config: read (but not write) from $XDG_CONFIG_HOME/git/config file

Teach git to read the "gitconfig" information from a new location,
$XDG_CONFIG_HOME/git/config; this allows the user to avoid
cluttering $HOME with many per-application configuration files.

In the order of reading, this file comes between the global
configuration file (typically $HOME/.gitconfig) and the system wide
configuration file (typically /etc/gitconfig).

We do not write to this new location (yet).

If $XDG_CONFIG_HOME is either not set or empty, $HOME/.config/git/config
will be used. This is in line with XDG specification.

If the new file does not exist, the behavior is unchanged.

Signed-off-by: Huynh Khoi Nguyen Nguyen <Huynh-Khoi-Nguyen.Nguyen@ensimag.imag.fr>
Signed-off-by: Valentin Duperray <Valentin.Duperray@ensimag.imag.fr>
Signed-off-by: Franck Jonas <Franck.Jonas@ensimag.imag.fr>
Signed-off-by: Lucien Kong <Lucien.Kong@ensimag.imag.fr>
Signed-off-by: Thomas Nguy <Thomas.Nguy@ensimag.imag.fr>
Signed-off-by: Matthieu Moy <Matthieu.Moy@imag.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

6 files changed, 158 insertions, 21 deletions

diff --git a/Documentation/git-config.txt b/Documentation/git-config.txt
index d9463cb387..09675cba4a 100644
--- a/Documentation/git-config.txt
+++ b/Documentation/git-config.txt
@@ -99,8 +99,8 @@ OPTIONS
 	For writing options: write to global ~/.gitconfig file rather than
 	the repository .git/config.
 +
-For reading options: read only from global ~/.gitconfig rather than
-from all available files.
+For reading options: read only from global ~/.gitconfig and from
+$XDG_CONFIG_HOME/git/config rather than from all available files.
 +
 See also <<FILES>>.
 
@@ -194,7 +194,7 @@ See also <<FILES>>.
 FILES
 -----
 
-If not set explicitly with '--file', there are three files where
+If not set explicitly with '--file', there are four files where
 'git config' will search for configuration options:
 
 $GIT_DIR/config::
@@ -204,6 +204,14 @@ $GIT_DIR/config::
 	User-specific configuration file. Also called "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
+	variable set in this file will be overwritten by whatever is in
+	~/.gitconfig.  It is a good idea not to create this file if
+	you sometimes use older versions of Git, as support for this
+	file was added fairly recently.
+
 $(prefix)/etc/gitconfig::
 	System-wide configuration file.
 
diff --git a/builtin/config.c b/builtin/config.c
index 33c8820af6..da54fd1e12 100644
--- a/builtin/config.c
+++ b/builtin/config.c
@@ -161,7 +161,7 @@ static int show_config(const char *key_, const char *value_, void *cb)
 static int get_value(const char *key_, const char *regex_)
 {
 	int ret = -1;
-	char *global = NULL, *repo_config = NULL;
+	char *global = NULL, *xdg = NULL, *repo_config = NULL;
 	const char *system_wide = NULL, *local;
 	struct config_include_data inc = CONFIG_INCLUDE_INIT;
 	config_fn_t fn;
@@ -169,12 +169,10 @@ static int get_value(const char *key_, const char *regex_)
 
 	local = given_config_file;
 	if (!local) {
-		const char *home = getenv("HOME");
 		local = repo_config = git_pathdup("config");
-		if (home)
-			global = xstrdup(mkpath("%s/.gitconfig", home));
 		if (git_config_system())
 			system_wide = git_etc_gitconfig();
+		home_config_paths(&global, &xdg, "config");
 	}
 
 	if (use_key_regexp) {
@@ -229,6 +227,8 @@ static int get_value(const char *key_, const char *regex_)
 
 	if (do_all && system_wide)
 		git_config_from_file(fn, system_wide, data);
+	if (do_all && xdg)
+		git_config_from_file(fn, xdg, data);
 	if (do_all && global)
 		git_config_from_file(fn, global, data);
 	if (do_all)
@@ -238,6 +238,8 @@ static int get_value(const char *key_, const char *regex_)
 		git_config_from_file(fn, local, data);
 	if (!do_all && !seen && global)
 		git_config_from_file(fn, global, data);
+	if (!do_all && !seen && xdg)
+		git_config_from_file(fn, xdg, data);
 	if (!do_all && !seen && system_wide)
 		git_config_from_file(fn, system_wide, data);
 
