make credential helpers builtins

There's no real reason for credential helpers to be separate binaries. I
did them this way originally under the notion that helper don't _need_
to be part of Git, and so can be built totally separately (and indeed,
the ones in contrib/credential are). But the ones in our main Makefile
build on libgit.a, and the resulting binaries are reasonably large.

We can slim down our total disk footprint by just making them builtins.
This reduces the size of:

  make strip install

from 29MB to 24MB on my Debian system.

Note that credential-cache can't operate without support for Unix
sockets. Currently we just don't build it at all when NO_UNIX_SOCKETS is
set. We could continue that with conditionals in the Makefile and our
list of builtins. But instead, let's build a dummy implementation that
dies with an informative message. That has two advantages:

  - it's simpler, because the conditional bits are all kept inside
    the credential-cache source

  - a user who is expecting it to exist will be told _why_ they can't
    use it, rather than getting the "credential-cache is not a git
    command" error which makes it look like the Git install is broken.

Note that our dummy implementation does still respond to "-h" in order
to appease t0012 (and this may be a little friendlier for users, as
well).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 157 insertions, 0 deletions

diff --git a/builtin/credential-cache.c b/builtin/credential-cache.c
new file mode 100644
index 0000000000..d0fafdeb9e
--- /dev/null
+++ b/builtin/credential-cache.c
@@ -0,0 +1,157 @@
+#include "builtin.h"
+#include "parse-options.h"
+
+#ifndef NO_UNIX_SOCKETS
+
+#include "credential.h"
+#include "string-list.h"
+#include "unix-socket.h"
+#include "run-command.h"
+
+#define FLAG_SPAWN 0x1
+#define FLAG_RELAY 0x2
+
+static int send_request(const char *socket, const struct strbuf *out)
+{
+	int got_data = 0;
+	int fd = unix_stream_connect(socket);
+
+	if (fd < 0)
+		return -1;
+
+	if (write_in_full(fd, out->buf, out->len) < 0)
+		die_errno("unable to write to cache daemon");
+	shutdown(fd, SHUT_WR);
+
+	while (1) {
+		char in[1024];
+		int r;
+
+		r = read_in_full(fd, in, sizeof(in));
+		if (r == 0 || (r < 0 && errno == ECONNRESET))
+			break;
+		if (r < 0)
+			die_errno("read error from cache daemon");
+		write_or_die(1, in, r);
+		got_data = 1;
+	}
+	close(fd);
+	return got_data;
+}
+
+static void spawn_daemon(const char *socket)
+{
+	struct child_process daemon = CHILD_PROCESS_INIT;
+	const char *argv[] = { NULL, NULL, NULL };
+	char buf[128];
+	int r;
+
+	argv[0] = "git-credential-cache--daemon";
+	argv[1] = socket;
+	daemon.argv = argv;
+	daemon.no_stdin = 1;
+	daemon.out = -1;
+
+	if (start_command(&daemon))
+		die_errno("unable to start cache daemon");
+	r = read_in_full(daemon.out, buf, sizeof(buf));
+	if (r < 0)
+		die_errno("unable to read result code from cache daemon");
+	if (r != 3 || memcmp(buf, "ok\n", 3))
+		die("cache daemon did not start: %.*s", r, buf);
+	close(daemon.out);
+}
+
+static void do_cache(const char *socket, const char *action, int timeout,
+		     int flags)
+{
+	struct strbuf buf = STRBUF_INIT;
+
+	strbuf_addf(&buf, "action=%s\n", action);
+	strbuf_addf(&buf, "timeout=%d\n", timeout);
+	if (flags & FLAG_RELAY) {
+		if (strbuf_read(&buf, 0, 0) < 0)
+			die_errno("unable to relay credential");
+	}
+
+	if (send_request(socket, &buf) < 0) {
+		if (errno != ENOENT && errno != ECONNREFUSED)
+			die_errno("unable to connect to cache daemon");
+		if (flags & FLAG_SPAWN) {
+			spawn_daemon(socket);
+			if (send_request(socket, &buf) < 0)
+				die_errno("unable to connect to cache daemon");
+		}
+	}
+	strbuf_release(&buf);
+}
+
+static char *get_socket_path(void)
+{
+	struct stat sb;
+	char *old_dir, *socket;
+	old_dir = expand_user_path("~/.git-credential-cache", 0);
+	if (old_dir && !stat(old_dir, &sb) && S_ISDIR(sb.st_mode))
+		socket = xstrfmt("%s/socket", old_dir);
+	else
+		socket = xdg_cache_home("credential/socket");
+	free(old_dir);
+	return socket;
+}
+
+int cmd_credential_cache(int argc, const char **argv, const char *prefix)
+{
+	char *socket_path = NULL;
+	int timeout = 900;
+	const char *op;
+	const char * const usage[] = {
+		"git credential-cache [<options>] <action>",
+		NULL
+	};
+	struct option options[] = {
+		OPT_INTEGER(0, "timeout", &timeout,
+			    "number of seconds to cache credentials"),
+		OPT_STRING(0, "socket", &socket_path, "path",
+			   "path of cache-daemon socket"),
+		OPT_END()
+	};
+
+	argc = parse_options(argc, argv, prefix, options, usage, 0);
+	if (!argc)
+		usage_with_options(usage, options);
+	op = argv[0];
+
+	if (!socket_path)
+		socket_path = get_socket_path();
+	if (!socket_path)
+		die("unable to find a suitable socket path; use --socket");
+
+	if (!strcmp(op, "exit"))
+		do_cache(socket_path, op, timeout, 0);
+	else if (!strcmp(op, "get") || !strcmp(op, "erase"))
+		do_cache(socket_path, op, timeout, FLAG_RELAY);
+	else if (!strcmp(op, "store"))
+		do_cache(socket_path, op, timeout, FLAG_RELAY|FLAG_SPAWN);
+	else
+		; /* ignore unknown operation */
+
+	return 0;
+}
+
+#else
+
+int cmd_credential_cache(int argc, const char **argv, const char *prefix)
+{
+	const char * const usage[] = {
+		"git credential-cache [options] <action>",
+		"",
+		"credential-cache is disabled in this build of Git",
+		NULL
+	};
+	struct option options[] = { OPT_END() };
+
+	argc = parse_options(argc, argv, prefix, options, usage, 0);
+	die(_("credential-cache unavailable; no unix socket support"));
+}
+
+#endif /* NO_UNIX_SOCKETS */