Merge branch 'pt/credential-xdg'

Tweak the sample "store" backend of the credential helper to honor
XDG configuration file locations when specified.

* pt/credential-xdg:
  t0302: "unreadable" test needs POSIXPERM
  t0302: test credential-store support for XDG_CONFIG_HOME
  git-credential-store: support XDG_CONFIG_HOME
  git-credential-store: support multiple credential files

Documentation/git-credential-store.txt

@@ -31,10 +31,41 @@ OPTIONS
 
 --file=<path>::
 
-	Use `<path>` to store credentials. The file will have its
+	Use `<path>` to lookup and store credentials. The file will have its
 	filesystem permissions set to prevent other users on the system
 	from reading it, but will not be encrypted or otherwise
-	protected. Defaults to `~/.git-credentials`.
+	protected. If not specified, credentials will be searched for from
+	`~/.git-credentials` and `$XDG_CONFIG_HOME/git/credentials`, and
+	credentials will be written to `~/.git-credentials` if it exists, or
+	`$XDG_CONFIG_HOME/git/credentials` if it exists and the former does
+	not. See also <<FILES>>.
+
+[[FILES]]
+FILES
+-----
+
+If not set explicitly with '--file', there are two files where
+git-credential-store will search for credentials in order of precedence:
+
+~/.git-credentials::
+	User-specific credentials file.
+
+$XDG_CONFIG_HOME/git/credentials::
+	Second user-specific credentials file. If '$XDG_CONFIG_HOME' is not set
+	or empty, `$HOME/.config/git/credentials` will be used. Any credentials
+	stored in this file will not be used if `~/.git-credentials` has a
+	matching credential as well. It is a good idea not to create this file
+	if you sometimes use older versions of Git that do not support it.
+
+For credential lookups, the files are read in the order given above, with the
+first matching credential found taking precedence over credentials found in
+files further down the list.
+
+Credential storage will by default write to the first existing file in the
+list. If none of these files exist, `~/.git-credentials` will be created and
+written to.
+
+When erasing credentials, matching credentials will be erased from all files.
 
 EXAMPLES
 --------

credential-store.c

@@ -6,7 +6,7 @@
 
 static struct lock_file credential_lock;
 
-static void parse_credential_file(const char *fn,
+static int parse_credential_file(const char *fn,
 				  struct credential *c,
 				  void (*match_cb)(struct credential *),
 				  void (*other_cb)(struct strbuf *))
@@ -14,18 +14,20 @@ static void parse_credential_file(const char *fn,
 	FILE *fh;
 	struct strbuf line = STRBUF_INIT;
 	struct credential entry = CREDENTIAL_INIT;
+	int found_credential = 0;
 
 	fh = fopen(fn, "r");
 	if (!fh) {
-		if (errno != ENOENT)
+		if (errno != ENOENT && errno != EACCES)
 			die_errno("unable to open %s", fn);
-		return;
+		return found_credential;
 	}
 
 	while (strbuf_getline(&line, fh, '\n') != EOF) {
 		credential_from_url(&entry, line.buf);
 		if (entry.username && entry.password &&
 		    credential_match(c, &entry)) {
+			found_credential = 1;
 			if (match_cb) {
 				match_cb(&entry);
 				break;
@@ -38,6 +40,7 @@ static void parse_credential_file(const char *fn,
 	credential_clear(&entry);
 	strbuf_release(&line);
 	fclose(fh);
+	return found_credential;
 }
 
 static void print_entry(struct credential *c)
@@ -64,21 +67,10 @@ static void rewrite_credential_file(const char *fn, struct credential *c,
 		die_errno("unable to commit credential store");
 }
 
-static void store_credential(const char *fn, struct credential *c)
+static void store_credential_file(const char *fn, struct credential *c)
 {
 	struct strbuf buf = STRBUF_INIT;
 
-	/*
-	 * Sanity check that what we are storing is actually sensible.
-	 * In particular, we can't make a URL without a protocol field.
-	 * Without either a host or pathname (depending on the scheme),
-	 * we have no primary key. And without a username and password,
-	 * we are not actually storing a credential.
-	 */
-	if (!c->protocol || !(c->host || c->path) ||
-	    !c->username || !c->password)
-		return;
-
 	strbuf_addf(&buf, "%s://", c->protocol);
 	strbuf_addstr_urlencode(&buf, c->username, 1);
 	strbuf_addch(&buf, ':');
@@ -95,8 +87,37 @@ static void store_credential(const char *fn, struct credential *c)
 	strbuf_release(&buf);
 }
 
