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[PATCH v4 1/4] git-credential-store: support multiple credential files

From
Paul Tan <pyokagan@gmail.com>
Date
Mar 18, 2015, 07:04 UTC
Message-ID
<1426662276-8728-1-git-send-email-pyokagan@gmail.com>

Previously, git-credential-store only supported storing credentials in a single file: ~/.git-credentials. In order to support the XDG base directory specification[1], git-credential-store needs to be able to lookup and erase credentials from multiple files, as well as to pick the appropriate file to write to so that the credentials can be found on subsequent lookups.

[1] http://standards.freedesktop.org/basedir-spec/basedir-spec-0.7.html

Note that some credential storage files may not be owned, readable or writable by the user, as they may be system-wide files that are meant to apply to every user.

Instead of a single file path, lookup_credential(), remove_credential() and store_credential() now take a precedence-ordered string_list of file paths. lookup_credential() expects both user-specific and system-wide credential files to be provided to support the use case of system administrators setting default credentials for users. remove_credential() and store_credential() expect only the user-specific credential files to be provided as usually the only config files that users are allowed to edit are their own user-specific ones.

lookup_credential() will read these (user-specific and system-wide) file paths in order until it finds the 1st matching credential and print it. As some files may be private and thus unreadable, any file which cannot be read will be ignored silently.

remove_credential() will erase credentials from all (user-specific) files in the list. This is because if credentials are only erased from the file with the highest precedence, a matching credential may still be found in a file further down the list. (Note that due to the lockfile code, this requires the directory to be writable, which should be so for user-specific config files)

store_credential() will write the credentials to the first existing (user-specific) file in the list. If none of the files in the list exist, store_credential() will write to the filename specified by the first item of the filename list. For backwards compatibility, this filename should be "~/.git-credentials".

Helped-by: Matthieu Moy <Matthieu.Moy@grenoble-inp.fr>
Helped-by: Junio C Hamano <gitster@pobox.com>
Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Paul Tan <pyokagan@gmail.com>
---
The previous version can be found at [1].
[1] http://thread.gmane.org/gmane.comp.version-control.git/265305/focus=265309
The changes are as follows:
* Remove default_fn argument from store_credential(). It now uses the
first item of the filenames string_list. Thanks Jeff, Matthieu and
Junio for your input in this discussion.
* Change filename string_list fns to duplicate strings by default
(STRING_LIST_INIT_DUP). This is to make memory ownership explicit --
when the string_list receives the file paths from xdg_config_home()
and expand_user_path(), it is responsible for freeing those strings.
Thanks Jeff for pointing this out.
 credential-store.c | 79 +++++++++++++++++++++++++++++++++++++-----------------
 1 file changed, 54 insertions(+), 25 deletions(-)
diff --git a/credential-store.c b/credential-store.c
index 925d3f4..8dad479 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)
+		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 +87,35 @@ 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 +124,20 @@ 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 +148,7 @@ 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",
@@ -139,20 +165,23 @@ int main(int argc, char **argv)
 
 	if (!file)
 		file = expand_user_path("~/.git-credentials");
-	if (!file)
+	if (file)
+		string_list_append(&fns, file);
+	else
 		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;
 }

-- 
2.1.4
Next: Paul Tan
Message 1 of 15 in “git-credential-store: support multiple credential files”
  1. 1/4 git-credential-store: support multiple credential filesPaul Tan, Mar 18, 2015
  2. 2/4 git-credential-store: support XDG_CONFIG_HOMEPaul Tan, Mar 18, 2015
  3. 3/4 docs/git-credential-store: document XDG file and precedencePaul Tan, Mar 18, 2015
  4. Matthieu MoyMar 18, 2015
  5. Paul TanMar 21, 2015
  6. 4/4 t0302: test credential-store support for XDG_CONFIG_HOMEPaul Tan, Mar 18, 2015
  7. Matthieu MoyMar 18, 2015
  8. Eric SunshineMar 18, 2015
  9. Matthieu MoyMar 19, 2015
  10. Paul TanMar 21, 2015
  11. Eric SunshineMar 18, 2015
  12. Eric SunshineMar 19, 2015
  13. Paul TanMar 21, 2015
  14. Eric SunshineMar 23, 2015
  15. Matthieu MoyMar 18, 2015

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