[PATCHv4] Read (but not write) from XDG configuration, XDG attributes and XDG ignore files

[Huynh Khoi Nguyen NGUYEN <Huynh-Khoi-Nguyen.Nguyen@ensimag.imag.fr>]

From: NGUYEN Huynh Khoi Nguyen <nguyenhu@ensibm.imag.fr>

Git will be able to read in $XDG_CONFIG_HOME/git/config, a new
configuration file following XDG specification. In the order of
reading, this file is between global configuration file and system
wide configuration file. Git will not be able to write in this new
configuration file. If core.excludesfile is not define, Git will read
the global exclude files in $XDG_CONFIG_HOME/git/ignore. Same goes for
core.attributesfile in $XDG_CONFIG_HOME/git/attributes. If
$XDG_CONFIG_HOME is either not set or empty, $HOME/.config will be
used.

Signed-off-by: Huynh Khoi Nguyen NGUYEN <Huynh-Khoi-Nguyen.Nguyen@ensimag.imag.fr>
Signed-off-by: Lucien KONG <Lucien.Kong@ensimag.imag.fr>
Signed-off-by: Valentin DUPERRAY <Valentin.Duperray@ensimag.imag.fr>
Signed-off-by: Thomas NGUY <Thomas.Nguy@ensimag.imag.fr>
Signed-off-by: Franck JONAS <Franck.Jonas@ensimag.imag.fr>
Signed-off-by: Matthieu Moy <Matthieu.Moy@grenoble-inp.fr>
---
 Documentation/git-config.txt    |   12 +++-
 attr.c                          |   10 +++
 builtin/config.c                |   28 ++++++---
 cache.h                         |    1 +
 config.c                        |   21 ++++---
 dir.c                           |    4 +
 path.c                          |   26 ++++++++
 t/t1306-read-xdg-config-file.sh |  133 +++++++++++++++++++++++++++++++++++++++
 8 files changed, 214 insertions(+), 21 deletions(-)
 create mode 100755 t/t1306-read-xdg-config-file.sh

diff --git a/Documentation/git-config.txt b/Documentation/git-config.txt
index d9463cb..7e344a2 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 +204,12 @@ $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.
+
 $(prefix)/etc/gitconfig::
 	System-wide configuration file.
 
diff --git a/attr.c b/attr.c
index 303751f..441387f 100644
--- a/attr.c
+++ b/attr.c
@@ -497,6 +497,9 @@ static int git_attr_system(void)
 static void bootstrap_attr_stack(void)
 {
 	struct attr_stack *elem;
+	char *xdg_attributes_file;
+
+	home_config_paths(NULL, &xdg_attributes_file, "attributes");
 
 	if (attr_stack)
 		return;
@@ -522,6 +525,13 @@ static void bootstrap_attr_stack(void)
 			elem->prev = attr_stack;
 			attr_stack = elem;
 		}
+	} else if (!access(xdg_attributes_file, R_OK)) {
+		elem = read_attr_from_file(xdg_attributes_file, 1);
+		if (elem) {
+			elem->origin = NULL;
+			elem->prev = attr_stack;
+			attr_stack = elem;
+		}
 	}
 
 	if (!is_bare_repository() || direction == GIT_ATTR_INDEX) {
diff --git a/builtin/config.c b/builtin/config.c
index 33c8820..da54fd1 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 06413e1..0632503 100644
--- a/cache.h
+++ b/cache.h
@@ -708,6 +708,7 @@ 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 71ef171..d1393b8 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)) {
diff --git a/dir.c b/dir.c
index ed1510f..e0c3589 100644
--- a/dir.c
+++ b/dir.c
@@ -1234,13 +1234,17 @@ int remove_dir_recursively(struct strbuf *path, int flag)
 void setup_standard_excludes(struct dir_struct *dir)
 {
 	const char *path;
+	char *xdg_path;
 
 	dir->exclude_per_dir = ".gitignore";
 	path = git_path("info/exclude");
+	home_config_paths(NULL, &xdg_path, "ignore");
 	if (!access(path, R_OK))
 		add_excludes_from_file(dir, path);
 	if (excludes_file && !access(excludes_file, R_OK))
 		add_excludes_from_file(dir, excludes_file);
+	else if (!access(xdg_path, R_OK))
+		add_excludes_from_file(dir, xdg_path);
 }
 
 int remove_path(const char *name)
diff --git a/path.c b/path.c
index 6f2aa69..53f3f53 100644
--- a/path.c
+++ b/path.c
@@ -122,6 +122,32 @@ 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 = strdup(mkpath("%s/.config", home));
+			xdg_home = to_free;
+		}
+		if (global)
+			*global = xstrdup(mkpath("%s/.gitconfig", home));
+	}
+
+	if (!xdg_home)
+		*xdg = NULL;
+	else
+		*xdg = xstrdup(mkpath("%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-read-xdg-config-file.sh b/t/t1306-read-xdg-config-file.sh
new file mode 100755
index 0000000..a8775c4
--- /dev/null
+++ b/t/t1306-read-xdg-config-file.sh
@@ -0,0 +1,133 @@
+#!/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/config /ignore and /attributes 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_expect_success 'Exclusion of a file in the XDG ignore file' '
+	git init git &&
+	cd git &&
+	echo foo >to_be_excluded &&
+	git add to_be_excluded &&
+	git rm --cached to_be_excluded &&
+	mkdir -p ../.config/git/ &&
+	echo to_be_excluded >../.config/git/ignore &&
+	test_must_fail git add to_be_excluded
+'
+
+
+test_expect_success 'Exclusion in both XDG and local ignore files' '
+	echo to_be_excluded >.gitignore &&
+	test_must_fail git add to_be_excluded
+'
+
+
+test_expect_success 'Exclusion in a non-XDG global ignore file' '
+	echo >../.config/git/ignore &&
+	rm .gitignore &&
+	echo to_be_excluded >../my_gitignore &&
+	git config core.excludesfile ../my_gitignore &&
+	test_when_finished "cd .. && rm -rf git && rm -r .config" &&
+	test_must_fail git add to_be_excluded
+'
+
+
+test_expect_success 'Checking attributes in the XDG attributes file' '
+	git init git &&
+	cd git &&
+	echo foo >f &&
+	git check-attr -a f >actual &&
+	test_line_count -eq 0 actual &&
+	cd .. &&
+	mkdir -p .config/git/ &&
+	echo "f attr_f" >.config/git/attributes &&
+	cd git &&
+	echo "f: attr_f: set" >expected &&
+	git check-attr -a f >actual &&
+	test_cmp expected actual
+'
+
+
+test_expect_success 'Checking attributes in both XDG and local ignore files' '
+	echo  "f -attr_f" >.gitattributes &&
+	echo "f: attr_f: unset" >expected &&
+	git check-attr -a f >actual &&
+	test_cmp expected actual
+'
+
+
+test_expect_success 'Checking attributes in a non-XDG global attributes file' '
+	rm .gitattributes &&
+	echo "f attr_f=test" >../my_gitattributes &&
+	git config core.attributesfile ../my_gitattributes &&
+	test_when_finished "cd .. && rm -rf git && rm -r .config" &&
+	echo "f: attr_f: test" >expected &&
+	git check-attr -a f >actual &&
+	test_cmp expected actual
+'
+
+
+test_done
-- 
1.7.8