[PATCH 1/2] git-credential-store: support XDG config dir

[Paul Tan <pyokagan@gmail.com>]

Teach git-credential-store to read/write credentials from
$XDG_CONFIG_HOME/git/credentials and ~/.git-credentials where
appropriate:

* get: call lookup_credential() on the XDG file first if it exists. If
  the credential can't be found, call lookup_credential() on the HOME
  file.
* erase: Call remove_credential() on both the XDG file if it exists and
  the HOME file if it exists.
* store: If the XDG file exists, call store_credential() on the XDG file
  and remove_credential() on the HOME file to prevent duplicates.
* If "--file" is provided, use the file for all operations instead.

In order to support the above, parse_credential_file() now returns 1 if
it finds a matching credential, and 0 if it does not. Likewise,
lookup_credential() returns 1 if it could find the credential, and 0 if
it could not.

Signed-off-by: Paul Tan <pyokagan@gmail.com>
---
 credential-store.c | 60 ++++++++++++++++++++++++++++++++++++++++--------------
 1 file changed, 45 insertions(+), 15 deletions(-)

diff --git a/credential-store.c b/credential-store.c
index 925d3f4..18b8897 100644
--- a/credential-store.c
+++ b/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)
 			die_errno("unable to open %s", fn);
-		return;
+		return 0;
 	}
 
 	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)
@@ -111,8 +114,7 @@ static void remove_credential(const char *fn, struct credential *c)
 
 static int lookup_credential(const char *fn, struct credential *c)
 {
-	parse_credential_file(fn, c, print_entry, NULL);
-	return c->username && c->password;
+	return parse_credential_file(fn, c, print_entry, NULL);
 }
 
 int main(int argc, char **argv)
@@ -124,6 +126,9 @@ int main(int argc, char **argv)
 	const char *op;
 	struct credential c = CREDENTIAL_INIT;
 	char *file = NULL;
+	char *home_file = NULL;
+	char *xdg_file = NULL;
+	int ret = 0;
 	struct option options[] = {
 		OPT_STRING(0, "file", &file, "path",
 			   "fetch and store credentials in <path>"),
@@ -137,21 +142,46 @@ int main(int argc, char **argv)
 		usage_with_options(usage, options);
 	op = argv[0];
 
-	if (!file)
-		file = expand_user_path("~/.git-credentials");
-	if (!file)
-		die("unable to set up default path; use --file");
+	if (!file) {
+		home_config_paths(NULL, &xdg_file, "credentials");
+		home_file = expand_user_path("~/.git-credentials");
+		if (!xdg_file && !home_file)
+			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);
-	else if (!strcmp(op, "erase"))
-		remove_credential(file, &c);
-	else if (!strcmp(op, "store"))
-		store_credential(file, &c);
-	else
+	if (!strcmp(op, "get")) {
+		if (file) {
+			lookup_credential(file, &c);
+		} else {
+			if (xdg_file && access_or_warn(xdg_file, R_OK, 0) == 0)
+				ret = lookup_credential(xdg_file, &c);
+			if (!ret && home_file && access_or_warn(home_file, R_OK, 0) == 0)
+				lookup_credential(home_file, &c);
+		}
+	} else if (!strcmp(op, "erase")) {
+		if (file) {
+			remove_credential(file, &c);
+		} else {
+			if (xdg_file && access(xdg_file, F_OK) == 0)
+				remove_credential(xdg_file, &c);
+			if (home_file && access(home_file, F_OK) == 0)
+				remove_credential(home_file, &c);
+		}
+	} else if (!strcmp(op, "store")) {
+		if (file) {
+			store_credential(file, &c);
+		} else if (xdg_file && access(xdg_file, F_OK) == 0) {
+			store_credential(xdg_file, &c);
+			if (home_file && access(home_file, F_OK) == 0 &&
+			    c.protocol && (c.host || c.path) && c.username
+			    && c.password)
+				remove_credential(home_file, &c);
+		} else
+			store_credential(home_file, &c);
+	} else
 		; /* Ignore unknown operation. */
 
 	return 0;
-- 
2.1.4