Mercurial > trustbridge > trustbridge

annotate common/linuxlockfile.c @ 1332:8362e30f7b55

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(issue139) Check that pid is not running if the lock can be aquired If the lock on the lockfile can be aquired it might still be possible that another process is running. So we read the pid from the lockfile and check if another process with the same installation prefix as us is running.
author Andre Heinecke <andre.heinecke@intevation.de>
date Wed, 15 Oct 2014 14:19:46 +0200
parents 7ea3a4c0e2ae
children 5d7b1650de1f
rev   line source
1160
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1 /* Copyright (C) 2014 by Bundesamt für Sicherheit in der Informationstechnik
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2 * Software engineering by Intevation GmbH
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3 *
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4 * This file is Free Software under the GNU GPL (v>=2)
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5 * and comes with ABSOLUTELY NO WARRANTY!
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6 * See LICENSE.txt for details.
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7 */
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8
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9 #ifndef WIN32
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10
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11 #include <fcntl.h>
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12 #include <stdio.h>
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13 #include <sys/types.h>
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14 #include <unistd.h>
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15 #include <string.h>
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16
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17 #include "logging.h"
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18 #include "util.h"
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19 #include "strhelp.h"
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20
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21 int
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22 open_lockfile(char *path)
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23 {
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24 int fd;
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25 char pidstr[20];
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26 size_t pidstrlen;
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27 struct flock lk;
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28 fd = open(path, O_RDWR | O_CREAT, 0600);
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29 if (fd != -1)
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30 {
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31 /* Get an exclusive lock on the whole file. */
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32 lk.l_type = F_WRLCK;
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33 lk.l_whence = SEEK_SET;
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34 lk.l_start = 0;
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35 lk.l_len = 0;
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36 fcntl(fd, F_SETLK, &lk);
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37 if (fcntl(fd, F_SETLK, &lk) != -1)
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38 {
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39 char oldpid[20];
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40 FILE *f = fopen(path, "r");
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41 size_t bytes_read;
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42 if (f)
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43 {
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44 bytes_read = fread(oldpid, 1, sizeof(oldpid), f);
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45 if (bytes_read)
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46 {
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47 char *oldPath,
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48 *newPath;
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49 if (bytes_read == sizeof(oldpid))
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50 {
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51 ERRORPRINTF ("Bad information in pidfile\n");
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52 }
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53 else
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54 {
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55 oldpid[bytes_read] = '\0';
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56 oldPath = get_proc_install_dir(oldpid);
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57 newPath = get_install_dir();
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58 if (oldPath && newPath && strcmp(oldPath, newPath) == 0)
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59 {
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60 DEBUGPRINTF("Got lock but process from %s is still"
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61 "running.\n", oldPath);
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62 xfree(oldPath);
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63 xfree(newPath);
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64 return -1;
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65 }
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66 xfree(oldPath);
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67 xfree(newPath);
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68 }
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69 }
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70 fclose(f);
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71 }
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72
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73 ftruncate(fd, 0);
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74 pidstrlen = (size_t)snprintf(pidstr, sizeof(pidstr), "%d",
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75 getpid());
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76 write(fd, pidstr, pidstrlen);
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77 }
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78 else
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79 {
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80 /* Lock can not be acquired. Bail out... */
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81 close(fd);
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82 DEBUGPRINTF("Could not get an exclusive lock on %s.\n", path);
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83 return -1;
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84 }
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85 }
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86 else
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87 {
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88 DEBUGPRINTF("Failed to open lock file: %s.\n", path);
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89 }
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90 return fd;
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91 }
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92
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93 void
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94 close_lockfile(int fd)
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95 {
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96 struct flock lk;
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97
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98 /* Delete the PID from file. */
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99 /* We do this instead of trying to unlink the file. */
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100 ftruncate(fd, 0);
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101
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102 /* Remove lock from the file. */
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103 lk.l_type = F_UNLCK;
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104 lk.l_whence = SEEK_SET;
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105 lk.l_start = 0;
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106 lk.l_len = 0;
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107 if (fcntl(fd, F_SETLK, &lk) == -1)
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108 {
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109 /* Lock can not be removed */
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110 DEBUGPRINTF("Could not remove lock from pid file.\n");
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111 }
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112 close(fd);
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113 }
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114
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115 #endif /* Not WIN32 */
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