repo: unconditionally create a global config backend

When a repository is initialised, we need to probe to see if there is
a global config to load. If this is not the case, the user isn't able
to write to the global config without creating the backend and adding
it themselves, which is inconvenient and overly complex.

Unconditionally create and add a backend for the global config file
regardless of whether it exists as a convenience for users.

To enable this, we allow creating backends to files that do not exist
yet, changing the semantics somewhat, and making some tests invalid.

1 files changed, 36 insertions, 5 deletions

diff --git a/src/config.c b/src/config.c
index 3f475ea63..99aa00f50 100644
--- a/src/config.c
+++ b/src/config.c
@@ -91,13 +91,15 @@ int git_config_add_file_ondisk(
 	int force)
 {
 	git_config_backend *file = NULL;
+	struct stat st;
 	int res;
 
 	assert(cfg && path);
 
-	if (!git_path_isfile(path)) {
-		giterr_set(GITERR_CONFIG, "Cannot find config file '%s'", path);
-		return GIT_ENOTFOUND;
+	res = p_stat(path, &st);
+	if (res < 0 && errno != ENOENT) {
+		giterr_set(GITERR_CONFIG, "Error stat'ing config file '%s'", path);
+		return -1;
 	}
 
 	if (git_config_file__ondisk(&file, path) < 0)
@@ -381,7 +383,6 @@ int git_config_set_string(git_config *cfg, const char *name, const char *value)
 
 	internal = git_vector_get(&cfg->files, 0);
 	if (!internal)
-		/* Should we auto-vivify .git/config? Tricky from this location */
 		return config_error_nofiles(name);
 	file = internal->file;
 
@@ -598,6 +599,33 @@ int git_config_find_system(char *system_config_path, size_t length)
 		system_config_path, length, git_config_find_system_r);
 }
 
+int git_config__global_location(git_buf *buf)
+{
+	const git_buf *paths;
+	const char *sep, *start;
+	size_t len;
+
+	if (git_futils_dirs_get(&paths, GIT_FUTILS_DIR_GLOBAL) < 0)
+		return -1;
+
+	/* no paths, so give up */
+	if (git_buf_len(paths) == 0)
+		return -1;
+
+	start = git_buf_cstr(paths);
+	sep = strchr(start, GIT_PATH_LIST_SEPARATOR);
+
+	if (sep)
+		len = sep - start;
+	else
+		len = paths->size;
+
+	if (git_buf_set(buf, start, len) < 0)
+		return -1;
+
+	return git_buf_joinpath(buf, buf->ptr, GIT_CONFIG_FILENAME_GLOBAL);
+}
+
 int git_config_open_default(git_config **out)
 {
 	int error;
@@ -606,9 +634,12 @@ int git_config_open_default(git_config **out)
 
 	error = git_config_new(&cfg);
 
-	if (!error && !git_config_find_global_r(&buf))
+	if (!error && (!git_config_find_global_r(&buf) ||
+		       !git_config__global_location(&buf))) {
 		error = git_config_add_file_ondisk(cfg, buf.ptr,
 			GIT_CONFIG_LEVEL_GLOBAL, 0);
+	} else {
+	}
 
 	if (!error && !git_config_find_xdg_r(&buf))
 		error = git_config_add_file_ondisk(cfg, buf.ptr,