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Justine Tunney 2020-06-15 07:18:57 -07:00
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libc/runtime/interruptiblecall.c Normal file
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/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney │
│ │
│ This program is free software; you can redistribute it and/or modify │
│ it under the terms of the GNU General Public License as published by │
│ the Free Software Foundation; version 2 of the License. │
│ │
│ This program 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 │
│ General Public License for more details. │
│ │
│ You should have received a copy of the GNU General Public License │
│ along with this program; if not, write to the Free Software │
│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
│ 02110-1301 USA │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/bits/progn.h"
#include "libc/bits/safemacros.h"
#include "libc/mem/mem.h"
#include "libc/runtime/interruptiblecall.h"
#include "libc/runtime/runtime.h"
#include "libc/sysv/consts/sa.h"
#include "libc/sysv/consts/sig.h"
STATIC_YOINK("_init_onntconsoleevent");
static struct InterruptibleCall *g_interruptiblecall;
noreturn static void interruptcall(int sig) {
longjmp(g_interruptiblecall->jb, 1);
unreachable;
}
/**
* Calls function that may be cancelled by a signal.
*
* @param state is allocated and zero'd by the caller; state→sig and
* state→sa_new.sa_mask may be set; it may be re-used w/o
* reinitializing; it may be static or heap memory; it may be stack
* memory if re-entrant behavior isn't needed
* @return the value returned by callback or -1 on interrupt; they may
* be differentiated using the state→returnval filed, which is only
* modified by this function when callbacks succeed
*/
intptr_t interruptiblecall(struct InterruptibleCall *icall,
intptr_t callback(intptr_t p1, intptr_t p2,
intptr_t p3, intptr_t p4),
intptr_t p1, intptr_t p2, intptr_t p3, intptr_t p4) {
intptr_t rc;
if (!icall->sig) icall->sig = SIGINT;
icall->sa_new.sa_handler = interruptcall;
icall->sa_new.sa_flags |= SA_RESTART | SA_RESETHAND;
if ((rc = (sigaction)(icall->sig, &icall->sa_new, &icall->sa_old)) != -1) {
g_interruptiblecall = PROGN((icall->prev = g_interruptiblecall), icall);
if (!setjmp(icall->jb)) {
icall->returnval = rc = callback(p1, p2, p3, p4);
} else {
rc = -1;
}
asm volatile("" ::: "memory");
struct InterruptibleCall *unwind;
for (;;) {
unwind = g_interruptiblecall;
(sigaction)(unwind->sig, &unwind->sa_old, NULL);
g_interruptiblecall = unwind->prev;
if (unwind == icall) break;
free_s(&unwind);
}
icall->prev = NULL;
}
return rc;
}