/* MDB Tools - A library for reading MS Access database files

 * Copyright (C) 2000 Brian Bruns

 *

 * This library is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Library General Public

 * License as published by the Free Software Foundation; either

 * version 2 of the License, or (at your option) any later version.

 *

 * This library is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * Library General Public License for more details.

 *

 * You should have received a copy of the GNU Library General Public

 * License along with this library; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA

 */

#include <inttypes.h>

#include <stddef.h>

#include "mdbtools.h"

#include "mdbprivate.h"

MdbFormatConstants MdbJet4Constants = {

  .pg_size = 4096,

    .row_count_offset = 0x0c,

    .tab_num_rows_offset = 16,

    .tab_num_cols_offset = 45,

    .tab_num_idxs_offset = 47,

    .tab_num_ridxs_offset = 51,

    .tab_usage_map_offset = 55,

    .tab_first_dpg_offset = 56,

    .tab_cols_start_offset = 63,

    .tab_ridx_entry_size = 12,

    .col_scale_offset = 11,

    .col_prec_offset = 12,

    .col_flags_offset = 15,

    .col_size_offset = 23,

    .col_num_offset = 5,

    .tab_col_entry_size = 25,

    .tab_free_map_offset = 59,

    .tab_col_offset_var = 7,

    .tab_col_offset_fixed = 21,

    .tab_row_col_num_offset = 9

};

MdbFormatConstants MdbJet3Constants = {

  .pg_size = 2048,

    .row_count_offset = 0x08,

    .tab_num_rows_offset = 12,

    .tab_num_cols_offset = 25,

    .tab_num_idxs_offset = 27,

    .tab_num_ridxs_offset = 31,

    .tab_usage_map_offset = 35,

    .tab_first_dpg_offset = 36,

    .tab_cols_start_offset = 43,

    .tab_ridx_entry_size = 8,

    .col_scale_offset = 9,

    .col_prec_offset = 10,

    .col_flags_offset = 13,

    .col_size_offset = 16,

    .col_num_offset = 1,

    .tab_col_entry_size = 18,

    .tab_free_map_offset = 39,

    .tab_col_offset_var = 3,

    .tab_col_offset_fixed = 14,

    .tab_row_col_num_offset = 5

};

static ssize_t _mdb_read_pg(MdbHandle *mdb, void *pg_buf, unsigned long pg);

/**

 * mdb_find_file:

 * @filename: path to MDB (database) file

 *

 * Finds and returns the absolute path to an MDB file.  Function will first try

 * to fstat file as passed, then search through the $MDBPATH if not found.

 *

 * Return value: gchar pointer to absolute path. Caller is responsible for

 * freeing.

 **/

static char *mdb_find_file(const char *file_name)

{

  struct stat status;

  gchar *mdbpath, **dir, *tmpfname;

  unsigned int i = 0;

  /* try the provided file name first */

  if (!stat(file_name, &status)) {

    char *result;

    result = g_strdup(file_name);

    if (!result)

      fprintf(stderr, "Can't alloc filename\n");

    return result;

  }

  /* Now pull apart $MDBPATH and try those */

  mdbpath = (gchar *) getenv("MDBPATH");

  /* no path, can't find file */

  if (!mdbpath || !strlen(mdbpath)) return NULL;

  dir = g_strsplit(mdbpath, ":", 0); 

  while (dir[i]) {

    if (!strlen(dir[i])) continue;

    tmpfname = g_strconcat(dir[i++], "/", file_name, NULL);

    if (!stat(tmpfname, &status)) {

      g_strfreev(dir);

      return tmpfname;

    }

    g_free(tmpfname);

  }

  g_strfreev(dir);

  return NULL;

}

/**

 * mdb_handle_from_stream:

 * @stream An open file stream

 * @flags MDB_NOFLAGS for read-only, MDB_WRITABLE for read/write

 *

 * Allocates, initializes, and return an MDB handle from a file stream pointing

 * to an MDB file.

