thodg/libgit2

diff --git a/include/git2/repository.h b/include/git2/repository.h
index 34dd904..d760c23 100644
--- a/include/git2/repository.h
+++ b/include/git2/repository.h
@@ -70,6 +70,20 @@ GIT_EXTERN(int) git_repository_discover(
 		int across_fs,
 		const char *ceiling_dirs);
 
+enum {
+	GIT_REPOSITORY_OPEN_NO_SEARCH = (1 << 0),
+	GIT_REPOSITORY_OPEN_CROSS_FS  = (1 << 1),
+};
+
+/**
+ * Find and open a repository with extended controls.
+ */
+GIT_EXTERN(int) git_repository_open_ext(
+	git_repository **repo,
+	const char *start_path,
+	uint32_t flags,
+	const char *ceiling_dirs);
+
 /**
  * Free a previously allocated repository
  *
diff --git a/src/attr.c b/src/attr.c
index 5cf96ac..c022893 100644
--- a/src/attr.c
+++ b/src/attr.c
@@ -347,6 +347,7 @@ static int collect_attr_files(
 
 int git_attr_cache__init(git_repository *repo)
 {
+	int ret;
 	git_attr_cache *cache = git_repository_attr_cache(repo);
 	git_config *cfg;
 
@@ -354,17 +355,18 @@ int git_attr_cache__init(git_repository *repo)
 		return 0;
 
 	/* cache config settings for attributes and ignores */
-	if (git_repository_config(&cfg, repo) < 0)
+	if (git_repository_config__weakptr(&cfg, repo) < 0)
 		return -1;
-	if (git_config_get_string(cfg, GIT_ATTR_CONFIG, &cache->cfg_attr_file)) {
-		giterr_clear();
-		cache->cfg_attr_file = NULL;
-	}
-	if (git_config_get_string(cfg, GIT_IGNORE_CONFIG, &cache->cfg_excl_file)) {
-		giterr_clear();
-		cache->cfg_excl_file = NULL;
-	}
-	git_config_free(cfg);
+
+	ret = git_config_get_string(cfg, GIT_ATTR_CONFIG, &cache->cfg_attr_file);
+	if (ret < 0 && ret != GIT_ENOTFOUND)
+		return ret;
+
+	ret = git_config_get_string(cfg, GIT_IGNORE_CONFIG, &cache->cfg_excl_file);
+	if (ret < 0 && ret != GIT_ENOTFOUND)
+		return ret;
+
+	giterr_clear();
 
 	/* allocate hashtable for attribute and ignore file contents */
 	if (cache->files == NULL) {
diff --git a/src/config.c b/src/config.c
index 250bfa6..f5cfa9e 100644
--- a/src/config.c
+++ b/src/config.c
@@ -327,11 +327,11 @@ int git_config_lookup_map_value(
 int git_config_get_mapped(git_config *cfg, const char *name, git_cvar_map *maps, size_t map_n, int *out)
 {
 	const char *value;
-	int error;
+	int ret;
 
-	error = git_config_get_string(cfg, name, &value);
-	if (error < 0)
-		return error;
+	ret = git_config_get_string(cfg, name, &value);
+	if (ret < 0)
+		return ret;
 
 	if (!git_config_lookup_map_value(maps, map_n, value, out))
 		return 0;
@@ -371,7 +371,7 @@ int git_config_get_int32(git_config *cfg, const char *name, int32_t *out)
 		giterr_set(GITERR_CONFIG, "Failed to parse '%s' as a 32-bit integer", value);
 		return -1;
 	}
-	
+
 	return 0;
 }
 
@@ -399,26 +399,17 @@ int git_config_get_bool(git_config *cfg, const char *name, int *out)
 int git_config_get_string(git_config *cfg, const char *name, const char **out)
 {
 	file_internal *internal;
-	git_config_file *file;
-	int ret = GIT_ENOTFOUND;
 	unsigned int i;
 
 	assert(cfg->files.length);
 
-	for (i = 0; i < cfg->files.length; ++i) {
-		internal = git_vector_get(&cfg->files, i);
-		file = internal->file;
-
-		ret = file->get(file, name, out);
-		if (ret == 0)
-			return 0;
+	*out = NULL;
 
-		/* File backend doesn't set error message on variable
-		 * not found */
-		if (ret == GIT_ENOTFOUND)
-			continue;
-
-		return ret;
+	git_vector_foreach(&cfg->files, i, internal) {
+		git_config_file *file = internal->file;
+		int ret = file->get(file, name, out);
+		if (ret != GIT_ENOTFOUND)
+			return ret;
 	}
 
 	giterr_set(GITERR_CONFIG, "Config variable '%s' not found", name);
diff --git a/src/diff.c b/src/diff.c
index 54e8dd1..fa841f7 100644
--- a/src/diff.c
+++ b/src/diff.c
@@ -253,7 +253,7 @@ static git_diff_list *git_diff_list_alloc(
 	diff->repo = repo;
 
 	/* load config values that affect diff behavior */
-	if (git_repository_config(&cfg, repo) < 0)
+	if (git_repository_config__weakptr(&cfg, repo) < 0)
 		goto fail;
 	if (config_bool(cfg, "core.symlinks", 1))
 		diff->diffcaps = diff->diffcaps | GIT_DIFFCAPS_HAS_SYMLINKS;
@@ -264,7 +264,6 @@ static git_diff_list *git_diff_list_alloc(
 	if (config_bool(cfg, "core.trustctime", 1))
 		diff->diffcaps = diff->diffcaps | GIT_DIFFCAPS_TRUST_CTIME;
 	/* Don't set GIT_DIFFCAPS_USE_DEV - compile time option in core git */
-	git_config_free(cfg);
 
 	if (opts == NULL)
 		return diff;
diff --git a/src/errors.c b/src/errors.c
index 70aa641..aad6c44 100644
--- a/src/errors.c
+++ b/src/errors.c
@@ -92,8 +92,12 @@ const char *git_lasterror(void)
 {
 	char *last_error = GIT_GLOBAL->error.last;
 
