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guile/libguile/scmsigs.c
2003-04-05 19:15:35 +00:00

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/* Copyright (C) 1995,1996,1997,1998,1999,2000,2001, 2002 Free Software Foundation, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#if HAVE_CONFIG_H
# include <config.h>
#endif
#include <signal.h>
#include <errno.h>
#include "libguile/_scm.h"
#include "libguile/async.h"
#include "libguile/eval.h"
#include "libguile/root.h"
#include "libguile/vectors.h"
#include "libguile/validate.h"
#include "libguile/scmsigs.h"
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#ifdef HAVE_SYS_TIME_H
#include <sys/time.h>
#endif
#ifdef __MINGW32__
#include <windows.h>
#define alarm(sec) (0)
/* This weird comma expression is because Sleep is void under Windows. */
#define sleep(sec) (Sleep ((sec) * 1000), 0)
#define usleep(usec) (Sleep ((usec) / 1000), 0)
#define kill(pid, sig) raise (sig)
#endif
/* SIGRETTYPE is the type that signal handlers return. See <signal.h> */
#ifdef RETSIGTYPE
# define SIGRETTYPE RETSIGTYPE
#else
# ifdef STDC_HEADERS
# define SIGRETTYPE void
# else
# define SIGRETTYPE int
# endif
#endif
/* take_signal is installed as the C signal handler whenever a Scheme
handler is set. when a signal arrives, take_signal will queue the
Scheme handler procedure for its thread. */
/* Scheme vectors with information about a signal. signal_handlers
contains the handler procedure or #f, signal_handler_cells contains
pre-queued cells for the handler (since we can't do fancy things
during signal delivery), signal_cell_handlers contains the SCM
value to be stuffed into the pre-queued cell upon delivery, and
signal_handler_threads points to the thread that a signal should be
delivered to.
*/
static SCM *signal_handlers;
static SCM signal_handler_cells;
static SCM signal_cell_handlers;
static SCM signal_handler_threads;
/* saves the original C handlers, when a new handler is installed.
set to SIG_ERR if the original handler is installed. */
#ifdef HAVE_SIGACTION
static struct sigaction orig_handlers[NSIG];
#else
static SIGRETTYPE (*orig_handlers[NSIG])(int);
#endif
static SIGRETTYPE
take_signal (int signum)
{
if (signum >= 0 && signum < NSIG)
{
SCM cell = SCM_VECTOR_REF(signal_handler_cells, signum);
SCM handler = SCM_VECTOR_REF(signal_cell_handlers, signum);
SCM thread = SCM_VECTOR_REF(signal_handler_threads, signum);
scm_root_state *root = scm_i_thread_root (thread);
if (SCM_CONSP (cell))
{
SCM_SETCAR (cell, handler);
root->pending_asyncs = 1;
}
}
#ifndef HAVE_SIGACTION
signal (signum, take_signal);
#endif
}
SCM
scm_sigaction (SCM signum, SCM handler, SCM flags)
{
return scm_sigaction_for_thread (signum, handler, flags, SCM_UNDEFINED);
}
static SCM
close_1 (SCM proc, SCM arg)
{
return scm_primitive_eval_x (scm_list_3 (scm_sym_lambda, SCM_EOL,
scm_list_2 (proc, arg)));
}
/* Make sure that signal SIGNUM can be delivered to THREAD, using
HANDLER. THREAD and HANDLER must either both be non-#f (which
means install the handler), or both #f (which means deinstall an
existing handler).
*/
struct install_handler_data {
int signum;
SCM thread;
SCM handler;
};
static SCM
scm_delq_spine_x (SCM cell, SCM list)
{
SCM s = list, prev = SCM_BOOL_F;
while (!SCM_EQ_P (cell, s))
{
if (SCM_NULLP (s))
return list;
prev = s;
s = SCM_CDR (s);
}
if (SCM_FALSEP (prev))
return SCM_CDR (cell);
else
{
SCM_SETCDR (prev, SCM_CDR (cell));
return list;
}
}
static void *
really_install_handler (void *data)
{
struct install_handler_data *args = data;
int signum = args->signum;
SCM thread = args->thread;
SCM handler = args->handler;
SCM cell;
SCM old_thread;
/* The following modifications are done while signals can be
delivered. That is not a real problem since the signal handler
will only touch the car of the handler cell and set the
pending_asyncs trigger of a thread. While the data structures
are in flux, the signal handler might store the wrong handler in
the cell, or set pending_asyncs of the wrong thread. We fix this
at the end by making sure that the cell has the right handler in
it, if any, and that pending_asyncs is set for the new thread.
