The change in a1e7e31519ec that caused to exit when the monitor

dies created a race condition between the monitor exiting and the
status being read.  All we really want to do is make sure that
select() notifies us that there is a status change when the monitor
dies unexpectedly so shutdown the socketpair connected to the monitor
for writing when it dies.  That way we can still read the status
that is pending on the socket and select() on Linux will tell us
that the fd is ready.

--HG--
branch : 1.7

diff --git a/exec.c b/exec.c
index 289c3de07b7bf34f7262ecb44e2fdf394a8d54f9..18266378e095c889f8777b27646b468019d79235 100644 (file)
--- a/exec.c
+++ b/exec.c
@@ -84,7 +84,7 @@ static void schedule_signal __P((int signo));
 static int log_io;
 #endif /* _PATH_SUDO_IO_LOGDIR */
 
-static int handle_signals __P((int fd, pid_t child,
+static int handle_signals __P((int sv[2], pid_t child,
     struct command_status *cstat));
 #ifdef SA_SIGINFO
 static void handler_nofwd __P((int s, siginfo_t *info, void *context));
@@ -377,7 +377,7 @@ sudo_execve(path, argv, envp, uid, cstat, dowait, bgmode)
        }
 #endif /* _PATH_SUDO_IO_LOGDIR */
        if (FD_ISSET(signal_pipe[0], fdsr)) {
-           n = handle_signals(signal_pipe[0], child, cstat);
+           n = handle_signals(sv, child, cstat);
            if (n == 0) {
                /* Child has exited, cstat is set, we are done. */
                goto done;
@@ -476,8 +476,8 @@ done:
  * Returns -1 on error, 0 on child exit, else 1.
  */
 static int
-handle_signals(fd, child, cstat)
-    int fd;
+handle_signals(sv, child, cstat)
+    int sv[2];
     pid_t child;
     struct command_status *cstat;
 {
@@ -521,17 +521,11 @@ handle_signals(fd, child, cstat)
                    /*
                     * On BSD we get ECONNRESET on sv[0] if monitor dies
                     * and select() will return with sv[0] readable.
-                    * On Linux that doesn't appear to happen so we
-                    * treat the monitor dying as a fatal error.
-                    * Note that the wait status we return is that of
-                    * the monitor and not the command; unfortunately
-                    * that is the best that we can do here.
+                    * On Linux that doesn't appear to happen so if the
+                    * monitor dies, shut down the socketpair to force a
+                    * select() notification.
                     */
-                   if (!WIFSTOPPED(status)) {
-                       cstat->type = CMD_WSTATUS;
-                       cstat->val = status;
-                       return 0;
-                   }
+                   (void) shutdown(sv[0], SHUT_WR);
                } else
 #endif
                {