-	if (!last_error[0])
+	if (!last_error[0]) {
+		const git_error *err = git_error_last();
+		if (err != NULL)
+			return err->message;
 		return NULL;
+	}
 
 	return last_error;
 }
diff --git a/src/path.c b/src/path.c
index 31d2e72..3c1a723 100644
--- a/src/path.c
+++ b/src/path.c
@@ -172,20 +172,22 @@ int git_path_root(const char *path)
 	if (isalpha(path[0]) && (path[1] == ':'))
 		offset += 2;
 
-	/* Are we dealing with a network path? */
-	else if (path[0] == '/' && path[1] == '/') {
+	/* Are we dealing with a windows network path? */
+	else if ((path[0] == '/' && path[1] == '/') ||
+		(path[0] == '\\' && path[1] == '\\'))
+	{
 		offset += 2;
-	
+
 		/* Skip the computer name segment */
-		while (*(path + offset) && *(path + offset) != '/')
+		while (path[offset] && path[offset] != '/' && path[offset] != '\\')
 			offset++;
 	}
 #endif
 
-	if (*(path + offset) == '/')
+	if (path[offset] == '/' || path[offset] == '\\')
 		return offset;
 
-	return -1;	/* Not a real error. Rather a signal than the path is not rooted */
+	return -1;	/* Not a real error - signals that path is not rooted */
 }
 
 int git_path_prettify(git_buf *path_out, const char *path, const char *base)
@@ -193,26 +195,21 @@ int git_path_prettify(git_buf *path_out, const char *path, const char *base)
 	char buf[GIT_PATH_MAX];
 
 	assert(path && path_out);
-	git_buf_clear(path_out);
 
 	/* construct path if needed */
 	if (base != NULL && git_path_root(path) < 0) {
 		if (git_buf_joinpath(path_out, base, path) < 0)
 			return -1;
-
 		path = path_out->ptr;
 	}
 
 	if (p_realpath(path, buf) == NULL) {
-		giterr_set(GITERR_OS, "Failed to resolve path '%s': %s",
-			path, strerror(errno));
+		giterr_set(GITERR_OS, "Failed to resolve path '%s'", path);
+		git_buf_clear(path_out);
 		return (errno == ENOENT) ? GIT_ENOTFOUND : -1;
 	}
 
-	if (git_buf_sets(path_out, buf) < 0)
-		return -1;
-
-	return 0;
+	return git_buf_sets(path_out, buf);
 }
 
 int git_path_prettify_dir(git_buf *path_out, const char *path, const char *base)
diff --git a/src/repository.c b/src/repository.c
index ce31328..413bb17 100644
--- a/src/repository.c
+++ b/src/repository.c
@@ -5,6 +5,7 @@
  * a Linking Exception. For full terms see the included COPYING file.
  */
 #include <stdarg.h>
+#include <ctype.h>
 
 #include "git2/object.h"
 
@@ -20,7 +21,7 @@
 #define GIT_OBJECTS_INFO_DIR GIT_OBJECTS_DIR "info/"
 #define GIT_OBJECTS_PACK_DIR GIT_OBJECTS_DIR "pack/"
 
-#define GIT_FILE_CONTENT_PREFIX "gitdir: "
+#define GIT_FILE_CONTENT_PREFIX "gitdir:"
 
 #define GIT_BRANCH_MASTER "master"
 
@@ -132,76 +133,294 @@ static int load_config_data(git_repository *repo)
 	return 0;
 }
 
-static int load_workdir(git_repository *repo)
+static int load_workdir(git_repository *repo, git_buf *parent_path)
 {
-	git_buf workdir_buf = GIT_BUF_INIT;
+	int         error;
+	git_config *config;
+	const char *worktree;
+	git_buf     worktree_buf = GIT_BUF_INIT;
 
 	if (repo->is_bare)
 		return 0;
 
-	git_path_dirname_r(&workdir_buf, repo->path_repository);
-	git_path_to_dir(&workdir_buf);
-
-	if (git_buf_oom(&workdir_buf))
+	if (git_repository_config__weakptr(&config, repo) < 0)
 		return -1;
 
-	repo->workdir = git_buf_detach(&workdir_buf);
-	git_buf_free(&workdir_buf);
+	error = git_config_get_string(config, "core.worktree", &worktree);
+	if (!error && worktree != NULL)
+		repo->workdir = git__strdup(worktree);
+	else if (error != GIT_ENOTFOUND)
+		return error;
+	else {
+		giterr_clear();
+
+		if (parent_path && git_path_isdir(parent_path->ptr))
+			repo->workdir = git_buf_detach(parent_path);
+		else {
+			git_path_dirname_r(&worktree_buf, repo->path_repository);
+			git_path_to_dir(&worktree_buf);
+			repo->workdir = git_buf_detach(&worktree_buf);
+		}
+	}
+
+	GITERR_CHECK_ALLOC(repo->workdir);
 
 	return 0;
 }
 
-int git_repository_open(git_repository **repo_out, const char *path)
+/*
+ * This function returns furthest offset into path where a ceiling dir
+ * is found, so we can stop processing the path at that point.
+ *
+ * Note: converting this to use git_bufs instead of GIT_PATH_MAX buffers on
+ * the stack could remove directories name limits, but at the cost of doing
+ * repeated malloc/frees inside the loop below, so let's not do it now.
+ */
+static int find_ceiling_dir_offset(
+	const char *path,
+	const char *ceiling_directories)
 {
-	git_buf path_buf = GIT_BUF_INIT;
-	git_repository *repo = NULL;
-	int res;
+	char buf[GIT_PATH_MAX + 1];
+	char buf2[GIT_PATH_MAX + 1];
+	const char *ceil, *sep;
+	int len, max_len = -1;
+	int min_len;
 
