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ocaml/runtime/signals.c

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/**************************************************************************/
/* */
/* OCaml */
/* */
/* Xavier Leroy and Damien Doligez, INRIA Rocquencourt */
/* */
/* Copyright 1996 Institut National de Recherche en Informatique et */
/* en Automatique. */
/* */
/* All rights reserved. This file is distributed under the terms of */
/* the GNU Lesser General Public License version 2.1, with the */
/* special exception on linking described in the file LICENSE. */
/* */
/**************************************************************************/
#define CAML_INTERNALS
/* Signal handling, code common to the bytecode and native systems */
#include <signal.h>
#include <errno.h>
#include "caml/alloc.h"
#include "caml/callback.h"
#include "caml/config.h"
#include "caml/fail.h"
#include "caml/memory.h"
#include "caml/misc.h"
#include "caml/mlvalues.h"
#include "caml/roots.h"
#include "caml/signals.h"
#include "caml/signals_machdep.h"
#include "caml/sys.h"
#include "caml/memprof.h"
#include "caml/finalise.h"
#ifndef NSIG
#define NSIG 64
#endif
CAMLexport int volatile caml_something_to_do = 0;
/* The set of pending signals (received but not yet processed) */
static intnat volatile signals_are_pending = 0;
CAMLexport intnat volatile caml_pending_signals[NSIG];
#ifdef POSIX_SIGNALS
/* This wrapper makes [sigprocmask] compatible with
[pthread_sigmask]. Indeed, the latter returns the error code while
the former sets [errno].
*/
static int sigprocmask_wrapper(int how, const sigset_t *set, sigset_t *oldset) {
if(sigprocmask(how, set, oldset) != 0) return errno;
else return 0;
}
CAMLexport int (*caml_sigmask_hook)(int, const sigset_t *, sigset_t *)
= sigprocmask_wrapper;
#endif
static int check_for_pending_signals(void)
{
int i;
for (i = 0; i < NSIG; i++) {
if (caml_pending_signals[i]) return 1;
}
return 0;
}
/* Execute all pending signals */
CAMLexport value caml_process_pending_signals_exn(void)
{
int i;
#ifdef POSIX_SIGNALS
sigset_t set;
#endif
if(!signals_are_pending)
return Val_unit;
signals_are_pending = 0;
/* Check that there is indeed a pending signal before issuing the
syscall in [caml_sigmask_hook]. */
if (!check_for_pending_signals())
return Val_unit;
#ifdef POSIX_SIGNALS
caml_sigmask_hook(/* dummy */ SIG_BLOCK, NULL, &set);
#endif
for (i = 0; i < NSIG; i++) {
if (!caml_pending_signals[i])
continue;
#ifdef POSIX_SIGNALS
if(sigismember(&set, i))
continue;
#endif
caml_pending_signals[i] = 0;
{
value exn = caml_execute_signal_exn(i, 0);
if (Is_exception_result(exn)) return exn;
}
}
return Val_unit;
}
CAMLno_tsan /* When called from [caml_record_signal], these memory
accesses may not be synchronized. */
void caml_set_action_pending(void)
{
caml_something_to_do = 1;
/* When this function is called without [caml_c_call] (e.g., in
[caml_modify]), this is only moderately effective on ports that cache
[Caml_state->young_limit] in a register, so it may take a while before the
register is reloaded from [Caml_state->young_limit]. */
Caml_state->young_limit = Caml_state->young_alloc_end;
}
/* Record the delivery of a signal, and arrange for it to be processed
as soon as possible:
- via caml_something_to_do, processed in
caml_process_pending_actions_exn.
- by playing with the allocation limit, processed in
caml_garbage_collection and caml_alloc_small_dispatch.
*/
CAMLno_tsan
CAMLexport void caml_record_signal(int signal_number)
{
caml_pending_signals[signal_number] = 1;
signals_are_pending = 1;
caml_set_action_pending();
}
/* Management of blocking sections. */
static void caml_enter_blocking_section_default(void)
{
}
static void caml_leave_blocking_section_default(void)
{
}
CAMLexport void (*caml_enter_blocking_section_hook)(void) =
caml_enter_blocking_section_default;
CAMLexport void (*caml_leave_blocking_section_hook)(void) =
caml_leave_blocking_section_default;
CAMLno_tsan /* The read of [caml_something_to_do] is not synchronized. */
CAMLexport void caml_enter_blocking_section(void)
{
while (1){
/* Process all pending signals now */
caml_raise_if_exception(caml_process_pending_signals_exn());
caml_enter_blocking_section_hook ();
/* Check again for pending signals.
