/* Copyright (C) 2000 MySQL AB & MySQL Finland AB & TCX DataKonsult AB

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.

   This program 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 General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */

/* open a isam-database */

#include "isamdef.h"
#if defined(MSDOS) || defined(__WIN__)
#ifdef __WIN__
#include <fcntl.h>
#else
#include <process.h>			/* Prototype for getpid */
#endif
#endif
#ifdef VMS
#include "static.c"
#endif

static void setup_functions(ISAM_SHARE *info);
static void setup_key_functions(N_KEYDEF *keyinfo);

#define get_next_element(to,pos,size) { memcpy((char*) to,pos,(size_t) size); \
					pos+=size;}

/******************************************************************************
** Return the shared struct if the table is already open.
** In MySQL the server will handle version issues.
******************************************************************************/

static N_INFO *test_if_reopen(char *filename)
{
  LIST *pos;

  for (pos=nisam_open_list ; pos ; pos=pos->next)
  {
    N_INFO *info=(N_INFO*) pos->data;
    ISAM_SHARE *share=info->s;
    if (!strcmp(share->filename,filename) && share->last_version)
      return info;
  }
  return 0;
}


/******************************************************************************
  open a isam database.
  By default exit with error if database is locked
  if handle_locking & HA_OPEN_WAIT_IF_LOCKED then wait if database is locked
  if handle_locking & HA_OPEN_IGNORE_IF_LOCKED then continue, but count-vars
    in st_i_info may be wrong. count-vars are automaticly fixed after next
    isam request.
******************************************************************************/


N_INFO *nisam_open(const char *name, int mode, uint handle_locking)
{
  int lock_error,kfile,open_mode,save_errno;
  uint i,j,len,errpos,head_length,base_pos,offset,info_length,extra;
  char name_buff[FN_REFLEN],*disk_cache,*disk_pos;
  N_INFO info,*m_info,*old_info;
  ISAM_SHARE share_buff,*share;
  DBUG_ENTER("nisam_open");

  LINT_INIT(m_info);
  kfile= -1;
  lock_error=1;
  errpos=0;
  head_length=sizeof(share_buff.state.header);
  bzero((byte*) &info,sizeof(info));

  VOID(fn_format(name_buff,name,"",N_NAME_IEXT,4+16+32));
  pthread_mutex_lock(&THR_LOCK_isam);
  if (!(old_info=test_if_reopen(name_buff)))
  {
    share= &share_buff;
    bzero((gptr) &share_buff,sizeof(share_buff));

    if ((kfile=my_open(name_buff,(open_mode=O_RDWR) | O_SHARE,MYF(0))) < 0)
    {
      if ((errno != EROFS && errno != EACCES) ||
	  mode != O_RDONLY ||
	  (kfile=my_open(name_buff,(open_mode=O_RDONLY) | O_SHARE,MYF(0))) < 0)
	goto err;
    }
    errpos=1;
    if (my_read(kfile,(char*) share->state.header.file_version,head_length,
		MYF(MY_NABP)))
      goto err;

    if (memcmp((byte*) share->state.header.file_version,
	       (byte*) nisam_file_magic, 3) ||
	share->state.header.file_version[3] == 0 ||
	(uchar) share->state.header.file_version[3] > 3)
    {
      DBUG_PRINT("error",("Wrong header in %s",name_buff));
      DBUG_DUMP("error_dump",(char*) share->state.header.file_version,
		head_length);
      my_errno=HA_ERR_CRASHED;
      goto err;
    }
    if (uint2korr(share->state.header.options) &
	~(HA_OPTION_PACK_RECORD | HA_OPTION_PACK_KEYS |
	  HA_OPTION_COMPRESS_RECORD | HA_OPTION_READ_ONLY_DATA |
	  HA_OPTION_TEMP_COMPRESS_RECORD))
    {
      DBUG_PRINT("error",("wrong options: 0x%lx",
			  uint2korr(share->state.header.options)));
      my_errno=HA_ERR_OLD_FILE;
      goto err;
    }
    info_length=uint2korr(share->state.header.header_length);
    base_pos=uint2korr(share->state.header.base_pos);
    if (!(disk_cache=(char*) my_alloca(info_length)))
    {
      my_errno=ENOMEM;
      goto err;
    }
    errpos=2;

