_file);
  	} else {
  		ref->flags |= GIT_REF_OID;
  		result = loose_parse_oid(&ref->target.oid, &ref_file);
  	}
  
  	git_buf_free(&ref_file);
  	return result;
  }
  
  static int loose_lookup_to_packfile(
  		struct packref **ref_out,
  		git_repository *repo,
  		const char *name)
  {
  	git_buf ref_file = GIT_BUF_INIT;
  	struct packref *ref = NULL;
  	size_t name_len;
  
  	*ref_out = NULL;
  
  	if (reference_read(&ref_file, NULL, repo->path_repository, name, NULL) < 0)
  		return -1;
  
  	git_buf_rtrim(&ref_file);
  
  	name_len = strlen(name);
  	ref = git__malloc(sizeof(struct packref) + name_len + 1);
  	GITERR_CHECK_ALLOC(ref);
  
  	memcpy(ref->name, name, name_len);
  	ref->name[name_len] = 0;
  
  	if (loose_parse_oid(&ref->oid, &ref_file) < 0) {
  		git_buf_free(&ref_file);
  		git__free(ref);
  		return -1;
  	}
  
  	ref->flags = GIT_PACKREF_WAS_LOOSE;
  
  	*ref_out = ref;
  	git_buf_free(&ref_file);
  	return 0;
  }
  
  static int loose_write(git_reference *ref)
  {
  	git_filebuf file = GIT_FILEBUF_INIT;
  	git_buf ref_path = GIT_BUF_INIT;
  	struct stat st;
  
  	/* Remove a possibly existing empty directory hierarchy
  	 * which name would collide with the reference name
  	 */
  	if (git_futils_rmdir_r(ref->name, ref->owner->path_repository,
  		GIT_RMDIR_SKIP_NONEMPTY) < 0)
  		return -1;
  
  	if (git_buf_joinpath(&ref_path, ref->owner->path_repository, ref->name) < 0)
  		return -1;
  
  	if (git_filebuf_open(&file, ref_path.ptr, GIT_FILEBUF_FORCE) < 0) {
  		git_buf_free(&ref_path);
  		return -1;
  	}
  
  	git_buf_free(&ref_path);
  
  	if (ref->flags & GIT_REF_OID) {
  		char oid[GIT_OID_HEXSZ + 1];
  
  		git_oid_fmt(oid, &ref->target.oid);
  		oid[GIT_OID_HEXSZ] = '\0';
  
  		git_filebuf_printf(&file, "%s\n", oid);
  
  	} else if (ref->flags & GIT_REF_SYMBOLIC) {
  		git_filebuf_printf(&file, GIT_SYMREF "%s\n", ref->target.symbolic);
  	} else {
  		assert(0); /* don't let this happen */
  	}
  
  	if (p_stat(ref_path.ptr, &st) == 0)
  		ref->mtime = st.st_mtime;
  
  	return git_filebuf_commit(&file, GIT_REFS_FILE_MODE);
  }
  
  static int packed_parse_peel(
  		struct packref *tag_ref,
  		const char **buffer_out,
  		const char *buffer_end)
  {
  	const char *buffer = *buffer_out + 1;
  
  	assert(buffer[-1] == '^');
  
  	/* Ensure it's not the first entry of the file */
  	if (tag_ref == NULL)
  		goto corrupt;
  
  	/* Ensure reference is a tag */
  	if (git__prefixcmp(tag_ref->name, GIT_REFS_TAGS_DIR) != 0)
  		goto corrupt;
  
  	if (buffer + GIT_OID_HEXSZ >= buffer_end)
  		goto corrupt;
  
  	/* Is this a valid object id? */
  	if (git_oid_fromstr(&tag_ref->peel, buffer) < 0)
  		goto corrupt;
  
  	buffer = buffer + GIT_OID_HEXSZ;
  	if (*buffer == '\r')
  		buffer++;
  
  	if (*buffer != '\n')
  		goto corrupt;
  
  	*buffer_out = buffer + 1;
  	return 0;
  
  corrupt:
  	giterr_set(GITERR_REFERENCE, "The packed references file is corrupted");
  	return -1;
  }
  
  static int packed_parse_oid(
  		struct packref **ref_out,
  		const char **buffer_out,
  		const char *buffer_end)
  {
  	struct packref *ref = NULL;
  
  	const char *buffer = *buffer_out;
  	const char *refname_begin, *refname_end;
  
  	size_t refname_len;
  	git_oid id;
  
  	refname_begin = (buffer + GIT_OID_HEXSZ + 1);
  	if (refname_begin >= buffer_end || refname_begin[-1] != ' ')
  		goto corrupt;
  
  	/* Is this a valid object id? */
  	if (git_oid_fromstr(&id, buffer) < 0)
  		goto corrupt;
  
  	refname_end = memchr(refname_begin, '\n', buffer_end - refname_begin);
  	if (refname_end == NULL)
  		goto corrupt;
  
  	if (refname_end[-1] == '\r')
  		refname_end--;
  
  	refname_len = refname_end - refname_begin;
  
  	ref = git__malloc(sizeof(struct packref) + refname_len + 1);
  	GITERR_CHECK_ALLOC(ref);
  
  	memcpy(ref->name, refname_begin, refname_len);
  	ref->name[refname_len] = 0;
  
  	git_oid_cpy(&ref->oid, &id);
  
  	ref->flags = 0;
  
  	*ref_out = ref;
  	*buffer_out = refname_end + 1;
  
  	return 0;
  
  corrupt:
  	git__free(ref);
  	giterr_set(GITERR_REFERENCE, "The packed references file is corrupted");
  	return -1;
  }
  
  static int packed_load(git_repository *repo)
  {
  	int result, updated;
  	git_buf packfile = GIT_BUF_INIT;
  	const char *buffer_start, *buffer_end;
  	git_refcache *ref_cache = &repo->references;
  
  	/* First we make sure we have allocated the hash table */
  	if (ref_cache->packfile == NULL) {
  		ref_cache->packfile = git_strmap_alloc();
  		GITERR_CHECK_ALLOC(ref_cache->packfile);
  	}
  
  	result = reference_read(&packfile, &ref_cache->packfile_time,
  		repo->path_repository, GIT_PACKEDREFS_FILE, &updated);
  
  	/*
  	 * If we couldn't find the file, we need to clear the table and
  	 * return. On any other error, we return that error. If everything
  	 * went fine and the file wasn't updated, then there's nothing new
  	 * for us here, so just return. Anything else means we need to
  	 * refresh the packed refs.
  	 */
  	if (result == GIT_ENOTFOUND) {
  		git_strmap_clear(ref_cache->packfile);
  		return 0;
  	}
  
  	if (result < 0)
  		return -1;
  
  	if (!updated)
  		return 0;
  
