865ca149dc
As mentioned in r16117 and the book "Advanced Programming in the Unix Environment" by W. Richard Stevens, we should ignore SIGINT and SIGQUIT before forking, since it is not guaranteed that the parent process starts running soon enough. To avoid calling sigaction() in the vforked child, instead block SIGINT and SIGQUIT before vfork() and keep the sigaction() to ignore after vfork(). The FreeBSD kernel discards ignored signals, even if they are blocked; therefore, it is not necessary to unblock SIGINT and SIGQUIT earlier.
100 lines
3.5 KiB
C
100 lines
3.5 KiB
C
/*
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* Copyright (c) 1988, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#if defined(LIBC_SCCS) && !defined(lint)
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static char sccsid[] = "@(#)system.c 8.1 (Berkeley) 6/4/93";
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#endif /* LIBC_SCCS and not lint */
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include "namespace.h"
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#include <sys/types.h>
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#include <sys/wait.h>
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#include <signal.h>
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#include <stdlib.h>
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#include <stddef.h>
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#include <string.h>
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#include <unistd.h>
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#include <paths.h>
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#include <errno.h>
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#include "un-namespace.h"
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#include "libc_private.h"
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int
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__system(const char *command)
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{
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pid_t pid, savedpid;
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int pstat;
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struct sigaction ign, intact, quitact;
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sigset_t newsigblock, oldsigblock;
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if (!command) /* just checking... */
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return(1);
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(void)sigemptyset(&newsigblock);
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(void)sigaddset(&newsigblock, SIGCHLD);
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(void)sigaddset(&newsigblock, SIGINT);
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(void)sigaddset(&newsigblock, SIGQUIT);
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(void)_sigprocmask(SIG_BLOCK, &newsigblock, &oldsigblock);
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switch(pid = vfork()) {
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case -1: /* error */
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(void)_sigprocmask(SIG_SETMASK, &oldsigblock, NULL);
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return (-1);
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case 0: /* child */
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/*
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* Restore original signal dispositions and exec the command.
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*/
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(void)_sigprocmask(SIG_SETMASK, &oldsigblock, NULL);
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execl(_PATH_BSHELL, "sh", "-c", command, (char *)NULL);
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_exit(127);
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}
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/*
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* If we are running means that the child has either completed
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* its execve, or has failed.
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* Block SIGINT/QUIT because sh -c handles it and wait for
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* it to clean up.
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*/
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memset(&ign, 0, sizeof(ign));
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ign.sa_handler = SIG_IGN;
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(void)sigemptyset(&ign.sa_mask);
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(void)_sigaction(SIGINT, &ign, &intact);
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(void)_sigaction(SIGQUIT, &ign, &quitact);
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savedpid = pid;
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do {
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pid = _wait4(savedpid, &pstat, 0, (struct rusage *)0);
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} while (pid == -1 && errno == EINTR);
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(void)_sigaction(SIGINT, &intact, NULL);
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(void)_sigaction(SIGQUIT, &quitact, NULL);
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(void)_sigprocmask(SIG_SETMASK, &oldsigblock, NULL);
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return(pid == -1 ? -1 : pstat);
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}
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__weak_reference(__system, system);
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__weak_reference(__system, _system);
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