text: /* Copyright (c) 2000, 2019, Oracle and/or its affiliates. All rights reserved.
  
     This program is free software; you can redistribute it and/or modify
     it under the terms of the GNU General Public License, version 2.0,
     as published by the Free Software Foundation.
  
     This program is also distributed with certain software (including
     but not limited to OpenSSL) that is licensed under separate terms,
     as designated in a particular file or component or in included license
     documentation.  The authors of MySQL hereby grant you an additional
     permission to link the program and your derivative works with the
     separately licensed software that they have included with MySQL.
  
     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, version 2.0, 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., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */
  
  /* Functions to handle fixed-length-records */
  
  #include <fcntl.h>
  #include <sys/types.h>
  
  #include "my_dbug.h"
  #include "my_inttypes.h"
  #include "my_io.h"
  #include "storage/myisam/myisam_sys.h"
  #include "storage/myisam/myisamdef.h"
  
  int _mi_write_static_record(MI_INFO *info, const uchar *record) {
    uchar temp[8]; /* max pointer length */
    if (info->s->state.dellink != HA_OFFSET_ERROR &&
        !info->append_insert_at_end) {
      my_off_t filepos = info->s->state.dellink;
      info->rec_cache.seek_not_done = true; /* We have done a seek */
      if (info->s->file_read(info, &temp[0], info->s->base.rec_reflength,
                             info->s->state.dellink + 1, MYF(MY_NABP)))
        goto err;
      info->s->state.dellink = _mi_rec_pos(info->s, temp);
      info->state->del--;
      info->state->empty -= info->s->base.pack_reclength;
      if (info->s->file_write(info, record, info->s->base.reclength, filepos,
                              MYF(MY_NABP)))
        goto err;
    } else {
      if (info->state->data_file_length >
          info->s->base.max_data_file_length - info->s->base.pack_reclength) {
        set_my_errno(HA_ERR_RECORD_FILE_FULL);
        return (2);
      }
      if (info->opt_flag & WRITE_CACHE_USED) { /* Cash in use */
        if (my_b_write(&info->rec_cache, record, info->s->base.reclength))
          goto err;
        if (info->s->base.pack_reclength != info->s->base.reclength) {
          uint length = info->s->base.pack_reclength - info->s->base.reclength;
          memset(temp, 0, length);
          if (my_b_write(&info->rec_cache, temp, length)) goto err;
        }
      } else {
        info->rec_cache.seek_not_done = true; /* We have done a seek */
        if (info->s->file_write(info, record, info->s->base.reclength,
                                info->state->data_file_length,
                                info->s->write_flag))
          goto err;
        if (info->s->base.pack_reclength != info->s->base.reclength) {
          uint length = info->s->base.pack_reclength - info->s->base.reclength;
          memset(temp, 0, length);
          if (info->s->file_write(
                  info, temp, length,
                  info->state->data_file_length + info->s->base.reclength,
                  info->s->write_flag))
            goto err;
        }
      }
      info->state->data_file_length += info->s->base.pack_reclength;
      info->s->state.split++;
    }
    return 0;
  err:
    return 1;
  }
  
  int _mi_update_static_record(MI_INFO *info, my_off_t pos, const uchar *record) {
    info->rec_cache.seek_not_done = true; /* We have done a seek */
    return (info->s->file_write(info, record, info->s->base.reclength, pos,
                                MYF(MY_NABP)) != 0);
  }
  
  int _mi_delete_static_record(MI_INFO *info) {
    uchar temp[9]; /* 1+sizeof(uint32) */
  
    info->state->del++;
    info->state->empty += info->s->base.pack_reclength;
    temp[0] = '\0'; /* Mark that record is deleted */
    _mi_dpointer(info, temp + 1, info->s->state.dellink);
    info->s->state.dellink = info->lastpos;
    info->rec_cache.seek_not_done = true;
    return (info->s->file_write(info, (uchar *)temp, 1 + info->s->rec_reflength,
                                info->lastpos, MYF(MY_NABP)) != 0);
  }
  
  int _mi_cmp_static_record(MI_INFO *info, const uchar *old) {
    DBUG_TRACE;
  
    if (info->opt_flag & WRITE_CACHE_USED) {
      if (flush_io_cache(&info->rec_cache)) {
        return -1;
      }
      info->rec_cache.seek_not_done = true; /* We have done a seek */
    }
  
    if ((info->opt_flag & READ_CHECK_USED)) { /* If check isn't disabled  */
      info->rec_cache.seek_not_done = true;   /* We have done a seek */
      if (info->s->file_read(info, info->rec_buff, info->s->base.reclength,
                             info->lastpos, MYF(MY_NABP)))
        return -1;
      if (memcmp(info->rec_buff, old, (uint)info->s->base.reclength)) {
        DBUG_DUMP("read", old, info->s->base.reclength);
        DBUG_DUMP("disk", info->rec_buff, info->s->base.reclength);
        set_my_errno(HA_ERR_RECORD_CHANGED); /* Record have changed */
        return 1;
      }
    }
    return 0;
  }
  
  int _mi_cmp_static_unique(MI_INFO *info, MI_UNIQUEDEF *def, const uchar *record,
                            my_off_t pos) {
    DBUG_TRACE;
  
    info->rec_cache.seek_not_done = true; /* We have done a seek */
    if (info->s->file_read(info, info->rec_buff, info->s->base.reclength, pos,
                           MYF(MY_NABP)))
      return -1;
    return mi_unique_comp(def, record, info->rec_buff, def->null_are_equal);
  }
  