  	/*
  	 * At this point, we want to refresh the packed refs. We already
  	 * have the contents in our buffer.
  	 */
  	git_strmap_clear(ref_cache->packfile);
  
  	buffer_start = (const char *)packfile.ptr;
  	buffer_end = (const char *)(buffer_start) + packfile.size;
  
  	while (buffer_start < buffer_end && buffer_start[0] == '#') {
  		buffer_start = strchr(buffer_start, '\n');
  		if (buffer_start == NULL)
  			goto parse_failed;
  
  		buffer_start++;
  	}
  
  	while (buffer_start < buffer_end) {
  		int err;
  		struct packref *ref = NULL;
  
  		if (packed_parse_oid(&ref, &buffer_start, buffer_end) < 0)
  			goto parse_failed;
  
  		if (buffer_start[0] == '^') {
  			if (packed_parse_peel(ref, &buffer_start, buffer_end) < 0)
  				goto parse_failed;
  		}
  
  		git_strmap_insert(ref_cache->packfile, ref->name, ref, err);
  		if (err < 0)
  			goto parse_failed;
  	}
  
  	git_buf_free(&packfile);
  	return 0;
  
  parse_failed:
  	git_strmap_free(ref_cache->packfile);
  	ref_cache->packfile = NULL;
  	git_buf_free(&packfile);
  	return -1;
  }
  
  
  struct dirent_list_data {
  	git_repository *repo;
  	size_t repo_path_len;
  	unsigned int list_flags;
  
  	int (*callback)(const char *, void *);
  	void *callback_payload;
  	int callback_error;
  };
  
  static int _dirent_loose_listall(void *_data, git_buf *full_path)
  {
  	struct dirent_list_data *data = (struct dirent_list_data *)_data;
  	const char *file_path = full_path->ptr + data->repo_path_len;
  
  	if (git_path_isdir(full_path->ptr) == true)
  		return git_path_direach(full_path, _dirent_loose_listall, _data);
  
  	/* do not add twice a reference that exists already in the packfile */
  	if ((data->list_flags & GIT_REF_PACKED) != 0 &&
  		git_strmap_exists(data->repo->references.packfile, file_path))
  		return 0;
  
  	if (data->list_flags != GIT_REF_LISTALL) {
  		if ((data->list_flags & loose_guess_rtype(full_path)) == 0)
  			return 0; /* we are filtering out this reference */
  	}
  
  	/* Locked references aren't returned */
  	if (!git__suffixcmp(file_path, GIT_FILELOCK_EXTENSION))
  		return 0;
  
  	if (data->callback(file_path, data->callback_payload))
  		data->callback_error = GIT_EUSER;
  
  	return data->callback_error;
  }
  
  static int _dirent_loose_load(void *data, git_buf *full_path)
  {
  	git_repository *repository = (git_repository *)data;
  	void *old_ref = NULL;
  	struct packref *ref;
  	const char *file_path;
  	int err;
  
  	if (git_path_isdir(full_path->ptr) == true)
  		return git_path_direach(full_path, _dirent_loose_load, repository);
  
  	file_path = full_path->ptr + strlen(repository->path_repository);
  
  	if (loose_lookup_to_packfile(&ref, repository, file_path) < 0)
  		return -1;
  
  	git_strmap_insert2(
  		repository->references.packfile, ref->name, ref, old_ref, err);
  	if (err < 0) {
  		git__free(ref);
  		return -1;
  	}
  
  	git__free(old_ref);
  	return 0;
  }
  
  /*
   * Load all the loose references from the repository
   * into the in-memory Packfile, and build a vector with
   * all the references so it can be written back to
   * disk.
   */
  static int packed_loadloose(git_repository *repository)
  {
  	git_buf refs_path = GIT_BUF_INIT;
  	int result;
  
  	/* the packfile must have been previously loaded! */
  	assert(repository->references.packfile);
  
  	if (git_buf_joinpath(&refs_path, repository->path_repository, GIT_REFS_DIR) < 0)
  		return -1;
  
  	/*
  	 * Load all the loose files from disk into the Packfile table.
  	 * This will overwrite any old packed entries with their
  	 * updated loose versions
  	 */
  	result = git_path_direach(&refs_path, _dirent_loose_load, repository);
  	git_buf_free(&refs_path);
  
  	return result;
  }
  
  /*
   * Write a single reference into a packfile
   */
  static int packed_write_ref(struct packref *ref, git_filebuf *file)
  {
  	char oid[GIT_OID_HEXSZ + 1];
  
  	git_oid_fmt(oid, &ref->oid);
  	oid[GIT_OID_HEXSZ] = 0;
  
  	/*
  	 * For references that peel to an object in the repo, we must
  	 * write the resulting peel on a separate line, e.g.
  	 *
  	 *	6fa8a902cc1d18527e1355773c86721945475d37 refs/tags/libgit2-0.4
  	 *	^2ec0cb7959b0bf965d54f95453f5b4b34e8d3100
  	 *
  	 * This obviously only applies to tags.
  	 * The required peels have already been loaded into `ref->peel_target`.
  	 */
  	if (ref->flags & GIT_PACKREF_HAS_PEEL) {
  		char peel[GIT_OID_HEXSZ + 1];
  		git_oid_fmt(peel, &ref->peel);
  		peel[GIT_OID_HEXSZ] = 0;
  
  		if (git_filebuf_printf(file, "%s %s\n^%s\n", oid, ref->name, peel) < 0)
  			return -1;
  	} else {
  		if (git_filebuf_printf(file, "%s %s\n", oid, ref->name) < 0)
  			return -1;
  	}
  
  	return 0;
  }
  
  /*
   * Find out what object this reference resolves to.
   *
   * For references that point to a 'big' tag (e.g. an
   * actual tag object on the repository), we need to
   * cache on the packfile the OID of the object to
   * which that 'big tag' is pointing to.
   */
  static int packed_find_peel(git_repository *repo, struct packref *ref)
  {
  	git_object *object;
  
  	if (ref->flags & GIT_PACKREF_HAS_PEEL)
  		return 0;
  
  	/*
  	 * Only applies to tags, i.e. references
  	 * in the /refs/tags folder
  	 */
  	if (git__prefixcmp(ref->name, GIT_REFS_TAGS_DIR) != 0)
  		return 0;
  
  	/*
  	 * Find the tagged object in the repository
  	 */
  	if (git_object_lookup(&object, repo, &ref->oid, GIT_OBJ_ANY) < 0)
  		return -1;
  