 *

 * Return value: The handle on success, NULL on failure

 */

static MdbHandle *mdb_handle_from_stream(FILE *stream, MdbFileFlags flags) {

  MdbHandle *mdb = g_malloc0(sizeof(MdbHandle));

  mdb_set_default_backend(mdb, "access");

    mdb_set_date_fmt(mdb, "%x %X");

    mdb_set_shortdate_fmt(mdb, "%x");

    mdb_set_bind_size(mdb, MDB_BIND_SIZE);

    mdb_set_boolean_fmt_numbers(mdb);

    mdb_set_repid_fmt(mdb, MDB_BRACES_4_2_2_8);

#ifdef HAVE_ICONV

  mdb->iconv_in = (iconv_t)-1;

  mdb->iconv_out = (iconv_t)-1;

#endif

  /* need something to bootstrap with, reassign after page 0 is read */

  mdb->fmt = &MdbJet3Constants;

  mdb->f = g_malloc0(sizeof(MdbFile));

  mdb->f->refs = 1;

  mdb->f->stream = stream;

  if (flags & MDB_WRITABLE) {

    mdb->f->writable = TRUE;

    }

  if (!mdb_read_pg(mdb, 0)) {

    // fprintf(stderr,"Couldn't read first page.\n");

    mdb_close(mdb);

    return NULL;

  }

  if (mdb->pg_buf[0] != 0) {

    mdb_close(mdb);

    return NULL; 

  }

  mdb->f->jet_version = mdb_get_byte(mdb->pg_buf, 0x14);

  switch(mdb->f->jet_version) {

  case MDB_VER_JET3:

    mdb->fmt = &MdbJet3Constants;

    break;

  case MDB_VER_JET4:

  case MDB_VER_ACCDB_2007:

  case MDB_VER_ACCDB_2010:

  case MDB_VER_ACCDB_2013:

  case MDB_VER_ACCDB_2016:

  case MDB_VER_ACCDB_2019:

    mdb->fmt = &MdbJet4Constants;

    break;

  default:

    fprintf(stderr,"Unknown Jet version: %x\n", mdb->f->jet_version);

    mdb_close(mdb);

    return NULL; 

  }

  unsigned char tmp_key[4] = { 0xC7, 0xDA, 0x39, 0x6B };

  mdbi_rc4(tmp_key, sizeof(tmp_key),

    mdb->pg_buf + 0x18,

    mdb->f->jet_version == MDB_VER_JET3 ? 126 : 128

  );

  if (mdb->f->jet_version == MDB_VER_JET3) {

    mdb->f->lang_id = mdb_get_int16(mdb->pg_buf, 0x3a);

  } else {

    mdb->f->lang_id = mdb_get_int16(mdb->pg_buf, 0x6e);

  }

  mdb->f->code_page = mdb_get_int16(mdb->pg_buf, 0x3c);

  mdb->f->db_key = mdb_get_int32(mdb->pg_buf, 0x3e);

    if (mdb->f->jet_version == MDB_VER_JET3) {

        /* JET4 needs additional masking with the DB creation date, currently unsupported */

        /* Bug - JET3 supports 20 byte passwords, this is currently just 14 bytes */

        memcpy(mdb->f->db_passwd, mdb->pg_buf + 0x42, sizeof(mdb->f->db_passwd));

    }

  mdb_iconv_init(mdb);

  return mdb;

}

/**

 * mdb_open_buffer:

 * @buffer A memory buffer containing an MDB file

 * @len Length of the buffer

 *

 * Opens an MDB file in memory and returns an MdbHandle to it.

 *

 * Return value: point to MdbHandle structure.

 */

MdbHandle *mdb_open_buffer(void *buffer, size_t len, MdbFileFlags flags) {

    FILE *file = NULL;

#ifdef HAVE_FMEMOPEN

    file = fmemopen(buffer, len, (flags & MDB_WRITABLE) ? "r+" : "r");

#else

    fprintf(stderr, "mdb_open_buffer requires a platform with support for fmemopen(3)\n");

#endif

    if (file == NULL) {

        fprintf(stderr, "Couldn't open memory buffer\n");

        return NULL;

    }

    return mdb_handle_from_stream(file, flags);

}

/**

 * mdb_open:

 * @filename: path to MDB (database) file

 * @flags: MDB_NOFLAGS for read-only, MDB_WRITABLE for read/write

 *

 * Opens an MDB file and returns an MdbHandle to it.  MDB File may be relative

 * to the current directory, a full path to the file, or relative to a 

 * component of $MDBPATH.

 *

 * Return value: pointer to MdbHandle structure.

 **/

MdbHandle *mdb_open(const char *filename, MdbFileFlags flags)

{

    FILE *file;

  char *filepath = mdb_find_file(filename);

  if (!filepath) {

    fprintf(stderr, "File not found\n");

    return NULL; 

  }

#ifdef _WIN32

    char *mode = (flags & MDB_WRITABLE) ? "rb+" : "rb";

#else

    char *mode = (flags & MDB_WRITABLE) ? "r+" : "r";

#endif

    if ((file = fopen(filepath, mode)) == NULL) {

    fprintf(stderr,"Couldn't open file %s\n",filepath);

    g_free(filepath);

    return NULL;

    }

    g_free(filepath);

    return mdb_handle_from_stream(file, flags);

}

/**

 * mdb_close:

 * @mdb: Handle to open MDB database file

 *

 * Dereferences MDB file, closes if reference count is 0, and destroys handle.

