xiolockfile.c

   1 /* source: xiolockfile.c */
   2 /* Copyright Gerhard Rieger and contributors (see file CHANGES) */
   3 /* Published under the GNU General Public License V.2, see file COPYING */
   4
   5 /* this file contains socats explicit locking mechanisms */
   6
   7 #include "xiosysincludes.h"
   8
   9 #include "compat.h"
  10 #include "mytypes.h"
  11 #include "error.h"
  12 #include "utils.h"
  13 #include "sysutils.h"
  14
  15 #include "sycls.h"
  16
  17 #include "xio.h"
  18 #include "xiolockfile.h"
  19
  20
  21 /* returns 0 if it could create lock; 1 if the lock exists; -1 on error */
  22 int xiogetlock(const char *lockfile) {
  23    char *s;
  24    struct stat strat;
  25    int fd;
  26    pid_t pid;
  27    char pidbuf[3*sizeof(pid_t)+1];
  28    size_t bytes;
  29
  30    if (Lstat(lockfile, &strat) == 0) {
  31       return 1;
  32    }
  33    switch (errno) {
  34    case ENOENT: break;
  35    default:
  36       Error3("Lstat(\"%s\", %p): %s", lockfile, &strat, strerror(errno));
  37       return -1;
  38    }
  39    /* in this moment, the file did not exist */
  40
  41    if ((s = Malloc(strlen(lockfile)+8)) == NULL) {
  42       errno = ENOMEM;
  43       return -1;
  44    }
  45    strcpy(s, lockfile);
  46    strcat(s, ".XXXXXX");
  47
  48    if ((fd = Mkstemp(s)) < 0) {
  49       Error2("mkstemp(\"%s\"): %s", s, strerror(errno));
  50       return -1;
  51    }
  52
  53    pid = Getpid();
  54    bytes = sprintf(pidbuf, F_pid"\n", pid);
  55    if (writefull(fd, pidbuf, bytes) < 0) {
  56       Error4("write(%d, %p, "F_Zu"): %s", fd, pidbuf, bytes, strerror(errno));
  57       return -1;
  58    }
  59    Fchmod(fd, 0644);
  60    Close(fd);
  61
  62    if (Link(s, lockfile) < 0) {
  63       int _errno = errno;
  64       Error3("link(\"%s\", \"%s\"): %s", s, lockfile, strerror(errno));
  65       Unlink(s);
  66       errno = _errno;
  67       return -1;
  68    }
  69    Unlink(s);
  70
  71    return 0;
  72 }
  73
  74 int xiounlock(const char *lockfile) {
  75    return Unlink(lockfile);
  76 }
  77
  78
  79 /* returns 0 when it could create lock, or -1 on error */
  80 int xiowaitlock(const char *lockfile, struct timespec *intervall) {
  81    int rc;
  82    int level = E_NOTICE;        /* first print a notice */
  83
  84    while ((rc = xiogetlock(lockfile)) == 1) {
  85       Msg1(level, "waiting for lock \"%s\"", lockfile);
  86       level = E_INFO;           /* afterwards only make info */
  87       Nanosleep(intervall, NULL);
  88    }
  89    return rc;
  90 }
  91
  92
  93 /* returns 0 when it could obtain lock or the lock is not valid
  94    (lockfile==NULL), 1 if it could not obtain the lock, or -1 on error */
  95 int xiolock(xiolock_t *lock) {
  96    int result;
  97
  98    if (lock->lockfile == NULL) {
  99       return 0;
 100    }
 101    if (lock->waitlock) {
 102       result = xiowaitlock(lock->lockfile, &lock->intervall);
 103    } else {
 104       result = xiogetlock(lock->lockfile);
 105    }
 106    if (result == 0) {
 107       Info1("obtained lock \"%s\"", lock->lockfile);
 108    }
 109    return result;
 110 }
 111
 112
 113 int xiofiledroplock(xiofile_t *xfd) {
 114    if (xfd->tag == XIO_TAG_DUAL) {
 115       xiofiledroplock((xiofile_t *)xfd->dual.stream[0]);
 116       xiofiledroplock((xiofile_t *)xfd->dual.stream[1]);
 117    } else {
 118       xfd->stream.havelock = false;
 119    }
 120    return 0;
 121 }