  	/*
  	 * If the tagged object is a Tag object, we need to resolve it;
  	 * if the ref is actually a 'weak' ref, we don't need to resolve
  	 * anything.
  	 */
  	if (git_object_type(object) == GIT_OBJ_TAG) {
  		git_tag *tag = (git_tag *)object;
  
  		/*
  		 * Find the object pointed at by this tag
  		 */
  		git_oid_cpy(&ref->peel, git_tag_target_id(tag));
  		ref->flags |= GIT_PACKREF_HAS_PEEL;
  
  		/*
  		 * The reference has now cached the resolved OID, and is
  		 * marked at such. When written to the packfile, it'll be
  		 * accompanied by this resolved oid
  		 */
  	}
  
  	git_object_free(object);
  	return 0;
  }
  
  /*
   * Remove all loose references
   *
   * Once we have successfully written a packfile,
   * all the loose references that were packed must be
   * removed from disk.
   *
   * This is a dangerous method; make sure the packfile
   * is well-written, because we are destructing references
   * here otherwise.
   */
  static int packed_remove_loose(git_repository *repo, git_vector *packing_list)
  {
  	unsigned int i;
  	git_buf full_path = GIT_BUF_INIT;
  	int failed = 0;
  
  	for (i = 0; i < packing_list->length; ++i) {
  		struct packref *ref = git_vector_get(packing_list, i);
  
  		if ((ref->flags & GIT_PACKREF_WAS_LOOSE) == 0)
  			continue;
  
  		if (git_buf_joinpath(&full_path, repo->path_repository, ref->name) < 0)
  			return -1; /* critical; do not try to recover on oom */
  
  		if (git_path_exists(full_path.ptr) == true && p_unlink(full_path.ptr) < 0) {
  			if (failed)
  				continue;
  
  			giterr_set(GITERR_REFERENCE,
  				"Failed to remove loose reference '%s' after packing: %s",
  				full_path.ptr, strerror(errno));
  
  			failed = 1;
  		}
  
  		/*
  		 * if we fail to remove a single file, this is *not* good,
  		 * but we should keep going and remove as many as possible.
  		 * After we've removed as many files as possible, we return
  		 * the error code anyway.
  		 */
  	}
  
  	git_buf_free(&full_path);
  	return failed ? -1 : 0;
  }
  
  static int packed_sort(const void *a, const void *b)
  {
  	const struct packref *ref_a = (const struct packref *)a;
  	const struct packref *ref_b = (const struct packref *)b;
  
  	return strcmp(ref_a->name, ref_b->name);
  }
  
  /*
   * Write all the contents in the in-memory packfile to disk.
   */
  static int packed_write(git_repository *repo)
  {
  	git_filebuf pack_file = GIT_FILEBUF_INIT;
  	unsigned int i;
  	git_buf pack_file_path = GIT_BUF_INIT;
  	git_vector packing_list;
  	unsigned int total_refs;
  
  	assert(repo && repo->references.packfile);
  
  	total_refs =
  		(unsigned int)git_strmap_num_entries(repo->references.packfile);
  
  	if (git_vector_init(&packing_list, total_refs, packed_sort) < 0)
  		return -1;
  
  	/* Load all the packfile into a vector */
  	{
  		struct packref *reference;
  
  		/* cannot fail: vector already has the right size */
  		git_strmap_foreach_value(repo->references.packfile, reference, {
  			git_vector_insert(&packing_list, reference);
  		});
  	}
  
  	/* sort the vector so the entries appear sorted on the packfile */
  	git_vector_sort(&packing_list);
  
  	/* Now we can open the file! */
  	if (git_buf_joinpath(&pack_file_path, repo->path_repository, GIT_PACKEDREFS_FILE) < 0)
  		goto cleanup_memory;
  
  	if (git_filebuf_open(&pack_file, pack_file_path.ptr, 0) < 0)
  		goto cleanup_packfile;
  
  	/* Packfiles have a header... apparently
  	 * This is in fact not required, but we might as well print it
  	 * just for kicks */
  	if (git_filebuf_printf(&pack_file, "%s\n", GIT_PACKEDREFS_HEADER) < 0)
  		goto cleanup_packfile;
  
  	for (i = 0; i < packing_list.length; ++i) {
  		struct packref *ref = (struct packref *)git_vector_get(&packing_list, i);
  
  		if (packed_find_peel(repo, ref) < 0)
  			goto cleanup_packfile;
  
  		if (packed_write_ref(ref, &pack_file) < 0)
  			goto cleanup_packfile;
  	}
  
  	/* if we've written all the references properly, we can commit
  	 * the packfile to make the changes effective */
  	if (git_filebuf_commit(&pack_file, GIT_PACKEDREFS_FILE_MODE) < 0)
  		goto cleanup_memory;
  
  	/* when and only when the packfile has been properly written,
  	 * we can go ahead and remove the loose refs */
  	 if (packed_remove_loose(repo, &packing_list) < 0)
  		 goto cleanup_memory;
  
  	 {
  		struct stat st;
  		if (p_stat(pack_file_path.ptr, &st) == 0)
  			repo->references.packfile_time = st.st_mtime;
  	 }
  
  	git_vector_free(&packing_list);
  	git_buf_free(&pack_file_path);
  
  	/* we're good now */
  	return 0;
  
  cleanup_packfile:
  	git_filebuf_cleanup(&pack_file);
  
  cleanup_memory:
  	git_vector_free(&packing_list);
  	git_buf_free(&pack_file_path);
  
  	return -1;
  }
  
  struct reference_available_t {
  	const char *new_ref;
  	const char *old_ref;
  	int available;
  };
  
  static int _reference_available_cb(const char *ref, void *data)
  {
  	struct reference_available_t *d;
  
  	assert(ref && data);
  	d = (struct reference_available_t *)data;
  
  	if (!d->old_ref || strcmp(d->old_ref, ref)) {
  		size_t reflen = strlen(ref);
  		size_t newlen = strlen(d->new_ref);
  		size_t cmplen = reflen < newlen ? reflen : newlen;
  		const char *lead = reflen < newlen ? d->new_ref : ref;
  
  		if (!strncmp(d->new_ref, ref, cmplen) && lead[cmplen] == '/') {
  			d->available = 0;
  			return -1;
  		}
  	}
  
  	return 0;
  }
  
  static int reference_path_available(
  	git_repository *repo,
  	const char *ref,
  	const char* old_ref)
  {
  	int error;
  	struct reference_available_t data;
  
  	data.new_ref = ref;
  	data.old_ref = old_ref;
  	data.available = 1;
  
  	error = git_reference_foreach(
  		repo, GIT_REF_LISTALL, _reference_available_cb, (void *)&data);
  	if (error < 0)
  		return error;
  
