connection.c

   1 /*
   2  * Support the max connections option.
   3  *
   4  * Copyright (C) 1998 Andrew Tridgell
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 3 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License along
  17  * with this program; if not, visit the http://fsf.org website.
  18  */
  19
  20 #include "rsync.h"
  21
  22 /* A simple routine to do connection counting.  This returns 1 on success
  23  * and 0 on failure, with errno also being set if the open() failed (errno
  24  * will be 0 if the lock request failed). */
  25 int claim_connection(char *fname, int max_connections)
  26 {
  27         int fd, i;
  28
  29         if (max_connections == 0)
  30                 return 1;
  31
  32         if ((fd = open(fname, O_RDWR|O_CREAT, 0600)) < 0)
  33                 return 0;
  34
  35         /* Find a free spot. */
  36         for (i = 0; i < max_connections; i++) {
  37                 if (lock_range(fd, i*4, 4))
  38                         return 1;
  39         }
  40
  41         close(fd);
  42
  43         /* A lock failure needs to return an errno of 0. */
  44         errno = 0;
  45         return 0;
  46 }