systemctl: minor optimizations

[elogind.git] / src / systemctl.c

diff --git a/src/systemctl.c b/src/systemctl.c
index 8cdc01aa49566f2bf5275f1fc49e6fdb74e223ba..dfa952ed46d5a31bbdd9af3861266ff7457c2eb3 100644 (file)
--- a/src/systemctl.c
+++ b/src/systemctl.c
@@ -121,7 +121,7 @@ static bool on_tty(void) {
         /* Note that this is invoked relatively early, before we start
          * the pager. That means the value we return reflects whether
          * we originally were started on a tty, not if we currently
-         * are. But this is intended, since we want color, and so on
+         * are. But this is intended, since we want colour and so on
          * when run in our own pager. */
 
         if (_unlikely_(t < 0))
@@ -141,6 +141,9 @@ static void spawn_ask_password_agent(void) {
         if (!arg_ask_password)
                 return;
 
+        if (arg_user)
+                return;
+
         parent = getpid();
 
         /* Spawns a temporary TTY agent, making sure it goes away when
@@ -151,13 +154,16 @@ static void spawn_ask_password_agent(void) {
 
         if (child == 0) {
                 /* In the child */
-
                 const char * const args[] = {
                         SYSTEMD_TTY_ASK_PASSWORD_AGENT_BINARY_PATH,
                         "--watch",
                         NULL
                 };
 
+                int fd;
+                bool stdout_is_tty, stderr_is_tty;
+
+                /* Make sure the agent goes away when the parent dies */
                 if (prctl(PR_SET_PDEATHSIG, SIGTERM) < 0)
                         _exit(EXIT_FAILURE);
 
@@ -166,6 +172,35 @@ static void spawn_ask_password_agent(void) {
                 if (getppid() != parent)
                         _exit(EXIT_SUCCESS);
 
+                /* Don't leak fds to the agent */
+                close_all_fds(NULL, 0);
+
+                stdout_is_tty = isatty(STDOUT_FILENO);
+                stderr_is_tty = isatty(STDERR_FILENO);
+
+                if (!stdout_is_tty || !stderr_is_tty) {
+                        /* Detach from stdout/stderr. and reopen
+                         * /dev/tty for them. This is important to
+                         * ensure that when systemctl is started via
+                         * popen() or a similar call that expects to
+                         * read EOF we actually do generate EOF and
+                         * not delay this indefinitely by because we
+                         * keep an unused copy of stdin around. */
+                        if ((fd = open("/dev/tty", O_WRONLY)) < 0) {
+                                log_error("Failed to open /dev/tty: %m");
+                                _exit(EXIT_FAILURE);
+                        }
+
+                        if (!stdout_is_tty)
+                                dup2(fd, STDOUT_FILENO);
+
+                        if (!stderr_is_tty)
+                                dup2(fd, STDERR_FILENO);
+
+                        if (fd > 2)
+                                close(fd);
+                }
+
                 execv(args[0], (char **) args);
                 _exit(EXIT_FAILURE);
         }