/*	$NetBSD: citrus_db.c,v 1.5 2008/02/09 14:56:20 junyoung Exp $	*/

/*-
 * Copyright (c)2003 Citrus Project,
 * All rights reserved.
 *
 * 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 AUTHOR 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 AUTHOR 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.
 */

#include <sys/cdefs.h>
#if defined(LIBC_SCCS) && !defined(lint)
__RCSID("$NetBSD: citrus_db.c,v 1.5 2008/02/09 14:56:20 junyoung Exp $");
#endif /* LIBC_SCCS and not lint */

#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <limits.h>
#include <sys/types.h>

#include "citrus_namespace.h"
#include "citrus_bcs.h"
#include "citrus_region.h"
#include "citrus_memstream.h"
#include "citrus_mmap.h"
#include "citrus_db.h"
#include "citrus_db_file.h"

struct _citrus_db {
  /* private */
  struct _region db_region;
  uint32_t (*db_hashfunc)(void *, struct _citrus_region *);
  void *db_hashfunc_closure;
};

int _citrus_db_open(struct _citrus_db **rdb, struct _region *r,
                    const char *magic,
                    uint32_t (*hashfunc)(void *, struct _citrus_region *),
                    void *hashfunc_closure) {
  struct _memstream ms;
  struct _citrus_db *db;
  struct _citrus_db_header_x *dhx;

  _memstream_bind(&ms, r);

  /* sanity check */
  dhx = _memstream_getregion(&ms, NULL, sizeof(*dhx));
  if (dhx == NULL)
    return EFTYPE;
  if (strncmp(dhx->dhx_magic, magic, _CITRUS_DB_MAGIC_SIZE) != 0)
    return EFTYPE;
  if (_memstream_seek(&ms, be32toh(dhx->dhx_entry_offset), SEEK_SET))
    return EFTYPE;

  if (be32toh(dhx->dhx_num_entries) * _CITRUS_DB_ENTRY_SIZE >
      _memstream_remainder(&ms))
    return EFTYPE;

  db = malloc(sizeof(*db));
  if (db == NULL)
    return errno;
  db->db_region = *r;
  db->db_hashfunc = hashfunc;
  db->db_hashfunc_closure = hashfunc_closure;
  *rdb = db;

  return 0;
}

void _citrus_db_close(struct _citrus_db *db) {
  free(db);
}

int _citrus_db_lookup(struct _citrus_db *db, struct _citrus_region *key,
                      struct _citrus_region *data,
                      struct _citrus_db_locator *dl) {
  uint32_t hashval, num_entries;
  size_t offset;
  struct _memstream ms;
  struct _citrus_db_header_x *dhx;
  struct _citrus_db_entry_x *dex;
  struct _citrus_region r;

  _memstream_bind(&ms, &db->db_region);

  dhx = _memstream_getregion(&ms, NULL, sizeof(*dhx));
  _DIAGASSERT(dhx);
  num_entries = be32toh(dhx->dhx_num_entries);
  if (num_entries == 0)
    return ENOENT;

  if (dl != NULL && dl->dl_offset > 0) {
    hashval = dl->dl_hashval;
    offset = dl->dl_offset;
    if (offset >= _region_size(&db->db_region))
      return ENOENT;
  } else {
    hashval = db->db_hashfunc(db->db_hashfunc_closure, key) % num_entries;
    offset = be32toh(dhx->dhx_entry_offset) + hashval * _CITRUS_DB_ENTRY_SIZE;
    if (dl)
      dl->dl_hashval = hashval;
  }
  do {
    /* seek to the next entry */
    if (_citrus_memory_stream_seek(&ms, offset, SEEK_SET))
      return EFTYPE;
    /* get the entry record */
    dex = _memstream_getregion(&ms, NULL, _CITRUS_DB_ENTRY_SIZE);
    if (dex == NULL)
      return EFTYPE;

    /* jump to next entry having the same hash value. */
    offset = be32toh(dex->dex_next_offset);

    /* save the current position */
    if (dl) {
      dl->dl_offset = offset;
      if (offset == 0)
        dl->dl_offset = _region_size(&db->db_region);
    }

    /* compare hash value. */
    if (be32toh(dex->dex_hash_value) != hashval)
      /* not found */
      break;
    /* compare key length */
    if (be32toh(dex->dex_key_size) == _region_size(key)) {
      /* seek to the head of the key. */
      if (_memstream_seek(&ms, be32toh(dex->dex_key_offset), SEEK_SET))
        return EFTYPE;
      /* get the region of the key */
      if (_memstream_getregion(&ms, &r, _region_size(key)) == NULL)
        return EFTYPE;
      /* compare key byte stream */
      if (memcmp(_region_head(&r), _region_head(key), _region_size(key)) == 0) {
        /* match */
        if (_memstream_seek(&ms, be32toh(dex->dex_data_offset), SEEK_SET))
          return EFTYPE;
        if (_memstream_getregion(&ms, data, be32toh(dex->dex_data_size)) ==
            NULL)
          return EFTYPE;
        return 0;
      }
    }
  } while (offset != 0);

  return ENOENT;
}

int _citrus_db_lookup_by_string(struct _citrus_db *db, const char *key,
                                struct _citrus_region *data,
                                struct _citrus_db_locator *dl) {
  struct _region r;

