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// Userspace emulation of `raise` and `signal`.
//
// WebAssembly doesn't support asynchronous signal delivery, so we can't
// support it in WASI libc. But we can make things like `raise` work.
#define _WASI_EMULATED_SIGNAL
#define _ALL_SOURCE
#define _GNU_SOURCE
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <assert.h>
void __SIG_IGN(int sig) {
// do nothing
}
_Noreturn
void __SIG_ERR(int sig) {
__builtin_trap();
}
_Noreturn
static void core_handler(int sig) {
fprintf(stderr, "Program received fatal signal: %s\n", strsignal(sig));
abort();
}
_Noreturn
static void terminate_handler(int sig) {
fprintf(stderr, "Program received termination signal: %s\n", strsignal(sig));
abort();
}
_Noreturn
static void stop_handler(int sig) {
fprintf(stderr, "Program received stop signal: %s\n", strsignal(sig));
abort();
}
static void continue_handler(int sig) {
// do nothing
}
static const sighandler_t default_handlers[_NSIG] = {
// Default behavior: "core".
[SIGABRT] = core_handler,
[SIGBUS] = core_handler,
[SIGFPE] = core_handler,
[SIGILL] = core_handler,
#if SIGIOT != SIGABRT
[SIGIOT] = core_handler,
#endif
[SIGQUIT] = core_handler,
[SIGSEGV] = core_handler,
[SIGSYS] = core_handler,
[SIGTRAP] = core_handler,
[SIGXCPU] = core_handler,
[SIGXFSZ] = core_handler,
#if defined(SIGUNUSED) && SIGUNUSED != SIGSYS
[SIGUNUSED] = core_handler,
#endif
// Default behavior: ignore.
[SIGCHLD] = SIG_IGN,
#if defined(SIGCLD) && SIGCLD != SIGCHLD
[SIGCLD] = SIG_IGN,
#endif
[SIGURG] = SIG_IGN,
[SIGWINCH] = SIG_IGN,
// Default behavior: "continue".
[SIGCONT] = continue_handler,
// Default behavior: "stop".
[SIGSTOP] = stop_handler,
[SIGTSTP] = stop_handler,
[SIGTTIN] = stop_handler,
[SIGTTOU] = stop_handler,
// Default behavior: "terminate".
[SIGHUP] = terminate_handler,
[SIGINT] = terminate_handler,
[SIGKILL] = terminate_handler,
[SIGUSR1] = terminate_handler,
[SIGUSR2] = terminate_handler,
[SIGPIPE] = terminate_handler,
[SIGALRM] = terminate_handler,
[SIGTERM] = terminate_handler,
[SIGSTKFLT] = terminate_handler,
[SIGVTALRM] = terminate_handler,
[SIGPROF] = terminate_handler,
[SIGIO] = terminate_handler,
#if SIGPOLL != SIGIO
[SIGPOLL] = terminate_handler,
#endif
[SIGPWR] = terminate_handler,
};
static sighandler_t handlers[_NSIG];
int raise(int sig) {
if (sig < 0 || sig >= _NSIG) {
errno = EINVAL;
return -1;
}
sighandler_t func = handlers[sig];
if (func == NULL) {
default_handlers[sig](sig);
} else {
func(sig);
}
return 0;
}
void (*signal(int sig, void (*func)(int)))(int) {
assert(SIG_DFL == NULL);
if (sig < 0 || sig >= _NSIG) {
errno = EINVAL;
return SIG_ERR;
}
if (sig == SIGKILL || sig == SIGSTOP) {
errno = EINVAL;
return SIG_ERR;
}
sighandler_t old = handlers[sig];
handlers[sig] = func;
return old;
}
extern __typeof(signal) bsd_signal __attribute__((weak, alias("signal")));
extern __typeof(signal) __sysv_signal __attribute__((weak, alias("signal")));
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