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 "share/usterr.h"
  23
  24 extern void ust_fork(void);
  25 extern void ust_potential_exec(void);
  26
  27 pid_t fork(void)
  28 {
  29         static pid_t (*plibc_func)(void) = NULL;
  30
  31         pid_t retval;
  32
  33         if(plibc_func == NULL) {
  34                 plibc_func = dlsym(RTLD_NEXT, "fork");
  35                 if(plibc_func == NULL) {
  36                         fprintf(stderr, "libcwrap: unable to find fork\n");
  37                         return -1;
  38                 }
  39         }
  40
  41         retval = plibc_func();
  42
  43         if(retval == 0)
  44                 ust_fork();
  45
  46         return retval;
  47 }
  48
  49 int execve(const char *filename, char *const argv[], char *const envp[])
  50 {
  51         static int (*plibc_func)(const char *filename, char *const argv[], char *const envp[]) = NULL;
  52
  53         pid_t retval;
  54
  55         if(plibc_func == NULL) {
  56                 plibc_func = dlsym(RTLD_NEXT, "execve");
  57                 if(plibc_func == NULL) {
  58                         fprintf(stderr, "libcwrap: unable to find execve\n");
  59                         return -1;
  60                 }
  61         }
  62
  63         ust_potential_exec();
  64
  65         retval = plibc_func(filename, argv, envp);
  66
  67         return retval;
  68 }