/*      $NetBSD: cdbr.c,v 1.2 2017/01/10 23:06:06 christos Exp $        */
/*-
* Copyright (c) 2010 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Joerg Sonnenberger.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
*    notice, this list of conditions and the following disclaimer in
*    the documentation and/or other materials provided with the
*    distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
* COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/

#if HAVE_NBTOOL_CONFIG_H
#include "nbtool_config.h"
#endif

#include <sys/cdefs.h>
__RCSID("$NetBSD: cdbr.c,v 1.2 2017/01/10 23:06:06 christos Exp $");

#if !defined(_KERNEL) && !defined(_STANDALONE)
#include "namespace.h"
#endif

#if !HAVE_NBTOOL_CONFIG_H
#include <sys/bitops.h>
#endif
#if !HAVE_NBTOOL_CONFIG_H || HAVE_SYS_ENDIAN_H
#include <sys/endian.h>
#endif

#if defined(_KERNEL) || defined(_STANDALONE)
#include <sys/cdbr.h>
#include <sys/kmem.h>
#include <sys/systm.h>
#include <lib/libkern/libkern.h>
#define SET_ERRNO(val)
#define malloc(size) kmem_alloc(size, KM_SLEEP)
#define free(ptr) kmem_free(ptr, sizeof(struct cdbr))
#else
#include <sys/mman.h>
#include <sys/stat.h>
#include <cdbr.h>
#include <errno.h>
#include <fcntl.h>
#include <inttypes.h>
#include <limits.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#define SET_ERRNO(val) errno = (val)
#endif

#if !defined(_KERNEL) && !defined(_STANDALONE)
#ifdef __weak_alias
__weak_alias(cdbr_close,_cdbr_close)
__weak_alias(cdbr_find,_cdbr_find)
__weak_alias(cdbr_get,_cdbr_get)
__weak_alias(cdbr_open,_cdbr_open)
__weak_alias(cdbr_open_mem,_cdbr_open_mem)
#endif
#endif

#if HAVE_NBTOOL_CONFIG_H
#define fast_divide32_prepare(d,m,s1,s2)        (void)0
#define fast_remainder32(v,d,m,s1,s2)           (v%d)
#endif

struct cdbr {
       void (*unmap)(void *, void *, size_t);
       void *cookie;
       uint8_t *mmap_base;
       size_t mmap_size;

       uint8_t *hash_base;
       uint8_t *offset_base;
       uint8_t *data_base;

       uint32_t data_size;
       uint32_t entries;
       uint32_t entries_index;
       uint32_t seed;

       uint8_t offset_size;
       uint8_t index_size;

       uint32_t entries_m;
       uint32_t entries_index_m;
       uint8_t entries_s1, entries_s2;
       uint8_t entries_index_s1, entries_index_s2;
};

#if !defined(_KERNEL) && !defined(_STANDALONE)
static void
cdbr_unmap(void *cookie __unused, void *base, size_t size)
{
       munmap(base, size);
}

/* ARGSUSED */
struct cdbr *
cdbr_open(const char *path, int flags)
{
       void *base;
       size_t size;
       int fd;
       struct cdbr *cdbr;
       struct stat sb;

       if ((fd = open(path, O_RDONLY)) == -1)
               return NULL;
       if (fstat(fd, &sb) == -1) {
               close(fd);
               return NULL;
       }

       if (sb.st_size >= SSIZE_MAX) {
               close(fd);
               SET_ERRNO(EINVAL);
               return NULL;
       }


       size = (size_t)sb.st_size;
       base = mmap(NULL, size, PROT_READ, MAP_FILE|MAP_SHARED, fd, 0);
       close(fd);

       if (base == MAP_FAILED)
               return NULL;

       cdbr = cdbr_open_mem(base, size, flags, cdbr_unmap, NULL);
       if (cdbr == NULL)
               munmap(base, size);
       return cdbr;
}
#endif

struct cdbr *
cdbr_open_mem(void *base, size_t size, int flags __unused,
   void (*unmap)(void *, void *, size_t), void *cookie)
{
       struct cdbr *cdbr;
       uint8_t *buf = base;
       if (size < 40 || memcmp(buf, "NBCDB\n\0\001", 8)) {
               SET_ERRNO(EINVAL);
               return NULL;
       }

       cdbr = malloc(sizeof(*cdbr));
       cdbr->unmap = unmap;
       cdbr->cookie = cookie;

       cdbr->data_size = le32dec(buf + 24);
       cdbr->entries = le32dec(buf + 28);
       cdbr->entries_index = le32dec(buf + 32);
       cdbr->seed = le32dec(buf + 36);

