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Handle sigmask better with nested signal handlers.

Browse source 
* atimer.c (sigmask_atimers): Remove.
Remaining use rewritten to use body of this function.
* atimer.c (block_atimers, unblock_atimers):
* callproc.c (block_child_signal, unblock_child_signal):
* sysdep.c (block_tty_out_signal, unblock_tty_out_signal):
New arg OLDSET.  All callers changed.
* atimer.c (block_atimers, unblock_atimers):
* callproc.c (block_child_signal, unblock_child_signal):
* keyboard.c (handle_interrupt):
* sound.c (vox_configure, vox_close):
Restore the old signal mask rather than unilaterally clearing bits
from the mask, in case a handler is running within another
handler.  All callers changed.
* lisp.h, process.c, process.h, term.c:
Adjust decls and callers to match new API.
* sysdep.c (emacs_sigaction_init): Don't worry about masking SIGFPE;
signal handlers aren't supposed to use floating point anyway.
(handle_arith_signal): Unblock just SIGFPE rather than clearing mask.

Fixes: debbugs:15561
This commit is contained in:
Paul Eggert 2014-03-25 07:43:26 -07:00
parent 1edb4a2ec6
commit 1e952f0a7a
10 changed files with 91 additions and 62 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

22
src/ChangeLog
View file

@ -1,3 +1,25 @@
2014-03-25 Paul Eggert <eggert@cs.ucla.edu>
Handle sigmask better with nested signal handlers (Bug#15561).
* atimer.c (sigmask_atimers): Remove.
Remaining use rewritten to use body of this function.
* atimer.c (block_atimers, unblock_atimers):
* callproc.c (block_child_signal, unblock_child_signal):
* sysdep.c (block_tty_out_signal, unblock_tty_out_signal):
New arg OLDSET. All callers changed.
* atimer.c (block_atimers, unblock_atimers):
* callproc.c (block_child_signal, unblock_child_signal):
* keyboard.c (handle_interrupt):
* sound.c (vox_configure, vox_close):
Restore the old signal mask rather than unilaterally clearing bits
from the mask, in case a handler is running within another
handler. All callers changed.
* lisp.h, process.c, process.h, term.c:
Adjust decls and callers to match new API.
* sysdep.c (emacs_sigaction_init): Don't worry about masking SIGFPE;
signal handlers aren't supposed to use floating point anyway.
(handle_arith_signal): Unblock just SIGFPE rather than clearing mask.
2014-03-23 Daniel Colascione <dancol@dancol.org>
Split gc_sweep into discrete functions for legibility and better

38
src/atimer.c
View file

@ -50,22 +50,17 @@ static bool alarm_timer_ok;
/* Block/unblock SIGALRM. */
static void
sigmask_atimers (int how)
block_atimers (sigset_t *oldset)
{
sigset_t blocked;
sigemptyset (&blocked);
sigaddset (&blocked, SIGALRM);
pthread_sigmask (how, &blocked, 0);
pthread_sigmask (SIG_BLOCK, &blocked, oldset);
}
static void
block_atimers (void)
unblock_atimers (sigset_t const *oldset)
{
sigmask_atimers (SIG_BLOCK);
}
static void
unblock_atimers (void)
{
sigmask_atimers (SIG_UNBLOCK);
pthread_sigmask (SIG_SETMASK, oldset, 0);
}
/* Function prototypes. */
@ -98,6 +93,7 @@ start_atimer (enum atimer_type type, struct timespec timestamp,
atimer_callback fn, void *client_data)
{
struct atimer *t;
sigset_t oldset;
/* Round TIME up to the next full second if we don't have
itimers. */
@ -122,7 +118,7 @@ start_atimer (enum atimer_type type, struct timespec timestamp,
t->fn = fn;
t->client_data = client_data;
block_atimers ();
block_atimers (&oldset);
/* Compute the timer's expiration time. */
switch (type)
@ -143,7 +139,7 @@ start_atimer (enum atimer_type type, struct timespec timestamp,
/* Insert the timer in the list of active atimers. */
schedule_atimer (t);
unblock_atimers ();
unblock_atimers (&oldset);
/* Arrange for a SIGALRM at the time the next atimer is ripe. */
set_alarm ();
@ -158,8 +154,9 @@ void
cancel_atimer (struct atimer *timer)
{
int i;
sigset_t oldset;
block_atimers ();
block_atimers (&oldset);
for (i = 0; i < 2; ++i)
{
@ -186,7 +183,7 @@ cancel_atimer (struct atimer *timer)
}
}
unblock_atimers ();
unblock_atimers (&oldset);
}
@ -217,7 +214,8 @@ append_atimer_lists (struct atimer *list_1, struct atimer *list_2)
void
stop_other_atimers (struct atimer *t)
{
block_atimers ();
sigset_t oldset;
block_atimers (&oldset);
if (t)
{
@ -242,7 +240,7 @@ stop_other_atimers (struct atimer *t)
stopped_atimers = append_atimer_lists (atimers, stopped_atimers);
atimers = t;
unblock_atimers ();
unblock_atimers (&oldset);
}
@ -256,8 +254,9 @@ run_all_atimers (void)
{
struct atimer *t = atimers;
struct atimer *next;
sigset_t oldset;
block_atimers ();
block_atimers (&oldset);
atimers = stopped_atimers;
stopped_atimers = NULL;
@ -268,7 +267,7 @@ run_all_atimers (void)
t = next;
}
unblock_atimers ();
unblock_atimers (&oldset);
}
}
@ -381,9 +380,10 @@ do_pending_atimers (void)
{
if (atimers)
{
block_atimers ();
sigset_t oldset;
block_atimers (&oldset);
run_timers ();
unblock_atimers ();
unblock_atimers (&oldset);
}
}

