sulogin: cleanup file descriptors usage

 - use _FILENO macros rather than magic numbers
 - check for dup() result

Signed-off-by: Karel Zak <kzak@redhat.com>

diff --git a/login-utils/sulogin.c b/login-utils/sulogin.c
index d7d44b607e1c1ab6e21d32926dea36a31fa617e3..db783a2a00fd0494b63940ef9a9979374ffd8f55 100644 (file)
--- a/login-utils/sulogin.c
+++ b/login-utils/sulogin.c
@@ -433,7 +433,7 @@ static void fixtty(void)
 
        reset_virtual_console(&tp, fl);
 
-       if (tcsetattr(0, TCSADRAIN, &tp))
+       if (tcsetattr(STDIN_FILENO, TCSADRAIN, &tp))
                warn(_("tcsetattr failed"));
 }
 
@@ -522,10 +522,12 @@ int main(int argc, char **argv)
 
                if ((fd = open(tty, O_RDWR)) < 0) {
                        warn(_("cannot open %s"), tty);
-                       fd = dup(0);
+                       fd = dup(STDIN_FILENO);
                }
 
-               if (!isatty(fd)) {
+               if (fd < 0) {
+                       warn(_("cannot duplicate stdin file descriptor"));
+               } else if (!isatty(fd)) {
                        warn(_("%s: not a tty"), tty);
                        close(fd);
                } else {
@@ -550,30 +552,31 @@ int main(int argc, char **argv)
                                if (ttypgrp > 0)
                                        ioctl(0, TIOCNOTTY, (char *)1);
                                sigaction(SIGHUP, &saved_sighup, NULL);
-                               close(0);
-                               close(1);
-                               close(2);
+                               close(STDIN_FILENO);
+                               close(STDOUT_FILENO);
+                               close(STDERR_FILENO);
                                if (fd > 2)
                                        close(fd);
                                if ((fd = open(tty, O_RDWR|O_NOCTTY)) < 0)
                                        warn(_("cannot open %s"), tty);
                                else {
-                                       ioctl(0, TIOCSCTTY, (char *)1);
+                                       ioctl(STDIN_FILENO, TIOCSCTTY, (char *)1);
                                        tcsetpgrp(fd, ppgrp);
-                                       dup2(fd, 0);
-                                       dup2(fd, 1);
-                                       dup2(fd, 2);
-                                       if (fd > 2)
+                                       dup2(fd, STDIN_FILENO);
+                                       dup2(fd, STDOUT_FILENO);
+                                       dup2(fd, STDERR_FILENO);
+
+                                       if (fd > STDERR_FILENO)
                                                close(fd);
                                }
                        } else
-                               if (fd > 2)
+                               if (fd > STDERR_FILENO)
                                        close(fd);
                }
        } else if (getpid() == 1) {
                /* We are init. We hence need to set a session anyway */
                setsid();
-               if (ioctl(0, TIOCSCTTY, (char *)1))
+               if (ioctl(STDIN_FILENO, TIOCSCTTY, (char *)1))
                        warn(_("TIOCSCTTY: ioctl failed"));
        }