diff options
author | Guillem Jover <guillem@hadrons.org> | 2010-01-10 00:10:21 +0100 |
---|---|---|
committer | Guillem Jover <guillem@hadrons.org> | 2010-01-10 15:29:46 +0100 |
commit | 2a81893cc028b40f7832bf033821a1aacfaaea68 (patch) | |
tree | f23ebf906256ddb1e80204df55ff6db4fb991f28 | |
parent | 98a2479f0ba02a0c54ff360aa5745ff5a6939b2e (diff) |
Add pidfile functions
Taken from FreeBSD.
Remove MAXPATHLEN from ‘struct pidfh’ and allocate pf_path dynamically,
as some systems do not have such limits. Use dev_t instead of __dev_t.
Replace EDOOFUS with EINVAL.
-rw-r--r-- | Makefile | 2 | ||||
-rw-r--r-- | Versions | 5 | ||||
-rw-r--r-- | include/libutil.h | 12 | ||||
-rw-r--r-- | src/pidfile.3 | 254 | ||||
-rw-r--r-- | src/pidfile.c | 255 |
5 files changed, 528 insertions, 0 deletions
@@ -31,6 +31,7 @@ LIB_SRCS := \ dehumanize_number.c \ inet_net_pton.c \ hash/md5.c \ + pidfile.c \ readpassphrase.c \ setmode.c \ strmode.c \ @@ -82,6 +83,7 @@ LIB_MANS := \ humanize_number.3 \ fmtcheck.3 \ nlist.3 \ + pidfile.3 \ setmode.3 \ getmode.3 \ strmode.3 \ @@ -53,5 +53,10 @@ LIBBSD_0.2 { readpassphrase; flopen; + + pidfile_open; + pidfile_write; + pidfile_close; + pidfile_remove; } LIBBSD_0.1; diff --git a/include/libutil.h b/include/libutil.h index 298bbc3..21a22cd 100644 --- a/include/libutil.h +++ b/include/libutil.h @@ -42,12 +42,24 @@ #include <features.h> #include <sys/types.h> +/* for pidfile.c */ +struct pidfh { + int pf_fd; + char *pf_path; + dev_t pf_dev; + ino_t pf_ino; +}; __BEGIN_DECLS int humanize_number(char *buf, size_t len, int64_t bytes, const char *suffix, int scale, int flags); int flopen(const char *_path, int _flags, ...); + +struct pidfh *pidfile_open(const char *path, mode_t mode, pid_t *pidptr); +int pidfile_write(struct pidfh *pfh); +int pidfile_close(struct pidfh *pfh); +int pidfile_remove(struct pidfh *pfh); __END_DECLS /* humanize_number(3) */ diff --git a/src/pidfile.3 b/src/pidfile.3 new file mode 100644 index 0000000..34214c0 --- /dev/null +++ b/src/pidfile.3 @@ -0,0 +1,254 @@ +.\" Copyright (c) 2005 Pawel Jakub Dawidek <pjd@FreeBSD.org> +.\" 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. +.\" +.\" $FreeBSD$ +.\" +.Dd October 20, 2008 +.Dt PIDFILE 3 +.Os +.Sh NAME +.Nm pidfile_open , +.Nm pidfile_write , +.Nm pidfile_close , +.Nm pidfile_remove +.Nd "library for PID files handling" +.Sh LIBRARY +.ds str-Lb-libbsd Utility functions from BSD systems (libbsd, \-lbsd) +.Lb libbsd +.Sh SYNOPSIS +.In libutil.h +.Ft "struct pidfh *" +.Fn pidfile_open "const char *path" "mode_t mode" "pid_t *pidptr" +.Ft int +.Fn pidfile_write "struct pidfh *pfh" +.Ft int +.Fn pidfile_close "struct pidfh *pfh" +.Ft int +.Fn pidfile_remove "struct pidfh *pfh" +.Sh DESCRIPTION +The +.Nm pidfile +family of functions allows daemons to handle PID files. +It uses +.Xr flopen 3 +to lock a pidfile and detect already running daemons. +.Pp +The +.Fn pidfile_open +function opens (or creates) a file specified by the +.Fa path +argument and locks it. +If a file can not be locked, a PID of an already running daemon is returned in +the +.Fa pidptr +argument (if it is not +.Dv NULL ) . +The function does not write process' PID into the file here, so it can be +used before +.Fn fork Ns ing +and exit with a proper error message when needed. +If the +.Fa path +argument is +.Dv NULL , +.Pa /var/run/ Ns Ao Va progname Ac Ns Pa .pid +file will be used. +.Pp +The +.Fn pidfile_write +function writes process' PID into a previously opened file. +.Pp +The +.Fn pidfile_close +function closes a pidfile. +It should be used after daemon +.Fn fork Ns s +to start a child process. +.Pp +The +.Fn pidfile_remove +function closes and removes a pidfile. +.Sh RETURN VALUES +The +.Fn pidfile_open +function returns a valid pointer to a +.Vt pidfh +structure on success, or +.Dv NULL +if an error occurs. +If an error occurs, +.Va errno +will be set. +.Pp +.Rv -std pidfile_write pidfile_close pidfile_remove +.Sh EXAMPLES +The following example shows in which order these functions should be used. +Note