[PATCH 4/8] Add set_git_dir() function

[Johannes Schindelin <Johannes.Schindelin@gmx.de>]

With the function set_git_dir() you can reset the path that will
be used for git_path(), git_dir() and friends.

The responsibility to close files and throw away information from the
old git_dir lies with the caller.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---

	This is just ripped out from the branch--new-workdir topic
	I was working on, just that it has a shorter name now.

	Ah, and just to be sure, it xstrdup()s the path.

 cache.h       |    1 +
 environment.c |    8 ++++++++
 2 files changed, 9 insertions(+), 0 deletions(-)

diff --git a/cache.h b/cache.h
index c0cab34..36963f2 100644
--- a/cache.h
+++ b/cache.h
@@ -216,6 +216,7 @@ extern char *get_refs_directory(void);
 extern char *get_index_file(void);
 extern char *get_graft_file(void);
 extern const char *get_git_work_tree(void);
+extern int set_git_dir(const char *path);
 
 #define ALTERNATE_DB_ENVIRONMENT "GIT_ALTERNATE_OBJECT_DIRECTORIES"
 
diff --git a/environment.c b/environment.c
index cb112a4..33c0f90 100644
--- a/environment.c
+++ b/environment.c
@@ -121,3 +121,11 @@ char *get_graft_file(void)
 		setup_git_env();
 	return git_graft_file;
 }
+
+int set_git_dir(const char *path)
+{
+	if (setenv(GIT_DIR_ENVIRONMENT, xstrdup(path), 1))
+		return error("Could not set GIT_DIR to '%s'", path);
+	setup_git_env();
+	return 0;
+}
-- 
1.5.3.rc3.18.g49a1