-	res = git_path_prettify_dir(&path_buf, path, NULL);
-	if (res < 0)
-		return res;
+	assert(path);
+
+	min_len = git_path_root(path) + 1;
 
-	/**
-	 * Check if the path we've been given is actually the path
-	 * of the working dir, by testing if it contains a `.git`
-	 * folder inside of it.
-	 */
-	if (git_path_contains_dir(&path_buf, GIT_DIR) == true)
-		git_buf_joinpath(&path_buf, path_buf.ptr, GIT_DIR);
+	if (ceiling_directories == NULL || min_len == 0)
+		return min_len;
+
+	for (sep = ceil = ceiling_directories; *sep; ceil = sep + 1) {
+		for (sep = ceil; *sep && *sep != GIT_PATH_LIST_SEPARATOR; sep++);
+		len = sep - ceil;
+
+		if (len == 0 || len >= (int)sizeof(buf) || git_path_root(ceil) == -1)
+			continue;
+
+		strncpy(buf, ceil, len);
+		buf[len] = '\0';
+
+		if (p_realpath(buf, buf2) == NULL)
+			continue;
+
+		len = strlen(buf2);
+		if (len > 0 && buf2[len-1] == '/')
+			buf[--len] = '\0';
+
+		if (!strncmp(path, buf2, len) &&
+			path[len] == '/' &&
+			len > max_len)
+		{
+			max_len = len;
+		}
+	}
+
+	return max_len <= min_len ? min_len : max_len;
+}
+
+/*
+ * Read the contents of `file_path` and set `path_out` to the repo dir that
+ * it points to.  Before calling, set `path_out` to the base directory that
+ * should be used if the contents of `file_path` are a relative path.
+ */
+static int read_gitfile(git_buf *path_out, const char *file_path)
+{
+	int     error = 0;
+	git_buf file = GIT_BUF_INIT;
+	size_t  prefix_len = strlen(GIT_FILE_CONTENT_PREFIX);
+
+	assert(path_out && file_path);
+
+	if (git_futils_readbuffer(&file, file_path) < 0)
+		return -1;
+
+	git_buf_rtrim(&file);
+
+	if (file.size <= prefix_len ||
+		memcmp(file.ptr, GIT_FILE_CONTENT_PREFIX, prefix_len) != 0)
+	{
+		giterr_set(GITERR_REPOSITORY, "The `.git` file at '%s' is malformed", file_path);
+		error = -1;
+	}
+	else if ((error = git_path_dirname_r(path_out, file_path)) >= 0) {
+		const char *gitlink = ((const char *)file.ptr) + prefix_len;
+		while (*gitlink && isspace(*gitlink)) gitlink++;
+		error = git_path_prettify_dir(path_out, gitlink, path_out->ptr);
+	}
 
-	if (valid_repository_path(&path_buf) == false) {
+	git_buf_free(&file);
+	return error;
+}
+
+static int find_repo(
+	git_buf *repo_path,
+	git_buf *parent_path,
+	const char *start_path,
+	uint32_t flags,
+	const char *ceiling_dirs)
+{
+	int error;
+	git_buf path = GIT_BUF_INIT;
+	struct stat st;
+	dev_t initial_device = 0;
+	bool try_with_dot_git = false;
+	int ceiling_offset;
+
+	git_buf_free(repo_path);
+
+	if ((error = git_path_prettify_dir(&path, start_path, NULL)) < 0)
+		return error;
+
+	ceiling_offset = find_ceiling_dir_offset(path.ptr, ceiling_dirs);
+
+	if ((error = git_buf_joinpath(&path, path.ptr, DOT_GIT)) < 0)
+		return error;
+
+	while (!error && !repo_path->size) {
+		if (p_stat(path.ptr, &st) == 0) {
+			/* check that we have not crossed device boundaries */
+			if (initial_device == 0)
+				initial_device = st.st_dev;
+			else if (st.st_dev != initial_device &&
+				(flags & GIT_REPOSITORY_OPEN_CROSS_FS) == 0)
+				break;
+
+			if (S_ISDIR(st.st_mode)) {
+				if (valid_repository_path(&path)) {
+					git_path_to_dir(&path);
+					git_buf_set(repo_path, path.ptr, path.size);
+					break;
+				}
+			}
+			else if (S_ISREG(st.st_mode)) {
+				git_buf repo_link = GIT_BUF_INIT;
+
+				if (!(error = read_gitfile(&repo_link, path.ptr))) {
+					if (valid_repository_path(&repo_link))
+						git_buf_swap(repo_path, &repo_link);
+					break;
+				}
+				git_buf_free(&repo_link);
+			}
+		}
+
+		/* move up one directory level */
+		if (git_path_dirname_r(&path, path.ptr) < 0) {
+			error = -1;
+			break;
+		}
+
+		if (try_with_dot_git) {
+			/* if we tried original dir with and without .git AND either hit
+			 * directory ceiling or NO_SEARCH was requested, then be done.
+			 */
+			if (path.ptr[ceiling_offset] == '\0' ||
+				(flags & GIT_REPOSITORY_OPEN_NO_SEARCH) != 0)
+				break;
+			/* otherwise look first for .git item */
+			error = git_buf_joinpath(&path, path.ptr, DOT_GIT);
+		}
+		try_with_dot_git = !try_with_dot_git;
+	}
+
+	if (!error && parent_path != NULL) {
+		if (!repo_path->size)
+			git_buf_clear(parent_path);
+		else {
+			git_path_dirname_r(parent_path, path.ptr);
+			git_path_to_dir(parent_path);
+		}
+		if (git_buf_oom(parent_path))
+			return -1;
+	}
+
+	git_buf_free(&path);
+
+	if (!repo_path->size && !error) {
 		giterr_set(GITERR_REPOSITORY,
-			"The given path (%s) is not a valid Git repository", git_buf_cstr(&path_buf));
-		git_buf_free(&path_buf);
-		return GIT_ENOTFOUND;
+			"Could not find repository from '%s'", start_path);
+		error = GIT_ENOTFOUND;
 	}
 
