compiler/clib/mkstemp.c

   1 /*
   2     Copyright © 1995-2008, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     POSIX function mkstemp().
   6 */
   7 #include <string.h>
   8 #include <errno.h>
   9 #include <fcntl.h>
  10 #include <proto/dos.h>
  11
  12 /*****************************************************************************
  13
  14     NAME */
  15 #include <stdlib.h>
  16
  17         int mkstemp(
  18
  19 /*  SYNOPSIS */
  20         char *template)
  21
  22 /*  FUNCTION
  23
  24     INPUTS
  25     A template that must end with 'XXXXXX'
  26
  27     RESULT
  28     A file descriptor of opened temporary file or -1 on error.
  29
  30     NOTES
  31
  32     EXAMPLE
  33
  34     BUGS
  35
  36     SEE ALSO
  37
  38     INTERNALS
  39
  40 ******************************************************************************/
  41 {
  42     char *c = template + strlen(template);
  43     char *c_start;
  44     BPTR  lock= NULL;
  45     int ctr = 0;
  46     static char filename_letters[] = "01234567890abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZFILLTO64";
  47
  48     while (c > template && *--c == 'X') {
  49         ctr++;
  50     }
  51
  52     if (ctr < 6) {
  53         errno = EINVAL;
  54         return -1;
  55     }
  56
  57     c++;
  58     c_start = c;
  59
  60     while (1) {
  61         while (*c) {
  62             *c = filename_letters[rand() & 0x3F];
  63             c++;
  64         }
  65
  66         if (!(lock = Lock(template, ACCESS_READ))) {
  67             int fd = open(template, O_WRITE|O_CREAT|O_EXCL);
  68             if (fd > 0)
  69                 return fd;
  70         }
  71         UnLock(lock);
  72         c = c_start;
  73         /*
  74          * Try around 1000 filenames and then give up.
  75          */
  76         if (++ctr > 1000)
  77             break;
  78     }
  79
  80     errno = EEXIST;
  81     return -1;
  82
  83 } /* mkstemp() */