generic-library/libbsd
1
0
Fork 0
mirror of https://gitlab.freedesktop.org/libbsd/libbsd.git synced 2025-01-24 02:51:43 +01:00
Code Issues Projects Releases Wiki Activity

Add pidfile functions

Browse Source 
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.
This commit is contained in:
Guillem Jover 2010-01-10 00:10:21 +01:00
parent 98a2479f0b
commit 2a81893cc0
5 changed files with 528 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
Makefile
View File

@ -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 \

5
Versions
View File

@ -53,5 +53,10 @@ LIBBSD_0.2 {
readpassphrase;
flopen;
pidfile_open;
pidfile_write;
pidfile_close;
pidfile_remove;
} LIBBSD_0.1;

12
include/libutil.h
View File

@ -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) */

254
src/pidfile.3 Normal file
View File

@ -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 .

255
src/pidfile.c Normal file
View File

@ -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));
}