X-Git-Url: http://git.cielonegro.org/gitweb.cgi?p=daemon.git;a=blobdiff_plain;f=pidfile.c;fp=pidfile.c;h=8fc42c9ae621bc371085ae4b83ceadf6273cf513;hp=0000000000000000000000000000000000000000;hb=7162d53967117a8eda4257244327d63f95633783;hpb=0aa9138f10ceb0258291ce0945e207393c2fe4cc diff --git a/pidfile.c b/pidfile.c new file mode 100644 index 0000000..8fc42c9 --- /dev/null +++ b/pidfile.c @@ -0,0 +1,256 @@ +/*- + * Copyright (c) 2005 Pawel Jakub Dawidek + * All rights reserved. + * + * 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. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``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 AUTHORS 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 "pidfile.h" +#include "flopen.h" + +#include +#include + +#include +#include +#include +#include +#include +#include +#include +#include + +static int _pidfile_remove(struct pidfh *pfh, int freeit); + +static int +pidfile_verify(struct pidfh *pfh) +{ + struct stat sb; + + if (pfh == NULL || pfh->pf_fd == -1) + return (EINVAL); + /* + * Check remembered descriptor. + */ + if (fstat(pfh->pf_fd, &sb) == -1) + return (errno); + if (sb.st_dev != pfh->pf_dev || sb.st_ino != pfh->pf_ino) + return (EINVAL); + return (0); +} + +static int +pidfile_read(const char *path, pid_t *pidptr) +{ + char buf[16], *endptr; + int error, fd, i; + + fd = open(path, O_RDONLY); + if (fd == -1) + return (errno); + + i = read(fd, buf, sizeof(buf) - 1); + error = errno; /* Remember errno in case close() wants to change it. */ + close(fd); + if (i == -1) + return (error); + else if (i == 0) + return (EAGAIN); + buf[i] = '\0'; + + *pidptr = strtol(buf, &endptr, 10); + if (endptr != &buf[i]) + return (EINVAL); + + return (0); +} + +struct pidfh * +pidfile_open(const char *path, mode_t mode, pid_t *pidptr) +{ + struct pidfh *pfh; + struct stat sb; + int error, fd, len, count; + struct timespec rqtp; + + pfh = malloc(sizeof(*pfh)); + if (pfh == NULL) + return (NULL); + + if (path == NULL) + len = snprintf(pfh->pf_path, sizeof(pfh->pf_path), + "/var/run/%s.pid", getprogname()); + else + len = snprintf(pfh->pf_path, sizeof(pfh->pf_path), + "%s", path); + if (len >= (int)sizeof(pfh->pf_path)) { + free(pfh); + errno = ENAMETOOLONG; + return (NULL); + } + + /* + * Open the PID file and obtain exclusive lock. + * We truncate PID file here only to remove old PID immediatelly, + * PID file will be truncated again in pidfile_write(), so + * pidfile_write() can be called multiple times. + */ + fd = flopen(pfh->pf_path, + O_WRONLY | O_CREAT | O_TRUNC | O_NONBLOCK, mode); + if (fd == -1) { + count = 0; + rqtp.tv_sec = 0; + rqtp.tv_nsec = 5000000; + if (errno == EWOULDBLOCK && pidptr != NULL) { + again: + errno = pidfile_read(pfh->pf_path, pidptr); + if (errno == 0) + errno = EEXIST; + else if (errno == EAGAIN) { + if (++count <= 3) { + nanosleep(&rqtp, 0); + goto again; + } + } + } + free(pfh); + return (NULL); + } + /* + * Remember file information, so in pidfile_write() we are sure we write + * to the proper descriptor. + */ + if (fstat(fd, &sb) == -1) { + error = errno; + unlink(pfh->pf_path); + close(fd); + free(pfh); + errno = error; + return (NULL); + } + + pfh->pf_fd = fd; + pfh->pf_dev = sb.st_dev; + pfh->pf_ino = sb.st_ino; + + return (pfh); +} + +int +pidfile_write(struct pidfh *pfh) +{ + char pidstr[16]; + int error, fd; + + /* + * Check remembered descriptor, so we don't overwrite some other + * file if pidfile was closed and descriptor reused. + */ + errno = pidfile_verify(pfh); + if (errno != 0) { + /* + * Don't close descriptor, because we are not sure if it's ours. + */ + return (-1); + } + fd = pfh->pf_fd; + + /* + * Truncate PID file, so multiple calls of pidfile_write() are allowed. + */ + if (ftruncate(fd, 0) == -1) { + error = errno; + _pidfile_remove(pfh, 0); + errno = error; + return (-1); + } + + snprintf(pidstr, sizeof(pidstr), "%u", getpid()); + if (pwrite(fd, pidstr, strlen(pidstr), 0) != (ssize_t)strlen(pidstr)) { + error = errno; + _pidfile_remove(pfh, 0); + errno = error; + return (-1); + } + + return (0); +} + +int +pidfile_close(struct pidfh *pfh) +{ + int error; + + error = pidfile_verify(pfh); + if (error != 0) { + errno = error; + return (-1); + } + + if (close(pfh->pf_fd) == -1) + error = errno; + free(pfh); + if (error != 0) { + errno = error; + return (-1); + } + return (0); +} + +static int +_pidfile_remove(struct pidfh *pfh, int freeit) +{ + int error; + + error = pidfile_verify(pfh); + if (error != 0) { + errno = error; + return (-1); + } + + if (unlink(pfh->pf_path) == -1) + error = errno; + if (flock(pfh->pf_fd, LOCK_UN) == -1) { + if (error == 0) + error = errno; + } + if (close(pfh->pf_fd) == -1) { + if (error == 0) + error = errno; + } + if (freeit) + free(pfh); + else + pfh->pf_fd = -1; + if (error != 0) { + errno = error; + return (-1); + } + return (0); +} + +int +pidfile_remove(struct pidfh *pfh) +{ + + return (_pidfile_remove(pfh, 1)); +}