Bug 597928

Created attachment 429307 [details]
change to 1.22 file: properly propagate upstream stop signals in su

This is actually not a bug with tcsh, but with /bin/su in coreutils. The following recent change broke the behavior of "suspend" in tcsh, and affects Fedora 11, 12, 13, and rawhide:

http://cvs.fedoraproject.org/viewvc/devel/coreutils/coreutils-pam.patch?r1=1.21&r2=1.22

The issue lies with su attempting to propagate stop signals from its child (tcsh) to itself, which will notify its parent (presumably another shell). The previous version (1.21) was incorrect in that it always sent itself a SIGSTOP regardless of what type of signal was received (the "suspend" command in tcsh sends a SIGTSTP). This worked because SIGSTOP can't be blocked (masked). The 1.22 version attempted to fix this by directly propagating the signal, but failed for SIGTSTP because it was blocked. My patch fixes both problems. The relevant code change is:

+  /* tcsh sends SIGTSTP to the process group, and so is already pending */
   kill(getpid(), WSTOPSIG(status));
+  if (WSTOPSIG(status) != SIGSTOP) {
+    sigemptyset(&blockset);
+    sigaddset(&blockset, WSTOPSIG(status));
+    sigprocmask(SIG_UNBLOCK, &blockset, &ourset);
+    /* signal taken here */
+    sigprocmask(SIG_SETMASK, &ourset, NULL);
+  }

I've been having the same problem on both Fedora 12 and 13. So fare my workaround has been:

alias suspend kill -STOP $$

This package has changed ownership in the Fedora Package Database.  Reassigning to the new owner of this component.

Moving bz to coreutils component.

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This bug still exists on Fedora 14

Fixed in coreutils-8.12-6.fc17 .

coreutils-8.12-6.fc16 has been submitted as an update for Fedora 16.
https://admin.fedoraproject.org/updates/coreutils-8.12-6.fc16

coreutils-8.12-6.fc16 has been pushed to the Fedora 16 stable repository.  If problems still persist, please make note of it in this bug report.