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/*
Copyright (c) 2000, 2001, 2004, 2006, 2007 MySQL AB, 2009 Sun Microsystems, Inc.
Use is subject to license terms.
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>
#ifdef HAVE_PREAD
#include <unistd.h>
#endif
/*
Read a chunk of bytes from a file from a given position
SYNOPSIOS
my_pread()
Filedes File decsriptor
Buffer Buffer to read data into
Count Number of bytes to read
offset Position to read from
MyFlags Flags
NOTES
This differs from the normal pread() call in that we don't care
to set the position in the file back to the original position
if the system doesn't support pread().
RETURN
(size_t) -1 Error
# Number of bytes read
*/
size_t my_pread(File Filedes, uchar *Buffer, size_t Count, my_off_t offset,
myf MyFlags)
{
size_t readbytes;
int error= 0;
DBUG_ENTER("my_pread");
DBUG_PRINT("my",("Fd: %d Seek: %lu Buffer: 0x%lx Count: %u MyFlags: %d",
Filedes, (ulong) offset, (long) Buffer, (uint) Count,
MyFlags));
for (;;)
{
#ifndef __WIN__
errno=0; /* Linux doesn't reset this */
#endif
#ifndef HAVE_PREAD
pthread_mutex_lock(&my_file_info[Filedes].mutex);
readbytes= (uint) -1;
error= (lseek(Filedes, offset, MY_SEEK_SET) == (my_off_t) -1 ||
(readbytes= read(Filedes, Buffer, (uint) Count)) != Count);
pthread_mutex_unlock(&my_file_info[Filedes].mutex);
#else
if ((error= ((readbytes= pread(Filedes, Buffer, Count, offset)) != Count)))
my_errno= errno ? errno : -1;
#endif
if (error || readbytes != Count)
{
DBUG_PRINT("warning",("Read only %d bytes off %u from %d, errno: %d",
(int) readbytes, (uint) Count,Filedes,my_errno));
#ifdef THREAD
if ((readbytes == 0 || readbytes == (size_t) -1) && errno == EINTR)
{
DBUG_PRINT("debug", ("my_pread() was interrupted and returned %d",
(int) readbytes));
continue; /* Interrupted */
}
#endif
if (MyFlags & (MY_WME | MY_FAE | MY_FNABP))
{
if (readbytes == (size_t) -1)
my_error(EE_READ, MYF(ME_BELL+ME_WAITTANG),
my_filename(Filedes),my_errno);
else if (MyFlags & (MY_NABP | MY_FNABP))
my_error(EE_EOFERR, MYF(ME_BELL+ME_WAITTANG),
my_filename(Filedes),my_errno);
}
if (readbytes == (size_t) -1 || (MyFlags & (MY_FNABP | MY_NABP)))
DBUG_RETURN(MY_FILE_ERROR); /* Return with error */
}
if (MyFlags & (MY_NABP | MY_FNABP))
DBUG_RETURN(0); /* Read went ok; Return 0 */
DBUG_RETURN(readbytes); /* purecov: inspected */
}
} /* my_pread */
/*
Write a chunk of bytes to a file at a given position
SYNOPSIOS
my_pwrite()
Filedes File decsriptor
Buffer Buffer to write data from
Count Number of bytes to write
offset Position to write to
MyFlags Flags
NOTES
This differs from the normal pwrite() call in that we don't care
to set the position in the file back to the original position
if the system doesn't support pwrite()
RETURN
(size_t) -1 Error
# Number of bytes read
*/
size_t my_pwrite(int Filedes, const uchar *Buffer, size_t Count,
my_off_t offset, myf MyFlags)
{
size_t writenbytes, written;
uint errors;
DBUG_ENTER("my_pwrite");
DBUG_PRINT("my",("Fd: %d Seek: %lu Buffer: 0x%lx Count: %u MyFlags: %d",
Filedes, (ulong) offset, (long) Buffer, (uint) Count,
MyFlags));
errors= 0;
written= 0;
for (;;)
{
#ifndef HAVE_PREAD
int error;
writenbytes= (size_t) -1;
pthread_mutex_lock(&my_file_info[Filedes].mutex);
error= (lseek(Filedes, offset, MY_SEEK_SET) != (my_off_t) -1 &&
(writenbytes = write(Filedes, Buffer, (uint) Count)) == Count);
pthread_mutex_unlock(&my_file_info[Filedes].mutex);
if (error)
break;
#else
if ((writenbytes= pwrite(Filedes, Buffer, Count,offset)) == Count)
break;
my_errno= errno;
#endif
if (writenbytes != (size_t) -1)
{ /* Safegueard */
written+=writenbytes;
Buffer+=writenbytes;
Count-=writenbytes;
offset+=writenbytes;
}
DBUG_PRINT("error",("Write only %u bytes", (uint) writenbytes));
#ifndef NO_BACKGROUND
#ifdef THREAD
if (my_thread_var->abort)
MyFlags&= ~ MY_WAIT_IF_FULL; /* End if aborted by user */
#endif
if ((my_errno == ENOSPC || my_errno == EDQUOT) &&
(MyFlags & MY_WAIT_IF_FULL))
{
wait_for_free_space(my_filename(Filedes), errors);
errors++;
continue;
}
if ((writenbytes && writenbytes != (size_t) -1) || my_errno == EINTR)
continue; /* Retry */
#endif
if (MyFlags & (MY_NABP | MY_FNABP))
{
if (MyFlags & (MY_WME | MY_FAE | MY_FNABP))
{
my_error(EE_WRITE, MYF(ME_BELL | ME_WAITTANG),
my_filename(Filedes),my_errno);
}
DBUG_RETURN(MY_FILE_ERROR); /* Error on read */
}
else
break; /* Return bytes written */
}
DBUG_EXECUTE_IF("check", my_seek(Filedes, -1, SEEK_SET, MYF(0)););
if (MyFlags & (MY_NABP | MY_FNABP))
DBUG_RETURN(0); /* Want only errors */
DBUG_RETURN(writenbytes+written); /* purecov: inspected */
} /* my_pwrite */
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