*/
/* Make sure we have a cell. */
cell = SCM_VECTOR_REF (signal_handler_cells, signum);
if (SCM_FALSEP (cell))
{
cell = scm_cons (SCM_BOOL_F, SCM_EOL);
SCM_VECTOR_SET (signal_handler_cells, signum, cell);
}
/* Make sure it is queued for the right thread. */
old_thread = SCM_VECTOR_REF (signal_handler_threads, signum);
if (!SCM_EQ_P (thread, old_thread))
{
scm_root_state *r;
if (!SCM_FALSEP (old_thread))
{
r = scm_i_thread_root (old_thread);
r->signal_asyncs = scm_delq_spine_x (cell, r->signal_asyncs);
}
if (!SCM_FALSEP (thread))
{
r = scm_i_thread_root (thread);
SCM_SETCDR (cell, r->signal_asyncs);
r->signal_asyncs = cell;
/* Set pending_asyncs just in case. A signal that is
delivered while we modify the data structures here might set
pending_asyncs of old_thread. */
r->pending_asyncs = 1;
}
SCM_VECTOR_SET (signal_handler_threads, signum, thread);
}
/* Set the new handler. */
if (SCM_FALSEP (handler))
{
SCM_VECTOR_SET (*signal_handlers, signum, SCM_BOOL_F);
SCM_VECTOR_SET (signal_cell_handlers, signum, SCM_BOOL_F);
}
else
{
SCM_VECTOR_SET (*signal_handlers, signum, handler);
SCM_VECTOR_SET (signal_cell_handlers, signum,
close_1 (handler, scm_int2num (signum)));
}
/* Now fix up the cell. It might contain the old handler but since
it is now queued for the new thread, we must make sure that the
new handler is run. Any signal that is delivered during the
following code will install the new handler, so we have no
problem.
*/
if (!SCM_FALSEP (SCM_CAR (cell)))
SCM_SETCAR (cell, SCM_VECTOR_REF (signal_cell_handlers, signum));
/* Phfew. That should be it. */
return NULL;
}
static void
install_handler (int signum, SCM thread, SCM handler)
{
/* We block asyncs while installing the handler. It would be safe
to leave them on, but we might run the wrong handler should a
signal be delivered.
*/
struct install_handler_data args;
args.signum = signum;
args.thread = thread;
args.handler = handler;
scm_c_call_with_blocked_asyncs (really_install_handler, &args);
}
/* user interface for installation of signal handlers. */
SCM_DEFINE (scm_sigaction_for_thread, "sigaction", 1, 3, 0,
(SCM signum, SCM handler, SCM flags, SCM thread),
"Install or report the signal handler for a specified signal.\n\n"
"@var{signum} is the signal number, which can be specified using the value\n"
"of variables such as @code{SIGINT}.\n\n"
"If @var{handler} is omitted, @code{sigaction} returns a pair: the\n"
"CAR is the current\n"
"signal hander, which will be either an integer with the value @code{SIG_DFL}\n"
"(default action) or @code{SIG_IGN} (ignore), or the Scheme procedure which\n"
"handles the signal, or @code{#f} if a non-Scheme procedure handles the\n"
"signal. The CDR contains the current @code{sigaction} flags for the handler.\n\n"
"If @var{handler} is provided, it is installed as the new handler for\n"
"@var{signum}. @var{handler} can be a Scheme procedure taking one\n"
"argument, or the value of @code{SIG_DFL} (default action) or\n"
"@code{SIG_IGN} (ignore), or @code{#f} to restore whatever signal handler\n"
"was installed before @code{sigaction} was first used. When\n"
"a scheme procedure has been specified, that procedure will run\n"
"in the given @var{thread}. When no thread has been given, the\n"
"thread that made this call to @code{sigaction} is used.\n"
"Flags can "
"optionally be specified for the new handler (@code{SA_RESTART} will\n"
"always be added if it's available and the system is using restartable\n"
"system calls.) The return value is a pair with information about the\n"
"old handler as described above.\n\n"
"This interface does not provide access to the \"signal blocking\"\n"
"facility. Maybe this is not needed, since the thread support may\n"
"provide solutions to the problem of consistent access to data\n"
"structures.")
