Refactor git_repository_open with new options

Add a new command `git_repository_open_ext` with extended options
that control how searching for a repository will be done.  The
existing `git_repository_open` and `git_repository_discover` are
reimplemented on top of it.  We may want to change the default
behavior of `git_repository_open` but this commit does not do that.

Improve support for "gitdir" files where the work dir is separate
from the repo and support for the "separate-git-dir" config.  Also,
add support for opening repos created with `git-new-workdir` script
(although I have only confirmed that they can be opened, not that
all functions work correctly).

There are also a few minor changes that came up:

- Fix `git_path_prettify` to allow in-place prettifying.

- Fix `git_path_root` to support backslashes on Win32.  This fix
  should help many repo open/discover scenarios - it is the one
  function called when opening before prettifying the path.

- Tweak `git_config_get_string` to set the "out" pointer to NULL
  if the config value is not found.  Allows some other cleanup.

- Fix a couple places that should have been calling
  `git_repository_config__weakptr` and were not.

- Fix `cl_git_sandbox_init` clar helper to support bare repos.

1 files changed, 12 insertions, 10 deletions

diff --git a/src/attr.c b/src/attr.c
index 5cf96acf7..c02289363 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) {