[PATCH] config: introduce GIT_GLOBAL_CONFIG to override ~/.gitconfig

[Ramkumar Ramachandra <artagnon@gmail.com>]

Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com>
---
 Documentation/git-config.txt |    3 +++
 path.c                       |    5 +++++
 t/t1306-xdg-files.sh         |    8 ++++++++
 3 files changed, 16 insertions(+), 0 deletions(-)

diff --git a/Documentation/git-config.txt b/Documentation/git-config.txt
index eaea079..c8db03f 100644
--- a/Documentation/git-config.txt
+++ b/Documentation/git-config.txt
@@ -205,6 +205,9 @@ $GIT_DIR/config::
 	User-specific configuration file. Also called "global"
 	configuration file.
 
+$GIT_GLOBAL_CONFIG::
+	Overrides the path of the global configuration file.
+
 $XDG_CONFIG_HOME/git/config::
 	Second user-specific configuration file. If $XDG_CONFIG_HOME is not set
 	or empty, $HOME/.config/git/config will be used. Any single-valued
diff --git a/path.c b/path.c
index cbbdf7d..9b09cee 100644
--- a/path.c
+++ b/path.c
@@ -131,10 +131,15 @@ char *git_path(const char *fmt, ...)
 
 void home_config_paths(char **global, char **xdg, char *file)
 {
+	char *global_config = getenv("GIT_GLOBAL_CONFIG");
 	char *xdg_home = getenv("XDG_CONFIG_HOME");
 	char *home = getenv("HOME");
 	char *to_free = NULL;
 
+	if (global_config) {
+		*global = mkpathdup("%s", global_config);
+		return;
+	}
 	if (!home) {
 		if (global)
 			*global = NULL;
diff --git a/t/t1306-xdg-files.sh b/t/t1306-xdg-files.sh
index 8b14ab1..5b0e08e 100755
--- a/t/t1306-xdg-files.sh
+++ b/t/t1306-xdg-files.sh
@@ -28,6 +28,14 @@ test_expect_success 'read config: xdg file exists and ~/.gitconfig exists' '
 	test_cmp expected actual
 '
 
+test_expect_success 'read config: $GIT_GLOBAL_CONFIG is set and ~/.gitconfig exists' '
+	>.gitconfig &&
+	echo "[alias]" >.gittestconfig &&
+	echo "	myalias = !echo in_gitconfig" >>.gittestconfig &&
+	echo in_gitconfig >expected &&
+	GIT_GLOBAL_CONFIG=~/.gittestconfig git myalias >actual &&
+	test_cmp expected actual
+'
 
 test_expect_success 'read with --get: xdg file exists and ~/.gitconfig doesn'\''t' '
 	rm .gitconfig &&
-- 
1.7.8.1.362.g5d6df.dirty