+	return error;
+}
+
+int git_repository_open_ext(
+	git_repository **repo_ptr,
+	const char *start_path,
+	uint32_t flags,
+	const char *ceiling_dirs)
+{
+	int error;
+	git_buf path = GIT_BUF_INIT, parent = GIT_BUF_INIT;
+	git_repository *repo;
+
+	*repo_ptr = NULL;
+
+	if ((error = find_repo(&path, &parent, start_path, flags, ceiling_dirs)) < 0)
+		return error;
+
 	repo = repository_alloc();
 	GITERR_CHECK_ALLOC(repo);
 
-	repo->path_repository = git_buf_detach(&path_buf);
+	repo->path_repository = git_buf_detach(&path);
 	GITERR_CHECK_ALLOC(repo->path_repository);
 
-	if (load_config_data(repo) < 0)
-		goto cleanup;
-
-	if (load_workdir(repo) < 0)
-		goto cleanup;
+	if ((error = load_config_data(repo)) < 0 ||
+		(error = load_workdir(repo, &parent)) < 0)
+	{
+		git_repository_free(repo);
+		return error;
+	}
 
-	*repo_out = repo;
+	*repo_ptr = repo;
 	return 0;
+}
 
- cleanup:
-	git_repository_free(repo);
-	git_buf_free(&path_buf);
-	return -1;
+int git_repository_open(git_repository **repo_out, const char *path)
+{
+	return git_repository_open_ext(
+		repo_out, path, GIT_REPOSITORY_OPEN_NO_SEARCH, NULL);
+}
+
+int git_repository_discover(
+	char *repository_path,
+	size_t size,
+	const char *start_path,
+	int across_fs,
+	const char *ceiling_dirs)
+{
+	git_buf path = GIT_BUF_INIT;
+	uint32_t flags = across_fs ? GIT_REPOSITORY_OPEN_CROSS_FS : 0;
+
+	assert(start_path && repository_path && size > 0);
+
+	*repository_path = '\0';
+
+	if (find_repo(&path, NULL, start_path, flags, ceiling_dirs) < 0)
+		return -1;
+
+	if (size < (size_t)(path.size + 1)) {
+		giterr_set(GITERR_REPOSITORY,
+			"The given buffer is too long to store the discovered path");
+		git_buf_free(&path);
+		return -1;
+	}
+
+	/* success: we discovered a repository */
+	git_buf_copy_cstr(repository_path, size, &path);
+	git_buf_free(&path);
+	return 0;
 }
 
 static int load_config(
-		git_config **out,
-		git_repository *repo,
-		const char *global_config_path,
-		const char *system_config_path)
+	git_config **out,
+	git_repository *repo,
+	const char *global_config_path,
+	const char *system_config_path)
 {
 	git_buf config_path = GIT_BUF_INIT;
 	git_config *cfg = NULL;
@@ -375,240 +594,6 @@ void git_repository_set_index(git_repository *repo, git_index *index)
 	GIT_REFCOUNT_OWN(repo->_index, repo);
 }
 
