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 |
40 | static 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. */ |
56 | static void |
57 | cancel_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 | |