  	if (!data.available) {
  		giterr_set(GITERR_REFERENCE,
  			"The path to reference '%s' collides with an existing one", ref);
  		return -1;
  	}
  
  	return 0;
  }
  
  static int reference_exists(int *exists, git_repository *repo, const char *ref_name)
  {
  	git_buf ref_path = GIT_BUF_INIT;
  
  	if (packed_load(repo) < 0)
  		return -1;
  
  	if (git_buf_joinpath(&ref_path, repo->path_repository, ref_name) < 0)
  		return -1;
  
  	if (git_path_isfile(ref_path.ptr) == true ||
  		git_strmap_exists(repo->references.packfile, ref_path.ptr))
  	{
  		*exists = 1;
  	} else {
  		*exists = 0;
  	}
  
  	git_buf_free(&ref_path);
  	return 0;
  }
  
  /*
   * Check if a reference could be written to disk, based on:
   *
   *	- Whether a reference with the same name already exists,
   *	and we are allowing or disallowing overwrites
   *
   *	- Whether the name of the reference would collide with
   *	an existing path
   */
  static int reference_can_write(
  	git_repository *repo,
  	const char *refname,
  	const char *previous_name,
  	int force)
  {
  	/* see if the reference shares a path with an existing reference;
  	 * if a path is shared, we cannot create the reference, even when forcing */
  	if (reference_path_available(repo, refname, previous_name) < 0)
  		return -1;
  
  	/* check if the reference actually exists, but only if we are not forcing
  	 * the rename. If we are forcing, it's OK to overwrite */
  	if (!force) {
  		int exists;
  
  		if (reference_exists(&exists, repo, refname) < 0)
  			return -1;
  
  		/* We cannot proceed if the reference already exists and we're not forcing
  		 * the rename; the existing one would be overwritten */
  		if (exists) {
  			giterr_set(GITERR_REFERENCE,
  				"A reference with that name (%s) already exists", refname);
  			return GIT_EEXISTS;
  		}
  	}
  
  	/* FIXME: if the reference exists and we are forcing, do we really need to
  	 * remove the reference first?
  	 *
  	 * Two cases:
  	 *
  	 *	- the reference already exists and is loose: not a problem, the file
  	 *	gets overwritten on disk
  	 *
  	 *	- the reference already exists and is packed: we write a new one as
  	 *	loose, which by all means renders the packed one useless
  	 */
  
  	return 0;
  }
  
  
  static int packed_lookup(git_reference *ref)
  {
  	struct packref *pack_ref = NULL;
  	git_strmap *packfile_refs;
  	khiter_t pos;
  
  	if (packed_load(ref->owner) < 0)
  		return -1;
  
  	/* maybe the packfile hasn't changed at all, so we don't
  	 * have to re-lookup the reference */
  	if ((ref->flags & GIT_REF_PACKED) &&
  		ref->mtime == ref->owner->references.packfile_time)
  		return 0;
  
  	if (ref->flags & GIT_REF_SYMBOLIC) {
  		git__free(ref->target.symbolic);
  		ref->target.symbolic = NULL;
  	}
  
  	/* Look up on the packfile */
  	packfile_refs = ref->owner->references.packfile;
  	pos = git_strmap_lookup_index(packfile_refs, ref->name);
  	if (!git_strmap_valid_index(packfile_refs, pos)) {
  		giterr_set(GITERR_REFERENCE, "Reference '%s' not found", ref->name);
  		return GIT_ENOTFOUND;
  	}
  
  	pack_ref = git_strmap_value_at(packfile_refs, pos);
  
  	ref->flags = GIT_REF_OID | GIT_REF_PACKED;
  	ref->mtime = ref->owner->references.packfile_time;
  	git_oid_cpy(&ref->target.oid, &pack_ref->oid);
  
  	return 0;
  }
  
  static int reference_lookup(git_reference *ref)
  {
  	int result;
  
  	result = loose_lookup(ref);
  	if (result == 0)
  		return 0;
  
  	/* only try to lookup this reference on the packfile if it
  	 * wasn't found on the loose refs; not if there was a critical error */
  	if (result == GIT_ENOTFOUND) {
  		giterr_clear();
  		result = packed_lookup(ref);
  		if (result == 0)
  			return 0;
  	}
  
  	/* unexpected error; free the reference */
  	git_reference_free(ref);
  	return result;
  }
  
  /*
   * Delete a reference.
   * This is an internal method; the reference is removed
   * from disk or the packfile, but the pointer is not freed
   */
  static int reference_delete(git_reference *ref)
  {
  	int result;
  
  	assert(ref);
  
  	/* If the reference is packed, this is an expensive operation.
  	 * We need to reload the packfile, remove the reference from the
  	 * packing list, and repack */
  	if (ref->flags & GIT_REF_PACKED) {
  		git_strmap *packfile_refs;
  		struct packref *packref;
  		khiter_t pos;
  
  		/* load the existing packfile */
  		if (packed_load(ref->owner) < 0)
  			return -1;
  
  		packfile_refs = ref->owner->references.packfile;
  		pos = git_strmap_lookup_index(packfile_refs, ref->name);
  		if (!git_strmap_valid_index(packfile_refs, pos)) {
  			giterr_set(GITERR_REFERENCE,
  				"Reference %s stopped existing in the packfile", ref->name);
  			return -1;
  		}
  
  		packref = git_strmap_value_at(packfile_refs, pos);
  		git_strmap_delete_at(packfile_refs, pos);
  
  		git__free(packref);
  		if (packed_write(ref->owner) < 0)
  			return -1;
  
  	/* If the reference is loose, we can just remove the reference
  	 * from the filesystem */
  	} else {
  		git_reference *ref_in_pack;
  		git_buf full_path = GIT_BUF_INIT;
  
  		if (git_buf_joinpath(&full_path, ref->owner->path_repository, ref->name) < 0)
  			return -1;
  
  		result = p_unlink(full_path.ptr);
  		git_buf_free(&full_path); /* done with path at this point */
  
  		if (result < 0) {
  			giterr_set(GITERR_OS, "Failed to unlink '%s'", full_path.ptr);
  			return -1;
  		}
  
