systemctl: minor optimizations

[elogind.git] / src / systemctl.c

diff --git a/src/systemctl.c b/src/systemctl.c
index 8527cd1aa00f2cf1064c0378c59cef4e9ddf1263..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))
@@ -161,6 +161,7 @@ static void spawn_ask_password_agent(void) {
                 };
 
                 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)
@@ -174,27 +175,31 @@ static void spawn_ask_password_agent(void) {
                 /* Don't leak fds to the agent */
                 close_all_fds(NULL, 0);
 
-                /* Detach from stdin/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_RDWR|O_CLOEXEC|O_NONBLOCK)) < 0) {
-                        log_error("Failed to open /dev/tty: %m");
-                        _exit(EXIT_FAILURE);
-                }
+                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);
+                        }
 
-                close(STDIN_FILENO);
-                close(STDOUT_FILENO);
-                close(STDERR_FILENO);
+                        if (!stdout_is_tty)
+                                dup2(fd, STDOUT_FILENO);
 
-                dup2(fd, STDIN_FILENO);
-                dup2(fd, STDOUT_FILENO);
-                dup2(fd, STDERR_FILENO);
+                        if (!stderr_is_tty)
+                                dup2(fd, STDERR_FILENO);
 
-                if (fd > 2)
-                        close(fd);
+                        if (fd > 2)
+                                close(fd);
+                }
 
                 execv(args[0], (char **) args);
                 _exit(EXIT_FAILURE);