  /* Read a fixed-length-record */
  /* Returns 0 if Ok. */
  /*	   1 if record is deleted */
  /*	  MY_FILE_ERROR on read-error or locking-error */
  
  int _mi_read_static_record(MI_INFO *info, my_off_t pos, uchar *record) {
    int error;
  
    if (pos != HA_OFFSET_ERROR) {
      if (info->opt_flag & WRITE_CACHE_USED &&
          info->rec_cache.pos_in_file <= pos && flush_io_cache(&info->rec_cache))
        return (-1);
      info->rec_cache.seek_not_done = true; /* We have done a seek */
  
      error = info->s->file_read(info, record, info->s->base.reclength, pos,
                                 MYF(MY_NABP)) != 0;
      fast_mi_writeinfo(info);
      if (!error) {
        if (!*record) {
          set_my_errno(HA_ERR_RECORD_DELETED);
          return (1); /* Record is deleted */
        }
        info->update |= HA_STATE_AKTIV; /* Record is read */
        return (0);
      }
      return (-1); /* Error on read */
    }
    fast_mi_writeinfo(info); /* No such record */
    return (-1);
  }
  
  int _mi_read_rnd_static_record(MI_INFO *info, uchar *buf, my_off_t filepos,
                                 bool skip_deleted_blocks) {
    int locked, error, cache_read;
    uint cache_length;
    MYISAM_SHARE *share = info->s;
    DBUG_TRACE;
  
    cache_read = 0;
    cache_length = 0;
    if (info->opt_flag & WRITE_CACHE_USED &&
        (info->rec_cache.pos_in_file <= filepos || skip_deleted_blocks) &&
        flush_io_cache(&info->rec_cache))
      return my_errno();
    if (info->opt_flag & READ_CACHE_USED) { /* Cache in use */
      if (filepos == my_b_tell(&info->rec_cache) &&
          (skip_deleted_blocks || !filepos)) {
        cache_read = 1; /* Read record using cache */
        cache_length =
            (uint)(info->rec_cache.read_end - info->rec_cache.read_pos);
      } else
        info->rec_cache.seek_not_done = true; /* Filepos is changed */
    }
    locked = 0;
    if (info->lock_type == F_UNLCK) {
      if (filepos >= info->state->data_file_length) { /* Test if new records */
        if (_mi_readinfo(info, F_RDLCK, 0)) return my_errno();
        locked = 1;
      } else { /* We don't nead new info */
        if ((!cache_read || share->base.reclength > cache_length) &&
            share->tot_locks == 0) { /* record not in cache */
          if (my_lock(share->kfile, F_RDLCK,
                      MYF(MY_SEEK_NOT_DONE) | info->lock_wait))
            return my_errno();
          locked = 1;
        }
      }
    }
    if (filepos >= info->state->data_file_length) {
      DBUG_PRINT("test", ("filepos: %ld (%ld)  records: %ld  del: %ld",
                          (long)filepos / share->base.reclength, (long)filepos,
                          (long)info->state->records, (long)info->state->del));
      fast_mi_writeinfo(info);
      set_my_errno(HA_ERR_END_OF_FILE);
      return HA_ERR_END_OF_FILE;
    }
    info->lastpos = filepos;
    info->nextpos = filepos + share->base.pack_reclength;
  
    if (!cache_read) /* No cacheing */
    {
      if ((error = _mi_read_static_record(info, filepos, buf))) {
        if (error > 0) {
          set_my_errno(HA_ERR_RECORD_DELETED);
          error = HA_ERR_RECORD_DELETED;
        } else
          error = my_errno();
      }
      return error;
    }
  
    /*
      Read record with caching. If my_b_read() returns true, less than the
      requested bytes have been read. In this case rec_cache.error is
      either -1 for a read error, or contains the number of bytes copied
      into the buffer.
    */
    error = my_b_read(&info->rec_cache, (uchar *)buf, share->base.reclength);
    if (info->s->base.pack_reclength != info->s->base.reclength && !error) {
      char tmp[8]; /* Skill fill bytes */
      error = my_b_read(&info->rec_cache, (uchar *)tmp,
                        info->s->base.pack_reclength - info->s->base.reclength);
    }
    if (locked) (void)_mi_writeinfo(info, 0); /* Unlock keyfile */
    if (!error) {
      if (!buf[0]) { /* Record is removed */
        set_my_errno(HA_ERR_RECORD_DELETED);
        return HA_ERR_RECORD_DELETED;
      }
      /* Found and may be updated */
      info->update |= HA_STATE_AKTIV | HA_STATE_KEY_CHANGED;
      return 0;
    }
    /* error is true. my_errno should be set if rec_cache.error == -1 */
    if (info->rec_cache.error != -1 || my_errno() == 0) {
      /*
        If we could not get a full record, we either have a broken record,
        or are at end of file.
      */
      if (info->rec_cache.error == 0)
        set_my_errno(HA_ERR_END_OF_FILE);
      else
        set_my_errno(HA_ERR_WRONG_IN_RECORD);
    }
    return my_errno(); /* Something wrong (EOF?) */
  }
  