freebsd-skq/lib/libc/stdlib/system.c
Konstantin Belousov 8495e8b1e9 Fix known issues which blow up the process after dlopen("libthr.so")
(or loading a dso linked to libthr.so into process which was not
linked against threading library).

- Remove libthr interposers of the libc functions, including
  __error(). Instead, functions calls are indirected through the
  interposing table, similar to how pthread stubs in libc are already
  done.  Libc by default points either to syscall trampolines or to
  existing libc implementations.  On libthr load, libthr rewrites the
  pointers to the cancellable implementations already in libthr.  The
  interposition table is separate from pthreads stubs indirection
  table to not pull pthreads stubs into static binaries.

- Postpone the malloc(3) internal mutexes initialization until libthr
  is loaded.  This avoids recursion between calloc(3) and static
  pthread_mutex_t initialization.

- Reinstall signal handlers with wrapper on libthr load.  The
  _rtld_is_dlopened(3) is used to avoid useless calls to sigaction(2)
  when libthr is statically referenced from the main binary.

In the process, fix openat(2), swapcontext(2) and setcontext(2)
interposing.  The libc symbols were exported at different versions
than libthr interposers.  Export both libc and libthr versions from
libc now, with default set to the higher version from libthr.

Remove unused and disconnected swapcontext(3) userspace implementation
from libc/gen.

No objections from:	deischen
Tested by:	pho, antoine (exp-run) (previous versions)
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
2015-01-03 18:38:46 +00:00

109 lines
3.6 KiB
C

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