diff options
Diffstat (limited to 'src/dfork.c')
| -rw-r--r-- | src/dfork.c | 207 |
1 files changed, 207 insertions, 0 deletions
diff --git a/src/dfork.c b/src/dfork.c new file mode 100644 index 0000000..f9e10fb --- /dev/null +++ b/src/dfork.c @@ -0,0 +1,207 @@ +/* $Id$ */ + +/* + * This file is part of libdaemon. + * + * libdaemon 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 2 of the License, or + * (at your option) any later version. + * + * libdaemon 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 libdaemon; if not, write to the Free Software Foundation, + * Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA. + */ + +#include <sys/types.h> +#include <unistd.h> +#include <errno.h> +#include <string.h> +#include <fcntl.h> +#include <sys/stat.h> +#include <stdio.h> +#include <stdlib.h> + +#include "dfork.h" +#include "dnonblock.h" +#include "dlog.h" + +static int _daemon_retval_pipe[2] = { -1, -1 }; + +static int _null_open(int f, int fd) { + int fd2; + + if ((fd2 = open("/dev/null", f)) < 0) + return -1; + + if (fd2 == fd) + return fd; + + if (dup2(fd2, fd) < 0) + return -1; + + close(fd2); + return fd; +} + +pid_t daemon_fork(void) { + pid_t pid; + int _pipe[2]; + FILE *pipe_in, *pipe_out; + + pid_t p = (pid_t) -1; + + if (pipe(_pipe) < 0 || !(pipe_out = fdopen(_pipe[0], "r")) || !(pipe_in = fdopen(_pipe[1], "w"))) { + daemon_log(LOG_ERR, "pipe() failed: %s", strerror(errno)); + return (pid_t) -1; + } + + daemon_nonblock(_pipe[1], 1); + + if ((pid = fork()) < 0) { // First fork + daemon_log(LOG_ERR, "First fork() failed: %s\n", strerror(errno)); + fclose(pipe_in); + fclose(pipe_out); + return (pid_t) -1; + + } else if (pid == 0) { + // First child + + fclose(pipe_out); + + if (_null_open(O_RDONLY, 0) < 0) { + daemon_log(LOG_ERR, "Failed to open /dev/null for STDIN: %s", strerror(errno)); + goto fail; + } + + if (_null_open(O_WRONLY, 1) < 0) { + daemon_log(LOG_ERR, "Failed to open /dev/null for STDOUT: %s", strerror(errno)); + goto fail; + } + + if (_null_open(O_WRONLY, 2) < 0) { + daemon_log(LOG_ERR, "Failed to open /dev/null for STDERR: %s", strerror(errno)); + goto fail; + } + + setsid(); + umask(0777); + chdir("/"); + + if ((pid = fork()) < 0) { // Second fork + daemon_log(LOG_ERR, "Second fork() failed: %s", strerror(errno)); + goto fail; + + } else if (pid == 0) { + // Second child + p = getpid(); + fwrite(&p, sizeof(p), 1, pipe_in); + fclose(pipe_in); + + + if (daemon_log_use & DAEMON_LOG_AUTO) + daemon_log_use = DAEMON_LOG_SYSLOG; + + return 0; + + } else { + // Second father + fclose(pipe_in); + exit(0); + } + + fail: + fwrite(&p, sizeof(p), 1, pipe_in); + fclose(pipe_in); + exit(0); + + } else { // First father + if (fread(&p, sizeof(p), 1, pipe_out) != 1) + p = (pid_t) -1; + + fclose(pipe_out); + return p; + } + +} + +int daemon_retval_init(void) { + if (pipe(_daemon_retval_pipe) < 0) + return -1; + + return 0; +} + +void daemon_retval_done(void) { + if (_daemon_retval_pipe[0] >= 0) + close(_daemon_retval_pipe[0]); + + if (_daemon_retval_pipe[1] >= 0) + close(_daemon_retval_pipe[1]); + + _daemon_retval_pipe[0] = _daemon_retval_pipe[1] = -1; +} + +int daemon_retval_send(int i) { + ssize_t r; + r = write(_daemon_retval_pipe[1], &i, sizeof(i)); + + daemon_retval_done(); + + if (r != sizeof(i)) { + + if (r < 0) + daemon_log(LOG_ERR, "read() failed while writing return value to pipe: %s", strerror(errno)); + else + daemon_log(LOG_ERR, "write() too short while writing return value from pipe"); + + return -1; + } + + return 0; +} + +int daemon_retval_wait(int timeout) { + ssize_t r; + int i; + + if (timeout > 0) { + struct timeval tv = { timeout, 0 }; + int s; + fd_set fds; + FD_ZERO(&fds); + FD_SET(_daemon_retval_pipe[0], &fds); + + if ((s = select(FD_SETSIZE, &fds, 0, 0, &tv)) != 1) { + + if (s < 0) + daemon_log(LOG_ERR, "select() failed while waiting for return value: %s", strerror(errno)); + else + daemon_log(LOG_ERR, "Timeout reached while wating for return value"); + + return -1; + } + } + + if ((r = read(_daemon_retval_pipe[0], &i, sizeof(i))) != sizeof(i)) { + + if (r < 0) + daemon_log(LOG_ERR, "read() failed while reading return value from pipe: %s", strerror(errno)); + else if (r == 0) + daemon_log(LOG_ERR, "read() failed with EOF while reading return value from pipe."); + else if (r > 0) + daemon_log(LOG_ERR, "read() too short while reading return value from pipe."); + + return -1; + } + + daemon_retval_done(); + + return i; +} + |