    VOID(my_seek(kfile,0L,MY_SEEK_SET,MYF(0)));
#ifndef NO_LOCKING
    if (!(handle_locking & HA_OPEN_TMP_TABLE))
    {
      if ((lock_error=my_lock(kfile,F_RDLCK,0L,F_TO_EOF,
			      MYF(handle_locking & HA_OPEN_WAIT_IF_LOCKED ?
				  0 : MY_DONT_WAIT))) &&
	  !(handle_locking & HA_OPEN_IGNORE_IF_LOCKED))
	goto err;
    }
#endif
    errpos=3;
    if (my_read(kfile,disk_cache,info_length,MYF(MY_NABP)))
      goto err;
    len=uint2korr(share->state.header.state_info_length);
    if (len != sizeof(N_STATE_INFO))
    {
      DBUG_PRINT("warning",
		 ("saved_state_info_length: %d  base_info_length: %d",
		  len,sizeof(N_STATE_INFO)));
    }
    if (len > sizeof(N_STATE_INFO))
      len=sizeof(N_STATE_INFO);
    share->state_length=len;
    memcpy(&share->state.header.file_version[0],disk_cache,(size_t) len);
    len=uint2korr(share->state.header.base_info_length);
    if (len != sizeof(N_BASE_INFO))
    {
      DBUG_PRINT("warning",("saved_base_info_length: %d  base_info_length: %d",
			    len,sizeof(N_BASE_INFO)));
      if (len <= offsetof(N_BASE_INFO,sortkey))
	share->base.sortkey=(ushort) ~0;
    }
    memcpy((char*) (byte*) &share->base,disk_cache+base_pos,
	   (size_t) min(len,sizeof(N_BASE_INFO)));
    disk_pos=disk_cache+base_pos+len;
    share->base.options=uint2korr(share->state.header.options);
    if (share->base.max_key_length > N_MAX_KEY_BUFF)
    {
      my_errno=HA_ERR_UNSUPPORTED;
      goto err;
    }
    if (share->base.options & HA_OPTION_COMPRESS_RECORD)
      share->base.max_key_length+=2;	/* For safety */

    if (!my_multi_malloc(MY_WME,
			 &share,sizeof(*share),
			 &share->keyinfo,share->base.keys*sizeof(N_KEYDEF),
			 &share->rec,(share->base.fields+1)*sizeof(N_RECINFO),
			 &share->blobs,sizeof(N_BLOB)*share->base.blobs,
			 &share->filename,strlen(name_buff)+1,
			 NullS))
      goto err;
    errpos=4;
    *share=share_buff;
    strmov(share->filename,name_buff);

    /* Fix key in used if old nisam-database */
    if (share->state_length <= offsetof(N_STATE_INFO,keys))
      share->state.keys=share->base.keys;

    share->blocksize=min(IO_SIZE,nisam_block_size);
    for (i=0 ; i < share->base.keys ; i++)
    {
      get_next_element(&share->keyinfo[i].base,disk_pos,sizeof(N_SAVE_KEYDEF));
      setup_key_functions(share->keyinfo+i);
      set_if_smaller(share->blocksize,share->keyinfo[i].base.block_length);
      for (j=0 ; j <= share->keyinfo[i].base.keysegs ; j++)
      {
	get_next_element(&share->keyinfo[i].seg[j],disk_pos,
			 sizeof(N_SAVE_KEYSEG));
      }
    }
    if (!share->blocksize)
    {
      my_errno=HA_ERR_CRASHED;
      goto err;
    }

    for (i=j=offset=0 ; i < share->base.fields ; i++)
    {
      get_next_element(&share->rec[i].base,disk_pos,sizeof(N_SAVE_RECINFO));
#ifndef NOT_PACKED_DATABASES
      share->rec[i].pack_type=0;
      share->rec[i].huff_tree=0;
#endif
      if (share->rec[i].base.type == (int) FIELD_BLOB)
      {
	share->blobs[j].pack_length=share->rec[i].base.length;
	share->blobs[j].offset=offset;
	j++;
	offset+=sizeof(char*);
      }
      offset+=share->rec[i].base.length;
    }
    share->rec[i].base.type=(int) FIELD_LAST;