-
-static int retrieve_device(dev_t *device_out, const char *path)
-{
-	int error;
-	struct stat path_info;
-
-	assert(device_out);
-
-	if ((error = git_path_lstat(path, &path_info)) == 0)
-		*device_out = path_info.st_dev;
-
-	return error;
-}
-
-/*
- * This function returns furthest offset into path where a ceiling dir
- * is found, so we can stop processing the path at that point.
- *
- * Note: converting this to use git_bufs instead of GIT_PATH_MAX buffers on
- * the stack could remove directories name limits, but at the cost of doing
- * repeated malloc/frees inside the loop below, so let's not do it now.
- */
-static int retrieve_ceiling_directories_offset(
-	const char *path,
-	const char *ceiling_directories)
-{
-	char buf[GIT_PATH_MAX + 1];
-	char buf2[GIT_PATH_MAX + 1];
-	const char *ceil, *sep;
-	int len, max_len = -1;
-	int min_len;
-
-	assert(path);
-
-	min_len = git_path_root(path) + 1;
-
-	if (ceiling_directories == NULL || min_len == 0)
-		return min_len;
-
-	for (sep = ceil = ceiling_directories; *sep; ceil = sep + 1) {
-		for (sep = ceil; *sep && *sep != GIT_PATH_LIST_SEPARATOR; sep++);
-		len = sep - ceil;
-
-		if (len == 0 || len >= (int)sizeof(buf) || git_path_root(ceil) == -1)
-			continue;
-
-		strncpy(buf, ceil, len);
-		buf[len] = '\0';
-
-		if (p_realpath(buf, buf2) == NULL)
-			continue;
-
-		len = strlen(buf2);
-		if (len > 0 && buf2[len-1] == '/')
-			buf[--len] = '\0';
-
-		if (!strncmp(path, buf2, len) &&
-			path[len] == '/' &&
-			len > max_len)
-		{
-			max_len = len;
-		}
-	}
-
-	return max_len <= min_len ? min_len : max_len;
-}
-
-/*
- * Read the contents of `file_path` and set `path_out` to the repo dir that
- * it points to.  Before calling, set `path_out` to the base directory that
- * should be used if the contents of `file_path` are a relative path.
- */
-static int read_gitfile(git_buf *path_out, const char *file_path, const char *base_path)
-{
-	git_buf file = GIT_BUF_INIT;
-
-	assert(path_out && file_path);
-
-	if (git_futils_readbuffer(&file, file_path) < 0)
-		return -1;
-
-	git_buf_rtrim(&file);
-
-	if (git__prefixcmp((char *)file.ptr, GIT_FILE_CONTENT_PREFIX) != 0 ||
-		strlen(GIT_FILE_CONTENT_PREFIX) == file.size) {
-		git_buf_free(&file);
-		giterr_set(GITERR_REPOSITORY, "The `.git` file at '%s' is corrupted", file_path);
-		return -1;
-	}
-
-	if (git_path_prettify_dir(path_out,
-		((char *)file.ptr) + strlen(GIT_FILE_CONTENT_PREFIX), base_path) < 0) {
-		git_buf_free(&file);
-		giterr_set(GITERR_REPOSITORY,
-			"The `.git` file at '%s' points to an invalid path.", file_path);
-		return -1;
-	}
-
-	git_buf_free(&file);
-	return 0;
-}
-
-int git_repository_discover(
-	char *repository_path,
-	size_t size,
-	const char *start_path,
-	int across_fs,
-	const char *ceiling_dirs)
-{
-	int res, ceiling_offset;
-	git_buf bare_path = GIT_BUF_INIT;
-	git_buf normal_path = GIT_BUF_INIT;
-	git_buf *found_path = NULL;
-	dev_t current_device = 0;
-
-	assert(start_path && repository_path);
-
-	*repository_path = '\0';
-
-	res = git_path_prettify_dir(&bare_path, start_path, NULL);
-	if (res < 0)
-		return res;
-
-	if (!across_fs) {
-		if (retrieve_device(&current_device, bare_path.ptr) < 0)
-			goto on_error;
-	}
-
-	ceiling_offset = retrieve_ceiling_directories_offset(bare_path.ptr, ceiling_dirs);
-
-	while(1) {
-		if (git_buf_joinpath(&normal_path, bare_path.ptr, DOT_GIT) < 0)
-			goto on_error;
-
-		/**
-		 * If the `.git` file is regular instead of
-		 * a directory, it should contain the path of the actual git repository
-		 */
-		if (git_path_isfile(normal_path.ptr) == true) {
-			git_buf gitfile_path = GIT_BUF_INIT;
-
-			if (read_gitfile(&gitfile_path, normal_path.ptr, bare_path.ptr) < 0) {
-				git_buf_free(&gitfile_path);
-				goto on_error;
-			}
-
-			if (valid_repository_path(&gitfile_path) == false) {
-				git_buf_free(&gitfile_path);
-				giterr_set(GITERR_REPOSITORY,
-					"The `.git` file found at '%s' points to an invalid git folder", normal_path.ptr);
-				goto on_error;
-			}
-
-			git_buf_swap(&normal_path, &gitfile_path);
-			found_path = &normal_path;
-
-			git_buf_free(&gitfile_path);
-			break;
-		}
-
-		/**
-		 * If the `.git` file is a folder, we check inside of it
-		 */
-		if (git_path_isdir(normal_path.ptr) == true) {
-			if (valid_repository_path(&normal_path) == true) {
-				found_path = &normal_path;
-				break;
-			}
-		}
-
-		/**
-		 * Otherwise, the repository may be bare, let's check
-		 * the root anyway
-		 */
-		if (valid_repository_path(&bare_path) == true) {
-			found_path = &bare_path;
-			break;
-		}
-
-		/**
-		 * If we didn't find it, walk up the tree
-		 */
-		if (git_path_dirname_r(&normal_path, bare_path.ptr) < 0)
-			goto on_error;
-
-		git_buf_swap(&bare_path, &normal_path);
-
-		if (!across_fs) {
-			dev_t new_device;
-			if (retrieve_device(&new_device, bare_path.ptr) < 0)
-				goto on_error;
-
-			if (current_device != new_device)
-				goto on_not_found;
-
-			current_device = new_device;
-		}
-
-		/* nothing has been found, lets try the parent directory
-		 * but stop if we hit one of the ceiling directories
-		 */
-		if (bare_path.ptr[ceiling_offset] == '\0')
-			goto on_not_found;
-	}
-
-	assert(found_path);
-
-	if (git_path_to_dir(found_path) < 0)
-		goto on_error;
-
-	if (size < (size_t)(found_path->size + 1)) {
-		giterr_set(GITERR_REPOSITORY,
-			"The given buffer is too long to store the discovered path");
-		goto on_error;
-	}
-
-	/* success: we discovered a repository */
-	git_buf_copy_cstr(repository_path, size, found_path);
-
-	git_buf_free(&bare_path);
-	git_buf_free(&normal_path);
-	return 0;
-
-on_error: /* unrecoverable error */
-	git_buf_free(&bare_path);
-	git_buf_free(&normal_path);
-	return -1;
-
-on_not_found: /* failed to discover the repository */
-	git_buf_free(&bare_path);
-	git_buf_free(&normal_path);
-	return GIT_ENOTFOUND;
-}
-
 static int check_repositoryformatversion(git_repository *repo)
 {
 	git_config *config;
diff --git a/tests-clar/clar_helpers.c b/tests-clar/clar_helpers.c
index 22db56f..0010453 100644
--- a/tests-clar/clar_helpers.c
+++ b/tests-clar/clar_helpers.c
@@ -28,9 +28,9 @@ void cl_git_mkfile(const char *filename, const char *content)
 	cl_must_pass(p_close(fd));
 }
 