20
src/callproc.c
View file

@ -108,20 +108,20 @@ static Lisp_Object call_process (ptrdiff_t, Lisp_Object *, int, ptrdiff_t);
/* Block SIGCHLD. */
void
block_child_signal (void)
block_child_signal (sigset_t *oldset)
{
sigset_t blocked;
sigemptyset (&blocked);
sigaddset (&blocked, SIGCHLD);
pthread_sigmask (SIG_BLOCK, &blocked, 0);
pthread_sigmask (SIG_BLOCK, &blocked, oldset);
}
/* Unblock SIGCHLD. */
void
unblock_child_signal (void)
unblock_child_signal (sigset_t const *oldset)
{
pthread_sigmask (SIG_SETMASK, &empty_mask, 0);
pthread_sigmask (SIG_SETMASK, oldset, 0);
}
/* Return the current buffer's working directory, or the home
@ -162,7 +162,8 @@ encode_current_directory (void)
void
record_kill_process (struct Lisp_Process *p, Lisp_Object tempfile)
{
block_child_signal ();
sigset_t oldset;
block_child_signal (&oldset);
if (p->alive)
{
@ -171,7 +172,7 @@ record_kill_process (struct Lisp_Process *p, Lisp_Object tempfile)
kill (- p->pid, SIGKILL);
}
unblock_child_signal ();
unblock_child_signal (&oldset);
}
/* Clean up files, file descriptors and processes created by Fcall_process. */
@ -313,6 +314,7 @@ call_process (ptrdiff_t nargs, Lisp_Object *args, int filefd,
char *tempfile = NULL;
int pid;
#else
sigset_t oldset;
pid_t pid;
#endif
int child_errno;
@ -629,7 +631,7 @@ call_process (ptrdiff_t nargs, Lisp_Object *args, int filefd,
#ifndef MSDOS
block_input ();
block_child_signal ();
block_child_signal (&oldset);
#ifdef WINDOWSNT
pid = child_setup (filefd, fd_output, fd_error, new_argv, 0, current_dir);
@ -671,7 +673,7 @@ call_process (ptrdiff_t nargs, Lisp_Object *args, int filefd,
if (pid == 0)
{
unblock_child_signal ();
unblock_child_signal (&oldset);
setsid ();
@ -707,7 +709,7 @@ call_process (ptrdiff_t nargs, Lisp_Object *args, int filefd,
}
}
unblock_child_signal ();
unblock_child_signal (&oldset);
unblock_input ();
#endif /* not MSDOS */