#ifndef NO_LOCKING
    if (! lock_error)
    {
      VOID(my_lock(kfile,F_UNLCK,0L,F_TO_EOF,MYF(MY_SEEK_NOT_DONE)));
      lock_error=1;			/* Database unlocked */
    }
#endif

    if ((info.dfile=my_open(fn_format(name_buff,name,"",N_NAME_DEXT,2+4),
			    mode | O_SHARE,
			    MYF(MY_WME))) < 0)
      goto err;
    errpos=5;

    share->kfile=kfile;
    share->mode=open_mode;
    share->this_process=(ulong) getpid();
    share->rnd= (int)	 share->this_process;	/* rnd-counter for splitts */
#ifndef DBUG_OFF
    share->rnd=0;				/* To make things repeatable */
#endif
    share->last_process= share->state.process;
    if (!(share->last_version=share->state.version))
      share->last_version=1;			/* Safety */
    share->rec_reflength=share->base.rec_reflength; /* May be changed */

    share->data_file_type=STATIC_RECORD;
    if (share->base.options & HA_OPTION_COMPRESS_RECORD)
    {
      share->data_file_type = COMPRESSED_RECORD;
      share->base.options|= HA_OPTION_READ_ONLY_DATA;
      info.s=share;
      if (_nisam_read_pack_info(&info,
				(pbool) test(!(share->base.options &
					       (HA_OPTION_PACK_RECORD |
						HA_OPTION_TEMP_COMPRESS_RECORD)))))
	goto err;
    }
    else if (share->base.options & HA_OPTION_PACK_RECORD)
      share->data_file_type = DYNAMIC_RECORD;
    my_afree((gptr) disk_cache);
    setup_functions(share);
#ifdef THREAD
    thr_lock_init(&share->lock);
    VOID(pthread_mutex_init(&share->intern_lock,MY_MUTEX_INIT_FAST));
#endif
  }
  else
  {
    share= old_info->s;
    if (mode == O_RDWR && share->mode == O_RDONLY)
    {
      my_errno=EACCES;				/* Can't open in write mode*/
      goto err;
    }
    if ((info.dfile=my_open(fn_format(name_buff,old_info->filename,"",
				      N_NAME_DEXT,2+4),
			    mode | O_SHARE,MYF(MY_WME))) < 0)
    {
      my_errno=errno;
      goto err;
    }
    errpos=5;
  }

  /* alloc and set up private structure parts */
  if (!my_multi_malloc(MY_WME,
		       &m_info,sizeof(N_INFO),
		       &info.blobs,sizeof(N_BLOB)*share->base.blobs,
		       &info.buff,(share->base.max_block*2+
				   share->base.max_key_length),
		       &info.lastkey,share->base.max_key_length*3+1,
		       &info.filename,strlen(name)+1,
		       NullS))
    goto err;
  errpos=6;
  strmov(info.filename,name);
  memcpy(info.blobs,share->blobs,sizeof(N_BLOB)*share->base.blobs);

  info.s=share;
  info.lastpos= NI_POS_ERROR;
  info.update= (short) (HA_STATE_NEXT_FOUND+HA_STATE_PREV_FOUND);
  info.opt_flag=READ_CHECK_USED;
  info.alloced_rec_buff_length=share->base.pack_reclength;
  info.this_uniq= (ulong) info.dfile;	/* Uniq number in process */
  info.this_loop=0;			/* Update counter */
  info.last_uniq= share->state.uniq;
  info.last_loop= share->state.loop;
  info.options=share->base.options |
    (mode == O_RDONLY ? HA_OPTION_READ_ONLY_DATA : 0);
  info.lock_type=F_UNLCK;
  info.errkey= -1;
  pthread_mutex_lock(&share->intern_lock);
  info.read_record=share->read_record;
  share->reopen++;
  if (share->base.options & HA_OPTION_READ_ONLY_DATA)
  {
    info.lock_type=F_RDLCK;
    share->r_locks++;
    info.this_uniq=share->state.uniq;	/* Row checksum */
  }
#ifndef NO_LOCKING
  if (handle_locking & HA_OPEN_TMP_TABLE)
#endif
  {
    share->w_locks++;			/* We don't have to update status */
    info.lock_type=F_WRLCK;
  }
  pthread_mutex_unlock(&share->intern_lock);