  		/* When deleting a loose reference, we have to ensure that an older
  		 * packed version of it doesn't exist */
  		if (git_reference_lookup(&ref_in_pack, ref->owner, ref->name) == 0) {
  			assert((ref_in_pack->flags & GIT_REF_PACKED) != 0);
  			return git_reference_delete(ref_in_pack);
  		}
  
  		giterr_clear();
  	}
  
  	return 0;
  }
  
  int git_reference_delete(git_reference *ref)
  {
  	int result = reference_delete(ref);
  	git_reference_free(ref);
  	return result;
  }
  
  int git_reference_lookup(git_reference **ref_out,
  	git_repository *repo, const char *name)
  {
  	return git_reference_lookup_resolved(ref_out, repo, name, 0);
  }
  
  int git_reference_name_to_id(
  	git_oid *out, git_repository *repo, const char *name)
  {
  	int error;
  	git_reference *ref;
  
  	if ((error = git_reference_lookup_resolved(&ref, repo, name, -1)) < 0)
  		return error;
  
  	git_oid_cpy(out, git_reference_target(ref));
  	git_reference_free(ref);
  	return 0;
  }
  
  int git_reference_lookup_resolved(
  	git_reference **ref_out,
  	git_repository *repo,
  	const char *name,
  	int max_nesting)
  {
  	git_reference *scan;
  	int result, nesting;
  
  	assert(ref_out && repo && name);
  
  	*ref_out = NULL;
  
  	if (max_nesting > MAX_NESTING_LEVEL)
  		max_nesting = MAX_NESTING_LEVEL;
  	else if (max_nesting < 0)
  		max_nesting = DEFAULT_NESTING_LEVEL;
  
  	scan = git__calloc(1, sizeof(git_reference));
  	GITERR_CHECK_ALLOC(scan);
  
  	scan->name = git__calloc(GIT_REFNAME_MAX + 1, sizeof(char));
  	GITERR_CHECK_ALLOC(scan->name);
  
  	if ((result = git_reference__normalize_name_lax(
  		scan->name,
  		GIT_REFNAME_MAX,
  		name)) < 0) {
  			git_reference_free(scan);
  			return result;
  	}
  
  	scan->target.symbolic = git__strdup(scan->name);
  	GITERR_CHECK_ALLOC(scan->target.symbolic);
  
  	scan->owner = repo;
  	scan->flags = GIT_REF_SYMBOLIC;
  
  	for (nesting = max_nesting;
  		 nesting >= 0 && (scan->flags & GIT_REF_SYMBOLIC) != 0;
  		 nesting--)
  	{
  		if (nesting != max_nesting)
  			strncpy(scan->name, scan->target.symbolic, GIT_REFNAME_MAX);
  
  		scan->mtime = 0;
  
  		if ((result = reference_lookup(scan)) < 0)
  			return result; /* lookup git_reference_free on scan already */
  	}
  
  	if ((scan->flags & GIT_REF_OID) == 0 && max_nesting != 0) {
  		giterr_set(GITERR_REFERENCE,
  			"Cannot resolve reference (>%u levels deep)", max_nesting);
  		git_reference_free(scan);
  		return -1;
  	}
  
  	*ref_out = scan;
  	return 0;
  }
  
  /**
   * Getters
   */
  git_ref_t git_reference_type(const git_reference *ref)
  {
  	assert(ref);
  
  	if (ref->flags & GIT_REF_OID)
  		return GIT_REF_OID;
  
  	if (ref->flags & GIT_REF_SYMBOLIC)
  		return GIT_REF_SYMBOLIC;
  
  	return GIT_REF_INVALID;
  }
  
  int git_reference_is_packed(git_reference *ref)
  {
  	assert(ref);
  	return !!(ref->flags & GIT_REF_PACKED);
  }
  
  const char *git_reference_name(const git_reference *ref)
  {
  	assert(ref);
  	return ref->name;
  }
  
  git_repository *git_reference_owner(const git_reference *ref)
  {
  	assert(ref);
  	return ref->owner;
  }
  
  const git_oid *git_reference_target(const git_reference *ref)
  {
  	assert(ref);
  
  	if ((ref->flags & GIT_REF_OID) == 0)
  		return NULL;
  
  	return &ref->target.oid;
  }
  
  const char *git_reference_symbolic_target(const git_reference *ref)
  {
  	assert(ref);
  
  	if ((ref->flags & GIT_REF_SYMBOLIC) == 0)
  		return NULL;
  
  	return ref->target.symbolic;
  }
  
  int git_reference_symbolic_create(
  	git_reference **ref_out,
  	git_repository *repo,
  	const char *name,
  	const char *target,
  	int force)
  {
  	char normalized[GIT_REFNAME_MAX];
  	git_reference *ref = NULL;
  	int error;
  
  	if ((error = git_reference__normalize_name_lax(
  		normalized,
  		sizeof(normalized),
  		name)) < 0)
  			return error;
  
  	if ((error = reference_can_write(repo, normalized, NULL, force)) < 0)
  		return error;
  
  	if (reference_alloc(&ref, repo, normalized) < 0)
  		return -1;
  
  	ref->flags |= GIT_REF_SYMBOLIC;
  
  	/* set the target; this will normalize the name automatically
  	 * and write the reference on disk */
  	if (git_reference_symbolic_set_target(ref, target) < 0) {
  		git_reference_free(ref);
  		return -1;
  	}
  	if (ref_out == NULL) {
  		git_reference_free(ref);
  	} else {
  		*ref_out = ref;
  	}
  
  	return 0;
  }
  
  int git_reference_create(
  	git_reference **ref_out,
  	git_repository *repo,
  	const char *name,
  	const git_oid *id,
  	int force)
  {
  	int error;
  	git_reference *ref = NULL;
  	char normalized[GIT_REFNAME_MAX];
  
  	if ((error = git_reference__normalize_name_lax(
  		normalized,
  		sizeof(normalized),
  		name)) < 0)
  			return error;
  
  	if ((error = reference_can_write(repo, normalized, NULL, force)) < 0)
  		return error;
  
  	if (reference_alloc(&ref, repo, name) < 0)
  		return -1;
  
  	ref->flags |= GIT_REF_OID;
  
  	/* set the oid; this will write the reference on disk */
  	if (git_reference_set_target(ref, id) < 0) {
  		git_reference_free(ref);
  		return -1;
  	}
  
  	if (ref_out == NULL) {
  		git_reference_free(ref);
  	} else {
  		*ref_out = ref;
  	}
  
  	return 0;
  }
  /*
   * Change the OID target of a reference.
   *
   * For both loose and packed references, just change
   * the oid in memory and (over)write the file in disk.
   *
   * We do not repack packed references because of performance
   * reasons.
   */
  int git_reference_set_target(git_reference *ref, const git_oid *id)
  {
  	git_odb *odb = NULL;
  
  	if ((ref->flags & GIT_REF_OID) == 0) {
  		giterr_set(GITERR_REFERENCE, "Cannot set OID on symbolic reference");
  		return -1;
  	}
  
  	assert(ref->owner);
  
  	if (git_repository_odb__weakptr(&odb, ref->owner) < 0)
  		return -1;
  