10
src/keyboard.c
View file

@ -10295,6 +10295,9 @@ static void
handle_interrupt (bool in_signal_handler)
{
char c;
sigset_t blocked;
sigemptyset (&blocked);
sigaddset (&blocked, SIGINT);
cancel_echoing ();
@ -10306,9 +10309,6 @@ handle_interrupt (bool in_signal_handler)
/* If SIGINT isn't blocked, don't let us be interrupted by
a SIGINT. It might be harmful due to non-reentrancy
in I/O functions. */
sigset_t blocked;
sigemptyset (&blocked);
sigaddset (&blocked, SIGINT);
pthread_sigmask (SIG_BLOCK, &blocked, 0);
}
@ -10393,7 +10393,7 @@ handle_interrupt (bool in_signal_handler)
struct gcpro gcpro1, gcpro2, gcpro3, gcpro4;
immediate_quit = 0;
pthread_sigmask (SIG_SETMASK, &empty_mask, 0);
pthread_sigmask (SIG_UNBLOCK, &blocked, 0);
saved = gl_state;
GCPRO4 (saved.object, saved.global_code,
saved.current_syntax_table, saved.old_prop);
@ -10414,7 +10414,7 @@ handle_interrupt (bool in_signal_handler)
}
}
pthread_sigmask (SIG_SETMASK, &empty_mask, 0);
pthread_sigmask (SIG_UNBLOCK, &blocked, 0);
/* TODO: The longjmp in this call throws the NS event loop integration off,
and it seems to do fine without this. Probably some attention

4
src/lisp.h
View file

@ -4238,8 +4238,8 @@ 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 block_tty_out_signal (sigset_t *);
extern void unblock_tty_out_signal (sigset_t const *);
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);

12
src/process.c
View file

@ -1663,6 +1663,7 @@ create_process (Lisp_Object process, char **new_argv, Lisp_Object current_dir)
bool pty_flag = 0;
char pty_name[PTY_NAME_SIZE];
Lisp_Object lisp_pty_name = Qnil;
sigset_t oldset;
inchannel = outchannel = -1;
@ -1728,7 +1729,7 @@ create_process (Lisp_Object process, char **new_argv, Lisp_Object current_dir)
setup_process_coding_systems (process);
block_input ();
block_child_signal ();
block_child_signal (&oldset);
#ifndef WINDOWSNT
/* vfork, and prevent local vars from being clobbered by the vfork. */
@ -1852,7 +1853,7 @@ create_process (Lisp_Object process, char **new_argv, Lisp_Object current_dir)
signal (SIGPIPE, SIG_DFL);
/* Stop blocking SIGCHLD in the child. */
unblock_child_signal ();
unblock_child_signal (&oldset);
if (pty_flag)
child_setup_tty (xforkout);
@ -1871,7 +1872,7 @@ create_process (Lisp_Object process, char **new_argv, Lisp_Object current_dir)
p->alive = 1;
/* Stop blocking in the parent. */
unblock_child_signal ();
unblock_child_signal (&oldset);
unblock_input ();
if (pid < 0)
@ -7070,8 +7071,9 @@ void
catch_child_signal (void)
{
struct sigaction action, old_action;
sigset_t oldset;
emacs_sigaction_init (&action, deliver_child_signal);
block_child_signal ();
block_child_signal (&oldset);
sigaction (SIGCHLD, &action, &old_action);
eassert (! (old_action.sa_flags & SA_SIGINFO));
@ -7080,7 +7082,7 @@ catch_child_signal (void)
= (old_action.sa_handler == SIG_DFL || old_action.sa_handler == SIG_IGN
? dummy_handler
: old_action.sa_handler);
unblock_child_signal ();
unblock_child_signal (&oldset);
}

4
src/process.h
View file

@ -213,8 +213,8 @@ enum
/* Defined in callproc.c. */
extern void block_child_signal (void);
extern void unblock_child_signal (void);
extern void block_child_signal (sigset_t *);
extern void unblock_child_signal (sigset_t const *);
extern Lisp_Object encode_current_directory (void);
extern void record_kill_process (struct Lisp_Process *, Lisp_Object);