  _region_init(&r, __UNCONST(key), strlen(key));

  return _citrus_db_lookup(db, &r, data, dl);
}

int _citrus_db_lookup8_by_string(struct _citrus_db *db, const char *key,
                                 uint8_t *rval, struct _citrus_db_locator *dl) {
  int ret;
  struct _region r;

  ret = _citrus_db_lookup_by_string(db, key, &r, dl);
  if (ret)
    return ret;

  if (_region_size(&r) != 1)
    return EFTYPE;

  if (rval)
    memcpy(rval, _region_head(&r), 1);

  return 0;
}

int _citrus_db_lookup16_by_string(struct _citrus_db *db, const char *key,
                                  uint16_t *rval,
                                  struct _citrus_db_locator *dl) {
  int ret;
  struct _region r;
  uint16_t val;

  ret = _citrus_db_lookup_by_string(db, key, &r, dl);
  if (ret)
    return ret;

  if (_region_size(&r) != 2)
    return EFTYPE;

  if (rval) {
    memcpy(&val, _region_head(&r), 2);
    *rval = be16toh(val);
  }

  return 0;
}

int _citrus_db_lookup32_by_string(struct _citrus_db *db, const char *key,
                                  uint32_t *rval,
                                  struct _citrus_db_locator *dl) {
  int ret;
  struct _region r;
  uint32_t val;

  ret = _citrus_db_lookup_by_string(db, key, &r, dl);
  if (ret)
    return ret;

  if (_region_size(&r) != 4)
    return EFTYPE;

  if (rval) {
    memcpy(&val, _region_head(&r), 4);
    *rval = be32toh(val);
  }

  return 0;
}

int _citrus_db_lookup_string_by_string(struct _citrus_db *db, const char *key,
                                       const char **rdata,
                                       struct _citrus_db_locator *dl) {
  int ret;
  struct _region r;

  ret = _citrus_db_lookup_by_string(db, key, &r, dl);
  if (ret)
    return ret;

  /* check whether the string is null terminated */
  if (_region_size(&r) == 0)
    return EFTYPE;
  if (*((const char *)_region_head(&r) + _region_size(&r) - 1) != '\0')
    return EFTYPE;

  if (rdata)
    *rdata = _region_head(&r);

  return 0;
}

int _citrus_db_get_number_of_entries(struct _citrus_db *db) {
  struct _memstream ms;
  struct _citrus_db_header_x *dhx;

  _memstream_bind(&ms, &db->db_region);

  dhx = _memstream_getregion(&ms, NULL, sizeof(*dhx));
  _DIAGASSERT(dhx);
  return (int)be32toh(dhx->dhx_num_entries);
}

int _citrus_db_get_entry(struct _citrus_db *db, int idx, struct _region *key,
                         struct _region *data) {
  uint32_t num_entries;
  size_t offset;
  struct _memstream ms;
  struct _citrus_db_header_x *dhx;
  struct _citrus_db_entry_x *dex;

  _memstream_bind(&ms, &db->db_region);

  dhx = _memstream_getregion(&ms, NULL, sizeof(*dhx));
  _DIAGASSERT(dhx);
  num_entries = be32toh(dhx->dhx_num_entries);
  if (idx < 0 || (uint32_t)idx >= num_entries)
    return EINVAL;

  /* seek to the next entry */
  offset = be32toh(dhx->dhx_entry_offset) + idx * _CITRUS_DB_ENTRY_SIZE;
  if (_citrus_memory_stream_seek(&ms, offset, SEEK_SET))
    return EFTYPE;
  /* get the entry record */
  dex = _memstream_getregion(&ms, NULL, _CITRUS_DB_ENTRY_SIZE);
  if (dex == NULL)
    return EFTYPE;
  /* seek to the head of the key. */
  if (_memstream_seek(&ms, be32toh(dex->dex_key_offset), SEEK_SET))
    return EFTYPE;
  /* get the region of the key. */
  if (_memstream_getregion(&ms, key, be32toh(dex->dex_key_size)) == NULL)
    return EFTYPE;
  /* seek to the head of the data. */
  if (_memstream_seek(&ms, be32toh(dex->dex_data_offset), SEEK_SET))
    return EFTYPE;
  /* get the region of the data. */
  if (_memstream_getregion(&ms, data, be32toh(dex->dex_data_size)) == NULL)
    return EFTYPE;

  return 0;
}