  	/* Don't let the user create references to OIDs that
  	 * don't exist in the ODB */
  	if (!git_odb_exists(odb, id)) {
  		giterr_set(GITERR_REFERENCE,
  			"Target OID for the reference doesn't exist on the repository");
  		return -1;
  	}
  
  	/* Update the OID value on `ref` */
  	git_oid_cpy(&ref->target.oid, id);
  
  	/* Write back to disk */
  	return loose_write(ref);
  }
  
  /*
   * Change the target of a symbolic reference.
   *
   * This is easy because symrefs cannot be inside
   * a pack. We just change the target in memory
   * and overwrite the file on disk.
   */
  int git_reference_symbolic_set_target(git_reference *ref, const char *target)
  {
  	int error;
  	char normalized[GIT_REFNAME_MAX];
  
  	if ((ref->flags & GIT_REF_SYMBOLIC) == 0) {
  		giterr_set(GITERR_REFERENCE,
  			"Cannot set symbolic target on a direct reference");
  		return -1;
  	}
  
  	if ((error = git_reference__normalize_name_lax(
  		normalized,
  		sizeof(normalized),
  		target)) < 0)
  			return error;
  
  	git__free(ref->target.symbolic);
  	ref->target.symbolic = git__strdup(normalized);
  	GITERR_CHECK_ALLOC(ref->target.symbolic);
  
  	return loose_write(ref);
  }
  
  int git_reference_rename(git_reference *ref, const char *new_name, int force)
  {
  	int result;
  	unsigned int normalization_flags;
  	git_buf aux_path = GIT_BUF_INIT;
  	char normalized[GIT_REFNAME_MAX];
  	bool should_head_be_updated = false;
  
  	normalization_flags = ref->flags & GIT_REF_SYMBOLIC ?
  		GIT_REF_FORMAT_ALLOW_ONELEVEL
  		: GIT_REF_FORMAT_NORMAL;
  
  	if ((result = git_reference_normalize_name(
  		normalized,
  		sizeof(normalized),
  		new_name,
  		normalization_flags)) < 0)
  			return result;
  
  	if ((result = reference_can_write(ref->owner, normalized, ref->name, force)) < 0)
  		return result;
  
  	/* Initialize path now so we won't get an allocation failure once
  	 * we actually start removing things. */
  	if (git_buf_joinpath(&aux_path, ref->owner->path_repository, new_name) < 0)
  		return -1;
  
  	/*
  	 * Check if we have to update HEAD.
  	 */
  	if ((should_head_be_updated = git_branch_is_head(ref)) < 0)
  		goto cleanup;
  
  	/*
  	 * Now delete the old ref and remove an possibly existing directory
  	 * named `new_name`. Note that using the internal `reference_delete`
  	 * method deletes the ref from disk but doesn't free the pointer, so
  	 * we can still access the ref's attributes for creating the new one
  	 */
  	if (reference_delete(ref) < 0)
  		goto cleanup;
  
  	/*
  	 * Finally we can create the new reference.
  	 */
  	if (ref->flags & GIT_REF_SYMBOLIC) {
  		result = git_reference_symbolic_create(
  			NULL, ref->owner, new_name, ref->target.symbolic, force);
  	} else {
  		result = git_reference_create(
  			NULL, ref->owner, new_name, &ref->target.oid, force);
  	}
  
  	if (result < 0)
  		goto rollback;
  
  	/*
  	 * Update HEAD it was poiting to the reference being renamed.
  	 */
  	if (should_head_be_updated && 
  		git_repository_set_head(ref->owner, new_name) < 0) {
  			giterr_set(GITERR_REFERENCE,
  				"Failed to update HEAD after renaming reference");
  			goto cleanup;
  	}
  
  	/*
  	 * Rename the reflog file, if it exists.
  	 */
  	if ((git_reference_has_log(ref)) && (git_reflog_rename(ref, new_name) < 0))
  		goto cleanup;
  
  	/*
  	 * Change the name of the reference given by the user.
  	 */
  	git__free(ref->name);
  	ref->name = git__strdup(new_name);
  
  	/* The reference is no longer packed */
  	ref->flags &= ~GIT_REF_PACKED;
  
  	git_buf_free(&aux_path);
  	return 0;
  
  cleanup:
  	git_buf_free(&aux_path);
  	return -1;
  
  rollback:
  	/*
  	 * Try to create the old reference again, ignore failures
  	 */
  	if (ref->flags & GIT_REF_SYMBOLIC)
  		git_reference_symbolic_create(
  			NULL, ref->owner, ref->name, ref->target.symbolic, 0);
  	else
  		git_reference_create(
  			NULL, ref->owner, ref->name, &ref->target.oid, 0);
  
  	/* The reference is no longer packed */
  	ref->flags &= ~GIT_REF_PACKED;
  
  	git_buf_free(&aux_path);
  	return -1;
  }
  
  int git_reference_resolve(git_reference **ref_out, const git_reference *ref)
  {
  	if (ref->flags & GIT_REF_OID)
  		return git_reference_lookup(ref_out, ref->owner, ref->name);
  	else
  		return git_reference_lookup_resolved(ref_out, ref->owner, ref->target.symbolic, -1);
  }
  
  int git_reference_packall(git_repository *repo)
  {
  	if (packed_load(repo) < 0 || /* load the existing packfile */
  		packed_loadloose(repo) < 0 || /* add all the loose refs */
  		packed_write(repo) < 0) /* write back to disk */
  		return -1;
  
  	return 0;
  }
  
  int git_reference_foreach(
  	git_repository *repo,
  	unsigned int list_flags,
  	git_reference_foreach_cb callback,
  	void *payload)
  {
  	int result;
  	struct dirent_list_data data;
  	git_buf refs_path = GIT_BUF_INIT;
  
  	/* list all the packed references first */
  	if (list_flags & GIT_REF_PACKED) {
  		const char *ref_name;
  		void *ref;
  		GIT_UNUSED(ref);
  
  		if (packed_load(repo) < 0)
  			return -1;
  
  		git_strmap_foreach(repo->references.packfile, ref_name, ref, {
  			if (callback(ref_name, payload))
  				return GIT_EUSER;
  		});
  	}
  
