| /* |
| mydaemon.c |
| |
| Copyright (c) 2000 The Regents of the University of Michigan. |
| All rights reserved. |
| |
| Copyright (c) 2000 Dug Song <dugsong@UMICH.EDU>. |
| Copyright (c) 2002 Andy Adamson <andros@UMICH.EDU>. |
| Copyright (c) 2002 Marius Aamodt Eriksen <marius@UMICH.EDU>. |
| Copyright (c) 2002 J. Bruce Fields <bfields@UMICH.EDU>. |
| Copyright (c) 2013 Jeff Layton <jlayton@redhat.com> |
| |
| All rights reserved, all wrongs reversed. |
| |
| 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. Neither the name of the University nor the names of its |
| contributors may be used to endorse or promote products derived |
| from this software without specific prior written permission. |
| |
| THIS SOFTWARE IS PROVIDED ``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 REGENTS OR CONTRIBUTORS 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 <sys/param.h> |
| #include <sys/types.h> |
| #include <sys/stat.h> |
| #include <fcntl.h> |
| #include <errno.h> |
| #include <unistd.h> |
| #include <stdio.h> |
| #include <stdlib.h> |
| #include <string.h> |
| #include <xlog.h> |
| |
| /** |
| * mydaemon - daemonize, but have parent wait to exit |
| * @nochdir: skip chdir()'ing the child to / after forking if true |
| * @noclose: skip closing stdin/stdout/stderr if true |
| * @pipefds: pointer to 2 element array of pipefds |
| * |
| * This function is like daemon(), but with our own special sauce to delay |
| * the exit of the parent until the child is set up properly. A pipe is created |
| * between parent and child. The parent process will wait to exit until the |
| * child dies or writes a '1' on the pipe signaling that it started |
| * successfully. |
| */ |
| void |
| mydaemon(int nochdir, int noclose, int *pipefds) |
| { |
| int pid, status, tempfd; |
| |
| if (pipe(pipefds) < 0) { |
| xlog_err("mydaemon: pipe() failed: errno %d (%s)\n", |
| errno, strerror(errno)); |
| exit(1); |
| } |
| if ((pid = fork ()) < 0) { |
| xlog_err("mydaemon: fork() failed: errno %d (%s)\n", |
| errno, strerror(errno)); |
| exit(1); |
| } |
| |
| if (pid != 0) { |
| /* |
| * Parent. Wait for status from child. |
| */ |
| close(pipefds[1]); |
| if (read(pipefds[0], &status, 1) != 1) |
| exit(1); |
| exit (0); |
| } |
| /* Child. */ |
| close(pipefds[0]); |
| setsid (); |
| if (nochdir == 0) { |
| if (chdir ("/") == -1) { |
| xlog_err("mydaemon: chdir() failed: errno %d (%s)\n", |
| errno, strerror(errno)); |
| exit(1); |
| } |
| } |
| |
| while (pipefds[1] <= 2) { |
| pipefds[1] = dup(pipefds[1]); |
| if (pipefds[1] < 0) { |
| xlog_err("mydaemon: dup() failed: errno %d (%s)\n", |
| errno, strerror(errno)); |
| exit(1); |
| } |
| } |
| |
| if (noclose == 0) { |
| tempfd = open("/dev/null", O_RDWR); |
| if (tempfd >= 0) { |
| dup2(tempfd, 0); |
| dup2(tempfd, 1); |
| dup2(tempfd, 2); |
| close(tempfd); |
| } else { |
| xlog_err("mydaemon: can't open /dev/null: errno %d " |
| "(%s)\n", errno, strerror(errno)); |
| exit(1); |
| } |
| } |
| |
| return; |
| } |
| |
| /** |
| * release_parent - tell the parent that it can exit now |
| * @pipefds: pipefd array that was previously passed to mydaemon() |
| * |
| * This function tells the parent process of mydaemon() that it's now clear |
| * to exit(0). |
| */ |
| void |
| release_parent(int *pipefds) |
| { |
| int status; |
| |
| if (pipefds[1] > 0) { |
| if (write(pipefds[1], &status, 1) != 1) { |
| xlog_err("WARN: writing to parent pipe failed: errno " |
| "%d (%s)\n", errno, strerror(errno)); |
| } |
| close(pipefds[1]); |
| pipefds[1] = -1; |
| } |
| } |
| |