1/* Copyright (C) 2002-2016 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Lesser General Public
6 License as published by the Free Software Foundation; either
7 version 2.1 of the License, or (at your option) any later version.
8
9 The GNU C Library is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 Lesser General Public License for more details.
13
14 You should have received a copy of the GNU Lesser General Public
15 License along with the GNU C Library; if not, see
16 <http://www.gnu.org/licenses/>. */
17
18#include <sched.h>
19#include <signal.h>
20#include <string.h> /* For the real memset prototype. */
21#include <sysdep.h>
22#include <unistd.h>
23#include <sys/wait.h>
24#include <libc-lock.h>
25
26/* We have to and actually can handle cancelable system(). The big
27 problem: we have to kill the child process if necessary. To do
28 this a cleanup handler has to be registered and is has to be able
29 to find the PID of the child. The main problem is to reliable have
30 the PID when needed. It is not necessary for the parent thread to
31 return. It might still be in the kernel when the cancellation
32 request comes. Therefore we have to use the clone() calls ability
33 to have the kernel write the PID into the user-level variable. */
34#ifndef FORK
35# define FORK() \
36 INLINE_SYSCALL (clone, 3, CLONE_PARENT_SETTID | SIGCHLD, 0, &pid)
37#endif
38
39#ifdef _LIBC_REENTRANT
40static void cancel_handler (void *arg);
41
42# define CLEANUP_HANDLER \
43 __libc_cleanup_region_start (1, cancel_handler, &pid)
44
45# define CLEANUP_RESET \
46 __libc_cleanup_region_end (0)
47#endif
48
49
50/* Linux has waitpid(), so override the generic unix version. */
51#include <sysdeps/posix/system.c>
52
53
54#ifdef _LIBC_REENTRANT
55/* The cancellation handler. */
56static void
57cancel_handler (void *arg)
58{
59 pid_t child = *(pid_t *) arg;
60
61 INTERNAL_SYSCALL_DECL (err);
62 INTERNAL_SYSCALL (kill, err, 2, child, SIGKILL);
63
64 TEMP_FAILURE_RETRY (__waitpid (child, NULL, 0));
65
66 DO_LOCK ();
67
68 if (SUB_REF () == 0)
69 {
70 (void) __sigaction (SIGQUIT, &quit, (struct sigaction *) NULL);
71 (void) __sigaction (SIGINT, &intr, (struct sigaction *) NULL);
72 }
73
74 DO_UNLOCK ();
75}
76#endif
77