1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
|
/*
pidfile.c - interact with pidfiles
Copyright (c) 1995 Martin Schulze <Martin.Schulze@Linux.DE>
This file is part of the sysklogd package, a kernel and system log daemon.
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 2 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, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111, USA
*/
#include "config.h"
#include "rsyslog.h"
/*
* Sat Aug 19 13:24:33 MET DST 1995: Martin Schulze
* First version (v0.2) released
*/
#include <stdio.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/file.h>
#include <string.h>
#include <errno.h>
#include <signal.h>
#ifdef __sun
#include <fcntl.h>
#endif
/* read_pid
*
* Reads the specified pidfile and returns the read pid.
* 0 is returned if either there's no pidfile, it's empty
* or no pid can be read.
*/
int read_pid (char *pidfile)
{
FILE *f;
int pid;
if (!(f=fopen(pidfile,"r")))
return 0;
fscanf(f,"%d", &pid);
fclose(f);
return pid;
}
/* check_pid
*
* Reads the pid using read_pid and looks up the pid in the process
* table (using /proc) to determine if the process already exists. If
* so 1 is returned, otherwise 0.
*/
int check_pid (char *pidfile)
{
int pid = read_pid(pidfile);
/* Amazing ! _I_ am already holding the pid file... */
if ((!pid) || (pid == getpid ()))
return 0;
/*
* The 'standard' method of doing this is to try and do a 'fake' kill
* of the process. If an ESRCH error is returned the process cannot
* be found -- GW
*/
/* But... errno is usually changed only on error.. */
if (kill(pid, 0) && errno == ESRCH)
return(0);
return pid;
}
/* write_pid
*
* Writes the pid to the specified file. If that fails 0 is
* returned, otherwise the pid.
*/
int write_pid (char *pidfile)
{
FILE *f;
int fd;
int pid;
if ( ((fd = open(pidfile, O_RDWR|O_CREAT, 0644)) == -1)
|| ((f = fdopen(fd, "r+")) == NULL) ) {
fprintf(stderr, "Can't open or create %s.\n", pidfile);
return 0;
}
/* It seems to be acceptable that we do not lock the pid file
* if we run under Solaris. In any case, it is highly unlikely
* that two instances try to access this file. And flock is really
* causing me grief on my initial steps on Solaris. Some time later,
* we might re-enable it (or use some alternate method).
* 2006-02-16 rgerhards
*/
#ifndef __sun
if (flock(fd, LOCK_EX|LOCK_NB) == -1) {
fscanf(f, "%d", &pid);
fclose(f);
printf("Can't lock, lock is held by pid %d.\n", pid);
return 0;
}
#endif
pid = getpid();
if (!fprintf(f,"%d\n", pid)) {
char errStr[1024];
strerror_r(errno, errStr, sizeof(errStr));
printf("Can't write pid , %s.\n", errStr);
close(fd);
return 0;
}
fflush(f);
#ifndef __sun
if (flock(fd, LOCK_UN) == -1) {
char errStr[1024];
strerror_r(errno, errStr, sizeof(errStr));
printf("Can't unlock pidfile %s, %s.\n", pidfile, errStr);
close(fd);
return 0;
}
#endif
close(fd);
return pid;
}
/* remove_pid
*
* Remove the the specified file. The result from unlink(2)
* is returned
*/
int remove_pid (char *pidfile)
{
return unlink (pidfile);
}
|
