132 lines
3.8 KiB
C++
132 lines
3.8 KiB
C++
/*
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* Copyright 2004 The WebRTC Project Authors. All rights reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#include "webrtc/base/posix.h"
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#include <sys/wait.h>
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#include <errno.h>
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#include <unistd.h>
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#if defined(WEBRTC_LINUX) && !defined(WEBRTC_ANDROID)
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#include "webrtc/base/linuxfdwalk.h"
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#endif
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#include "webrtc/base/logging.h"
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namespace rtc {
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#if defined(WEBRTC_LINUX) && !defined(WEBRTC_ANDROID)
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static void closefds(void *close_errors, int fd) {
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if (fd <= 2) {
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// We leave stdin/out/err open to the browser's terminal, if any.
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return;
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}
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if (close(fd) < 0) {
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*static_cast<bool *>(close_errors) = true;
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}
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}
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#endif
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enum {
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EXIT_FLAG_CHDIR_ERRORS = 1 << 0,
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#if defined(WEBRTC_LINUX) && !defined(WEBRTC_ANDROID)
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EXIT_FLAG_FDWALK_ERRORS = 1 << 1,
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EXIT_FLAG_CLOSE_ERRORS = 1 << 2,
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#endif
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EXIT_FLAG_SECOND_FORK_FAILED = 1 << 3,
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};
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bool RunAsDaemon(const char *file, const char *const argv[]) {
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// Fork intermediate child to daemonize.
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pid_t pid = fork();
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if (pid < 0) {
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LOG_ERR(LS_ERROR) << "fork()";
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return false;
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} else if (!pid) {
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// Child.
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// We try to close all fds and change directory to /, but if that fails we
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// keep going because it's not critical.
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int exit_code = 0;
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if (chdir("/") < 0) {
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exit_code |= EXIT_FLAG_CHDIR_ERRORS;
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}
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#if defined(WEBRTC_LINUX) && !defined(WEBRTC_ANDROID)
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bool close_errors = false;
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if (fdwalk(&closefds, &close_errors) < 0) {
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exit_code |= EXIT_FLAG_FDWALK_ERRORS;
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}
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if (close_errors) {
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exit_code |= EXIT_FLAG_CLOSE_ERRORS;
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}
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#endif
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// Fork again to become a daemon.
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pid = fork();
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// It is important that everything here use _exit() and not exit(), because
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// exit() would call the destructors of all global variables in the whole
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// process, which is both unnecessary and unsafe.
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if (pid < 0) {
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exit_code |= EXIT_FLAG_SECOND_FORK_FAILED;
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_exit(exit_code); // if second fork failed
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} else if (!pid) {
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// Child.
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// Successfully daemonized. Run command.
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// WEBRTC_POSIX requires the args to be typed as non-const for historical
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// reasons, but it mandates that the actual implementation be const, so
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// the cast is safe.
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execvp(file, const_cast<char *const *>(argv));
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_exit(255); // if execvp failed
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}
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// Parent.
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// Successfully spawned process, but report any problems to the parent where
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// we can log them.
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_exit(exit_code);
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}
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// Parent. Reap intermediate child.
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int status;
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pid_t child = waitpid(pid, &status, 0);
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if (child < 0) {
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LOG_ERR(LS_ERROR) << "Error in waitpid()";
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return false;
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}
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if (child != pid) {
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// Should never happen (see man page).
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LOG(LS_ERROR) << "waitpid() chose wrong child???";
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return false;
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}
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if (!WIFEXITED(status)) {
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LOG(LS_ERROR) << "Intermediate child killed uncleanly"; // Probably crashed
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return false;
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}
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int exit_code = WEXITSTATUS(status);
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if (exit_code & EXIT_FLAG_CHDIR_ERRORS) {
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LOG(LS_WARNING) << "Child reported probles calling chdir()";
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}
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#if defined(WEBRTC_LINUX) && !defined(WEBRTC_ANDROID)
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if (exit_code & EXIT_FLAG_FDWALK_ERRORS) {
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LOG(LS_WARNING) << "Child reported problems calling fdwalk()";
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}
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if (exit_code & EXIT_FLAG_CLOSE_ERRORS) {
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LOG(LS_WARNING) << "Child reported problems calling close()";
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}
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#endif
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if (exit_code & EXIT_FLAG_SECOND_FORK_FAILED) {
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LOG(LS_ERROR) << "Failed to daemonize";
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// This means the command was not launched, so failure.
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return false;
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}
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return true;
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}
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} // namespace rtc
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