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/* Copyright (C) 2000 MySQL 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; 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 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 */
uint my_pread(File Filedes, byte *Buffer, uint Count, my_off_t offset,
myf MyFlags)
{
uint 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, Count, MyFlags));
for (;;)
{
#ifndef __WIN__
errno=0; /* Linux doesn't reset this */
#endif
#ifndef HAVE_PREAD
off_t old_offset;
pthread_mutex_lock(&my_file_info[Filedes].mutex);
/*
As we cannot change the file pointer, we save the old position,
before seeking to the given offset
*/
error= (old_offset= (off_t)lseek(Filedes, 0L, MY_SEEK_CUR)) == -1L ||
lseek(Filedes, offset, MY_SEEK_SET) == -1L;
if (!error) /* Seek was successful */
{
if ((readbytes = (uint) read(Filedes, Buffer, Count)) == -1L)
my_errno= errno;
/*
We should seek back, even if read failed. If this fails,
we will return an error. If read failed as well, we will
save the errno from read, not from lseek().
*/
if ((error= (lseek(Filedes, old_offset, MY_SEEK_SET) == -1L)) &&
readbytes != -1L)
my_errno= errno;
}
pthread_mutex_unlock(&my_file_info[Filedes].mutex);
#else
if ((error= ((readbytes =
(uint) pread(Filedes, Buffer, Count, offset)) != Count)))
my_errno= errno;
#endif
if (error || readbytes != Count)
{
DBUG_PRINT("warning",("Read only %d bytes off %u from %d, errno: %d",
(int) readbytes, Count,Filedes,my_errno));
#ifdef THREAD
if ((readbytes == 0 || (int) readbytes == -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 ((int) readbytes == -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 ((int) readbytes == -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 */
uint my_pwrite(int Filedes, const byte *Buffer, uint Count, my_off_t offset,
myf MyFlags)
{
uint writenbytes,errors;
ulong written;
DBUG_ENTER("my_pwrite");
DBUG_PRINT("my",("Fd: %d Seek: %lu Buffer: 0x%lx Count: %d MyFlags: %d",
Filedes, (ulong) offset, (long) Buffer, Count, MyFlags));
errors=0; written=0L;
for (;;)
{
#ifndef HAVE_PREAD
int error= 0;
off_t old_offset;
writenbytes= (uint) -1;
pthread_mutex_lock(&my_file_info[Filedes].mutex);
/*
As we cannot change the file pointer, we save the old position,
before seeking to the given offset
*/
error= ((old_offset= (off_t)lseek(Filedes, 0L, MY_SEEK_CUR)) == -1L ||
lseek(Filedes, offset, MY_SEEK_SET) == -1L);
if (!error) /* Seek was successful */
{
if ((writenbytes = (uint) write(Filedes, Buffer, Count)) == -1L)
my_errno= errno;
/*
We should seek back, even if write failed. If this fails,
we will return an error. If write failed as well, we will
save the errno from write, not from lseek().
*/
if ((error= (lseek(Filedes, old_offset, MY_SEEK_SET) == -1L)) &&
writenbytes != -1L)
my_errno= errno;
}
pthread_mutex_unlock(&my_file_info[Filedes].mutex);
if (!error && writenbytes == Count)
break;
#else
if ((writenbytes = (uint) pwrite(Filedes, Buffer, Count,offset)) == Count)
break;
else
my_errno= errno;
#endif
if ((int) writenbytes != -1)
{ /* Safegueard */
written+=writenbytes;
Buffer+=writenbytes;
Count-=writenbytes;
offset+=writenbytes;
}
DBUG_PRINT("error",("Write only %d bytes",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))
{
if (!(errors++ % MY_WAIT_GIVE_USER_A_MESSAGE))
my_error(EE_DISK_FULL,MYF(ME_BELL | ME_NOREFRESH),
my_filename(Filedes),my_errno,MY_WAIT_FOR_USER_TO_FIX_PANIC);
VOID(sleep(MY_WAIT_FOR_USER_TO_FIX_PANIC));
continue;
}
if ((writenbytes > 0 && (uint) writenbytes != (uint) -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 */
}
if (MyFlags & (MY_NABP | MY_FNABP))
DBUG_RETURN(0); /* Want only errors */
DBUG_RETURN(writenbytes+written); /* purecov: inspected */
} /* my_pwrite */
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