1/*
2Copyright (c) 2012, Broadcom Europe Ltd
3All rights reserved.
4
5Redistribution and use in source and binary forms, with or without
6modification, are permitted provided that the following conditions are met:
7 * Redistributions of source code must retain the above copyright
8 notice, this list of conditions and the following disclaimer.
9 * Redistributions in binary form must reproduce the above copyright
10 notice, this list of conditions and the following disclaimer in the
11 documentation and/or other materials provided with the distribution.
12 * Neither the name of the copyright holder nor the
13 names of its contributors may be used to endorse or promote products
14 derived from this software without specific prior written permission.
15
16THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
17ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
18WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
19DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY
20DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
21(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
22LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
23ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
25SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26*/
27
28#include "vcfiled_check.h"
29#include <errno.h>
30#include <stdio.h>
31#include <stdlib.h>
32#include <string.h>
33#include <unistd.h>
34#include <syslog.h>
35#include <sys/stat.h>
36#include <fcntl.h>
37
38int vcfiled_lock(const char *lockfile, VCFILED_LOGMSG_T logmsg)
39{
40 int rc, fd;
41 char pidbuf[32];
42 char *lockdir = strdup(lockfile);
43 char *sep = strrchr(lockdir, '/');
44 int ret = -1;
45 if (!sep)
46 {
47 free(lockdir);
48 return -1;
49 }
50 *sep = '\0';
51
52 if (mkdir(lockdir, S_IRWXU | S_IRGRP|S_IXGRP) < 0)
53 {
54 if (errno != EEXIST)
55 {
56 logmsg(LOG_CRIT, "could not create %s:%s\n", lockdir,strerror(errno));
57 goto finish;
58 }
59 }
60 fd = open(lockfile, O_RDWR | O_CREAT | O_EXCL, 0640);
61 if (fd<0)
62 {
63 if (errno != EEXIST)
64 {
65 logmsg(LOG_CRIT, "could not create lockfile %s:%s\n", lockfile, strerror(errno));
66 goto finish;
67 }
68 else
69 {
70 // it already exists - reopen it and try to lock it
71 fd = open(lockfile, O_RDWR);
72 if (fd<0)
73 {
74 logmsg(LOG_CRIT, "could not re-open lockfile %s:%s\n", lockfile, strerror(errno));
75 goto finish;
76 }
77 }
78 }
79 // at this point, we have opened the file, and can use discretionary locking,
80 // which should work even over NFS
81
82 struct flock flock;
83 memset(&flock, 0, sizeof(flock));
84 flock.l_type = F_WRLCK;
85 flock.l_whence = SEEK_SET;
86 flock.l_start = 0;
87 flock.l_len = 1;
88 if (fcntl(fd, F_SETLK, &flock) < 0)
89 {
90 // if we failed to lock, then it might mean we're already running, or
91 // something else bad.
92 if (errno == EACCES || errno == EAGAIN)
93 {
94 // already running
95 int pid = 0, rc = read(fd, pidbuf, sizeof(pidbuf));
96 if (rc)
97 pid = atoi(pidbuf);
98 logmsg(LOG_CRIT, "already running at pid %d\n", pid);
99 close(fd);
100 goto finish;
101 }
102 else
103 {
104 logmsg(LOG_CRIT, "could not lock %s:%s\n", lockfile, strerror(errno));
105 close(fd);
106 goto finish;
107 }
108 }
109 snprintf(pidbuf,sizeof(pidbuf),"%d", getpid());
110 rc = write(fd, pidbuf, strlen(pidbuf)+1);
111 if (rc<0)
112 {
113 logmsg(LOG_CRIT, "could not write pid:%s\n", strerror(errno));
114 goto finish;
115 }
116 /* do not close the file, as that will release the lock - it will
117 * will close automatically when the program exits.
118 */
119 ret = 0;
120finish:
121 free(lockdir);
122 /* coverity[leaked_handle] - fd left open on purpose */
123 return ret;
124}
125
126int vcfiled_is_running(const char *filename)
127{
128 int ret;
129
130 int fd = open(filename, O_RDONLY);
131 if (fd < 0)
132 {
133 // file not there, so filed not running
134 ret = 0;
135 }
136
137 else
138 {
139 struct flock flock;
140 memset(&flock, 0, sizeof(flock));
141 flock.l_type = F_WRLCK;
142 flock.l_whence = SEEK_SET;
143 flock.l_start = 0;
144 flock.l_len = 1;
145 int rc = fcntl(fd, F_GETLK, &flock);
146 if (rc != 0)
147 {
148 /* could not access lock info */
149 printf("%s: Could not access lockfile %s: %s\n",
150 "vmcs_main", filename, strerror(errno));
151 ret = 0;
152 }
153 else if (flock.l_pid == 0)
154 {
155 /* file is unlocked, so filed not running */
156 ret = 0;
157 }
158 else
159 {
160 /* file is locked, so filed is running */
161 ret = 1;
162 }
163 }
164 /* coverity[leaked_handle] - fd left open on purpose */
165 return ret;
166}
167
168
169
170