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/*
* libjingle
* Copyright 2004--2009, Google Inc.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
* EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
* OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "talk/base/posix.h"
#include <sys/wait.h>
#include <errno.h>
#include <unistd.h>
#ifdef LINUX
#include "talk/base/linuxfdwalk.h"
#endif
#include "talk/base/logging.h"
namespace talk_base {
#ifdef LINUX
static void closefds(void *close_errors, int fd) {
if (fd <= 2) {
// We leave stdin/out/err open to the browser's terminal, if any.
return;
}
if (close(fd) < 0) {
*static_cast<bool *>(close_errors) = true;
}
}
#endif
enum {
EXIT_FLAG_CHDIR_ERRORS = 1 << 0,
#ifdef LINUX
EXIT_FLAG_FDWALK_ERRORS = 1 << 1,
EXIT_FLAG_CLOSE_ERRORS = 1 << 2,
#endif
EXIT_FLAG_SECOND_FORK_FAILED = 1 << 3,
};
bool RunAsDaemon(const char *file, const char *const argv[]) {
// Fork intermediate child to daemonize.
pid_t pid = fork();
if (pid < 0) {
LOG_ERR(LS_ERROR) << "fork()";
return false;
} else if (!pid) {
// Child.
// We try to close all fds and change directory to /, but if that fails we
// keep going because it's not critical.
int exit_code = 0;
if (chdir("/") < 0) {
exit_code |= EXIT_FLAG_CHDIR_ERRORS;
}
#ifdef LINUX
bool close_errors = false;
if (fdwalk(&closefds, &close_errors) < 0) {
exit_code |= EXIT_FLAG_FDWALK_ERRORS;
}
if (close_errors) {
exit_code |= EXIT_FLAG_CLOSE_ERRORS;
}
#endif
// Fork again to become a daemon.
pid = fork();
// It is important that everything here use _exit() and not exit(), because
// exit() would call the destructors of all global variables in the whole
// process, which is both unnecessary and unsafe.
if (pid < 0) {
exit_code |= EXIT_FLAG_SECOND_FORK_FAILED;
_exit(exit_code); // if second fork failed
} else if (!pid) {
// Child.
// Successfully daemonized. Run command.
// POSIX requires the args to be typed as non-const for historical
// reasons, but it mandates that the actual implementation be const, so
// the cast is safe.
execvp(file, const_cast<char *const *>(argv));
_exit(255); // if execvp failed
}
// Parent.
// Successfully spawned process, but report any problems to the parent where
// we can log them.
_exit(exit_code);
}
// Parent. Reap intermediate child.
int status;
pid_t child = waitpid(pid, &status, 0);
if (child < 0) {
LOG_ERR(LS_ERROR) << "Error in waitpid()";
return false;
}
if (child != pid) {
// Should never happen (see man page).
LOG(LS_ERROR) << "waitpid() chose wrong child???";
return false;
}
if (!WIFEXITED(status)) {
LOG(LS_ERROR) << "Intermediate child killed uncleanly"; // Probably crashed
return false;
}
int exit_code = WEXITSTATUS(status);
if (exit_code & EXIT_FLAG_CHDIR_ERRORS) {
LOG(LS_WARNING) << "Child reported probles calling chdir()";
}
#ifdef LINUX
if (exit_code & EXIT_FLAG_FDWALK_ERRORS) {
LOG(LS_WARNING) << "Child reported problems calling fdwalk()";
}
if (exit_code & EXIT_FLAG_CLOSE_ERRORS) {
LOG(LS_WARNING) << "Child reported problems calling close()";
}
#endif
if (exit_code & EXIT_FLAG_SECOND_FORK_FAILED) {
LOG(LS_ERROR) << "Failed to daemonize";
// This means the command was not launched, so failure.
return false;
}
return true;
}
} // namespace talk_base
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