Commit 9ae8f997 authored by Jim Blandy's avatar Jim Blandy

Interact properly with shells lacking job control (sh, rc, es...)

	* sysdep.c [BSD] (inherited_pgroup): New variable.
	(narrow_foreground_group, widen_foreground_group): New functions.
	(init_sys_modes): Call narrow_foreground_group.
	(reset_sys_modes): Call widen_foreground_group.
	* emacs.c [BSD] (inherited_pgroup): Add extern declaration.
	[BSD] (main): Set inherited_pgroup, and put ourselves in our own
	pgroup.
parent 9b37b1c2
......@@ -81,6 +81,11 @@ int inhibit_window_system;
priority; Those functions have their own extern declaration. */
int emacs_priority;
#ifdef BSD
/* See sysdep.c. */
extern int inherited_pgroup;
#endif
#ifdef HAVE_X_WINDOWS
/* If non-zero, -d was specified, meaning we're using some window system. */
int display_arg;
......@@ -292,18 +297,19 @@ main (argc, argv, envp)
#endif
clearerr (stdin);
#if 0 /* Without EMACS_SET_TTY_PGRP, this causes Emacs to hang
when run under a non-job-control shell.
EMACS_SET_TTY_PGRP seems correct, but breaks even more. */
#ifdef BSD
{
int pid = getpid ();
setpgrp (0, pid);
EMACS_SET_TTY_PGRP (0, &pid);
}
#ifdef GETPGRP_NO_ARG
inherited_pgroup = getpgrp (0);
#else /* THISSENTENCE_NO_VERB */
inherited_pgroup = getpgrp (0);
#endif
setpgrp (0, getpid ());
}
#endif
#ifdef APOLLO
#ifndef APOLLO_SR10
/* If USE_DOMAIN_ACLS environment variable exists,
......
......@@ -756,6 +756,54 @@ unrequest_sigio ()
#endif /* FASYNC */
#endif /* F_SETFL */
/* Saving and restoring the process group of Emacs's terminal. */
#ifdef BSD
/* The process group of which Emacs was a member when it initially
started.
If Emacs was in its own process group (i.e. inherited_pgroup ==
getpid ()), then we know we're running under a shell with job
control (Emacs would never be run as part of a pipeline).
Everything is fine.
If Emacs was not in its own process group, then we know we're
running under a shell (or a caller) that doesn't know how to
separate itself from Emacs (like sh). Emacs must be in its own
process group in order to receive SIGIO correctly. In this
situation, we put ourselves in our own pgroup, forcibly set the
tty's pgroup to our pgroup, and make sure to restore and reinstate
the tty's pgroup just like any other terminal setting. If
inherited_group was not the tty's pgroup, then we'll get a
SIGTTmumble when we try to change the tty's pgroup, and a CONT if
it goes foreground in the future, which is what should happen. */
int inherited_pgroup;
/* Split off the foreground process group to Emacs alone.
When we are in the foreground, but not started in our own process
group, redirect the TTY to point to our own process group. We need
to be in our own process group to receive SIGIO properly. */
narrow_foreground_group ()
{
int me = getpid ();
setpgrp (0, inherited_pgroup);
if (inherited_pgroup != me)
EMACS_SET_TTY_PGRP (0, &me);
setpgrp (0, me);
}
/* Set the tty to our original foreground group. */
widen_foreground_group ()
{
if (inherited_pgroup != getpid ())
EMACS_SET_TTY_PGRP (0, &inherited_pgroup);
setpgrp (0, inherited_pgroup);
}
#endif
/* Getting and setting emacs_tty structures. */
/* Set *TC to the parameters associated with the terminal FD.
......@@ -982,6 +1030,11 @@ init_sys_modes ()
#endif
#endif /* not VMS */
#ifdef BSD
if (! read_socket_hook && EQ (Vwindow_system, Qnil))
narrow_foreground_group ();
#endif
EMACS_GET_TTY (input_fd, &old_tty);
if (!read_socket_hook && EQ (Vwindow_system, Qnil))
......@@ -1334,6 +1387,10 @@ reset_sys_modes ()
#ifdef AIX
hft_reset ();
#endif
#ifdef BSD
widen_foreground_group ();
#endif
}
#ifdef HAVE_PTYS
......
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