12
src/sound.c
View file

@ -702,7 +702,7 @@ vox_configure (struct sound_device *sd)
{
int val;
#ifdef USABLE_SIGIO
sigset_t blocked;
sigset_t oldset, blocked;
#endif
eassert (sd->fd >= 0);
@ -714,7 +714,7 @@ vox_configure (struct sound_device *sd)
#ifdef USABLE_SIGIO
sigemptyset (&blocked);
sigaddset (&blocked, SIGIO);
pthread_sigmask (SIG_BLOCK, &blocked, 0);
pthread_sigmask (SIG_BLOCK, &blocked, &oldset);
#endif
val = sd->format;
@ -748,7 +748,7 @@ vox_configure (struct sound_device *sd)
turn_on_atimers (1);
#ifdef USABLE_SIGIO
pthread_sigmask (SIG_UNBLOCK, &blocked, 0);
pthread_sigmask (SIG_SETMASK, &oldset, 0);
#endif
}
@ -764,10 +764,10 @@ vox_close (struct sound_device *sd)
be interrupted by a signal. Block the ones we know to cause
troubles. */
#ifdef USABLE_SIGIO
sigset_t blocked;
sigset_t blocked, oldset;
sigemptyset (&blocked);
sigaddset (&blocked, SIGIO);
pthread_sigmask (SIG_BLOCK, &blocked, 0);
pthread_sigmask (SIG_BLOCK, &blocked, &oldset);
#endif
turn_on_atimers (0);
@ -776,7 +776,7 @@ vox_close (struct sound_device *sd)
turn_on_atimers (1);
#ifdef USABLE_SIGIO
pthread_sigmask (SIG_UNBLOCK, &blocked, 0);
pthread_sigmask (SIG_SETMASK, &oldset, 0);
#endif
/* Close the device. */

21
src/sysdep.c
View file

@ -692,21 +692,21 @@ init_foreground_group (void)
/* Block and unblock SIGTTOU. */
void
block_tty_out_signal (void)
block_tty_out_signal (sigset_t *oldset)
{
#ifdef SIGTTOU
sigset_t blocked;
sigemptyset (&blocked);
sigaddset (&blocked, SIGTTOU);
pthread_sigmask (SIG_BLOCK, &blocked, 0);
pthread_sigmask (SIG_BLOCK, &blocked, oldset);
#endif
}
void
unblock_tty_out_signal (void)
unblock_tty_out_signal (sigset_t const *oldset)
{
#ifdef SIGTTOU
pthread_sigmask (SIG_SETMASK, &empty_mask, 0);
pthread_sigmask (SIG_SETMASK, oldset, 0);
#endif
}
@ -721,10 +721,11 @@ static void
tcsetpgrp_without_stopping (int fd, pid_t pgid)
{
#ifdef SIGTTOU
sigset_t oldset;
block_input ();
block_tty_out_signal ();
block_tty_out_signal (&oldset);
tcsetpgrp (fd, pgid);
unblock_tty_out_signal ();
unblock_tty_out_signal (&oldset);
unblock_input ();
#endif
}
@ -1525,9 +1526,6 @@ emacs_sigaction_init (struct sigaction *action, signal_handler_t handler)
#endif
}
if (! IEEE_FLOATING_POINT)
sigaddset (&action->sa_mask, SIGFPE);
action->sa_handler = handler;
action->sa_flags = emacs_sigaction_flags ();
}
@ -1643,7 +1641,10 @@ deliver_fatal_thread_signal (int sig)
static _Noreturn void
handle_arith_signal (int sig)
{
pthread_sigmask (SIG_SETMASK, &empty_mask, 0);
sigset_t blocked;
sigemptyset (&blocked);
sigaddset (&blocked, sig);
pthread_sigmask (SIG_UNBLOCK, &blocked, 0);
xsignal0 (Qarith_error);
}

10
src/term.c
View file

@ -3944,9 +3944,10 @@ dissociate_if_controlling_tty (int fd)
/* 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 ();
sigset_t oldset;
block_tty_out_signal (&oldset);
ioctl (fd, TIOCNOTTY, 0);
unblock_tty_out_signal ();
unblock_tty_out_signal (&oldset);
#endif
}
}
@ -3970,6 +3971,7 @@ init_tty (const char *name, const char *terminal_type, bool must_succeed)
int status;
struct tty_display_info *tty = NULL;
struct terminal *terminal = NULL;
sigset_t oldset;
bool ctty = false; /* True if asked to open controlling tty. */
if (!terminal_type)
@ -4059,11 +4061,11 @@ init_tty (const char *name, const char *terminal_type, bool must_succeed)
/* On some systems, tgetent tries to access the controlling
terminal. */
block_tty_out_signal ();
block_tty_out_signal (&oldset);
status = tgetent (tty->termcap_term_buffer, terminal_type);
if (tty->termcap_term_buffer[TERMCAP_BUFFER_SIZE - 1])
emacs_abort ();
unblock_tty_out_signal ();
unblock_tty_out_signal (&oldset);
if (status < 0)
{