mariadb/mysys/my_chsize.c
Vladislav Vaintroub 4e92af9f43 This is the downport of
Bug#24509 - 2048 file descriptor limit on windows needs increasing, also 
WL#3049 - improved Windows I/O
                        
The patch replaces the use of the POSIX I/O interfaces in mysys on Windows with 
the Win32 API calls (CreateFile, WriteFile, etc). The Windows HANDLE for the open 
file is stored in the my_file_info struct, along with a flag for append mode 
because the Windows API does not support opening files in append mode in all cases)
The default max open files has been increased to 16384 and can be increased further
by setting --max-open-files=<value> during the server start.
                              
Another major change in this patch that almost all Windows specific file IO code
has been moved to a new file my_winfile.c, greatly reducing the amount of code 
in #ifdef blocks within mysys, thus improving readability.
                               
                                    
Minor enhancements:
- my_(f)stat() is changed to use __stati64 structure with  64 file size
and timestamps. It will return correct file size now (C runtime implementation
used to report outdated information)
- my_lock on Windows is prepared to handle additional timeout parameter
- after review : changed __WIN__ to _WIN32 in the new and changed code.
2009-09-11 22:26:35 +02:00

107 lines
2.8 KiB
C

/* 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 "m_string.h"
/*
Change size of file.
SYNOPSIS
my_chsize()
fd File descriptor
new_length New file size
filler If we don't have truncate, fill up all bytes after
new_length with this character
MyFlags Flags
DESCRIPTION
my_chsize() truncates file if shorter else fill with the filler character.
The function also changes the file pointer. Usually it points to the end
of the file after execution.
RETURN VALUE
0 Ok
1 Error
*/
int my_chsize(File fd, my_off_t newlength, int filler, myf MyFlags)
{
my_off_t oldsize;
uchar buff[IO_SIZE];
DBUG_ENTER("my_chsize");
DBUG_PRINT("my",("fd: %d length: %lu MyFlags: %d",fd,(ulong) newlength,
MyFlags));
if ((oldsize= my_seek(fd, 0L, MY_SEEK_END, MYF(MY_WME+MY_FAE))) == newlength)
DBUG_RETURN(0);
DBUG_PRINT("info",("old_size: %ld", (ulong) oldsize));
if (oldsize > newlength)
{
#ifdef _WIN32
if (my_win_chsize(fd, newlength))
{
my_errno= errno;
goto err;
}
DBUG_RETURN(0);
#elif defined(HAVE_FTRUNCATE)
if (ftruncate(fd, (off_t) newlength))
{
my_errno= errno;
goto err;
}
DBUG_RETURN(0);
#elif defined(HAVE_CHSIZE)
if (chsize(fd, (off_t) newlength))
{
my_errno=errno;
goto err;
}
DBUG_RETURN(0);
#else
/*
Fill space between requested length and true length with 'filler'
We should never come here on any modern machine
*/
if (my_seek(fd, newlength, MY_SEEK_SET, MYF(MY_WME+MY_FAE))
== MY_FILEPOS_ERROR)
{
goto err;
}
swap_variables(my_off_t, newlength, oldsize);
#endif
}
/* Full file with 'filler' until it's as big as requested */
bfill(buff, IO_SIZE, filler);
while (newlength-oldsize > IO_SIZE)
{
if (my_write(fd, buff, IO_SIZE, MYF(MY_NABP)))
goto err;
oldsize+= IO_SIZE;
}
if (my_write(fd,buff,(size_t) (newlength-oldsize), MYF(MY_NABP)))
goto err;
DBUG_RETURN(0);
err:
DBUG_PRINT("error", ("errno: %d", errno));
if (MyFlags & MY_WME)
my_error(EE_CANT_CHSIZE, MYF(ME_BELL+ME_WAITTANG), my_errno);
DBUG_RETURN(1);
} /* my_chsize */