/*
 * This is a really simple stupid standalone program which will find two
 * filenames with the same CRC, used to test the directory iterator.
 *
 * cc -I /usr/src/sys test_dupkey.c /usr/src/sys/libkern/crc32.c \
 * /usr/src/sys/libkern/icrc32.c -o test_dupkey
 *
 * $DragonFly: src/sbin/hammer/test_dupkey.c,v 1.1 2008/06/26 04:07:57 dillon Exp $
 */

#include "hammer_util.h"

static uint32_t namekey(const char *name);
static void randomname(char *name);

uint32_t bitmap[0x80000000U / 32];

int
main(int ac, char **av)
{
        char name[32];
        uint32_t key;
        uint32_t *ptr;
        uint32_t mask;
        uint32_t count;
        uint32_t saved;

        srandom(0);     /* reproducable random sequence number */
        count = 0;
        for (;;) {
                randomname(name);
                key = namekey(name);
                ptr = &bitmap[key / 32];
                mask = 1 << (key & 31);
                if (*ptr & mask)
                        break;
                *ptr |= mask;
                ++count;
        }
        printf("duplicate found at count %d key %08x\n", count, key);
        printf("'%s' and", name);
        saved = key;

        srandom(0);
        count = 0;
        for (;;) {
                randomname(name);
                key = namekey(name);
                if (saved == key)
                        break;
                ++count;
        }
        printf(" '%s'\n", name);

        return(0);
}

static
uint32_t
namekey(const char *name)
{
        uint32_t key;

        key = crc32(name, strlen(name)) & 0x7FFFFFFF;
        if (key == 0)
                key = 1;
        return(key);
}

static
void
randomname(char *name)
{
        int len = random() % 16 + 8;
        int i;

        for (i = 0; i < len; ++i)
                name[i] = random() % 26 + 'a';
        name[i] = 0;
}