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/* io.h - Virtual disk input/output
Copyright (C) 1993 Werner Almesberger <>
Copyright (C) 1998 Roman Hodek <>
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, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
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, see <>.
On Debian systems, the complete text of the GNU General Public License
can be found in /usr/share/common-licenses/GPL-3 file.
/* FAT32, VFAT, Atari format support, and various fixes additions May 1998
* by Roman Hodek <> */
#ifndef _IO_H
#define _IO_H
#include <sys/types.h> /* for loff_t */
/* In earlier versions, an own llseek() was used, but glibc lseek() is
* sufficient (or even better :) for 64 bit offsets in the meantime */
#define llseek lseek64
void fs_open(char *path,int rw);
/* Opens the file system PATH. If RW is zero, the file system is opened
read-only, otherwise, it is opened read-write. */
void fs_read(loff_t pos,int size,void *data);
/* Reads SIZE bytes starting at POS into DATA. Performs all applicable
changes. */
int fs_test(loff_t pos,int size);
/* Returns a non-zero integer if SIZE bytes starting at POS can be read without
errors. Otherwise, it returns zero. */
void fs_write(loff_t pos,int size,void *data);
/* If write_immed is non-zero, SIZE bytes are written from DATA to the disk,
starting at POS. If write_immed is zero, the change is added to a list in
memory. */
int fs_close(int write);
/* Closes the file system, performs all pending changes if WRITE is non-zero
and removes the list of changes. Returns a non-zero integer if the file
system has been changed since the last fs_open, zero otherwise. */
int fs_changed(void);
/* Determines whether the file system has changed. See fs_close. */
extern unsigned device_no;
/* Major number of device (0 if file) and size (in 512 byte sectors) */