lib/tempnam.c

   1 /*
   2  * $Id$
   3  */
   4
   5 /* A reasonably functional tmpnam. */
   6
   7 /* Originally by Tom Hageman, tom@basil.icce.rug.nl */
   8
   9 /*
  10  * This tmpnam() was changed by Gerben_Wierda@RnA.nl to serve as
  11  * tempnam() for squid-1.1.6. It ignores the directory parameter, every
  12  * temp file is written in /tmp.
  13  */
  14
  15 #include "config.h"
  16
  17 #if HAVE_LIBC_H
  18 #include <libc.h>
  19 #endif
  20 #if HAVE_STDIO_H
  21 #include <stdio.h>
  22 #endif
  23 #if HAVE_TYPES_H
  24 #include <sys/types.h>
  25 #endif
  26 #if HAVE_LIMITS_H
  27 #include <limits.h>
  28 #endif
  29 #if HAVE_UNISTD_H
  30 #include <unistd.h>
  31 #endif
  32
  33 #undef TMP_MAX
  34
  35 #define _tmp            "/tmp/"
  36 #define lengthof_tmp    5
  37
  38 #ifndef LONG_BIT
  39 #define LONG_BIT        (CHAR_BIT * 4)  /* assume sizeof(long) == 4 */
  40 #endif
  41
  42 #define L_tmpmin        (lengthof_tmp + 5)      /* 5 chars for pid. */
  43
  44 #if (L_tmpnam > L_tmpmin)
  45 #if (L_tmpnam > L_tmpmin + LONG_BIT / 6)        /* base 64 */
  46 #define TMP_MAX ULONG_MAX
  47 #else
  48 #define TMP_MAX ((1L << (6 * (L_tmpnam - L_tmpmin))) - 1)
  49 #endif
  50 #else
  51 #ifndef L_tmpnam
  52 #error "tmpnam: L_tmpnam undefined"
  53 #else
  54 #error "tmpnam: L_tmpnam too small"
  55 #endif
  56 #endif
  57
  58
  59 static char *
  60 _tmpnam(void)
  61 {
  62     static const char digits[] =
  63 #if (L_tmpnam >= L_tmpmin + LONG_BIT / 4)
  64         "0123456789abcdef";
  65 #define TMP_BASE        16
  66 #else
  67         "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_-";
  68 #define TMP_BASE        64
  69 #endif
  70     static unsigned long lastcount = 0;
  71     static char buffer[L_tmpnam + 1];
  72     char *s = buffer;
  73     unsigned long count = lastcount;
  74     pid_t pid = getpid();
  75
  76     if (sizeof(_tmp) - 1 != lengthof_tmp)
  77         abort();                /* Consistency error. */
  78
  79     for (;;) {
  80         register int i = L_tmpnam;
  81         register unsigned long c;
  82         register unsigned int p;
  83
  84         /* Build filename. (the hard way) */
  85         s += i;
  86         *s = '\0';
  87
  88         c = (count == TMP_MAX) ? 0 : ++count;
  89         do {
  90             *--s = digits[c % TMP_BASE];
  91             c /= TMP_BASE;
  92         } while (--i > L_tmpmin);
  93
  94         p = (unsigned int) pid;
  95         do {
  96             *--s = digits[p % 10];
  97             p /= 10;
  98         } while (--i > lengthof_tmp);
  99
 100         do {
 101             *--s = _tmp[--i];
 102         } while (i > 0);
 103
 104         /* Check that the file doesn't exist. */
 105         if (access(s, 0) != 0)
 106             break;
 107
 108         /* It exists; retry unless we tried them all. */
 109         if (count == lastcount) {
 110             s = NULL;
 111             break;
 112         }
 113     }
 114
 115     lastcount = count;
 116
 117     return s;
 118 }
 119
 120 char *
 121 tempnam(const char *dir, const char *pfx)
 122 {
 123     return _tmpnam();
 124 }
 125
 126 #ifdef TEST
 127 int
 128 main()
 129 {
 130     char *t;
 131     int n = 0;
 132     while ((t = tempnam(NULL, NULL))) {
 133         printf("%s\n", t);
 134         if (++n == 1000)
 135             break;
 136     }
 137     return 1;
 138 }
 139 #endif