compat/tempnam.c

   1 /*
   2  * Copyright (C) 1996-2018 The Squid Software Foundation and contributors
   3  *
   4  * Squid software is distributed under GPLv2+ license and includes
   5  * contributions from numerous individuals and organizations.
   6  * Please see the COPYING and CONTRIBUTORS files for details.
   7  */
   8
   9 /* A reasonably functional tmpnam. */
  10
  11 /* Originally by Tom Hageman, tom@basil.icce.rug.nl */
  12
  13 /*
  14  * This tmpnam() was changed by Gerben_Wierda@RnA.nl to serve as
  15  * tempnam() for squid-1.1.6. It ignores the directory parameter, every
  16  * temp file is written in /tmp.
  17  */
  18
  19 #include "squid.h"
  20 #include "compat/tempnam.h"
  21
  22 #if HAVE_LIBC_H
  23 #include <libc.h>
  24 #endif
  25 #if HAVE_LIMITS_H
  26 #include <limits.h>
  27 #endif
  28 #if HAVE_UNISTD_H
  29 #include <unistd.h>
  30 #endif
  31
  32 #undef TMP_MAX
  33
  34 #define _tmp        "/tmp/"
  35 #define lengthof_tmp    5
  36
  37 #ifndef LONG_BIT
  38 #define LONG_BIT    (CHAR_BIT * 4)  /* assume sizeof(long) == 4 */
  39 #endif
  40
  41 #define L_tmpmin    (lengthof_tmp + 5)  /* 5 chars for pid. */
  42
  43 #if (L_tmpnam > L_tmpmin)
  44 #if (L_tmpnam > L_tmpmin + LONG_BIT / 6)    /* base 64 */
  45 #define TMP_MAX ULONG_MAX
  46 #else
  47 #define TMP_MAX ((1L << (6 * (L_tmpnam - L_tmpmin))) - 1)
  48 #endif
  49 #else
  50 #ifndef L_tmpnam
  51 #error "tmpnam: L_tmpnam undefined"
  52 #else
  53 #error "tmpnam: L_tmpnam too small"
  54 #endif
  55 #endif
  56
  57 static char *
  58 _tmpnam(void)
  59 {
  60     static const char digits[] =
  61 #if (L_tmpnam >= L_tmpmin + LONG_BIT / 4)
  62         "0123456789abcdef";
  63 #define TMP_BASE    16
  64 #else
  65         "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_-";
  66 #define TMP_BASE    64
  67 #endif
  68     static unsigned long lastcount = 0;
  69     static char buffer[L_tmpnam + 1];
  70     char *s = buffer;
  71     unsigned long count = lastcount;
  72     pid_t pid = getpid();
  73
  74     if (sizeof(_tmp) - 1 != lengthof_tmp)
  75         abort();        /* Consistency error. */
  76
  77     for (;;) {
  78         register int i = L_tmpnam;
  79         register unsigned long c;
  80         register unsigned int p;
  81
  82         /* Build filename. (the hard way) */
  83         s += i;
  84         *s = '\0';
  85
  86         c = (count == TMP_MAX) ? 0 : ++count;
  87         do {
  88             *--s = digits[c % TMP_BASE];
  89             c /= TMP_BASE;
  90         } while (--i > L_tmpmin);
  91
  92         p = (unsigned int) pid;
  93         do {
  94             *--s = digits[p % 10];
  95             p /= 10;
  96         } while (--i > lengthof_tmp);
  97
  98         do {
  99             *--s = _tmp[--i];
 100         } while (i > 0);
 101
 102         /* Check that the file doesn't exist. */
 103         if (access(s, 0) != 0)
 104             break;
 105
 106         /* It exists; retry unless we tried them all. */
 107         if (count == lastcount) {
 108             s = NULL;
 109             break;
 110         }
 111     }
 112
 113     lastcount = count;
 114
 115     return s;
 116 }
 117
 118 char *
 119 tempnam(const char *dir, const char *pfx)
 120 {
 121     return _tmpnam();
 122 }
 123
 124 #ifdef TEST
 125 int
 126 main()
 127 {
 128     char *t;
 129     int n = 0;
 130     while ((t = tempnam(NULL, NULL))) {
 131         printf("%s\n", t);
 132         if (++n == 1000)
 133             break;
 134     }
 135     return 1;
 136 }
 137 #endif
 138