compat/tempnam.c

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