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emacsclient -t should not suspend Emacs server

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* lisp.h, sysdep.c (block_tty_out_signal, unblock_tty_out_signal):
New functions.
* term.c (init_tty): Use them instead of rolling our own code.
* sysdep.c (tcsetpgrp_without_stopping): Likewise.  Here, this
switches from 'signal' to 'pthread_sigmask', which is safer in
multithreaded applications.
* term.c (Fresume_tty): Don't bother dissociating if O_IGNORE_CTTY,
which has already arranged for that.
(dissociate_if_controlling_tty): If setsid fails, fall back on TIOCNOTTY.
This is the main part of the bug fix.

Fixes: debbugs:13387
This commit is contained in:
Paul Eggert 2013-01-10 18:40:58 -08:00
parent a778dd57d0
commit b895642720
4 changed files with 57 additions and 16 deletions
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14
src/ChangeLog
View file

@ -1,3 +1,17 @@
2013-01-11 Paul Eggert <eggert@cs.ucla.edu>
emacsclient -t should not suspend Emacs server (Bug#13387)
* lisp.h, sysdep.c (block_tty_out_signal, unblock_tty_out_signal):
New functions.
* term.c (init_tty): Use them instead of rolling our own code.
* sysdep.c (tcsetpgrp_without_stopping): Likewise. Here, this
switches from 'signal' to 'pthread_sigmask', which is safer in
multithreaded applications.
* term.c (Fresume_tty): Don't bother dissociating if O_IGNORE_CTTY,
which has already arranged for that.
(dissociate_if_controlling_tty): If setsid fails, fall back on TIOCNOTTY.
This is the main part of the bug fix.
2013-01-10 Rainer Orth <ro@CeBiTec.Uni-Bielefeld.DE> (tiny change)
* gtkutil.c (xg_initialize): Add ifdef HAVE_FREETYPE around

2
src/lisp.h
View file

@ -3462,6 +3462,8 @@ extern void init_sigio (int);
extern void sys_subshell (void);
extern void sys_suspend (void);
extern void discard_tty_input (void);
extern void block_tty_out_signal (void);
extern void unblock_tty_out_signal (void);
extern void init_sys_modes (struct tty_display_info *);
extern void reset_sys_modes (struct tty_display_info *);
extern void init_all_sys_modes (void);

26
src/sysdep.c
View file

@ -714,6 +714,27 @@ init_foreground_group (void)
inherited_pgroup = getpid () == pgrp ? 0 : pgrp;
}
/* Block and unblock SIGTTOU. */
void
block_tty_out_signal (void)
{
#ifdef SIGTTOU
sigset_t blocked;
sigemptyset (&blocked);
sigaddset (&blocked, SIGTTOU);
pthread_sigmask (SIG_BLOCK, &blocked, 0);
#endif
}
void
unblock_tty_out_signal (void)
{
#ifdef SIGTTOU
pthread_sigmask (SIG_SETMASK, &empty_mask, 0);
#endif
}
/* Safely set a controlling terminal FD's process group to PGID.
If we are not in the foreground already, POSIX requires tcsetpgrp
to deliver a SIGTTOU signal, which would stop us. This is an
@ -725,11 +746,10 @@ static void
tcsetpgrp_without_stopping (int fd, pid_t pgid)
{
#ifdef SIGTTOU
signal_handler_t handler;
block_input ();
handler = signal (SIGTTOU, SIG_IGN);
block_tty_out_signal ();
tcsetpgrp (fd, pgid);
signal (SIGTTOU, handler);
unblock_tty_out_signal ();
unblock_input ();
#endif
}

31
src/term.c
View file

@ -2423,7 +2423,7 @@ frame's terminal). */)
if (fd == -1)
error ("Can not reopen tty device %s: %s", t->display_info.tty->name, strerror (errno));
if (strcmp (t->display_info.tty->name, DEV_TTY))
if (!O_IGNORE_CTTY && strcmp (t->display_info.tty->name, DEV_TTY) != 0)
dissociate_if_controlling_tty (fd);
t->display_info.tty->output = fdopen (fd, "w+");
@ -2903,13 +2903,23 @@ set_tty_hooks (struct terminal *terminal)
terminal->delete_terminal_hook = &delete_tty;
}
/* Drop the controlling terminal if fd is the same device. */
/* If FD is the controlling terminal, drop it. */
static void
dissociate_if_controlling_tty (int fd)
{
pid_t pgid = tcgetpgrp (fd); /* If tcgetpgrp succeeds, fd is the ctty. */
if (0 <= pgid)
setsid ();
/* If tcgetpgrp succeeds, fd is the controlling terminal,
so dissociate it by invoking setsid. */
if (0 <= tcgetpgrp (fd) && setsid () < 0)
{
#ifdef TIOCNOTTY
/* setsid failed, presumably because Emacs is already a process
group leader. Fall back on the obsolescent way to dissociate
a controlling tty. */
block_tty_out_signal ();
ioctl (fd, TIOCNOTTY, 0);
unblock_tty_out_signal ();
#endif
}
}
/* Create a termcap display on the tty device with the given name and
@ -3030,14 +3040,9 @@ init_tty (const char *name, const char *terminal_type, int must_succeed)
/* On some systems, tgetent tries to access the controlling
terminal. */
{
sigset_t blocked;
sigemptyset (&blocked);
sigaddset (&blocked, SIGTTOU);
pthread_sigmask (SIG_BLOCK, &blocked, 0);
status = tgetent (tty->termcap_term_buffer, terminal_type);
pthread_sigmask (SIG_UNBLOCK, &blocked, 0);
}
block_tty_out_signal ();
status = tgetent (tty->termcap_term_buffer, terminal_type);
unblock_tty_out_signal ();
if (status < 0)
{