-void cl_git_append2file(const char *filename, const char *new_content)
+void cl_git_write2file(const char *filename, const char *new_content, int flags)
 {
-	int fd = p_open(filename, O_WRONLY | O_APPEND | O_CREAT);
+	int fd = p_open(filename, flags);
 	cl_assert(fd != 0);
 	if (!new_content)
 		new_content = "\n";
@@ -39,6 +39,16 @@ void cl_git_append2file(const char *filename, const char *new_content)
 	cl_must_pass(p_chmod(filename, 0644));
 }
 
+void cl_git_append2file(const char *filename, const char *new_content)
+{
+	cl_git_write2file(filename, new_content, O_WRONLY | O_APPEND | O_CREAT);
+}
+
+void cl_git_rewritefile(const char *filename, const char *new_content)
+{
+	cl_git_write2file(filename, new_content, O_WRONLY | O_CREAT | O_TRUNC);
+}
+
 static const char *_cl_sandbox = NULL;
 static git_repository *_cl_repo = NULL;
 
@@ -52,11 +62,12 @@ git_repository *cl_git_sandbox_init(const char *sandbox)
 
 	p_chdir(sandbox);
 
-	/* Rename `sandbox/.gitted` to `sandbox/.git` which must be done since
-	 * we cannot store a folder named `.git` inside the fixtures folder of
-	 * our libgit2 repo.
+	/* If this is not a bare repo, then rename `sandbox/.gitted` to
+	 * `sandbox/.git` which must be done since we cannot store a folder
+	 * named `.git` inside the fixtures folder of our libgit2 repo.
 	 */
-	cl_git_pass(p_rename(".gitted", ".git"));
+	if (p_access(".gitted", F_OK) == 0)
+		cl_git_pass(p_rename(".gitted", ".git"));
 
 	/* If we have `gitattributes`, rename to `.gitattributes`.  This may
 	 * be necessary if we don't want the attributes to be applied in the
diff --git a/tests-clar/clar_libgit2.h b/tests-clar/clar_libgit2.h
index 5c034a3..bb2feee 100644
--- a/tests-clar/clar_libgit2.h
+++ b/tests-clar/clar_libgit2.h
@@ -57,6 +57,8 @@ GIT_INLINE(void) cl_assert_strequal_internal(
 /* Write the contents of a buffer to disk */
 void cl_git_mkfile(const char *filename, const char *content);
 void cl_git_append2file(const char *filename, const char *new_content);
+void cl_git_rewritefile(const char *filename, const char *new_content);
+void cl_git_write2file(const char *filename, const char *new_content, int mode);
 
 /* Git sandbox setup helpers */
 
diff --git a/tests-clar/repo/open.c b/tests-clar/repo/open.c
index c3a7dad..28bae40 100644
--- a/tests-clar/repo/open.c
+++ b/tests-clar/repo/open.c
@@ -1,25 +1,27 @@
 #include "clar_libgit2.h"
-#include "posix.h"
-
-static git_repository *repo;
+#include "fileops.h"
 
 void test_repo_open__cleanup(void)
 {
-	git_repository_free(repo);
+	cl_git_sandbox_cleanup();
+
+	if (git_path_isdir("alternate"))
+		git_futils_rmdir_r("alternate", 1);
 }
 
 void test_repo_open__bare_empty_repo(void)
 {
-	cl_git_pass(git_repository_open(&repo, cl_fixture("empty_bare.git")));
+	git_repository *repo = cl_git_sandbox_init("empty_bare.git");
 
 	cl_assert(git_repository_path(repo) != NULL);
 	cl_assert(git__suffixcmp(git_repository_path(repo), "/") == 0);
-
 	cl_assert(git_repository_workdir(repo) == NULL);
 }
 
 void test_repo_open__standard_empty_repo_through_gitdir(void)
 {
+	git_repository *repo;
+
 	cl_git_pass(git_repository_open(&repo, cl_fixture("empty_standard_repo/.gitted")));
 
 	cl_assert(git_repository_path(repo) != NULL);
@@ -27,20 +29,246 @@ void test_repo_open__standard_empty_repo_through_gitdir(void)
 
 	cl_assert(git_repository_workdir(repo) != NULL);
 	cl_assert(git__suffixcmp(git_repository_workdir(repo), "/") == 0);
+
+	git_repository_free(repo);
 }
 
