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77 lines
2.4 KiB
C
77 lines
2.4 KiB
C
/* Copyright (C) 2002-2017 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#include <sched.h>
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#include <signal.h>
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#include <string.h> /* For the real memset prototype. */
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#include <sysdep.h>
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#include <unistd.h>
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#include <sys/wait.h>
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#include <libc-lock.h>
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/* We have to and actually can handle cancelable system(). The big
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problem: we have to kill the child process if necessary. To do
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this a cleanup handler has to be registered and is has to be able
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to find the PID of the child. The main problem is to reliable have
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the PID when needed. It is not necessary for the parent thread to
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return. It might still be in the kernel when the cancellation
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request comes. Therefore we have to use the clone() calls ability
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to have the kernel write the PID into the user-level variable. */
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#ifndef FORK
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# define FORK() \
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INLINE_SYSCALL (clone, 3, CLONE_PARENT_SETTID | SIGCHLD, 0, &pid)
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#endif
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#ifdef _LIBC_REENTRANT
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static void cancel_handler (void *arg);
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# define CLEANUP_HANDLER \
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__libc_cleanup_region_start (1, cancel_handler, &pid)
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# define CLEANUP_RESET \
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__libc_cleanup_region_end (0)
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#endif
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/* Linux has waitpid(), so override the generic unix version. */
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#include <sysdeps/posix/system.c>
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#ifdef _LIBC_REENTRANT
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/* The cancellation handler. */
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static void
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cancel_handler (void *arg)
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{
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pid_t child = *(pid_t *) arg;
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INTERNAL_SYSCALL_DECL (err);
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INTERNAL_SYSCALL (kill, err, 2, child, SIGKILL);
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TEMP_FAILURE_RETRY (__waitpid (child, NULL, 0));
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DO_LOCK ();
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if (SUB_REF () == 0)
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{
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(void) __sigaction (SIGQUIT, &quit, (struct sigaction *) NULL);
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(void) __sigaction (SIGINT, &intr, (struct sigaction *) NULL);
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}
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DO_UNLOCK ();
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}
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#endif
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