 *

 **/

void 

mdb_close(MdbHandle *mdb)

{

  if (!mdb) return; 

  mdb_free_catalog(mdb);

  g_free(mdb->stats);

  g_free(mdb->backend_name);

  if (mdb->f) {

    if (mdb->f->refs > 1) {

      mdb->f->refs--;

    } else {

      if (mdb->f->stream) fclose(mdb->f->stream);

      g_free(mdb->f);

    }

  }

  mdb_iconv_close(mdb);

    mdb_remove_backends(mdb);

  g_free(mdb);

}

/**

 * mdb_clone_handle:

 * @mdb: Handle to open MDB database file

 *

 * Clones an existing database handle.  Cloned handle shares the file descriptor

 * but has its own page buffer, page position, and similar internal variables.

 *

 * Return value: new handle to the database.

 */

MdbHandle *mdb_clone_handle(MdbHandle *mdb)

{

  MdbHandle *newmdb;

  MdbCatalogEntry *entry, *data;

  unsigned int i;

  newmdb = (MdbHandle *) g_memdup2(mdb, sizeof(MdbHandle));

  memset(&newmdb->catalog, 0, sizeof(MdbHandle) - offsetof(MdbHandle, catalog));

  newmdb->catalog = g_ptr_array_new();

  for (i=0;i<mdb->num_catalog;i++) {

    entry = g_ptr_array_index(mdb->catalog,i);

    data = g_memdup2(entry,sizeof(MdbCatalogEntry));

    data->mdb = newmdb;

    data->props = NULL;

    g_ptr_array_add(newmdb->catalog, data);

  }

  mdb_iconv_init(newmdb);

  mdb_set_default_backend(newmdb, mdb->backend_name);

  // formats for the source handle may have been changed from

  // the backend's default formats, so we need to explicitly copy them here

  mdb_set_date_fmt(newmdb, mdb->date_fmt);

  mdb_set_shortdate_fmt(newmdb, mdb->shortdate_fmt);

  mdb_set_repid_fmt(newmdb, mdb->repid_fmt);

  if (mdb->f) {

    mdb->f->refs++;

  }

  return newmdb;

}

/* 

** mdb_read a wrapper for read that bails if anything is wrong 

*/

ssize_t mdb_read_pg(MdbHandle *mdb, unsigned long pg)

{

  ssize_t len;

  if (pg && mdb->cur_pg == pg) return mdb->fmt->pg_size;

  len = _mdb_read_pg(mdb, mdb->pg_buf, pg);

  //fprintf(stderr, "read page %ld type %02x\n", pg, mdb->pg_buf[0]);

  mdb->cur_pg = pg;

  /* kan - reset the cur_pos on a new page read */

  mdb->cur_pos = 0; /* kan */

  return len;

}

ssize_t mdb_read_alt_pg(MdbHandle *mdb, unsigned long pg)

{

  return _mdb_read_pg(mdb, mdb->alt_pg_buf, pg);

}

static ssize_t _mdb_read_pg(MdbHandle *mdb, void *pg_buf, unsigned long pg)

{

  ssize_t len;

  off_t offset = pg * mdb->fmt->pg_size;

    if (fseeko(mdb->f->stream, 0, SEEK_END) == -1) {

        fprintf(stderr, "Unable to seek to end of file\n");

        return 0;

    }

    if (ftello(mdb->f->stream) < offset) { 

        fprintf(stderr,"offset %" PRIu64 " is beyond EOF\n",(uint64_t)offset);

        return 0;

    }

  if (mdb->stats && mdb->stats->collect) 

    mdb->stats->pg_reads++;

  if (fseeko(mdb->f->stream, offset, SEEK_SET) == -1) {

        fprintf(stderr, "Unable to seek to page %lu\n", pg);

        return 0;

    }

  len = fread(pg_buf, 1, mdb->fmt->pg_size, mdb->f->stream);

  if (ferror(mdb->f->stream)) {

    perror("read");

    return 0;

  }

    memset(pg_buf + len, 0, mdb->fmt->pg_size - len);

  /*

   * unencrypt the page if necessary.

   * it might make sense to cache the unencrypted data blocks?