 void test_repo_open__standard_empty_repo_through_workdir(void)
 {
-	cl_fixture_sandbox("empty_standard_repo");
-	cl_git_pass(p_rename("empty_standard_repo/.gitted", "empty_standard_repo/.git"));
-
-	cl_git_pass(git_repository_open(&repo, "empty_standard_repo"));
+	git_repository *repo = cl_git_sandbox_init("empty_standard_repo");
 
 	cl_assert(git_repository_path(repo) != NULL);
 	cl_assert(git__suffixcmp(git_repository_path(repo), "/") == 0);
 
 	cl_assert(git_repository_workdir(repo) != NULL);
 	cl_assert(git__suffixcmp(git_repository_workdir(repo), "/") == 0);
+}
+
+
+void test_repo_open__open_with_discover(void)
+{
+	static const char *variants[] = {
+		"attr", "attr/", "attr/.git", "attr/.git/",
+		"attr/sub", "attr/sub/", "attr/sub/sub", "attr/sub/sub/",
+		NULL
+	};
+	git_repository *repo;
+	const char **scan;
+
+	cl_fixture_sandbox("attr");
+	cl_git_pass(p_rename("attr/.gitted", "attr/.git"));
+
+	for (scan = variants; *scan != NULL; scan++) {
+		cl_git_pass(git_repository_open_ext(&repo, *scan, 0, NULL));
+		cl_assert(git__suffixcmp(git_repository_path(repo), "attr/.git/") == 0);
+		cl_assert(git__suffixcmp(git_repository_workdir(repo), "attr/") == 0);
+		git_repository_free(repo);
+	}
+
+	cl_fixture_cleanup("attr");
+}
+
+void test_repo_open__gitlinked(void)
+{
+	/* need to have both repo dir and workdir set up correctly */
+	git_repository *repo = cl_git_sandbox_init("empty_standard_repo");
+	git_repository *repo2;
+
+	cl_must_pass(p_mkdir("alternate", 0777));
+	cl_git_mkfile("alternate/.git", "gitdir: ../empty_standard_repo/.git");
+
+	cl_git_pass(git_repository_open(&repo2, "alternate"));
+
+	cl_assert(git_repository_path(repo2) != NULL);
+	cl_assert_(git__suffixcmp(git_repository_path(repo2), "empty_standard_repo/.git/") == 0, git_repository_path(repo2));
+	cl_assert_equal_s(git_repository_path(repo), git_repository_path(repo2));
+
+	cl_assert(git_repository_workdir(repo2) != NULL);
+	cl_assert_(git__suffixcmp(git_repository_workdir(repo2), "alternate/") == 0, git_repository_workdir(repo2));
+
+	git_repository_free(repo2);
+}
+
+void test_repo_open__from_git_new_workdir(void)
+{
+	/* The git-new-workdir script that ships with git sets up a bunch of
+	 * symlinks to create a second workdir that shares the object db with
+	 * another checkout.  Libgit2 can open a repo that has been configured
+	 * this way.
+	 */
+	cl_git_sandbox_init("empty_standard_repo");
+
+#ifndef GIT_WIN32
+	git_repository *repo2;
+	git_buf link_tgt = GIT_BUF_INIT, link = GIT_BUF_INIT, body = GIT_BUF_INIT;
+	const char **scan;
+	int link_fd;
+	static const char *links[] = {
+		"config", "refs", "logs/refs", "objects", "info", "hooks",
+		"packed-refs", "remotes", "rr-cache", "svn", NULL
+	};
+	static const char *copies[] = {
+		"HEAD", NULL
+	};
+
+	cl_git_pass(p_mkdir("alternate", 0777));
+	cl_git_pass(p_mkdir("alternate/.git", 0777));
+
+	for (scan = links; *scan != NULL; scan++) {
+		git_buf_joinpath(&link_tgt, "empty_standard_repo/.git", *scan);
+		if (git_path_exists(link_tgt.ptr)) {
+			git_buf_joinpath(&link_tgt, "../../empty_standard_repo/.git", *scan);
+			git_buf_joinpath(&link, "alternate/.git", *scan);
+			if (strchr(*scan, '/'))
+				git_futils_mkpath2file(link.ptr, 0777);
+			cl_assert_(symlink(link_tgt.ptr, link.ptr) == 0, strerror(errno));
+		}
+	}
+	for (scan = copies; *scan != NULL; scan++) {
+		git_buf_joinpath(&link_tgt, "empty_standard_repo/.git", *scan);
+		if (git_path_exists(link_tgt.ptr)) {
+			git_buf_joinpath(&link, "alternate/.git", *scan);
+			cl_git_pass(git_futils_readbuffer(&body, link_tgt.ptr));
+
+			cl_assert((link_fd = git_futils_creat_withpath(link.ptr, 0777, 0666)) >= 0);
+			cl_must_pass(p_write(link_fd, body.ptr, body.size));
+			p_close(link_fd);
+		}
+	}
+
+	git_buf_free(&link_tgt);
+	git_buf_free(&link);
+	git_buf_free(&body);
+
+
+	cl_git_pass(git_repository_open(&repo2, "alternate"));
+
+	cl_assert(git_repository_path(repo2) != NULL);
+	cl_assert_(git__suffixcmp(git_repository_path(repo2), "alternate/.git/") == 0, git_repository_path(repo2));
+
+	cl_assert(git_repository_workdir(repo2) != NULL);
