henrike@webrtc.org | 0e118e7 | 2013-07-10 00:45:36 +0000 | [diff] [blame] | 1 | /* |
| 2 | * libjingle |
| 3 | * Copyright 2004--2009, Google Inc. |
| 4 | * |
| 5 | * Redistribution and use in source and binary forms, with or without |
| 6 | * modification, are permitted provided that the following conditions are met: |
| 7 | * |
| 8 | * 1. Redistributions of source code must retain the above copyright notice, |
| 9 | * this list of conditions and the following disclaimer. |
| 10 | * 2. Redistributions in binary form must reproduce the above copyright notice, |
| 11 | * this list of conditions and the following disclaimer in the documentation |
| 12 | * and/or other materials provided with the distribution. |
| 13 | * 3. The name of the author may not be used to endorse or promote products |
| 14 | * derived from this software without specific prior written permission. |
| 15 | * |
| 16 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED |
| 17 | * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF |
| 18 | * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO |
| 19 | * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| 20 | * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, |
| 21 | * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; |
| 22 | * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, |
| 23 | * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR |
| 24 | * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF |
| 25 | * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| 26 | */ |
| 27 | |
| 28 | #include "talk/base/posix.h" |
| 29 | |
| 30 | #include <sys/wait.h> |
| 31 | #include <errno.h> |
| 32 | #include <unistd.h> |
| 33 | |
| 34 | #ifdef LINUX |
| 35 | #include "talk/base/linuxfdwalk.h" |
| 36 | #endif |
| 37 | #include "talk/base/logging.h" |
| 38 | |
| 39 | namespace talk_base { |
| 40 | |
| 41 | #ifdef LINUX |
| 42 | static void closefds(void *close_errors, int fd) { |
| 43 | if (fd <= 2) { |
| 44 | // We leave stdin/out/err open to the browser's terminal, if any. |
| 45 | return; |
| 46 | } |
| 47 | if (close(fd) < 0) { |
| 48 | *static_cast<bool *>(close_errors) = true; |
| 49 | } |
| 50 | } |
| 51 | #endif |
| 52 | |
| 53 | enum { |
| 54 | EXIT_FLAG_CHDIR_ERRORS = 1 << 0, |
| 55 | #ifdef LINUX |
| 56 | EXIT_FLAG_FDWALK_ERRORS = 1 << 1, |
| 57 | EXIT_FLAG_CLOSE_ERRORS = 1 << 2, |
| 58 | #endif |
| 59 | EXIT_FLAG_SECOND_FORK_FAILED = 1 << 3, |
| 60 | }; |
| 61 | |
| 62 | bool RunAsDaemon(const char *file, const char *const argv[]) { |
| 63 | // Fork intermediate child to daemonize. |
| 64 | pid_t pid = fork(); |
| 65 | if (pid < 0) { |
| 66 | LOG_ERR(LS_ERROR) << "fork()"; |
| 67 | return false; |
| 68 | } else if (!pid) { |
| 69 | // Child. |
| 70 | |
| 71 | // We try to close all fds and change directory to /, but if that fails we |
| 72 | // keep going because it's not critical. |
| 73 | int exit_code = 0; |
| 74 | if (chdir("/") < 0) { |
| 75 | exit_code |= EXIT_FLAG_CHDIR_ERRORS; |
| 76 | } |
| 77 | #ifdef LINUX |
| 78 | bool close_errors = false; |
| 79 | if (fdwalk(&closefds, &close_errors) < 0) { |
| 80 | exit_code |= EXIT_FLAG_FDWALK_ERRORS; |
| 81 | } |
| 82 | if (close_errors) { |
| 83 | exit_code |= EXIT_FLAG_CLOSE_ERRORS; |
| 84 | } |
| 85 | #endif |
| 86 | |
| 87 | // Fork again to become a daemon. |
| 88 | pid = fork(); |
| 89 | // It is important that everything here use _exit() and not exit(), because |
| 90 | // exit() would call the destructors of all global variables in the whole |
| 91 | // process, which is both unnecessary and unsafe. |
| 92 | if (pid < 0) { |
| 93 | exit_code |= EXIT_FLAG_SECOND_FORK_FAILED; |
| 94 | _exit(exit_code); // if second fork failed |
| 95 | } else if (!pid) { |
| 96 | // Child. |
| 97 | // Successfully daemonized. Run command. |
| 98 | // POSIX requires the args to be typed as non-const for historical |
| 99 | // reasons, but it mandates that the actual implementation be const, so |
| 100 | // the cast is safe. |
| 101 | execvp(file, const_cast<char *const *>(argv)); |
| 102 | _exit(255); // if execvp failed |
| 103 | } |
| 104 | |
| 105 | // Parent. |
| 106 | // Successfully spawned process, but report any problems to the parent where |
| 107 | // we can log them. |
| 108 | _exit(exit_code); |
| 109 | } |
| 110 | |
| 111 | // Parent. Reap intermediate child. |
| 112 | int status; |
| 113 | pid_t child = waitpid(pid, &status, 0); |
| 114 | if (child < 0) { |
| 115 | LOG_ERR(LS_ERROR) << "Error in waitpid()"; |
| 116 | return false; |
| 117 | } |
| 118 | if (child != pid) { |
| 119 | // Should never happen (see man page). |
| 120 | LOG(LS_ERROR) << "waitpid() chose wrong child???"; |
| 121 | return false; |
| 122 | } |
| 123 | if (!WIFEXITED(status)) { |
| 124 | LOG(LS_ERROR) << "Intermediate child killed uncleanly"; // Probably crashed |
| 125 | return false; |
| 126 | } |
| 127 | |
| 128 | int exit_code = WEXITSTATUS(status); |
| 129 | if (exit_code & EXIT_FLAG_CHDIR_ERRORS) { |
| 130 | LOG(LS_WARNING) << "Child reported probles calling chdir()"; |
| 131 | } |
| 132 | #ifdef LINUX |
| 133 | if (exit_code & EXIT_FLAG_FDWALK_ERRORS) { |
| 134 | LOG(LS_WARNING) << "Child reported problems calling fdwalk()"; |
| 135 | } |
| 136 | if (exit_code & EXIT_FLAG_CLOSE_ERRORS) { |
| 137 | LOG(LS_WARNING) << "Child reported problems calling close()"; |
| 138 | } |
| 139 | #endif |
| 140 | if (exit_code & EXIT_FLAG_SECOND_FORK_FAILED) { |
| 141 | LOG(LS_ERROR) << "Failed to daemonize"; |
| 142 | // This means the command was not launched, so failure. |
| 143 | return false; |
| 144 | } |
| 145 | return true; |
| 146 | } |
| 147 | |
| 148 | } // namespace talk_base |