#define FUNC_NAME s_scm_sigaction_for_thread
{
int csig;
#ifdef HAVE_SIGACTION
struct sigaction action;
struct sigaction old_action;
#else
SIGRETTYPE (* chandler) (int) = SIG_DFL;
SIGRETTYPE (* old_chandler) (int);
#endif
int query_only = 0;
int save_handler = 0;
SCM old_handler;
SCM_VALIDATE_INUM_COPY (1, signum, csig);
if (csig < 0 || csig > NSIG)
SCM_OUT_OF_RANGE (1, signum);
#if defined(HAVE_SIGACTION)
#if defined(SA_RESTART) && defined(HAVE_RESTARTABLE_SYSCALLS)
/* don't allow SA_RESTART to be omitted if HAVE_RESTARTABLE_SYSCALLS
is defined, since libguile would be likely to produce spurious
EINTR errors. */
action.sa_flags = SA_RESTART;
#else
action.sa_flags = 0;
#endif
if (!SCM_UNBNDP (flags))
{
SCM_VALIDATE_INUM (3, flags);
action.sa_flags |= SCM_INUM (flags);
}
sigemptyset (&action.sa_mask);
#endif
if (SCM_UNBNDP (thread))
thread = scm_current_thread ();
else
{
SCM_VALIDATE_THREAD (4, thread);
if (scm_c_thread_exited_p (thread))
SCM_MISC_ERROR ("thread has already exited", SCM_EOL);
}
SCM_DEFER_INTS;
old_handler = SCM_VECTOR_REF(*signal_handlers, csig);
if (SCM_UNBNDP (handler))
query_only = 1;
else if (SCM_EQ_P (scm_integer_p (handler), SCM_BOOL_T))
{
if (SCM_NUM2LONG (2, handler) == (long) SIG_DFL
|| SCM_NUM2LONG (2, handler) == (long) SIG_IGN)
{
#ifdef HAVE_SIGACTION
action.sa_handler = (SIGRETTYPE (*) (int)) SCM_INUM (handler);
#else
chandler = (SIGRETTYPE (*) (int)) SCM_INUM (handler);
#endif
install_handler (csig, SCM_BOOL_F, SCM_BOOL_F);
}
else
SCM_OUT_OF_RANGE (2, handler);
}
else if (SCM_FALSEP (handler))
{
/* restore the default handler. */
#ifdef HAVE_SIGACTION
if (orig_handlers[csig].sa_handler == SIG_ERR)
query_only = 1;
else
{
action = orig_handlers[csig];
orig_handlers[csig].sa_handler = SIG_ERR;
install_handler (csig, SCM_BOOL_F, SCM_BOOL_F);
}
#else
if (orig_handlers[csig] == SIG_ERR)
query_only = 1;
else
{
chandler = orig_handlers[csig];
orig_handlers[csig] = SIG_ERR;
install_handler (csig, SCM_BOOL_F, SCM_BOOL_F);
}
#endif
}
else
{
SCM_VALIDATE_NIM (2, handler);
#ifdef HAVE_SIGACTION
action.sa_handler = take_signal;
if (orig_handlers[csig].sa_handler == SIG_ERR)
save_handler = 1;
#else
chandler = take_signal;
if (orig_handlers[csig] == SIG_ERR)
save_handler = 1;
#endif
install_handler (csig, thread, handler);
}
/* XXX - Silently ignore setting handlers for `program error signals'
because they can't currently be handled by Scheme code.