@@ -255,6 +257,7 @@ static int get_value(const char *key_, const char *regex_)
 free_strings:
 	free(repo_config);
 	free(global);
+	free(xdg);
 	return ret;
 }
 
@@ -379,13 +382,20 @@ int cmd_config(int argc, const char **argv, const char *prefix)
 	}
 
 	if (use_global_config) {
-		char *home = getenv("HOME");
-		if (home) {
-			char *user_config = xstrdup(mkpath("%s/.gitconfig", home));
+		char *user_config = NULL;
+		char *xdg_config = NULL;
+
+		home_config_paths(&user_config, &xdg_config, "config");
+
+		if (access(user_config, R_OK) && !access(xdg_config, R_OK) &&
+		    (actions == ACTION_LIST ||
+		     actions == ACTION_GET_COLOR ||
+		     actions == ACTION_GET_COLORBOOL))
+			given_config_file = xdg_config;
+		else if (user_config)
 			given_config_file = user_config;
-		} else {
+		else
 			die("$HOME not set");
-		}
 	}
 	else if (use_system_config)
 		given_config_file = git_etc_gitconfig();
diff --git a/cache.h b/cache.h
index 06413e1584..fbba2d687a 100644
--- a/cache.h
+++ b/cache.h
@@ -619,6 +619,8 @@ extern char *git_snpath(char *buf, size_t n, const char *fmt, ...)
 	__attribute__((format (printf, 3, 4)));
 extern char *git_pathdup(const char *fmt, ...)
 	__attribute__((format (printf, 1, 2)));
+extern char *mkpathdup(const char *fmt, ...)
+	__attribute__((format (printf, 1, 2)));
 
 /* Return a statically allocated filename matching the sha1 signature */
 extern char *mkpath(const char *fmt, ...) __attribute__((format (printf, 1, 2)));
@@ -708,6 +710,7 @@ int set_shared_perm(const char *path, int mode);
 int safe_create_leading_directories(char *path);
 int safe_create_leading_directories_const(const char *path);
 int mkdir_in_gitdir(const char *path);
+extern void home_config_paths(char **global, char **xdg, char *file);
 extern char *expand_user_path(const char *path);
 const char *enter_repo(const char *path, int strict);
 static inline int is_absolute_path(const char *path)
diff --git a/config.c b/config.c
index 71ef171cab..d28a499b0b 100644
--- a/config.c
+++ b/config.c
@@ -929,7 +929,10 @@ int git_config_system(void)
 int git_config_early(config_fn_t fn, void *data, const char *repo_config)
 {
 	int ret = 0, found = 0;
-	const char *home = NULL;
+	char *xdg_config = NULL;
+	char *user_config = NULL;
+
+	home_config_paths(&user_config, &xdg_config, "config");
 
 	if (git_config_system() && !access(git_etc_gitconfig(), R_OK)) {
 		ret += git_config_from_file(fn, git_etc_gitconfig(),
@@ -937,14 +940,14 @@ int git_config_early(config_fn_t fn, void *data, const char *repo_config)
 		found += 1;
 	}
 
-	home = getenv("HOME");
-	if (home) {
-		char buf[PATH_MAX];
-		char *user_config = mksnpath(buf, sizeof(buf), "%s/.gitconfig", home);
-		if (!access(user_config, R_OK)) {
-			ret += git_config_from_file(fn, user_config, data);
-			found += 1;
-		}
+	if (!access(xdg_config, R_OK)) {
+		ret += git_config_from_file(fn, xdg_config, data);
+		found += 1;
+	}
+
+	if (!access(user_config, R_OK)) {
+		ret += git_config_from_file(fn, user_config, data);
+		found += 1;
 	}
 
 	if (repo_config && !access(repo_config, R_OK)) {
@@ -963,6 +966,8 @@ int git_config_early(config_fn_t fn, void *data, const char *repo_config)
 		break;
 	}
 
+	free(xdg_config);
+	free(user_config);
 	return ret == 0 ? found : ret;
 }
 
diff --git a/path.c b/path.c
index 6f2aa699ad..66acd24fa8 100644
--- a/path.c
+++ b/path.c
@@ -87,6 +87,21 @@ char *git_pathdup(const char *fmt, ...)
 	return xstrdup(path);
 }
 
