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, 17 insertions, 6 deletions

diff --git a/tests-clar/clar_helpers.c b/tests-clar/clar_helpers.c
index 22db56f0c..001045360 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