| 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 <sched.h> |
| 24 | #include <stdarg.h> |
| 25 | #include <ust/tracectl.h> |
| 26 | #include "usterr.h" |
| 27 | |
| 28 | struct user_desc; |
| 29 | |
| 30 | pid_t fork(void) |
| 31 | { |
| 32 | static pid_t (*plibc_func)(void) = NULL; |
| 33 | ust_fork_info_t fork_info; |
| 34 | |
| 35 | pid_t retval; |
| 36 | |
| 37 | if(plibc_func == NULL) { |
| 38 | plibc_func = dlsym(RTLD_NEXT, "fork"); |
| 39 | if(plibc_func == NULL) { |
| 40 | fprintf(stderr, "libcwrap: unable to find fork\n"); |
| 41 | return -1; |
| 42 | } |
| 43 | } |
| 44 | |
| 45 | ust_before_fork(&fork_info); |
| 46 | |
| 47 | /* Do the real fork */ |
| 48 | retval = plibc_func(); |
| 49 | |
| 50 | if(retval == 0) { |
| 51 | /* child */ |
| 52 | ust_after_fork_child(&fork_info); |
| 53 | } |
| 54 | else { |
| 55 | ust_after_fork_parent(&fork_info); |
| 56 | } |
| 57 | |
| 58 | return retval; |
| 59 | } |
| 60 | |
| 61 | int execve(const char *filename, char *const argv[], char *const envp[]) |
| 62 | { |
| 63 | static int (*plibc_func)(const char *filename, char *const argv[], char *const envp[]) = NULL; |
| 64 | |
| 65 | pid_t retval; |
| 66 | |
| 67 | if(plibc_func == NULL) { |
| 68 | plibc_func = dlsym(RTLD_NEXT, "execve"); |
| 69 | if(plibc_func == NULL) { |
| 70 | fprintf(stderr, "libinterfork: unable to find execve\n"); |
| 71 | return -1; |
| 72 | } |
| 73 | } |
| 74 | |
| 75 | ust_potential_exec(); |
| 76 | |
| 77 | retval = plibc_func(filename, argv, envp); |
| 78 | |
| 79 | return retval; |
| 80 | } |
| 81 | |
| 82 | struct interfork_clone_info { |
| 83 | int (*fn)(void *); |
| 84 | void *arg; |
| 85 | ust_fork_info_t fork_info; |
| 86 | }; |
| 87 | |
| 88 | static int clone_fn(void *arg) |
| 89 | { |
| 90 | struct interfork_clone_info *info = (struct interfork_clone_info *)arg; |
| 91 | |
| 92 | /* clone is now done and we are in child */ |
| 93 | ust_after_fork_child(&info->fork_info); |
| 94 | |
| 95 | return info->fn(info->arg); |
| 96 | } |
| 97 | |
| 98 | int clone(int (*fn)(void *), void *child_stack, int flags, void *arg, ...) |
| 99 | { |
| 100 | static int (*plibc_func)(int (*fn)(void *), void *child_stack, int flags, void *arg, pid_t *ptid, struct user_desc *tls, pid_t *ctid) = NULL; |
| 101 | |
| 102 | /* varargs */ |
| 103 | pid_t *ptid; |
| 104 | struct user_desc *tls; |
| 105 | pid_t *ctid; |
| 106 | |
| 107 | int retval; |
| 108 | |
| 109 | va_list ap; |
| 110 | |
| 111 | va_start(ap, arg); |
| 112 | ptid = va_arg(ap, pid_t *); |
| 113 | tls = va_arg(ap, struct user_desc *); |
| 114 | ctid = va_arg(ap, pid_t *); |
| 115 | va_end(ap); |
| 116 | |
| 117 | if(plibc_func == NULL) { |
| 118 | plibc_func = dlsym(RTLD_NEXT, "clone"); |
| 119 | if(plibc_func == NULL) { |
| 120 | fprintf(stderr, "libinterfork: unable to find clone\n"); |
| 121 | return -1; |
| 122 | } |
| 123 | } |
| 124 | |
| 125 | if(flags & CLONE_VM) { |
| 126 | /* creating a thread, no need to intervene, just pass on the arguments */ |
| 127 | retval = plibc_func(fn, child_stack, flags, arg, ptid, tls, ctid); |
| 128 | } |
| 129 | else { |
| 130 | /* creating a real process, we need to intervene */ |
| 131 | struct interfork_clone_info info = { fn: fn, arg: arg }; |
| 132 | |
| 133 | ust_before_fork(&info.fork_info); |
| 134 | |
| 135 | retval = plibc_func(clone_fn, child_stack, flags, &info, ptid, tls, ctid); |
| 136 | |
| 137 | /* The child doesn't get here */ |
| 138 | ust_after_fork_parent(&info.fork_info); |
| 139 | } |
| 140 | |
| 141 | return retval; |
| 142 | } |