/* Copyright (c) 2000, 2013, 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 as published by

   the Free Software Foundation; version 2 of the License.

   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., 51 Franklin St, Fifth Floor, Boston, MA 02110-1335  USA */

#include "mysys_priv.h"

#include "mysys_err.h"

#include <my_base.h>

#include <errno.h>

/*

  Read a chunk of bytes from a file with retry's if needed

  The parameters are:

    File descriptor

    Buffer to hold at least Count bytes

    Bytes to read

    Flags on what to do on error

    Return:

      -1 on error

      0  if flag has bits MY_NABP or MY_FNABP set

      N  number of bytes read.

*/

size_t my_read(File Filedes, uchar *Buffer, size_t Count, myf MyFlags)

{

  size_t readbytes, save_count= 0;

  DBUG_ENTER("my_read");

  DBUG_PRINT("my",("fd: %d  Buffer: %p  Count: %lu  MyFlags: %lu",

                   Filedes, Buffer, (ulong) Count, MyFlags));

  if (!(MyFlags & (MY_WME | MY_FAE | MY_FNABP)))

    MyFlags|= my_global_flags;

  for (;;)

  {

    errno= 0;         /* Linux, Windows don't reset this on EOF/success */

#ifdef _WIN32

    readbytes= my_win_read(Filedes, Buffer, Count);

#else

    readbytes= read(Filedes, Buffer, Count);

#endif

    DBUG_EXECUTE_IF ("simulate_file_read_error",

                     {

                       errno= ENOSPC;

                       readbytes= (size_t) -1;

                       DBUG_SET("-d,simulate_file_read_error");

                       DBUG_SET("-d,simulate_my_b_fill_error");

                     });

    if (readbytes != Count)

    {

      int got_errno= my_errno= errno;

      DBUG_PRINT("warning",("Read only %d bytes off %lu from %d, errno: %d",

                            (int) readbytes, (ulong) Count, Filedes,

                            got_errno));

      if (got_errno == 0 || (readbytes != (size_t) -1 &&

                         (MyFlags & (MY_NABP | MY_FNABP))))

        my_errno= HA_ERR_FILE_TOO_SHORT;

      if ((readbytes == 0 || (int) readbytes == -1) && got_errno == EINTR)

      {  

        DBUG_PRINT("debug", ("my_read() was interrupted and returned %ld",

                             (long) readbytes));

        continue;                              /* Interrupted */

      }

      /* Do a read retry if we didn't get enough data on first read */

      if (readbytes != (size_t) -1 && readbytes != 0 &&

          (MyFlags & MY_FULL_IO))

      {

        Buffer+= readbytes;

        Count-= readbytes;

        save_count+= readbytes;

        continue;

      }

      if (MyFlags & (MY_WME | MY_FAE | MY_FNABP))

      {

        if (readbytes == (size_t) -1)

          my_error(EE_READ,

                   MYF(ME_BELL | (MyFlags & (ME_NOTE | ME_ERROR_LOG))),

                   my_filename(Filedes), got_errno);

        else if (MyFlags & (MY_NABP | MY_FNABP))

          my_error(EE_EOFERR,

                   MYF(ME_BELL | (MyFlags & (ME_NOTE | ME_ERROR_LOG))),

                   my_filename(Filedes), got_errno);

      }

      if (readbytes == (size_t) -1 ||

          ((MyFlags & (MY_FNABP | MY_NABP)) && !(MyFlags & MY_FULL_IO)))

        DBUG_RETURN(MY_FILE_ERROR);  /* Return with error */

    }

    if (MyFlags & (MY_NABP | MY_FNABP))

      readbytes= 0;     /* Ok on read */

    else

      readbytes+= save_count;

    break;

  }

  DBUG_RETURN(readbytes);

} /* my_read */