*/
switch (csig)
{
/* This list of program error signals is from the GNU Libc
Reference Manual */
case SIGFPE:
case SIGILL:
case SIGSEGV:
#ifdef SIGBUS
case SIGBUS:
#endif
case SIGABRT:
#if defined(SIGIOT) && (SIGIOT != SIGABRT)
case SIGIOT:
#endif
#ifdef SIGTRAP
case SIGTRAP:
#endif
#ifdef SIGEMT
case SIGEMT:
#endif
#ifdef SIGSYS
case SIGSYS:
#endif
query_only = 1;
}
#ifdef HAVE_SIGACTION
if (query_only)
{
if (sigaction (csig, 0, &old_action) == -1)
SCM_SYSERROR;
}
else
{
if (sigaction (csig, &action , &old_action) == -1)
SCM_SYSERROR;
if (save_handler)
orig_handlers[csig] = old_action;
}
if (old_action.sa_handler == SIG_DFL || old_action.sa_handler == SIG_IGN)
old_handler = scm_long2num ((long) old_action.sa_handler);
SCM_ALLOW_INTS;
return scm_cons (old_handler, SCM_MAKINUM (old_action.sa_flags));
#else
if (query_only)
{
if ((old_chandler = signal (csig, SIG_IGN)) == SIG_ERR)
SCM_SYSERROR;
if (signal (csig, old_chandler) == SIG_ERR)
SCM_SYSERROR;
}
else
{
if ((old_chandler = signal (csig, chandler)) == SIG_ERR)
SCM_SYSERROR;
if (save_handler)
orig_handlers[csig] = old_chandler;
}
if (old_chandler == SIG_DFL || old_chandler == SIG_IGN)
old_handler = scm_long2num ((long) old_chandler);
SCM_ALLOW_INTS;
return scm_cons (old_handler, SCM_MAKINUM (0));
#endif
}
#undef FUNC_NAME
SCM_DEFINE (scm_restore_signals, "restore-signals", 0, 0, 0,
(void),
"Return all signal handlers to the values they had before any call to\n"
"@code{sigaction} was made. The return value is unspecified.")
#define FUNC_NAME s_scm_restore_signals
{
int i;
for (i = 0; i < NSIG; i++)
{
#ifdef HAVE_SIGACTION
if (orig_handlers[i].sa_handler != SIG_ERR)
{
if (sigaction (i, &orig_handlers[i], NULL) == -1)
SCM_SYSERROR;
orig_handlers[i].sa_handler = SIG_ERR;
SCM_VECTOR_SET (*signal_handlers, i, SCM_BOOL_F);
}
#else
if (orig_handlers[i] != SIG_ERR)
{
if (signal (i, orig_handlers[i]) == SIG_ERR)
SCM_SYSERROR;
orig_handlers[i] = SIG_ERR;
SCM_VECTOR_SET (*signal_handlers, i, SCM_BOOL_F);
}
#endif
}
return SCM_UNSPECIFIED;
}
#undef FUNC_NAME
SCM_DEFINE (scm_alarm, "alarm", 1, 0, 0,
(SCM i),
"Set a timer to raise a @code{SIGALRM} signal after the specified\n"
"number of seconds (an integer). It's advisable to install a signal\n"
"handler for\n"
"@code{SIGALRM} beforehand, since the default action is to terminate\n"
"the process.\n\n"
"The return value indicates the time remaining for the previous alarm,\n"
"if any. The new value replaces the previous alarm. If there was\n"
"no previous alarm, the return value is zero.")
#define FUNC_NAME s_scm_alarm
{
unsigned int j;
SCM_VALIDATE_INUM (1, i);
j = alarm (SCM_INUM (i));
return SCM_MAKINUM (j);
}
#undef FUNC_NAME
#ifdef HAVE_SETITIMER
SCM_DEFINE (scm_setitimer, "setitimer", 5, 0, 0,
(SCM which_timer,
SCM interval_seconds, SCM interval_microseconds,
SCM value_seconds, SCM value_microseconds),
"Set the timer specified by @var{which_timer} according to the given\n"
"@var{interval_seconds}, @var{interval_microseconds},\n"
"@var{value_seconds}, and @var{value_microseconds} values.\n"
"\n"
"Return information about the timer's previous setting."