-static void remove_credential(const char *fn, struct credential *c)
+static void store_credential(const struct string_list *fns, struct credential *c)
 {
+	struct string_list_item *fn;
+
+	/*
+	 * Sanity check that what we are storing is actually sensible.
+	 * In particular, we can't make a URL without a protocol field.
+	 * Without either a host or pathname (depending on the scheme),
+	 * we have no primary key. And without a username and password,
+	 * we are not actually storing a credential.
+	 */
+	if (!c->protocol || !(c->host || c->path) || !c->username || !c->password)
+		return;
+
+	for_each_string_list_item(fn, fns)
+		if (!access(fn->string, F_OK)) {
+			store_credential_file(fn->string, c);
+			return;
+		}
+	/*
+	 * Write credential to the filename specified by fns->items[0], thus
+	 * creating it
+	 */
+	if (fns->nr)
+		store_credential_file(fns->items[0].string, c);
+}
+
+static void remove_credential(const struct string_list *fns, struct credential *c)
+{
+	struct string_list_item *fn;
+
 	/*
 	 * Sanity check that we actually have something to match
 	 * against. The input we get is a restrictive pattern,
@@ -105,14 +126,20 @@ static void remove_credential(const char *fn, struct credential *c)
 	 * to empty input. So explicitly disallow it, and require that the
 	 * pattern have some actual content to match.
 	 */
-	if (c->protocol || c->host || c->path || c->username)
-		rewrite_credential_file(fn, c, NULL);
+	if (!c->protocol && !c->host && !c->path && !c->username)
+		return;
+	for_each_string_list_item(fn, fns)
+		if (!access(fn->string, F_OK))
+			rewrite_credential_file(fn->string, c, NULL);
 }
 
-static int lookup_credential(const char *fn, struct credential *c)
+static void lookup_credential(const struct string_list *fns, struct credential *c)
 {
-	parse_credential_file(fn, c, print_entry, NULL);
-	return c->username && c->password;
+	struct string_list_item *fn;
+
+	for_each_string_list_item(fn, fns)
+		if (parse_credential_file(fn->string, c, print_entry, NULL))
+			return; /* Found credential */
 }
 
 int main(int argc, char **argv)
@@ -123,6 +150,7 @@ int main(int argc, char **argv)
 	};
 	const char *op;
 	struct credential c = CREDENTIAL_INIT;
+	struct string_list fns = STRING_LIST_INIT_DUP;
 	char *file = NULL;
 	struct option options[] = {
 		OPT_STRING(0, "file", &file, "path",
@@ -137,22 +165,30 @@ int main(int argc, char **argv)
 		usage_with_options(usage, options);
 	op = argv[0];
 
-	if (!file)
-		file = expand_user_path("~/.git-credentials");
-	if (!file)
+	if (file) {
+		string_list_append(&fns, file);
+	} else {
+		if ((file = expand_user_path("~/.git-credentials")))
+			string_list_append_nodup(&fns, file);
+		home_config_paths(NULL, &file, "credentials");
+		if (file)
+			string_list_append_nodup(&fns, file);
+	}
+	if (!fns.nr)
 		die("unable to set up default path; use --file");
 
 	if (credential_read(&c, stdin) < 0)
 		die("unable to read credential");
 
 	if (!strcmp(op, "get"))
-		lookup_credential(file, &c);
+		lookup_credential(&fns, &c);
 	else if (!strcmp(op, "erase"))
-		remove_credential(file, &c);
+		remove_credential(&fns, &c);
 	else if (!strcmp(op, "store"))
-		store_credential(file, &c);
+		store_credential(&fns, &c);
 	else
 		; /* Ignore unknown operation. */
 