that it is safe to pass +.Dv NULL +to +.Fn pidfile_write , +.Fn pidfile_remove +and +.Fn pidfile_close +functions. +.Bd -literal +struct pidfh *pfh; +pid_t otherpid, childpid; + +pfh = pidfile_open("/var/run/daemon.pid", 0600, &otherpid); +if (pfh == NULL) { + if (errno == EEXIST) { + errx(EXIT_FAILURE, "Daemon already running, pid: %jd.", + (intmax_t)otherpid); + } + /* If we cannot create pidfile from other reasons, only warn. */ + warn("Cannot open or create pidfile"); +} + +if (daemon(0, 0) == -1) { + warn("Cannot daemonize"); + pidfile_remove(pfh); + exit(EXIT_FAILURE); +} + +pidfile_write(pfh); + +for (;;) { + /* Do work. */ + childpid = fork(); + switch (childpid) { + case -1: + syslog(LOG_ERR, "Cannot fork(): %s.", strerror(errno)); + break; + case 0: + pidfile_close(pfh); + /* Do child work. */ + break; + default: + syslog(LOG_INFO, "Child %jd started.", (intmax_t)childpid); + break; + } +} + +pidfile_remove(pfh); +exit(EXIT_SUCCESS); +.Ed +.Sh ERRORS +The +.Fn pidfile_open +function will fail if: +.Bl -tag -width Er +.It Bq Er EEXIST +Some process already holds the lock on the given pidfile, meaning that a +daemon is already running. +.It Bq Er ENAMETOOLONG +Specified pidfile's name is too long. +.It Bq Er EINVAL +Some process already holds the lock on the given pidfile, but PID read +from there is invalid. +.It Bq Er EAGAIN +Some process already holds the lock on the given pidfile, but the file +is truncated. +Most likely, the existing daemon is writing new PID into +the file. +.El +.Pp +The +.Fn pidfile_open +function may also fail and set +.Va errno +for any errors specified for the +.Xr fstat 2 , +.Xr open 2 , +and +.Xr read 2 +calls. +.Pp +The +.Fn pidfile_write +function will fail if: +.Bl -tag -width Er +.It Bq Er EINVAL +Improper function use. +Probably called before +.Fn pidfile_open . +.El +.Pp +The +.Fn pidfile_write +function may also fail and set +.Va errno +for any errors specified for the +.Xr fstat 2 , +.Xr ftruncate 2 , +and +.Xr write 2 +calls. +.Pp +The +.Fn pidfile_close +function may fail and set +.Va errno +for any errors specified for the +.Xr close 2 +and +.Xr fstat 2 +calls. +.Pp +The +.Fn pidfile_remove +function will fail if: +.Bl -tag -width Er +.It Bq Er EINVAL +Improper function use. +Probably called not from the process which made +.Fn pidfile_write . +.El +.Pp +The +.Fn pidfile_remove +function may also fail and set +.Va errno +for any errors specified for the +.Xr close 2 , +.Xr fstat 2 , +.Xr write 2 , +and +.Xr unlink 2 +system calls and the +.Xr flopen 3 +library function. +.Sh SEE ALSO +.Xr open 2 , +.Xr daemon 3 , +.Xr flopen 3 +.Sh AUTHORS +.An -nosplit +The +.Nm pidfile +functionality is based on ideas from +.An John-Mark Gurney Aq jmg@FreeBSD.org . +.Pp +The code and manual page was written by +.An Pawel Jakub Dawidek Aq pjd@FreeBSD.org . diff --git a/src/pidfile.c b/src/pidfile.c new file mode 100644 index 0000000..e93d323 --- /dev/null +++ b/src/pidfile.c @@ -0,0 +1,255 @@ +/*- + * Copyright (c) 2005 Pawel Jakub Dawidek <pjd@FreeBSD.org> + * 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 <sys/cdefs.h> +__FBSDID("$FreeBSD$"); + +#include <sys/param.h> +#include <sys/file.h> +#include <sys/stat.h> + +#include <stdio.h> +#include <stdlib.h> +#include <unistd.h> +#include <fcntl.h> +#include <string.h> +#include <time.h> +#include <err.h> +#include <errno.h> +#include <libutil.h> + +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 = asprintf(&pfh->pf_path, "/var/run/%s.pid", getprogname()); + if (len < 0) { + free(pfh); + return (NULL); + } + } else + pfh->pf_path = strdup(path); + + /* + * 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->pf_path); + 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); + free(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->pf_path); + 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 (close(pfh->pf_fd) == -1) { + if (error == 0) + error = errno; + } + if (freeit) { + free(pfh->pf_path); + 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)); +} |