daemon: opt-out on features that require posix

Windows does not supply the POSIX-functions fork(), setuuid(), setgid(),
setsid() and initgroups(). Error out if --user or --detach is specified
when if so.

MinGW doesn't have prototypes and headers for inet_ntop and inet_pton,
so include our implementation instead. MSVC does, so avoid doing so
there.

Signed-off-by: Erik Faye-Lund <kusmabite@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 64 insertions, 24 deletions

diff --git a/daemon.c b/daemon.c
index 17028b6de8..13435b4667 100644
--- a/daemon.c
+++ b/daemon.c
@@ -940,6 +940,62 @@ static void sanitize_stdfds(void)
 		close(fd);
 }
 
+#ifdef NO_POSIX_GOODIES
+
+struct credentials;
+
+static void drop_privileges(struct credentials *cred)
+{
+	/* nothing */
+}
+
+static void daemonize(void)
+{
+	die("--detach not supported on this platform");
+}
+
+static struct credentials *prepare_credentials(const char *user_name,
+    const char *group_name)
+{
+	die("--user not supported on this platform");
+}
+
+#else
+
+struct credentials {
+	struct passwd *pass;
+	gid_t gid;
+};
+
+static void drop_privileges(struct credentials *cred)
+{
+	if (cred && (initgroups(cred->pass->pw_name, cred->gid) ||
+	    setgid (cred->gid) || setuid(cred->pass->pw_uid)))
+		die("cannot drop privileges");
+}
+
+static struct credentials *prepare_credentials(const char *user_name,
+    const char *group_name)
+{
+	static struct credentials c;
+
+	c.pass = getpwnam(user_name);
+	if (!c.pass)
+		die("user not found - %s", user_name);
+
+	if (!group_name)
+		c.gid = c.pass->pw_gid;
+	else {
+		struct group *group = getgrnam(group_name);
+		if (!group)
+			die("group not found - %s", group_name);
+
+		c.gid = group->gr_gid;
+	}
+
+	return &c;
+}
+
 static void daemonize(void)
 {
 	switch (fork()) {
@@ -957,6 +1013,7 @@ static void daemonize(void)
 	close(2);
 	sanitize_stdfds();
 }
+#endif
 
 static void store_pid(const char *path)
 {
@@ -967,7 +1024,8 @@ static void store_pid(const char *path)
 		die_errno("failed to write pid file '%s'", path);
 }
 
-static int serve(struct string_list *listen_addr, int listen_port, struct passwd *pass, gid_t gid)
+static int serve(struct string_list *listen_addr, int listen_port,
+    struct credentials *cred)
 {
 	struct socketlist socklist = { NULL, 0, 0 };
 
@@ -976,10 +1034,7 @@ static int serve(struct string_list *listen_addr, int listen_port, struct passwd
 		die("unable to allocate any listen sockets on port %u",
 		    listen_port);
 
-	if (pass && gid &&
-	    (initgroups(pass->pw_name, gid) || setgid (gid) ||
-	     setuid(pass->pw_uid)))
-		die("cannot drop privileges");
+	drop_privileges(cred);
 
 	return service_loop(&socklist);
 }
@@ -991,9 +1046,7 @@ int main(int argc, char **argv)
 	int serve_mode = 0, inetd_mode = 0;
 	const char *pid_file = NULL, *user_name = NULL, *group_name = NULL;
 	int detach = 0;
-	struct passwd *pass = NULL;
-	struct group *group;
-	gid_t gid = 0;
+	struct credentials *cred = NULL;
 	int i;
 
 	git_extract_argv0_path(argv[0]);
@@ -1139,21 +1192,8 @@ int main(int argc, char **argv)
 	if (group_name && !user_name)
 		die("--group supplied without --user");
 
-	if (user_name) {
-		pass = getpwnam(user_name);
-		if (!pass)
-			die("user not found - %s", user_name);
-
-		if (!group_name)
-			gid = pass->pw_gid;
-		else {
-			group = getgrnam(group_name);
-			if (!group)
-				die("group not found - %s", group_name);
-
-			gid = group->gr_gid;
-		}
-	}
+	if (user_name)
+		cred = prepare_credentials(user_name, group_name);
 
 	if (strict_paths && (!ok_paths || !*ok_paths))
 		die("option --strict-paths requires a whitelist");
@@ -1187,5 +1227,5 @@ int main(int argc, char **argv)
 	cld_argv[argc] = "--serve";
 	cld_argv[argc+1] = NULL;
 
-	return serve(&listen_addr, listen_port, pass, gid);
+	return serve(&listen_addr, listen_port, cred);
 }