  	/* now list the loose references, trying not to
  	 * duplicate the ref names already in the packed-refs file */
  
  	data.repo_path_len = strlen(repo->path_repository);
  	data.list_flags = list_flags;
  	data.repo = repo;
  	data.callback = callback;
  	data.callback_payload = payload;
  	data.callback_error = 0;
  
  	if (git_buf_joinpath(&refs_path, repo->path_repository, GIT_REFS_DIR) < 0)
  		return -1;
  
  	result = git_path_direach(&refs_path, _dirent_loose_listall, &data);
  
  	git_buf_free(&refs_path);
  
  	return data.callback_error ? GIT_EUSER : result;
  }
  
  static int cb__reflist_add(const char *ref, void *data)
  {
  	return git_vector_insert((git_vector *)data, git__strdup(ref));
  }
  
  int git_reference_list(
  	git_strarray *array,
  	git_repository *repo,
  	unsigned int list_flags)
  {
  	git_vector ref_list;
  
  	assert(array && repo);
  
  	array->strings = NULL;
  	array->count = 0;
  
  	if (git_vector_init(&ref_list, 8, NULL) < 0)
  		return -1;
  
  	if (git_reference_foreach(
  			repo, list_flags, &cb__reflist_add, (void *)&ref_list) < 0) {
  		git_vector_free(&ref_list);
  		return -1;
  	}
  
  	array->strings = (char **)ref_list.contents;
  	array->count = ref_list.length;
  	return 0;
  }
  
  int git_reference_reload(git_reference *ref)
  {
  	return reference_lookup(ref);
  }
  
  void git_repository__refcache_free(git_refcache *refs)
  {
  	assert(refs);
  
  	if (refs->packfile) {
  		struct packref *reference;
  
  		git_strmap_foreach_value(refs->packfile, reference, {
  			git__free(reference);
  		});
  
  		git_strmap_free(refs->packfile);
  	}
  }
  
  static int is_valid_ref_char(char ch)
  {
  	if ((unsigned) ch <= ' ')
  		return 0;
  
  	switch (ch) {
  	case '~':
  	case '^':
  	case ':':
  	case '\\':
  	case '?':
  	case '[':
  	case '*':
  		return 0;
  	default:
  		return 1;
  	}
  }
  
  static int ensure_segment_validity(const char *name)
  {
  	const char *current = name;
  	char prev = '\0';
  
  	if (*current == '.')
  		return -1; /* Refname starts with "." */
  
  	for (current = name; ; current++) {
  		if (*current == '\0' || *current == '/')
  			break;
  
  		if (!is_valid_ref_char(*current))
  			return -1; /* Illegal character in refname */
  
  		if (prev == '.' && *current == '.')
  			return -1; /* Refname contains ".." */
  
  		if (prev == '@' && *current == '{')
  			return -1; /* Refname contains "@{" */
  
  		prev = *current;
  	}
  
  	return (int)(current - name);
  }
  
  static bool is_all_caps_and_underscore(const char *name, size_t len)
  {
  	size_t i;
  	char c;
  
  	assert(name && len > 0);
  
  	for (i = 0; i < len; i++)
  	{
  		c = name[i];
  		if ((c < 'A' || c > 'Z') && c != '_')
  			return false;
  	}
  
  	if (*name == '_' || name[len - 1] == '_')
  		return false;
  
  	return true;
  }
  
  int git_reference__normalize_name(
  	git_buf *buf,
  	const char *name,
  	unsigned int flags)
  {
  	// Inspired from https://github.com/git/git/blob/f06d47e7e0d9db709ee204ed13a8a7486149f494/refs.c#L36-100
  
  	char *current;
  	int segment_len, segments_count = 0, error = GIT_EINVALIDSPEC;
  	unsigned int process_flags;
  	bool normalize = (buf != NULL);
  	assert(name);
  
  	process_flags = flags;
  	current = (char *)name;
  
  	if (normalize)
  		git_buf_clear(buf);
  
  	while (true) {
  		segment_len = ensure_segment_validity(current);
  		if (segment_len < 0) {
  			if ((process_flags & GIT_REF_FORMAT_REFSPEC_PATTERN) &&
  					current[0] == '*' &&
  					(current[1] == '\0' || current[1] == '/')) {
  				/* Accept one wildcard as a full refname component. */
  				process_flags &= ~GIT_REF_FORMAT_REFSPEC_PATTERN;
  				segment_len = 1;
  			} else
  				goto cleanup;
  		}
  
  		if (segment_len > 0) {
  			if (normalize) {
  				size_t cur_len = git_buf_len(buf);
  
  				git_buf_joinpath(buf, git_buf_cstr(buf), current);
  				git_buf_truncate(buf,
  					cur_len + segment_len + (segments_count ? 1 : 0));
  
  				if (git_buf_oom(buf)) {
  					error = -1;
  					goto cleanup;
  				}
  			}
  
  			segments_count++;
  		}
  
  		if (current[segment_len] == '\0')
  			break;
  
  		current += segment_len + 1;
  	}
  
  	/* A refname can not be empty */
  	if (segment_len == 0 && segments_count == 0)
  		goto cleanup;
  
  	/* A refname can not end with "." */
  	if (current[segment_len - 1] == '.')
  		goto cleanup;
  
  	/* A refname can not end with "/" */
  	if (current[segment_len - 1] == '/')
  		goto cleanup;
  
  	/* A refname can not end with ".lock" */
  	if (!git__suffixcmp(name, GIT_FILELOCK_EXTENSION))
  		goto cleanup;
  
  	if ((segments_count == 1 ) && !(flags & GIT_REF_FORMAT_ALLOW_ONELEVEL))
  		goto cleanup;
  
  	if ((segments_count == 1 ) &&
  		!(is_all_caps_and_underscore(name, (size_t)segment_len) ||
  			((flags & GIT_REF_FORMAT_REFSPEC_PATTERN) && !strcmp("*", name))))
  			goto cleanup;
  
  	if ((segments_count > 1)
  		&& (is_all_caps_and_underscore(name, strchr(name, '/') - name)))
  			goto cleanup;
  
  	error = 0;
  
  cleanup:
  	if (error == GIT_EINVALIDSPEC)
  		giterr_set(
  			GITERR_REFERENCE,
  			"The given reference name '%s' is not valid", name);
  
  	return error;
  }
  
  int git_reference_normalize_name(
  	char *buffer_out,
  	size_t buffer_size,
  	const char *name,
  	unsigned int flags)
  {
  	git_buf buf = GIT_BUF_INIT;
  	int error;
  
  	if ((error = git_reference__normalize_name(&buf, name, flags)) < 0)
  		goto cleanup;
  
  	if (git_buf_len(&buf) > buffer_size - 1) {
  		giterr_set(
  		GITERR_REFERENCE,
  		"The provided buffer is too short to hold the normalization of '%s'", name);
  		error = GIT_EBUFS;
  		goto cleanup;
  	}
  
  	git_buf_copy_cstr(buffer_out, buffer_size, &buf);
  
  	error = 0;
  
  cleanup:
  	git_buf_free(&buf);
  	return error;
  }
  
  int git_reference__normalize_name_lax(
  	char *buffer_out,
  	size_t out_size,
  	const char *name)
  {
  	return git_reference_normalize_name(
  		buffer_out,
  		out_size,
  		name,
  		GIT_REF_FORMAT_ALLOW_ONELEVEL);
  }
  #define GIT_REF_TYPEMASK (GIT_REF_OID | GIT_REF_SYMBOLIC)
  
  int git_reference_cmp(git_reference *ref1, git_reference *ref2)
  {
  	assert(ref1 && ref2);
  
