setup_git_env(): introduce git_path_from_env() helper

"Check the value of an environment and fall back to a known path
inside $GIT_DIR" is repeated a few times to determine the location
of the data store, the index and the graft file, but the return
value of getenv is not guaranteed to survive across further
invocations of setenv or even getenv.

Make sure to xstrdup() the value we receive from getenv(3), and
encapsulate the pattern into a helper function.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/environment.c b/environment.c
index 4de7b812ad2220fc43ad41dedb0c9b594f61e286..565f65293bb25ebdcb6ada262bcca9164c3ea113 100644 (file)
--- a/environment.c
+++ b/environment.c
@@ -124,6 +124,12 @@ static char *expand_namespace(const char *raw_namespace)
        return strbuf_detach(&buf, NULL);
 }
 
+static char *git_path_from_env(const char *envvar, const char *path)
+{
+       const char *value = getenv(envvar);
+       return value ? xstrdup(value) : git_pathdup("%s", path);
+}
+
 static void setup_git_env(void)
 {
        const char *gitfile;
@@ -134,15 +140,9 @@ static void setup_git_env(void)
                git_dir = DEFAULT_GIT_DIR_ENVIRONMENT;
        gitfile = read_gitfile(git_dir);
        git_dir = xstrdup(gitfile ? gitfile : git_dir);
-       git_object_dir = getenv(DB_ENVIRONMENT);
-       if (!git_object_dir)
-               git_object_dir = git_pathdup("objects");
-       git_index_file = getenv(INDEX_ENVIRONMENT);
-       if (!git_index_file)
-               git_index_file = git_pathdup("index");
-       git_graft_file = getenv(GRAFT_ENVIRONMENT);
-       if (!git_graft_file)
-               git_graft_file = git_pathdup("info/grafts");
+       git_object_dir = git_path_from_env(DB_ENVIRONMENT, "objects");
+       git_index_file = git_path_from_env(INDEX_ENVIRONMENT, "index");
+       git_graft_file = git_path_from_env(GRAFT_ENVIRONMENT, "info/grafts");
        if (getenv(NO_REPLACE_OBJECTS_ENVIRONMENT))
                check_replace_refs = 0;
        namespace = expand_namespace(getenv(GIT_NAMESPACE_ENVIRONMENT));