diff options
| -rw-r--r-- | include/unistd.h | 43 | ||||
| -rw-r--r-- | src/unistd/daemon.c | 99 |
2 files changed, 142 insertions, 0 deletions
diff --git a/include/unistd.h b/include/unistd.h index 2d7ee16..3812c8c 100644 --- a/include/unistd.h +++ b/include/unistd.h @@ -800,6 +800,7 @@ int fexecv(int, char* const[]); */ int fexecve(int, char* const[], char* const[]); + #if defined(__PLAN9_SOURCE) || defined(__SLIBC_SOURCE) /** * Search the environment variable $PATH for an executable @@ -918,6 +919,48 @@ char* searchpath3(const char*, const char*, const char*) #endif +#if defined(__BSD_SOURCE) || defined(__XOPEN_SOURCE) +/** + * Detach the process from the controlling terminal + * and run in the background. + * + * The function shall change the working directory + * to '/' to avoid block a mountpoint from being + * unmounted. It shall also change direct stdin, + * stdout, and stderr to '/dev/null'. It shall + * then double-fork, and between the fork, become + * a session leader, temporarily, so that the + * it no longer has a controlling terminal. + * + * Note well, this function does not implement a + * reliable or particularly correct mechanism for + * daemonising a process. It shall not be used! + * Note, the GNU implementation is slightly + * different because of a bug. + * + * @param nochdir The not change working directory to '/'. + * @param noclose The not redirect stdin, stdout, and stderr to '/dev/null'. + * @return Zero on success, -1 on error. + * + * @throws EACCES If `nochdir` is zero, and the user is denied access to '/'. + * @throws Any error specified for open(3). + * @throws Any error specified for dup2(3). + * @throws Any error specified for fork(3). + * @throws Any error specified for setsid(3). + * + * @since Always. + */ +int daemon(int, int) + __deprecated("Portable programs should implement this mechanism " + "manually. Non-portable programs may use 'daemonise'."); +#endif + + +#if defined(__SLIBC_SOURCE) +int daemonise(const char* int); /* TODO */ +#endif + + #endif diff --git a/src/unistd/daemon.c b/src/unistd/daemon.c new file mode 100644 index 0000000..5d7c34d --- /dev/null +++ b/src/unistd/daemon.c @@ -0,0 +1,99 @@ +/** + * slibc — Yet another C library + * Copyright © 2015 Mattias Andrée (maandree@member.fsf.org) + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, either version 3 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <http://www.gnu.org/licenses/>. + */ +#include <unistd.h> +#include <fcntl.h> + + + +/** + * Detach the process from the controlling terminal + * and run in the background. + * + * The function shall change the working directory + * to '/' to avoid block a mountpoint from being + * unmounted. It shall also change direct stdin, + * stdout, and stderr to '/dev/null'. It shall + * then double-fork, and between the fork, become + * a session leader, temporarily, so that the + * it no longer has a controlling terminal. + * + * Note well, this function does not implement a + * reliable or particularly correct mechanism for + * daemonising a process. It shall not be used! + * Note, the GNU implementation is slightly + * different because of a bug. + * + * @param nochdir The not change working directory to '/'. + * @param noclose The not redirect stdin, stdout, and stderr to '/dev/null'. + * @return Zero on success, -1 on error. + * + * @throws EACCES If `nochdir` is zero, and the user is denied access to '/'. + * @throws Any error specified for open(3). + * @throws Any error specified for dup2(3). + * @throws Any error specified for fork(3). + * @throws Any error specified for setsid(3). + * + * @since Always. + */ +int daemon(int nochdir, int noclose) +{ + int fd = -1; + int saved_errno; + + if (nochdir ? 0 : chdir("/")) + return -1; + + if (noclose == 0) + { + if (fd = open("/dev/null", O_RDWR), fd < 0) + return -1; + + if (dup2(fd, 0) < 0) goto fail; + if (dup2(fd, 1) < 0) goto fail; + if (dup2(fd, 2) < 0) goto fail; + + if (fd > 2) + close(fd); + } + + switch (fork()) + { + case 0: break; + case -1: return -1; + default: _exit(0); + } + + if (setsid() < 0) + return -1; + + switch (fork()) + { + case 0: break; + case -1: return -1; + default: _exit(0); + } + + return 0; + fail: + saved_errno = errno; + if (fd > 2) + close (fd); + errno = saved_errno; + return -1; +} + |