+	string_list_clear(&fns, 0);
 	return 0;
 }

t/t0302-credential-store.sh

@@ -6,4 +6,118 @@ test_description='credential-store tests'
 
 helper_test store
 
+test_expect_success 'when xdg file does not exist, xdg file not created' '
+	test_path_is_missing "$HOME/.config/git/credentials" &&
+	test -s "$HOME/.git-credentials"
+'
+
+test_expect_success 'setup xdg file' '
+	rm -f "$HOME/.git-credentials" &&
+	mkdir -p "$HOME/.config/git" &&
+	>"$HOME/.config/git/credentials"
+'
+
+helper_test store
+
+test_expect_success 'when xdg file exists, home file not created' '
+	test -s "$HOME/.config/git/credentials" &&
+	test_path_is_missing "$HOME/.git-credentials"
+'
+
+test_expect_success 'setup custom xdg file' '
+	rm -f "$HOME/.git-credentials" &&
+	rm -f "$HOME/.config/git/credentials" &&
+	mkdir -p "$HOME/xdg/git" &&
+	>"$HOME/xdg/git/credentials"
+'
+
+XDG_CONFIG_HOME="$HOME/xdg"
+export XDG_CONFIG_HOME
+helper_test store
+unset XDG_CONFIG_HOME
+
+test_expect_success 'if custom xdg file exists, home and xdg files not created' '
+	test_when_finished "rm -f $HOME/xdg/git/credentials" &&
+	test -s "$HOME/xdg/git/credentials" &&
+	test_path_is_missing "$HOME/.git-credentials" &&
+	test_path_is_missing "$HOME/.config/git/credentials"
+'
+
+test_expect_success 'get: use home file if both home and xdg files have matches' '
+	echo "https://home-user:home-pass@example.com" >"$HOME/.git-credentials" &&
+	mkdir -p "$HOME/.config/git" &&
+	echo "https://xdg-user:xdg-pass@example.com" >"$HOME/.config/git/credentials" &&
+	check fill store <<-\EOF
+	protocol=https
+	host=example.com
+	--
+	protocol=https
+	host=example.com
+	username=home-user
+	password=home-pass
+	--
+	EOF
+'
+
+test_expect_success 'get: use xdg file if home file has no matches' '
+	>"$HOME/.git-credentials" &&
+	mkdir -p "$HOME/.config/git" &&
+	echo "https://xdg-user:xdg-pass@example.com" >"$HOME/.config/git/credentials" &&
+	check fill store <<-\EOF
+	protocol=https
+	host=example.com
+	--
+	protocol=https
+	host=example.com
+	username=xdg-user
+	password=xdg-pass
+	--
+	EOF
+'
+
+test_expect_success POSIXPERM 'get: use xdg file if home file is unreadable' '
+	echo "https://home-user:home-pass@example.com" >"$HOME/.git-credentials" &&
+	chmod -r "$HOME/.git-credentials" &&
+	mkdir -p "$HOME/.config/git" &&
+	echo "https://xdg-user:xdg-pass@example.com" >"$HOME/.config/git/credentials" &&
+	check fill store <<-\EOF
+	protocol=https
+	host=example.com
+	--
+	protocol=https
+	host=example.com
+	username=xdg-user
+	password=xdg-pass
+	--
+	EOF
+'
+
+test_expect_success 'store: if both xdg and home files exist, only store in home file' '
+	>"$HOME/.git-credentials" &&
+	mkdir -p "$HOME/.config/git" &&
+	>"$HOME/.config/git/credentials" &&
+	check approve store <<-\EOF &&
+	protocol=https
+	host=example.com
+	username=store-user
+	password=store-pass
+	EOF
+	echo "https://store-user:store-pass@example.com" >expected &&
+	test_cmp expected "$HOME/.git-credentials" &&
+	test_must_be_empty "$HOME/.config/git/credentials"
+'
+
+
+test_expect_success 'erase: erase matching credentials from both xdg and home files' '
+	echo "https://home-user:home-pass@example.com" >"$HOME/.git-credentials" &&
+	mkdir -p "$HOME/.config/git" &&
+	echo "https://xdg-user:xdg-pass@example.com" >"$HOME/.config/git/credentials" &&
+	check reject store <<-\EOF &&
+	protocol=https
+	host=example.com
+	EOF
+	test_must_be_empty "$HOME/.git-credentials" &&
+	test_must_be_empty "$HOME/.config/git/credentials"
+'
+
 test_done