If none, done; otherwise, try again */
if (! signals_are_pending) break;
caml_leave_blocking_section_hook ();
}
}
CAMLexport void caml_enter_blocking_section_no_pending(void)
{
caml_enter_blocking_section_hook ();
}
CAMLexport void caml_leave_blocking_section(void)
{
int saved_errno;
/* Save the value of errno (PR#5982). */
saved_errno = errno;
caml_leave_blocking_section_hook ();
/* Some other thread may have switched
[signals_are_pending] to 0 even though there are still
pending signals (masked in the other thread). To handle this
case, we force re-examination of all signals by setting it back
to 1.
Another case where this is necessary (even in a single threaded
setting) is when the blocking section unmasks a pending signal:
If the signal is pending and masked but has already been
examined by [caml_process_pending_signals_exn], then
[signals_are_pending] is 0 but the signal needs to be
handled at this point. */
if (check_for_pending_signals()) {
signals_are_pending = 1;
caml_set_action_pending();
}
errno = saved_errno;
}
/* Execute a signal handler immediately */
static value caml_signal_handlers = 0;
value caml_execute_signal_exn(int signal_number, int in_signal_handler)
{
value res;
value handler;
#ifdef POSIX_SIGNALS
sigset_t nsigs, sigs;
/* Block the signal before executing the handler, and record in sigs
the original signal mask */
sigemptyset(&nsigs);
sigaddset(&nsigs, signal_number);
caml_sigmask_hook(SIG_BLOCK, &nsigs, &sigs);
#endif
handler = Field(caml_signal_handlers, signal_number);
res = caml_callback_exn(
handler,
Val_int(caml_rev_convert_signal_number(signal_number)));
#ifdef POSIX_SIGNALS
if (! in_signal_handler) {
/* Restore the original signal mask */
caml_sigmask_hook(SIG_SETMASK, &sigs, NULL);
} else if (Is_exception_result(res)) {
/* Restore the original signal mask and unblock the signal itself */
sigdelset(&sigs, signal_number);
caml_sigmask_hook(SIG_SETMASK, &sigs, NULL);
}
#endif
return res;
}
void caml_update_young_limit (void)
{
/* The minor heap grows downwards. The first trigger is the largest one. */
Caml_state->young_limit =
caml_memprof_young_trigger < Caml_state->young_trigger ?
Caml_state->young_trigger : caml_memprof_young_trigger;
if(caml_something_to_do)
Caml_state->young_limit = Caml_state->young_alloc_end;
}
/* Arrange for a garbage collection to be performed as soon as possible */
void caml_request_major_slice (void)
{
Caml_state->requested_major_slice = 1;
caml_set_action_pending();
}
void caml_request_minor_gc (void)
{
Caml_state->requested_minor_gc = 1;
caml_set_action_pending();
}
value caml_do_pending_actions_exn(void)
{
value exn;
caml_something_to_do = 0;
// Do any pending minor collection or major slice
caml_check_urgent_gc(Val_unit);
caml_update_young_limit();
// Call signal handlers first
exn = caml_process_pending_signals_exn();
if (Is_exception_result(exn)) goto exception;
// Call memprof callbacks
exn = caml_memprof_handle_postponed_exn();
if (Is_exception_result(exn)) goto exception;
// Call finalisers
exn = caml_final_do_calls_exn();
if (Is_exception_result(exn)) goto exception;
return Val_unit;
exception:
/* If an exception is raised during an asynchronous callback, then
it might be the case that we did not run all the callbacks we
needed. Therefore, we set [caml_something_to_do] again in order
to force reexamination of callbacks. */
caml_set_action_pending();
return exn;
}
CAMLno_tsan /* The access to [caml_something_to_do] is not synchronized. */
Caml_inline value process_pending_actions_with_root_exn(value extra_root)
{
if (caml_something_to_do) {
CAMLparam1(extra_root);
value exn = caml_do_pending_actions_exn();
if (Is_exception_result(exn))
CAMLreturn(exn);
CAMLdrop;