  	/* let's put symbolic refs before OIDs */
  	if ((ref1->flags & GIT_REF_TYPEMASK) != (ref2->flags & GIT_REF_TYPEMASK))
  		return (ref1->flags & GIT_REF_SYMBOLIC) ? -1 : 1;
  
  	if (ref1->flags & GIT_REF_SYMBOLIC)
  		return strcmp(ref1->target.symbolic, ref2->target.symbolic);
  
  	return git_oid_cmp(&ref1->target.oid, &ref2->target.oid);
  }
  
  /* Update the reference named `ref_name` so it points to `oid` */
  int git_reference__update(git_repository *repo, const git_oid *oid, const char *ref_name)
  {
  	git_reference *ref;
  	int res;
  
  	res = git_reference_lookup(&ref, repo, ref_name);
  
  	/* If we haven't found the reference at all, we assume we need to create
  	 * a new reference and that's it */
  	if (res == GIT_ENOTFOUND) {
  		giterr_clear();
  		return git_reference_create(NULL, repo, ref_name, oid, 1);
  	}
  
  	if (res < 0)
  		return -1;
  
  	/* If we have found a reference, but it's symbolic, we need to update
  	 * the direct reference it points to */
  	if (git_reference_type(ref) == GIT_REF_SYMBOLIC) {
  		git_reference *aux;
  		const char *sym_target;
  
  		/* The target pointed at by this reference */
  		sym_target = git_reference_symbolic_target(ref);
  
  		/* resolve the reference to the target it points to */
  		res = git_reference_resolve(&aux, ref);
  
  		/*
  		 * if the symbolic reference pointed to an inexisting ref,
  		 * this is means we're creating a new branch, for example.
  		 * We need to create a new direct reference with that name
  		 */
  		if (res == GIT_ENOTFOUND) {
  			giterr_clear();
  			res = git_reference_create(NULL, repo, sym_target, oid, 1);
  			git_reference_free(ref);
  			return res;
  		}
  
  		/* free the original symbolic reference now; not before because
  		 * we're using the `sym_target` pointer */
  		git_reference_free(ref);
  
  		if (res < 0)
  			return -1;
  
  		/* store the newly found direct reference in its place */
  		ref = aux;
  	}
  
  	/* ref is made to point to `oid`: ref is either the original reference,
  	 * or the target of the symbolic reference we've looked up */
  	res = git_reference_set_target(ref, oid);
  	git_reference_free(ref);
  	return res;
  }
  
  struct glob_cb_data {
  	const char *glob;
  	int (*callback)(const char *, void *);
  	void *payload;
  };
  
  static int fromglob_cb(const char *reference_name, void *payload)
  {
  	struct glob_cb_data *data = (struct glob_cb_data *)payload;
  
  	if (!p_fnmatch(data->glob, reference_name, 0))
  		return data->callback(reference_name, data->payload);
  
  	return 0;
  }
  
  int git_reference_foreach_glob(
  	git_repository *repo,
  	const char *glob,
  	unsigned int list_flags,
  	int (*callback)(
  		const char *reference_name,
  		void *payload),
  	void *payload)
  {
  	struct glob_cb_data data;
  
  	assert(repo && glob && callback);
  
  	data.glob = glob;
  	data.callback = callback;
  	data.payload = payload;
  
  	return git_reference_foreach(
  			repo, list_flags, fromglob_cb, &data);
  }
  
  int git_reference_has_log(
  	git_reference *ref)
  {
  	git_buf path = GIT_BUF_INIT;
  	int result;
  
  	assert(ref);
  
  	if (git_buf_join_n(&path, '/', 3, ref->owner->path_repository, GIT_REFLOG_DIR, ref->name) < 0)
  		return -1;
  
  	result = git_path_isfile(git_buf_cstr(&path));
  	git_buf_free(&path);
  
  	return result;
  }
  
  int git_reference_is_branch(git_reference *ref)
  {
  	assert(ref);
  	return git__prefixcmp(ref->name, GIT_REFS_HEADS_DIR) == 0;
  }
  
  int git_reference_is_remote(git_reference *ref)
  {
  	assert(ref);
  	return git__prefixcmp(ref->name, GIT_REFS_REMOTES_DIR) == 0;
  }
  
  static int peel_error(int error, git_reference *ref, const char* msg)
  {
  	giterr_set(
  		GITERR_INVALID,
  		"The reference '%s' cannot be peeled - %s", git_reference_name(ref), msg);
  	return error;
  }
  
  static int reference_target(git_object **object, git_reference *ref)
  {
  	const git_oid *oid;
  
  	oid = git_reference_target(ref);
  
  	return git_object_lookup(object, git_reference_owner(ref), oid, GIT_OBJ_ANY);
  }
  
  int git_reference_peel(
  		git_object **peeled,
  		git_reference *ref,
  		git_otype target_type)
  {
  	git_reference *resolved = NULL;
  	git_object *target = NULL;
  	int error;
  
  	assert(ref);
  
  	if ((error = git_reference_resolve(&resolved, ref)) < 0)
  		return peel_error(error, ref, "Cannot resolve reference");
  
  	if ((error = reference_target(&target, resolved)) < 0) {
  		peel_error(error, ref, "Cannot retrieve reference target");
  		goto cleanup;
  	}
  
  	if (target_type == GIT_OBJ_ANY && git_object_type(target) != GIT_OBJ_TAG)
  		error = git_object__dup(peeled, target);
  	else
  		error = git_object_peel(peeled, target, target_type);
  
  cleanup:
  	git_object_free(target);
  	git_reference_free(resolved);
  	return error;
  }
  
  int git_reference__is_valid_name(
  	const char *refname,
  	unsigned int flags)
  {
  	int error;
  
  	error = git_reference__normalize_name(NULL, refname, flags) == 0;
  	giterr_clear();
  
  	return error;
  }
  
  int git_reference_is_valid_name(
  	const char *refname)
  {
  	return git_reference__is_valid_name(
  		refname,
  		GIT_REF_FORMAT_ALLOW_ONELEVEL);
  }
  