| 1 | /* |
| 2 | * Copyright (C) 2009 Pierre-Marc Fournier |
| 3 | * Copyright (C) 2011-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
| 4 | * |
| 5 | * This library is free software; you can redistribute it and/or |
| 6 | * modify it under the terms of the GNU Lesser General Public |
| 7 | * License as published by the Free Software Foundation; version 2.1 of |
| 8 | * the License. |
| 9 | * |
| 10 | * This library is distributed in the hope that it will be useful, |
| 11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 13 | * Lesser General Public License for more details. |
| 14 | * |
| 15 | * You should have received a copy of the GNU Lesser General Public |
| 16 | * License along with this library; if not, write to the Free Software |
| 17 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| 18 | */ |
| 19 | |
| 20 | #define _GNU_SOURCE |
| 21 | #include <lttng/ust-dlfcn.h> |
| 22 | #include <unistd.h> |
| 23 | #include <stdio.h> |
| 24 | #include <signal.h> |
| 25 | #include <sched.h> |
| 26 | #include <stdarg.h> |
| 27 | #include <errno.h> |
| 28 | |
| 29 | #include <lttng/ust.h> |
| 30 | |
| 31 | pid_t fork(void) |
| 32 | { |
| 33 | static pid_t (*plibc_func)(void) = NULL; |
| 34 | sigset_t sigset; |
| 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, "libustfork: unable to find \"fork\" symbol\n"); |
| 41 | errno = ENOSYS; |
| 42 | return -1; |
| 43 | } |
| 44 | } |
| 45 | |
| 46 | ust_before_fork(&sigset); |
| 47 | /* Do the real fork */ |
| 48 | retval = plibc_func(); |
| 49 | if (retval == 0) { |
| 50 | /* child */ |
| 51 | ust_after_fork_child(&sigset); |
| 52 | } else { |
| 53 | ust_after_fork_parent(&sigset); |
| 54 | } |
| 55 | return retval; |
| 56 | } |
| 57 | |
| 58 | int daemon(int nochdir, int noclose) |
| 59 | { |
| 60 | static int (*plibc_func)(int nochdir, int noclose) = NULL; |
| 61 | sigset_t sigset; |
| 62 | int retval; |
| 63 | |
| 64 | if (plibc_func == NULL) { |
| 65 | plibc_func = dlsym(RTLD_NEXT, "daemon"); |
| 66 | if (plibc_func == NULL) { |
| 67 | fprintf(stderr, "libustfork: unable to find \"daemon\" symbol\n"); |
| 68 | errno = ENOSYS; |
| 69 | return -1; |
| 70 | } |
| 71 | } |
| 72 | |
| 73 | ust_before_fork(&sigset); |
| 74 | /* Do the real daemon call */ |
| 75 | retval = plibc_func(nochdir, noclose); |
| 76 | if (retval == 0) { |
| 77 | /* child, parent called _exit() directly */ |
| 78 | ust_after_fork_child(&sigset); |
| 79 | } else { |
| 80 | /* on error in the parent */ |
| 81 | ust_after_fork_parent(&sigset); |
| 82 | } |
| 83 | return retval; |
| 84 | } |
| 85 | |
| 86 | #ifdef __linux__ |
| 87 | |
| 88 | struct user_desc; |
| 89 | |
| 90 | struct ustfork_clone_info { |
| 91 | int (*fn)(void *); |
| 92 | void *arg; |
| 93 | sigset_t sigset; |
| 94 | }; |
| 95 | |
| 96 | static int clone_fn(void *arg) |
| 97 | { |
| 98 | struct ustfork_clone_info *info = (struct ustfork_clone_info *) arg; |
| 99 | |
| 100 | /* clone is now done and we are in child */ |
| 101 | ust_after_fork_child(&info->sigset); |
| 102 | return info->fn(info->arg); |
| 103 | } |
| 104 | |
| 105 | int clone(int (*fn)(void *), void *child_stack, int flags, void *arg, ...) |
| 106 | { |
| 107 | static int (*plibc_func)(int (*fn)(void *), void *child_stack, |
| 108 | int flags, void *arg, pid_t *ptid, |
| 109 | struct user_desc *tls, pid_t *ctid) = NULL; |
| 110 | /* var args */ |
| 111 | pid_t *ptid; |
| 112 | struct user_desc *tls; |
| 113 | pid_t *ctid; |
| 114 | /* end of var args */ |
| 115 | va_list ap; |
| 116 | int retval; |
| 117 | |
| 118 | va_start(ap, arg); |
| 119 | ptid = va_arg(ap, pid_t *); |
| 120 | tls = va_arg(ap, struct user_desc *); |
| 121 | ctid = va_arg(ap, pid_t *); |
| 122 | va_end(ap); |
| 123 | |
| 124 | if (plibc_func == NULL) { |
| 125 | plibc_func = dlsym(RTLD_NEXT, "clone"); |
| 126 | if (plibc_func == NULL) { |
| 127 | fprintf(stderr, "libustfork: unable to find \"clone\" symbol.\n"); |
| 128 | errno = ENOSYS; |
| 129 | return -1; |
| 130 | } |
| 131 | } |
| 132 | |
| 133 | if (flags & CLONE_VM) { |
| 134 | /* |
| 135 | * Creating a thread, no need to intervene, just pass on |
| 136 | * the arguments. |
| 137 | */ |
| 138 | retval = plibc_func(fn, child_stack, flags, arg, ptid, |
| 139 | tls, ctid); |
| 140 | } else { |
| 141 | /* Creating a real process, we need to intervene. */ |
| 142 | struct ustfork_clone_info info = { .fn = fn, .arg = arg }; |
| 143 | |
| 144 | ust_before_fork(&info.sigset); |
| 145 | retval = plibc_func(clone_fn, child_stack, flags, &info, |
| 146 | ptid, tls, ctid); |
| 147 | /* The child doesn't get here. */ |
| 148 | ust_after_fork_parent(&info.sigset); |
| 149 | } |
| 150 | return retval; |
| 151 | } |
| 152 | |
| 153 | #elif defined (__FreeBSD__) |
| 154 | |
| 155 | pid_t rfork(int flags) |
| 156 | { |
| 157 | static pid_t (*plibc_func)(void) = NULL; |
| 158 | sigset_t sigset; |
| 159 | pid_t retval; |
| 160 | |
| 161 | if (plibc_func == NULL) { |
| 162 | plibc_func = dlsym(RTLD_NEXT, "rfork"); |
| 163 | if (plibc_func == NULL) { |
| 164 | fprintf(stderr, "libustfork: unable to find \"rfork\" symbol\n"); |
| 165 | errno = ENOSYS; |
| 166 | return -1; |
| 167 | } |
| 168 | } |
| 169 | |
| 170 | ust_before_fork(&sigset); |
| 171 | /* Do the real rfork */ |
| 172 | retval = plibc_func(); |
| 173 | if (retval == 0) { |
| 174 | /* child */ |
| 175 | ust_after_fork_child(&sigset); |
| 176 | } else { |
| 177 | ust_after_fork_parent(&sigset); |
| 178 | } |
| 179 | return retval; |
| 180 | } |
| 181 | |
| 182 | /* |
| 183 | * On BSD, no need to override vfork, because it runs in the context of |
| 184 | * the parent, with parent waiting until execve or exit is executed in |
| 185 | * the child. |
| 186 | */ |
| 187 | |
| 188 | #else |
| 189 | #warning "Unknown OS. You might want to ensure that fork/clone/vfork/fork handling is complete." |
| 190 | #endif |