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annotate common/linuxlockfile.c @ 1250:7ea3a4c0e2ae

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This should be serious software.
author Andre Heinecke <andre.heinecke@intevation.de>
date Thu, 25 Sep 2014 15:53:49 +0200
parents 2a1206932f53
children 8362e30f7b55
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
782
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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
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16 #include "logging.h"
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17
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18 int
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19 open_lockfile(char *path)
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20 {
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21 int fd;
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22 char pidstr[20];
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23 size_t pidstrlen;
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24 struct flock lk;
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25 fd = open(path, O_RDWR | O_CREAT, 0600);
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26 if (fd != -1)
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27 {
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28 /* Get an exclusive lock on the whole file. */
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29 lk.l_type = F_WRLCK;
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30 lk.l_whence = SEEK_SET;
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31 lk.l_start = 0;
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32 lk.l_len = 0;
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33 if (fcntl(fd, F_SETLK, &lk) != -1)
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34 {
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35 /* FIXME (issue139): For extra security we should check if there is
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36 already a pid in the file. If so we should check in
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37 /proc/$PID if there is still a process of the same name
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38 as ours running... */
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39 ftruncate(fd, 0);
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40 pidstrlen = (size_t)snprintf(pidstr, sizeof(pidstr), "%d", getpid());
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41 write(fd, pidstr, pidstrlen);
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42 }
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43 else
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44 {
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45 /* Lock can not be acquired. Bail out... */
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46 close(fd);
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47 DEBUGPRINTF("Could not get an exclusive lock on %s.\n", path);
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48 return -1;
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49 }
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50 }
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51 else
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52 {
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53 DEBUGPRINTF("Failed to open lock file: %s.\n", path);
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54 }
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55 return fd;
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56 }
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57
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58 void
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59 close_lockfile(int fd)
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60 {
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61 struct flock lk;
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62
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63 /* Delete the PID from file. */
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64 /* We do this instead of trying to unlink the file. */
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65 ftruncate(fd, 0);
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66
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67 /* Remove lock from the file. */
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68 lk.l_type = F_UNLCK;
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69 lk.l_whence = SEEK_SET;
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70 lk.l_start = 0;
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71 lk.l_len = 0;
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72 if (fcntl(fd, F_SETLK, &lk) == -1)
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73 {
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74 /* Lock can not be removed */
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75 DEBUGPRINTF("Could not remove lock from pid file.\n");
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76 }
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77 close(fd);
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78 }
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79
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80 #endif /* Not WIN32 */
http://wald.intevation.org/projects/trustbridge/