+	cl_assert_(git__suffixcmp(git_repository_workdir(repo2), "alternate/") == 0, git_repository_workdir(repo2));
+
+	git_repository_free(repo2);
+#endif
+}
+
+void test_repo_open__failures(void)
+{
+	git_repository *base, *repo;
+	git_buf ceiling = GIT_BUF_INIT;
+
+	base = cl_git_sandbox_init("attr");
+	cl_git_pass(git_buf_sets(&ceiling, git_repository_workdir(base)));
+
+	/* fail with no searching */
+	cl_git_fail(git_repository_open(&repo, "attr/sub"));
+	cl_git_fail(git_repository_open_ext(
+		&repo, "attr/sub", GIT_REPOSITORY_OPEN_NO_SEARCH, NULL));
+
+	/* fail with ceiling too low */
+	cl_git_pass(git_buf_joinpath(&ceiling, ceiling.ptr, "sub"));
+	cl_git_fail(git_repository_open_ext(&repo, "attr/sub", 0, ceiling.ptr));
+
+	/* fail with no repo */
+	cl_git_pass(p_mkdir("alternate", 0777));
+	cl_git_pass(p_mkdir("alternate/.git", 0777));
+	cl_git_fail(git_repository_open_ext(&repo, "alternate", 0, NULL));
+	cl_git_fail(git_repository_open_ext(&repo, "alternate/.git", 0, NULL));
+
+	git_buf_free(&ceiling);
+}
+
+void test_repo_open__bad_gitlinks(void)
+{
+	git_repository *repo;
+	static const char *bad_links[] = {
+		"garbage\n", "gitdir", "gitdir:\n", "gitdir: foobar",
+		"gitdir: ../invalid", "gitdir: ../invalid2",
+		"gitdir: ../attr/.git with extra stuff",
+		NULL
+	};
+	const char **scan;
+
+	cl_git_sandbox_init("attr");
+
+	cl_git_pass(p_mkdir("alternate", 0777));
+	cl_git_pass(p_mkdir("invalid", 0777));
+	cl_git_pass(git_futils_mkdir_r("invalid2/.git", NULL, 0777));
+
+	for (scan = bad_links; *scan != NULL; scan++) {
+		cl_git_rewritefile("alternate/.git", *scan);
+		cl_git_fail(git_repository_open_ext(&repo, "alternate", 0, NULL));
+	}
+
+	git_futils_rmdir_r("invalid", 1);
+	git_futils_rmdir_r("invalid2", 1);
+}
+
+static void unposix_path(git_buf *path)
+{
+	char *src, *tgt;
+
+	src = tgt = path->ptr;
+
+	/* convert "/d/..." to "d:\..." */
+	if (src[0] == '/' && isalpha(src[1]) && src[2] == '/') {
+		*tgt++ = src[1];
+		*tgt++ = ':';
+		*tgt++ = '\\';
+		src += 3;
+	}
+
+	while (*src) {
+		*tgt++ = (*src == '/') ? '\\' : *src;
+		src++;
+	}
+
+	*tgt = '\0';
+}
+
+void test_repo_open__win32_path(void)
+{
+#ifdef GIT_WIN32
+	git_repository *repo = cl_git_sandbox_init("empty_standard_repo"), *repo2;
+	git_buf winpath = GIT_BUF_INIT;
+	char *src, *tgt;
+	static const char *repo_path = "empty_standard_repo/.git/";
+	static const char *repo_wd   = "empty_standard_repo/";
+
+	cl_assert(git__suffixcmp(git_repository_path(repo), repo_path) == 0);
+	cl_assert(git__suffixcmp(git_repository_workdir(repo), repo_wd) == 0);
+
+	cl_git_pass(git_buf_sets(&winpath, git_repository_path(repo)));
+	unposix_path(&winpath);
+	cl_git_pass(git_repository_open(&repo2, winpath.ptr));
+	cl_assert(git__suffixcmp(git_repository_path(repo2), repo_path) == 0);
+	cl_assert(git__suffixcmp(git_repository_workdir(repo2), repo_wd) == 0);
+	git_repository_free(repo2);
+
+	cl_git_pass(git_buf_sets(&winpath, git_repository_path(repo)));
+	git_buf_truncate(&winpath, winpath.size - 1); /* remove trailing '/' */
+	unposix_path(&winpath);
+	cl_git_pass(git_repository_open(&repo2, winpath.ptr));
+	cl_assert(git__suffixcmp(git_repository_path(repo2), repo_path) == 0);
+	cl_assert(git__suffixcmp(git_repository_workdir(repo2), repo_wd) == 0);
+	git_repository_free(repo2);
+
+	cl_git_pass(git_buf_sets(&winpath, git_repository_workdir(repo)));
+	unposix_path(&winpath);
+	cl_git_pass(git_repository_open(&repo2, winpath.ptr));
+	cl_assert(git__suffixcmp(git_repository_path(repo2), repo_path) == 0);
+	cl_assert(git__suffixcmp(git_repository_workdir(repo2), repo_wd) == 0);
+	git_repository_free(repo2);
+
+	cl_git_pass(git_buf_sets(&winpath, git_repository_workdir(repo)));
+	git_buf_truncate(&winpath, winpath.size - 1); /* remove trailing '/' */
+	unposix_path(&winpath);
+	cl_git_pass(git_repository_open(&repo2, winpath.ptr));
+	cl_assert(git__suffixcmp(git_repository_path(repo2), repo_path) == 0);
+	cl_assert(git__suffixcmp(git_repository_workdir(repo2), repo_wd) == 0);
+	git_repository_free(repo2);
 
-	cl_fixture_cleanup("empty_standard_repo");
+	git_buf_free(&winpath);
+#endif
 }