#3595: problems suspending mutt when called from shell script
---------------------------+----------------------
Reporter: blmassingill | Owner: mutt-dev
Type: defect | Status: new
Priority: minor | Milestone:
Component: mutt | Version: 1.5.21
Resolution: | Keywords:
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Comment (by zsdzsd):
Are you sure it works in 1.4.2? I tried compiling 1.4.2.3 and I still
get the same problem.
The problem, which shows up in programs such as grepm (I add that
mainly for people searching the bug list), may be related to
the following code in signal.c:
{{{
RETSIGTYPE sighandler (int sig)
{
int save_errno = errno;
struct sigaction act;
switch (sig)
{
case SIGTSTP: /* user requested a suspend */
if (!option (OPTSUSPEND))
break;
IsEndwin = isendwin ();
curs_set (1);
if (!IsEndwin)
endwin ();
kill (0, SIGSTOP);
}}}
This codes assumes that a SIGSTOP is just as good as a SIGTSTP, but
(perhaps) when mutt is running inside a subshell (a la) grepm, the two
signals are not handled analogously. Or perhaps the issue is as I
speculate below (*).
I tried making the following change to signal.c in 1.4.2.3:
{{{
RETSIGTYPE sighandler (int sig)
{
int save_errno = errno;
sigset_t mask; /* NEW */
struct sigaction act;
switch (sig)
{
case SIGTSTP: /* user requested a suspend */
if (!option (OPTSUSPEND))
break;
IsEndwin = isendwin ();
curs_set (1);
if (!IsEndwin)
endwin ();
/* OLD kill (0, SIGSTOP); */
/* REST OF THIS TO "HERE" IS NEW: */
sigemptyset(&mask);
sigaddset(&mask, SIGTSTP);
sigprocmask(SIG_UNBLOCK, &mask, NULL);
signal(SIGTSTP, SIG_DFL); /* reset disposition to default */
sigemptyset(&act.sa_mask);
sigaddset(&act.sa_mask, SIGTSTP);
act.sa_flags = 0;
act.sa_handler = sighandler;
kill(0, SIGTSTP);
/* wait to be CONTinued... */
sigprocmask(SIG_BLOCK, &mask, NULL); /* DO I WANT THIS?? */
sigaction(SIGTSTP, &act, NULL);
/* HERE */
}}}
and the situation is much improved, but (annoyingly) there is the
occasional situation in which the problem occurs. (See (*) below.)
I tried replacing
{{{
kill(0, SIGTSTP);
}}}
with
{{{
kill(getpid(), SIGTSTP);
}}}
and that didn't work any better. (The thought being that the subshell
which called mutt has
already received SIGSTSP, so it doesn't need another signal.)
(*) I speculate that there is some race condition between when mutt
and the subshell process the SIGTSTP. But even if this is true, I'm
not immediately sure how to deal with this.
Are there any signal handling / process groups / terminal emulator
wizards here who could comment?
--
Ticket URL: <http://dev.mutt.org/trac/ticket/3595#comment:1>
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