reactos/lib/crtdll/io/mktemp.c

   1 /*
   2  * COPYRIGHT:   See COPYING in the top level directory
   3  *              Copyright (C) 1994 DJ Delorie, see COPYING.DJ for details
   4  * PROJECT:     ReactOS system libraries
   5  * FILE:        lib/crtdll/io/mktemp.c
   6  * PURPOSE:     Makes a temp file based on a template
   7  * PROGRAMER:   DJ Delorie
   8                                 Boudewijn Dekker
   9  * UPDATE HISTORY:
  10  *              28/12/98: Appropriated for the Reactos Kernel
  11  */
  12
  13 /* Copyright (C) 1996 DJ Delorie, see COPYING.DJ for details */
  14 /* Copyright (C) 1995 DJ Delorie, see COPYING.DJ for details */
  15
  16 #include <crtdll/stdio.h>
  17 #include <crtdll/string.h>
  18 #include <crtdll/io.h>
  19
  20
  21 char* _mktemp (char *_template)
  22 {
  23   static int count = 0;
  24   char *cp, *dp;
  25   int i, len, xcount, loopcnt;
  26
  27
  28
  29   len = strlen (_template);
  30   cp = _template + len;
  31
  32   xcount = 0;
  33   while (xcount < 6 && cp > _template && cp[-1] == 'X')
  34     xcount++, cp--;
  35
  36   if (xcount) {
  37     dp = cp;
  38     while (dp > _template && dp[-1] != '/' && dp[-1] != '\\' && dp[-1] != ':')
  39       dp--;
  40
  41     /* Keep the first characters of the template, but turn the rest into
  42        Xs.  */
  43     while (cp > dp + 8 - xcount) {
  44       *--cp = 'X';
  45       xcount = (xcount >= 6) ? 6 : 1 + xcount;
  46     }
  47
  48     /* If dots occur too early -- squash them.  */
  49     while (dp < cp) {
  50       if (*dp == '.') *dp = 'a';
  51       dp++;
  52     }
  53
  54     /* Try to add ".tmp" to the filename.  Truncate unused Xs.  */
  55     if (cp + xcount + 3 < _template + len)
  56       strcpy (cp + xcount, ".tmp");
  57     else
  58       cp[xcount] = 0;
  59
  60     /* This loop can run up to 2<<(5*6) times, or about 10^9 times.  */
  61     for (loopcnt = 0; loopcnt < (1 << (5 * xcount)); loopcnt++) {
  62       int c = count++;
  63       for (i = 0; i < xcount; i++, c >>= 5)
  64         cp[i] = "abcdefghijklmnopqrstuvwxyz012345"[c & 0x1f];
  65       if (_access(_template,0) == -1)
  66         return _template;
  67     }
  68   }
  69
  70   /* Failure:  truncate the template and return NULL.  */
  71   *_template = 0;
  72   return 0;
  73 }