sbin/hammer/test_dupkey.c

   1 /*
   2  * This is a really simple stupid standalone program which will find two
   3  * filenames with the same CRC, used to test the directory iterator.
   4  *
   5  * cc -I /usr/src/sys test_dupkey.c /usr/src/sys/libkern/crc32.c \
   6  * /usr/src/sys/libkern/icrc32.c -o test_dupkey
   7  *
   8  * $DragonFly: src/sbin/hammer/test_dupkey.c,v 1.1 2008/06/26 04:07:57 dillon Exp $
   9  */
  10
  11 #include "hammer_util.h"
  12
  13 static uint32_t namekey(const char *name);
  14 static void randomname(char *name);
  15
  16 uint32_t bitmap[0x80000000U / 32];
  17
  18 int
  19 main(int ac, char **av)
  20 {
  21         char name[32];
  22         uint32_t key;
  23         uint32_t *ptr;
  24         uint32_t mask;
  25         uint32_t count;
  26         uint32_t saved;
  27
  28         srandom(0);     /* reproducable random sequence number */
  29         count = 0;
  30         for (;;) {
  31                 randomname(name);
  32                 key = namekey(name);
  33                 ptr = &bitmap[key / 32];
  34                 mask = 1 << (key & 31);
  35                 if (*ptr & mask)
  36                         break;
  37                 *ptr |= mask;
  38                 ++count;
  39         }
  40         printf("duplicate found at count %d key %08x\n", count, key);
  41         printf("'%s' and", name);
  42         saved = key;
  43
  44         srandom(0);
  45         count = 0;
  46         for (;;) {
  47                 randomname(name);
  48                 key = namekey(name);
  49                 if (saved == key)
  50                         break;
  51                 ++count;
  52         }
  53         printf(" '%s'\n", name);
  54 }
  55
  56 static
  57 uint32_t
  58 namekey(const char *name)
  59 {
  60         uint32_t key;
  61
  62         key = crc32(name, strlen(name)) & 0x7FFFFFFF;
  63         if (key == 0)
  64                 key = 1;
  65         return(key);
  66 }
  67
  68 static
  69 void
  70 randomname(char *name)
  71 {
  72         int len = random() % 16 + 8;
  73         int i;
  74
  75         for (i = 0; i < len; ++i)
  76                 name[i] = random() % 26 + 'a';
  77         name[i] = 0;
  78 }
  79
  80