+char *mkpathdup(const char *fmt, ...)
+{
+	char *path;
+	struct strbuf sb = STRBUF_INIT;
+	va_list args;
+
+	va_start(args, fmt);
+	strbuf_vaddf(&sb, fmt, args);
+	va_end(args);
+	path = xstrdup(cleanup_path(sb.buf));
+
+	strbuf_release(&sb);
+	return path;
+}
+
 char *mkpath(const char *fmt, ...)
 {
 	va_list args;
@@ -122,6 +137,32 @@ char *git_path(const char *fmt, ...)
 	return cleanup_path(pathname);
 }
 
+void home_config_paths(char **global, char **xdg, char *file)
+{
+	char *xdg_home = getenv("XDG_CONFIG_HOME");
+	char *home = getenv("HOME");
+	char *to_free = NULL;
+
+	if (!home) {
+		if (global)
+			*global = NULL;
+	} else {
+		if (!xdg_home) {
+			to_free = mkpathdup("%s/.config", home);
+			xdg_home = to_free;
+		}
+		if (global)
+			*global = mkpathdup("%s/.gitconfig", home);
+	}
+
+	if (!xdg_home)
+		*xdg = NULL;
+	else
+		*xdg = mkpathdup("%s/git/%s", xdg_home, file);
+
+	free(to_free);
+}
+
 char *git_path_submodule(const char *path, const char *fmt, ...)
 {
 	char *pathname = get_pathname();
diff --git a/t/t1306-xdg-files.sh b/t/t1306-xdg-files.sh
new file mode 100755
index 0000000000..5b971d93eb
--- /dev/null
+++ b/t/t1306-xdg-files.sh
@@ -0,0 +1,70 @@
+#!/bin/sh
+#
+# Copyright (c) 2012 Valentin Duperray, Lucien Kong, Franck Jonas,
+#		     Thomas Nguy, Khoi Nguyen
+#		     Grenoble INP Ensimag
+#
+
+test_description='Compatibility with $XDG_CONFIG_HOME/git/ files'
+
+. ./test-lib.sh
+
+test_expect_success 'read config: xdg file exists and ~/.gitconfig doesn'\''t' '
+	mkdir -p .config/git &&
+	echo "[alias]" >.config/git/config &&
+	echo "	myalias = !echo in_config" >>.config/git/config &&
+	echo in_config >expected &&
+	git myalias >actual &&
+	test_cmp expected actual
+'
+
+
+test_expect_success 'read config: xdg file exists and ~/.gitconfig exists' '
+	>.gitconfig &&
+	echo "[alias]" >.gitconfig &&
+	echo "	myalias = !echo in_gitconfig" >>.gitconfig &&
+	echo in_gitconfig >expected &&
+	git myalias >actual &&
+	test_cmp expected actual
+'
+
+
+test_expect_success 'read with --get: xdg file exists and ~/.gitconfig doesn'\''t' '
+	rm .gitconfig &&
+	echo "[user]" >.config/git/config &&
+	echo "	name = read_config" >>.config/git/config &&
+	echo read_config >expected &&
+	git config --get user.name >actual &&
+	test_cmp expected actual
+'
+
+
+test_expect_success 'read with --get: xdg file exists and ~/.gitconfig exists' '
+	>.gitconfig &&
+	echo "[user]" >.gitconfig &&
+	echo "	name = read_gitconfig" >>.gitconfig &&
+	echo read_gitconfig >expected &&
+	git config --get user.name >actual &&
+	test_cmp expected actual
+'
+
+
+test_expect_success 'read with --list: xdg file exists and ~/.gitconfig doesn'\''t' '
+	rm .gitconfig &&
+	echo user.name=read_config >expected &&
+	git config --global --list >actual &&
+	test_cmp expected actual
+'
+
+
+test_expect_success 'read with --list: xdg file exists and ~/.gitconfig exists' '
+	>.gitconfig &&
+	echo "[user]" >.gitconfig &&
+	echo "	name = read_gitconfig" >>.gitconfig &&
+	echo user.name=read_gitconfig >expected &&
+	git config --global --list >actual &&
+	test_cmp expected actual
+'
+
+
+test_done