scsh-0.6/scsh/sighandlers1.c

78 lines
2.4 KiB
C

/* Need to define sig2interrupt vector.
** Interrupt-system mutators should probably hold interrupts while they
** operate.
*/
#include <unistd.h>
#include <sys/types.h>
#include <signal.h>
#include <stdio.h>
#include "cstuff.h"
/* Make sure our exports match up w/the implementation: */
#include "sighandlers1.h"
/* Import the OS-dependent set of signals and their translations
** to S48 vm interrupts.
*/
#include "signals1.h"
extern int errno;
/* Translate Unix signal numbers to S48 interrupt numbers. */
s48_value sig2interrupt(s48_value _signal)
{
int signal = s48_extract_fixnum (_signal);
return s48_enter_fixnum (( signal < 0 || signal > max_sig ) ? -1 :
sig2int[signal]);
}
/* This guy is responsible for making the default action for a
** Unix signal happen. Because S48's signal handler system is
** interposed between delivery-to-the-process and
** delivery-to-the-scheme-handler, when the user sets a signal
** handler to default, we install a Scheme proc that calls this
** guy, instead of just slapping a SIGDFL in as the Unix handler.
** We only have to do this for signals whose default isn't "ignore," i.e.:
** Posix: SIGALRM SIGHUP SIGINT SIGQUIT SIGTERM SIGUSR1 SIGUSR2
** Non-Posix: SIGINFO SIGPOLL SIGPROF SIGVTALRM SIGXCPU SIGXFSZ SIGIO
** This way, the S48 signal-blocking mechanism can work.
**
** Weird, I know.
*/
s48_value do_default_sigaction(s48_value _signal)
{
sigset_t ss, old_ss;
struct sigaction default_action, old_action;
int signal = s48_extract_fixnum(_signal);
/* fprintf(stderr, "Doing default for signal %d\n", signal); */
sigfillset(&ss); /* Block everyone. */
sigprocmask(SIG_SETMASK, &ss, &old_ss);
default_action.sa_handler = SIG_DFL; /* Set for default. */
sigemptyset(&default_action.sa_mask);
default_action.sa_flags = 0;
sigaction(signal, &default_action, &old_action);
raise(signal); /* Raise the signal. */
sigdelset(&ss, signal);
sigprocmask(SIG_SETMASK, &ss, 0); /* Handle it. */
/* Most likely, we'll never get to here, as the default for
** the signals we're handling is "terminate," but we'll play it safe.
*/
sigaction(signal, &old_action, 0); /* Restore old handler, */
sigprocmask(SIG_SETMASK, &old_ss, 0); /* and mask. */
return S48_UNSPECIFIC;
}
s48_value s48_init_sighandlers(void)
{
S48_EXPORT_FUNCTION(sig2interrupt);
S48_EXPORT_FUNCTION(do_default_sigaction);
return S48_UNSPECIFIC;
}