"\n"
"Errors are handled as described in the guile info pages under ``POSIX\n"
"Interface Conventions''.\n"
"\n"
"The timers available are: @code{ITIMER_REAL}, @code{ITIMER_VIRTUAL},\n"
"and @code{ITIMER_PROF}.\n"
"\n"
"The return value will be a list of two cons pairs representing the\n"
"current state of the given timer. The first pair is the seconds and\n"
"microseconds of the timer @code{it_interval}, and the second pair is\n"
"the seconds and microseconds of the timer @code{it_value}.")
#define FUNC_NAME s_scm_setitimer
{
int rv;
int c_which_timer;
struct itimerval new_timer;
struct itimerval old_timer;
c_which_timer = SCM_NUM2INT(1, which_timer);
new_timer.it_interval.tv_sec = SCM_NUM2LONG(2, interval_seconds);
new_timer.it_interval.tv_usec = SCM_NUM2LONG(3, interval_microseconds);
new_timer.it_value.tv_sec = SCM_NUM2LONG(4, value_seconds);
new_timer.it_value.tv_usec = SCM_NUM2LONG(5, value_microseconds);
SCM_SYSCALL(rv = setitimer(c_which_timer, &new_timer, &old_timer));
if(rv != 0)
SCM_SYSERROR;
return scm_list_2(scm_cons(scm_long2num(old_timer.it_interval.tv_sec),
scm_long2num(old_timer.it_interval.tv_usec)),
scm_cons(scm_long2num(old_timer.it_value.tv_sec),
scm_long2num(old_timer.it_value.tv_usec)));
}
#undef FUNC_NAME
#endif /* HAVE_SETITIMER */
#ifdef HAVE_GETITIMER
SCM_DEFINE (scm_getitimer, "getitimer", 1, 0, 0,
(SCM which_timer),
"Return information about the timer specified by @var{which_timer}"
"\n"
"Errors are handled as described in the guile info pages under ``POSIX\n"
"Interface Conventions''.\n"
"\n"
"The timers available are: @code{ITIMER_REAL}, @code{ITIMER_VIRTUAL},\n"
"and @code{ITIMER_PROF}.\n"
"\n"
"The return value will be a list of two cons pairs representing the\n"
"current state of the given timer. The first pair is the seconds and\n"
"microseconds of the timer @code{it_interval}, and the second pair is\n"
"the seconds and microseconds of the timer @code{it_value}.")
#define FUNC_NAME s_scm_getitimer
{
int rv;
int c_which_timer;
struct itimerval old_timer;
c_which_timer = SCM_NUM2INT(1, which_timer);
SCM_SYSCALL(rv = getitimer(c_which_timer, &old_timer));
if(rv != 0)
SCM_SYSERROR;
return scm_list_2(scm_cons(scm_long2num(old_timer.it_interval.tv_sec),
scm_long2num(old_timer.it_interval.tv_usec)),
scm_cons(scm_long2num(old_timer.it_value.tv_sec),
scm_long2num(old_timer.it_value.tv_usec)));
}
#undef FUNC_NAME
#endif /* HAVE_GETITIMER */
#ifdef HAVE_PAUSE
SCM_DEFINE (scm_pause, "pause", 0, 0, 0,
(),
"Pause the current process (thread?) until a signal arrives whose\n"
"action is to either terminate the current process or invoke a\n"
"handler procedure. The return value is unspecified.")
#define FUNC_NAME s_scm_pause
{
pause ();
return SCM_UNSPECIFIED;
}
#undef FUNC_NAME
#endif
SCM_DEFINE (scm_sleep, "sleep", 1, 0, 0,
(SCM i),
"Wait for the given number of seconds (an integer) or until a signal\n"
"arrives. The return value is zero if the time elapses or the number\n"
"of seconds remaining otherwise.")