  /* Allocate buffer for one record */

  extra=0;
  if (share->base.options & HA_OPTION_PACK_RECORD)
    extra=ALIGN_SIZE(MAX_DYN_BLOCK_HEADER)+N_SPLITT_LENGTH+
      DYN_DELETE_BLOCK_HEADER;
  if (!(info.rec_alloc=(byte*) my_malloc(share->base.pack_reclength+extra+
					 6,
					 MYF(MY_WME | MY_ZEROFILL))))
    goto err;
  if (extra)
    info.rec_buff=info.rec_alloc+ALIGN_SIZE(MAX_DYN_BLOCK_HEADER);
  else
    info.rec_buff=info.rec_alloc;

  *m_info=info;
#ifdef THREAD
  thr_lock_data_init(&share->lock,&m_info->lock,NULL);
#endif

  m_info->open_list.data=(void*) m_info;
  nisam_open_list=list_add(nisam_open_list,&m_info->open_list);

  pthread_mutex_unlock(&THR_LOCK_isam);
  nisam_log_simple(LOG_OPEN,m_info,share->filename,
		   (uint) strlen(share->filename));
  DBUG_RETURN(m_info);

err:
  save_errno=my_errno ? my_errno : HA_ERR_END_OF_FILE;
  switch (errpos) {
  case 6:
    my_free((gptr) m_info,MYF(0));
    /* fall through */
  case 5:
    VOID(my_close(info.dfile,MYF(0)));
    if (old_info)
      break;					/* Don't remove open table */
    /* fall through */
  case 4:
    my_free((gptr) share,MYF(0));
    /* fall through */
  case 3:
#ifndef NO_LOCKING
    if (! lock_error)
      VOID(my_lock(kfile, F_UNLCK, 0L, F_TO_EOF, MYF(MY_SEEK_NOT_DONE)));
#endif
    /* fall through */
  case 2:
    my_afree((gptr) disk_cache);
    /* fall through */
  case 1:
    VOID(my_close(kfile,MYF(0)));
    /* fall through */
  case 0:
  default:
    break;
  }
  pthread_mutex_unlock(&THR_LOCK_isam);
  my_errno=save_errno;
  DBUG_RETURN (NULL);
} /* nisam_open */


	/* Set up functions in structs */

static void setup_functions(register ISAM_SHARE *share)
{
  if (share->base.options & HA_OPTION_COMPRESS_RECORD)
  {
    share->read_record=_nisam_read_pack_record;
    share->read_rnd=_nisam_read_rnd_pack_record;
  }
  else if (share->base.options & HA_OPTION_PACK_RECORD)
  {
    share->read_record=_nisam_read_dynamic_record;
    share->read_rnd=_nisam_read_rnd_dynamic_record;
    share->delete_record=_nisam_delete_dynamic_record;
    share->compare_record=_nisam_cmp_dynamic_record;

    /* add bits used to pack data to pack_reclength for faster allocation */
    share->base.pack_reclength+= share->base.pack_bits;
    if (share->base.blobs)
    {
      share->update_record=_nisam_update_blob_record;
      share->write_record=_nisam_write_blob_record;
    }
    else
    {
      share->write_record=_nisam_write_dynamic_record;
      share->update_record=_nisam_update_dynamic_record;
    }
  }
  else
  {
    share->read_record=_nisam_read_static_record;
    share->read_rnd=_nisam_read_rnd_static_record;
    share->delete_record=_nisam_delete_static_record;
    share->compare_record=_nisam_cmp_static_record;
    share->update_record=_nisam_update_static_record;
    share->write_record=_nisam_write_static_record;
  }
  return;
}


static void setup_key_functions(register N_KEYDEF *keyinfo)
{
  if (keyinfo->base.flag & (HA_PACK_KEY | HA_SPACE_PACK_USED))
  {
    keyinfo->bin_search=_nisam_seq_search;
    keyinfo->get_key=_nisam_get_key;
  }
  else
  {
    keyinfo->bin_search=_nisam_bin_search;
    keyinfo->get_key=_nisam_get_static_key;
  }
  return;
}

/*
  Calculate a long checksum for a memoryblock. Used to verify pack_isam

  SYNOPSIS
    checksum()
      mem	Pointer to memory block
      count	Count of bytes
*/

ulong _nisam_checksum(const byte *mem, uint count)
{
  ulong crc;
  for (crc= 0; count-- ; mem++)
    crc= ((crc << 1) + *((uchar*) mem)) +
      test(crc & ((ulong) 1L << (8*sizeof(ulong)-1)));
  return crc;
}