}
return extra_root;
}
CAMLno_tsan /* The access to [caml_something_to_do] is not synchronized. */
int caml_check_pending_actions()
{
return caml_something_to_do;
}
value caml_process_pending_actions_with_root(value extra_root)
{
value res = process_pending_actions_with_root_exn(extra_root);
return caml_raise_if_exception(res);
}
CAMLexport value caml_process_pending_actions_exn(void)
{
return process_pending_actions_with_root_exn(Val_unit);
}
CAMLexport void caml_process_pending_actions(void)
{
value exn = process_pending_actions_with_root_exn(Val_unit);
caml_raise_if_exception(exn);
}
/* OS-independent numbering of signals */
#ifndef SIGABRT
#define SIGABRT -1
#endif
#ifndef SIGALRM
#define SIGALRM -1
#endif
#ifndef SIGFPE
#define SIGFPE -1
#endif
#ifndef SIGHUP
#define SIGHUP -1
#endif
#ifndef SIGILL
#define SIGILL -1
#endif
#ifndef SIGINT
#define SIGINT -1
#endif
#ifndef SIGKILL
#define SIGKILL -1
#endif
#ifndef SIGPIPE
#define SIGPIPE -1
#endif
#ifndef SIGQUIT
#define SIGQUIT -1
#endif
#ifndef SIGSEGV
#define SIGSEGV -1
#endif
#ifndef SIGTERM
#define SIGTERM -1
#endif
#ifndef SIGUSR1
#define SIGUSR1 -1
#endif
#ifndef SIGUSR2
#define SIGUSR2 -1
#endif
#ifndef SIGCHLD
#define SIGCHLD -1
#endif
#ifndef SIGCONT
#define SIGCONT -1
#endif
#ifndef SIGSTOP
#define SIGSTOP -1
#endif
#ifndef SIGTSTP
#define SIGTSTP -1
#endif
#ifndef SIGTTIN
#define SIGTTIN -1
#endif
#ifndef SIGTTOU
#define SIGTTOU -1
#endif
#ifndef SIGVTALRM
#define SIGVTALRM -1
#endif
#ifndef SIGPROF
#define SIGPROF -1
#endif
#ifndef SIGBUS
#define SIGBUS -1
#endif
#ifndef SIGPOLL
#define SIGPOLL -1
#endif
#ifndef SIGSYS
#define SIGSYS -1
#endif
#ifndef SIGTRAP
#define SIGTRAP -1
#endif
#ifndef SIGURG
#define SIGURG -1
#endif
#ifndef SIGXCPU
#define SIGXCPU -1
#endif
#ifndef SIGXFSZ
#define SIGXFSZ -1
#endif
static int posix_signals[] = {
SIGABRT, SIGALRM, SIGFPE, SIGHUP, SIGILL, SIGINT, SIGKILL, SIGPIPE,
SIGQUIT, SIGSEGV, SIGTERM, SIGUSR1, SIGUSR2, SIGCHLD, SIGCONT,
SIGSTOP, SIGTSTP, SIGTTIN, SIGTTOU, SIGVTALRM, SIGPROF, SIGBUS,
SIGPOLL, SIGSYS, SIGTRAP, SIGURG, SIGXCPU, SIGXFSZ
};
CAMLexport int caml_convert_signal_number(int signo)
{
if (signo < 0 && signo >= -(sizeof(posix_signals) / sizeof(int)))
return posix_signals[-signo-1];
else
return signo;
}
CAMLexport int caml_rev_convert_signal_number(int signo)
{
int i;
for (i = 0; i < sizeof(posix_signals) / sizeof(int); i++)
if (signo == posix_signals[i]) return -i - 1;
return signo;
}
/* Installation of a signal handler (as per [Sys.signal]) */
CAMLprim value caml_install_signal_handler(value signal_number, value action)
{
CAMLparam2 (signal_number, action);
CAMLlocal1 (res);
int sig, act, oldact;
sig = caml_convert_signal_number(Int_val(signal_number));
if (sig < 0 || sig >= NSIG)
caml_invalid_argument("Sys.signal: unavailable signal");
switch(action) {
case Val_int(0): /* Signal_default */
act = 0;
break;
case Val_int(1): /* Signal_ignore */
act = 1;
break;
default: /* Signal_handle */
act = 2;
break;
}
oldact = caml_set_signal_action(sig, act);
switch (oldact) {
case 0: /* was Signal_default */
res = Val_int(0);
break;
case 1: /* was Signal_ignore */
res = Val_int(1);
break;
case 2: /* was Signal_handle */
res = caml_alloc_small (1, 0);
Field(res, 0) = Field(caml_signal_handlers, sig);
break;
default: /* error in caml_set_signal_action */
caml_sys_error(NO_ARG);
}
if (Is_block(action)) {
if (caml_signal_handlers == 0) {
caml_signal_handlers = caml_alloc(NSIG, 0);
caml_register_global_root(&caml_signal_handlers);
}
caml_modify(&Field(caml_signal_handlers, sig), Field(action, 0));
}
caml_raise_if_exception(caml_process_pending_signals_exn());
CAMLreturn (res);
}
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