       if (cdbr->data_size < 0x100)
               cdbr->offset_size = 1;
       else if (cdbr->data_size < 0x10000)
               cdbr->offset_size = 2;
       else
               cdbr->offset_size = 4;

       if (cdbr->entries_index < 0x100)
               cdbr->index_size = 1;
       else if (cdbr->entries_index < 0x10000)
               cdbr->index_size = 2;
       else
               cdbr->index_size = 4;

       cdbr->mmap_base = base;
       cdbr->mmap_size = size;

       cdbr->hash_base = cdbr->mmap_base + 40;
       cdbr->offset_base = cdbr->hash_base + cdbr->entries_index * cdbr->index_size;
       if (cdbr->entries_index * cdbr->index_size % cdbr->offset_size)
               cdbr->offset_base += cdbr->offset_size -
                   cdbr->entries_index * cdbr->index_size % cdbr->offset_size;
       cdbr->data_base = cdbr->offset_base + (cdbr->entries + 1) * cdbr->offset_size;

       if (cdbr->hash_base < cdbr->mmap_base ||
           cdbr->offset_base < cdbr->mmap_base ||
           cdbr->data_base < cdbr->mmap_base ||
           cdbr->data_base + cdbr->data_size < cdbr->mmap_base ||
           cdbr->data_base + cdbr->data_size >
           cdbr->mmap_base + cdbr->mmap_size) {
               SET_ERRNO(EINVAL);
               free(cdbr);
               return NULL;
       }

       if (cdbr->entries) {
               fast_divide32_prepare(cdbr->entries, &cdbr->entries_m,
                   &cdbr->entries_s1, &cdbr->entries_s2);
       }
       if (cdbr->entries_index) {
               fast_divide32_prepare(cdbr->entries_index,
                   &cdbr->entries_index_m,
                   &cdbr->entries_index_s1, &cdbr->entries_index_s2);
       }

       return cdbr;
}

static inline uint32_t
get_uintX(const uint8_t *addr, uint32_t idx, int size)
{
       addr += idx * size;

       if (size == 4)
               return /* LINTED */le32toh(*(const uint32_t *)addr);
       else if (size == 2)
               return /* LINTED */le16toh(*(const uint16_t *)addr);
       else
               return *addr;
}

uint32_t
cdbr_entries(struct cdbr *cdbr)
{

       return cdbr->entries;
}

int
cdbr_get(struct cdbr *cdbr, uint32_t idx, const void **data, size_t *data_len)
{
       uint32_t start, end;

       if (idx >= cdbr->entries) {
               SET_ERRNO(EINVAL);
               return -1;
       }

       start = get_uintX(cdbr->offset_base, idx, cdbr->offset_size);
       end = get_uintX(cdbr->offset_base, idx + 1, cdbr->offset_size);

       if (start > end) {
               SET_ERRNO(EIO);
               return -1;
       }

       if (end > cdbr->data_size) {
               SET_ERRNO(EIO);
               return -1;
       }

       *data = cdbr->data_base + start;
       *data_len = end - start;

       return 0;
}

int
cdbr_find(struct cdbr *cdbr, const void *key, size_t key_len,
   const void **data, size_t *data_len)
{
       uint32_t hashes[3], idx;

       if (cdbr->entries_index == 0) {
               SET_ERRNO(EINVAL);
               return -1;
       }

       mi_vector_hash(key, key_len, cdbr->seed, hashes);

       hashes[0] = fast_remainder32(hashes[0], cdbr->entries_index,
           cdbr->entries_index_m, cdbr->entries_index_s1,
           cdbr->entries_index_s2);
       hashes[1] = fast_remainder32(hashes[1], cdbr->entries_index,
           cdbr->entries_index_m, cdbr->entries_index_s1,
           cdbr->entries_index_s2);
       hashes[2] = fast_remainder32(hashes[2], cdbr->entries_index,
           cdbr->entries_index_m, cdbr->entries_index_s1,
           cdbr->entries_index_s2);

       idx = get_uintX(cdbr->hash_base, hashes[0], cdbr->index_size);
       idx += get_uintX(cdbr->hash_base, hashes[1], cdbr->index_size);
       idx += get_uintX(cdbr->hash_base, hashes[2], cdbr->index_size);

       return cdbr_get(cdbr, fast_remainder32(idx, cdbr->entries,
           cdbr->entries_m, cdbr->entries_s1, cdbr->entries_s2), data,
           data_len);
}

void
cdbr_close(struct cdbr *cdbr)
{
       if (cdbr->unmap)
               (*cdbr->unmap)(cdbr->cookie, cdbr->mmap_base, cdbr->mmap_size);
       free(cdbr);
}

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