my_write.c

/* 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 02110-1301  USA */

#include "mysys_priv.h"
#include "mysys_err.h"
#include <errno.h>


        /* Write a chunk of bytes to a file */

size_t my_write(File Filedes, const uchar *Buffer, size_t Count, myf MyFlags)
{
  size_t writtenbytes, written;
  uint errors;
  DBUG_ENTER("my_write");
  DBUG_PRINT("my",("fd: %d  Buffer: %p  Count: %lu  MyFlags: %d",
                   Filedes, Buffer, (ulong) Count, MyFlags));
  errors= 0; written= 0;

  /* The behavior of write(fd, buf, 0) is not portable */
  if (unlikely(!Count))
    DBUG_RETURN(0);
  
  DBUG_EXECUTE_IF ("simulate_no_free_space_error",
                   { DBUG_SET("+d,simulate_file_write_error");});
  for (;;)
  {
#ifdef _WIN32
    writtenbytes= my_win_write(Filedes, Buffer, Count);
#else
    writtenbytes= write(Filedes, Buffer, Count);
#endif
    DBUG_EXECUTE_IF("simulate_file_write_error",
                    {
                      errno= ENOSPC;
                      writtenbytes= (size_t) -1;
                    });
    if (writtenbytes == Count)
      break;
    if (writtenbytes != (size_t) -1)
    {                                           /* Safeguard */
      written+= writtenbytes;
      Buffer+= writtenbytes;
      Count-= writtenbytes;
    }
    my_errno= errno;
    DBUG_PRINT("error",("Write only %ld bytes, error: %d",
                        (long) writtenbytes, my_errno));
#ifndef NO_BACKGROUND
    if (my_thread_var->abort)
      MyFlags&= ~ MY_WAIT_IF_FULL;              /* End if aborted by user */

    if ((my_errno == ENOSPC || my_errno == EDQUOT) &&
        (MyFlags & MY_WAIT_IF_FULL))
    {
      wait_for_free_space(my_filename(Filedes), errors);
      errors++;
      DBUG_EXECUTE_IF("simulate_no_free_space_error",
                      { DBUG_SET("-d,simulate_file_write_error");});
      continue;
    }

    if ((writtenbytes == 0 || writtenbytes == (size_t) -1))
    {
      if (my_errno == EINTR)
      {
        DBUG_PRINT("debug", ("my_write() was interrupted and returned %ld",
                             (long) writtenbytes));
        continue;                               /* Interrupted */
      }

      if (!writtenbytes && !errors++)           /* Retry once */
      {
        /* We may come here if the file quota is exeeded */
        errno= EFBIG;                           /* Assume this is the error */
        continue;
      }
    }
    else
      continue;                                 /* Retry */
#endif
    if (MyFlags & (MY_NABP | MY_FNABP))
    {
      if (MyFlags & (MY_WME | MY_FAE | MY_FNABP))
      {
        char errbuf[MYSYS_STRERROR_SIZE];
        my_error(EE_WRITE, MYF(ME_BELL+ME_WAITTANG), my_filename(Filedes),
                 my_errno, my_strerror(errbuf, sizeof(errbuf), my_errno));
      }
      DBUG_RETURN(MY_FILE_ERROR);               /* Error on read */
    }
    else
      break;                                    /* Return bytes written */
  }
  if (MyFlags & (MY_NABP | MY_FNABP))
    DBUG_RETURN(0);                     /* Want only errors */
  DBUG_RETURN(writtenbytes+written);
} /* my_write */