[PATCH 2/2] login: use isatty() before using the tty's fd

[Yann Droneaud <yann@xxxxxxxxxxx>]

When launched, check fd 0 (stdin) using isatty(), bail out if not.
When the tty device is re-opened, check it using isatty(), leave if not.
This will help to prevent some possible races.

Signed-off-by: Yann Droneaud <yann@xxxxxxxxxxx>
---
 login-utils/login.c |   19 +++++++++++++++++++
 1 files changed, 19 insertions(+), 0 deletions(-)

diff --git a/login-utils/login.c b/login-utils/login.c
index fdc8078..6918db6 100644
--- a/login-utils/login.c
+++ b/login-utils/login.c
@@ -495,6 +495,12 @@ main(int argc, char **argv)
     for (cnt = getdtablesize(); cnt > 2; cnt--)
       close(cnt);
 
+    if (!isatty(0)) {
+	syslog(LOG_ERR, _("FATAL: bad tty"));
+	sleep(1);
+	exit(1);
+    }
+
     ttyn = ttyname(0);
 
     if (ttyn == NULL || *ttyn == '\0') {
@@ -554,6 +560,12 @@ main(int argc, char **argv)
 
     openlog("login", LOG_ODELAY, LOG_AUTHPRIV);
 
+    if (!isatty(0)) {
+	syslog(LOG_ERR, _("FATAL: bad tty"));
+	sleep(1);
+	exit(1);
+    }
+
 #if 0
     /* other than iso-8859-1 */
     printf("\033(K");
@@ -1216,6 +1228,13 @@ Michael Riepe <michael@xxxxxxxxxxxxxxxxxxxx>
      */
     if (ioctl(0, TIOCSCTTY, 1))
 	    syslog(LOG_ERR, _("TIOCSCTTY failed: %m"));
+
+    if (!isatty(0)) {
+	syslog(LOG_ERR, _("FATAL: bad tty"));
+	sleep(1);
+	exit(1);
+    }
+
 #endif
     signal(SIGINT, SIG_DFL);
 
-- 
1.6.2.5

--
To unsubscribe from this list: send the line "unsubscribe util-linux-ng" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html