#define FUNC_NAME s_scm_sleep
{
unsigned long j;
SCM_VALIDATE_INUM_MIN (1, i,0);
j = scm_thread_sleep (SCM_INUM(i));
return scm_ulong2num (j);
}
#undef FUNC_NAME
SCM_DEFINE (scm_usleep, "usleep", 1, 0, 0,
(SCM i),
"Sleep for I microseconds. @code{usleep} is not available on\n"
"all platforms.")
#define FUNC_NAME s_scm_usleep
{
unsigned long j;
SCM_VALIDATE_INUM_MIN (1, i,0);
j = scm_thread_usleep (SCM_INUM (i));
return scm_ulong2num (j);
}
#undef FUNC_NAME
SCM_DEFINE (scm_raise, "raise", 1, 0, 0,
(SCM sig),
"Sends a specified signal @var{sig} to the current process, where\n"
"@var{sig} is as described for the kill procedure.")
#define FUNC_NAME s_scm_raise
{
SCM_VALIDATE_INUM (1, sig);
SCM_DEFER_INTS;
if (kill (getpid (), (int) SCM_INUM (sig)) != 0)
SCM_SYSERROR;
SCM_ALLOW_INTS;
return SCM_UNSPECIFIED;
}
#undef FUNC_NAME
void
scm_init_scmsigs ()
{
int i;
signal_handlers =
SCM_VARIABLE_LOC (scm_c_define ("signal-handlers",
scm_c_make_vector (NSIG, SCM_BOOL_F)));
signal_handler_cells =
scm_permanent_object (scm_c_make_vector (NSIG, SCM_BOOL_F));
signal_cell_handlers =
scm_permanent_object (scm_c_make_vector (NSIG, SCM_BOOL_F));
signal_handler_threads =
scm_permanent_object (scm_c_make_vector (NSIG, SCM_BOOL_F));
for (i = 0; i < NSIG; i++)
{
#ifdef HAVE_SIGACTION
orig_handlers[i].sa_handler = SIG_ERR;
#else
orig_handlers[i] = SIG_ERR;
#endif
#ifdef HAVE_RESTARTABLE_SYSCALLS
/* If HAVE_RESTARTABLE_SYSCALLS is defined, it's important that
signals really are restartable. don't rely on the same
run-time that configure got: reset the default for every signal.
*/
#ifdef HAVE_SIGINTERRUPT
siginterrupt (i, 0);
#elif defined(SA_RESTART)
{
struct sigaction action;
sigaction (i, NULL, &action);
if (!(action.sa_flags & SA_RESTART))
{
action.sa_flags |= SA_RESTART;
sigaction (i, &action, NULL);
}
}
#endif
/* if neither siginterrupt nor SA_RESTART are available we may
as well assume that signals are always restartable. */
#endif
}
scm_c_define ("NSIG", scm_long2num (NSIG));
scm_c_define ("SIG_IGN", scm_long2num ((long) SIG_IGN));
scm_c_define ("SIG_DFL", scm_long2num ((long) SIG_DFL));
#ifdef SA_NOCLDSTOP
scm_c_define ("SA_NOCLDSTOP", scm_long2num (SA_NOCLDSTOP));
#endif
#ifdef SA_RESTART
scm_c_define ("SA_RESTART", scm_long2num (SA_RESTART));
#endif
#if defined(HAVE_SETITIMER) || defined(HAVE_GETITIMER)
/* Stuff needed by setitimer and getitimer. */
scm_c_define ("ITIMER_REAL", SCM_MAKINUM (ITIMER_REAL));
scm_c_define ("ITIMER_VIRTUAL", SCM_MAKINUM (ITIMER_VIRTUAL));
scm_c_define ("ITIMER_PROF", SCM_MAKINUM (ITIMER_PROF));
#endif /* defined(HAVE_SETITIMER) || defined(HAVE_GETITIMER) */
#include "libguile/scmsigs.x"
}
/*
Local Variables:
c-file-style: "gnu"
End:
*/