blob: e8536c2e4104773f4c4ab50f927a96be878bf957 [file] [log] [blame]
/*
* Copyright (c) 2000-2001 Silicon Graphics, Inc.
* 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.
*
* This program is distributed in the hope that it would 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 the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <xfs/xfs.h>
#include <unistd.h>
#include <sys/mman.h>
#include <sys/stat.h>
/*
* our custom mmap b/c Linux doesn't have MAP_AUTOGROW
* and for an empty file we need to write to last byte
* to ensure it can be accessed
*/
void *
mmap_autogrow(size_t len, int fd, off_t offset)
{
struct stat buf;
char nul_buffer[] = "";
/* prealloc file if it is an empty file */
if (fstat(fd, &buf) == -1) {;
return (void*)MAP_FAILED;
}
if (buf.st_size < offset+len) {
(void)lseek(fd, offset+len-1, SEEK_SET);
(void)write(fd, nul_buffer, 1);
}
return mmap( 0, len, PROT_READ | PROT_WRITE, MAP_SHARED, fd, offset );
}