   */

  if (pg != 0 && mdb->f->db_key != 0)

  {

    uint32_t tmp_key_i = mdb->f->db_key ^ pg;

    unsigned char tmp_key[4] = {

      tmp_key_i & 0xFF, (tmp_key_i >> 8) & 0xFF,

      (tmp_key_i >> 16) & 0xFF, (tmp_key_i >> 24) & 0xFF };

    mdbi_rc4(tmp_key, sizeof(tmp_key), pg_buf, mdb->fmt->pg_size);

  }

  return mdb->fmt->pg_size;

}

void mdb_swap_pgbuf(MdbHandle *mdb)

{

char tmpbuf[MDB_PGSIZE];

  memcpy(tmpbuf,mdb->pg_buf, MDB_PGSIZE);

  memcpy(mdb->pg_buf,mdb->alt_pg_buf, MDB_PGSIZE);

  memcpy(mdb->alt_pg_buf,tmpbuf,MDB_PGSIZE);

}

unsigned char mdb_get_byte(void *buf, int offset)

{

  return ((unsigned char *)(buf))[offset];

}

unsigned char mdb_pg_get_byte(MdbHandle *mdb, int offset)

{

  if (offset < 0 || offset+1 > mdb->fmt->pg_size) return -1;

  mdb->cur_pos++;

  return mdb->pg_buf[offset];

}

int mdb_get_int16(void *buf, int offset)

{

    unsigned char *u8_buf = (unsigned char *)buf + offset;

    return ((uint32_t)u8_buf[0] << 0) + ((uint32_t)u8_buf[1] << 8);

}

int mdb_pg_get_int16(MdbHandle *mdb, int offset)

{

  if (offset < 0 || offset+2 > mdb->fmt->pg_size) return -1;

  mdb->cur_pos+=2;

  return mdb_get_int16(mdb->pg_buf, offset);

}

long mdb_get_int32_msb(void *buf, int offset)

{

    unsigned char *u8_buf = (unsigned char *)buf + offset;

    return

        ((uint32_t)u8_buf[0] << 24) +

        ((uint32_t)u8_buf[1] << 16) +

        ((uint32_t)u8_buf[2] << 8) +

        ((uint32_t)u8_buf[3] << 0);

}

long mdb_get_int32(void *buf, int offset)

{

    unsigned char *u8_buf = (unsigned char *)buf + offset;

    return

        ((uint32_t)u8_buf[0] << 0) +

        ((uint32_t)u8_buf[1] << 8) +

        ((uint32_t)u8_buf[2] << 16) +

        ((uint32_t)u8_buf[3] << 24);

}

long mdb_pg_get_int32(MdbHandle *mdb, int offset)

{

  if (offset <0 || offset+4 > mdb->fmt->pg_size) return -1;

  mdb->cur_pos+=4;

  return mdb_get_int32(mdb->pg_buf, offset);

}

float mdb_get_single(void *buf, int offset)

{

  union {uint32_t g; float f;} f;

    unsigned char *u8_buf = (unsigned char *)buf + offset;

    f.g = ((uint32_t)u8_buf[0] << 0) +

        ((uint32_t)u8_buf[1] << 8) +

        ((uint32_t)u8_buf[2] << 16) +

        ((uint32_t)u8_buf[3] << 24);

  return f.f;

}

float mdb_pg_get_single(MdbHandle *mdb, int offset)

{

       if (offset <0 || offset+4 > mdb->fmt->pg_size) return -1;

       mdb->cur_pos+=4;

       return mdb_get_single(mdb->pg_buf, offset);

}

double mdb_get_double(void *buf, int offset)

{

  union {uint64_t g; double d;} d;

    unsigned char *u8_buf = (unsigned char *)buf + offset;

    d.g = ((uint64_t)u8_buf[0] << 0) +

           ((uint64_t)u8_buf[1] << 8) +

           ((uint64_t)u8_buf[2] << 16) +

           ((uint64_t)u8_buf[3] << 24) +

           ((uint64_t)u8_buf[4] << 32) +

           ((uint64_t)u8_buf[5] << 40) +

           ((uint64_t)u8_buf[6] << 48) +

           ((uint64_t)u8_buf[7] << 56);

  return d.d;

}

double mdb_pg_get_double(MdbHandle *mdb, int offset)

{

  if (offset <0 || offset+8 > mdb->fmt->pg_size) return -1;

  mdb->cur_pos+=8;

  return mdb_get_double(mdb->pg_buf, offset);

}

int 

mdb_set_pos(MdbHandle *mdb, int pos)

{

  if (pos<0 || pos >= mdb->fmt->pg_size) return 0;

  mdb->cur_pos=pos;

  return pos;

}

int mdb_get_pos(MdbHandle *mdb)

{

  return mdb->cur_pos;

}