Merge branch 'for-pierre-marc' of git://git.infradead.org/users/jblunck/ust
[ust.git] / libinterfork / interfork.c
1 /* Copyright (C) 2009 Pierre-Marc Fournier
2 *
3 * This library is free software; you can redistribute it and/or
4 * modify it under the terms of the GNU Lesser General Public
5 * License as published by the Free Software Foundation; either
6 * version 2.1 of the License, or (at your option) any later version.
7 *
8 * This library is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
11 * Lesser General Public License for more details.
12 *
13 * You should have received a copy of the GNU Lesser General Public
14 * License along with this library; if not, write to the Free Software
15 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
16 */
17
18 #define _GNU_SOURCE
19 #include <dlfcn.h>
20 #include <unistd.h>
21 #include <stdio.h>
22 #include <signal.h>
23 #include "usterr.h"
24
25 extern void ust_fork(void);
26 extern void ust_potential_exec(void);
27
28 pid_t fork(void)
29 {
30 static pid_t (*plibc_func)(void) = NULL;
31
32 pid_t retval;
33
34 int result;
35 sigset_t all_sigs;
36 sigset_t orig_sigs;
37
38 if(plibc_func == NULL) {
39 plibc_func = dlsym(RTLD_NEXT, "fork");
40 if(plibc_func == NULL) {
41 fprintf(stderr, "libcwrap: unable to find fork\n");
42 return -1;
43 }
44 }
45
46 /* Disable interrupts. This is to avoid that the child
47 * intervenes before it is properly setup for tracing. It is
48 * safer to disable all signals, because then we know we are not
49 * breaking anything by restoring the original mask.
50 */
51
52 /* FIXME:
53 - only do this if tracing is active
54 */
55
56 /* Disable signals */
57 sigfillset(&all_sigs);
58 result = sigprocmask(SIG_BLOCK, &all_sigs, &orig_sigs);
59 if(result == -1) {
60 PERROR("sigprocmask");
61 return -1;
62 }
63
64 /* Do the real fork */
65 retval = plibc_func();
66
67 if(retval == 0) {
68 /* child */
69 ust_fork();
70 }
71
72 /* Restore signals */
73 result = sigprocmask(SIG_BLOCK, &orig_sigs, NULL);
74 if(result == -1) {
75 PERROR("sigprocmask");
76 return -1;
77 }
78
79 return retval;
80 }
81
82 int execve(const char *filename, char *const argv[], char *const envp[])
83 {
84 static int (*plibc_func)(const char *filename, char *const argv[], char *const envp[]) = NULL;
85
86 pid_t retval;
87
88 if(plibc_func == NULL) {
89 plibc_func = dlsym(RTLD_NEXT, "execve");
90 if(plibc_func == NULL) {
91 fprintf(stderr, "libcwrap: unable to find execve\n");
92 return -1;
93 }
94 }
95
96 ust_potential_exec();
97
98 retval = plibc_func(filename, argv, envp);
99
100 return retval;
101 }
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