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/* io.c - Virtual disk input/output */
/* Written 1993 by Werner Almesberger */
/*
* Thu Feb 26 01:15:36 CET 1998: Martin Schulze <joey@infodrom.north.de>
* Fixed nasty bug that caused every file with a name like
* xxxxxxxx.xxx to be treated as bad name that needed to be fixed.
*/
/* FAT32, VFAT, Atari format support, and various fixes additions May 1998
* by Roman Hodek <Roman.Hodek@informatik.uni-erlangen.de> */
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <errno.h>
#include <fcntl.h>
#include <linux/fd.h>
#include "dosfsck.h"
#include "common.h"
#include "io.h"
typedef struct _change {
void *data;
loff_t pos;
int size;
struct _change *next;
} CHANGE;
static CHANGE *changes,*last;
static int fd,did_change = 0;
unsigned device_no;
/* Use the _llseek system call directly, because there (once?) was a bug in
* the glibc implementation of it. */
#include <linux/unistd.h>
#if defined(__alpha) || defined (__ia64__)
/* On alpha, the syscall is simply lseek, because it's a 64 bit system. */
static loff_t llseek( int fd, loff_t offset, int whence )
{
return lseek(fd, offset, whence);
}
#else
# ifndef __NR__llseek
# error _llseek system call not present
# endif
static _syscall5( int, _llseek, uint, fd, ulong, hi, ulong, lo,
loff_t *, res, uint, wh );
static loff_t llseek( int fd, loff_t offset, int whence )
{
loff_t actual;
if (_llseek(fd, offset>>32, offset&0xffffffff, &actual, whence) != 0)
return (loff_t)-1;
return actual;
}
#endif
void fs_open(char *path,int rw)
{
struct stat stbuf;
if ((fd = open(path,rw ? O_RDWR : O_RDONLY)) < 0)
pdie("open %s",path);
changes = last = NULL;
did_change = 0;
if (fstat(fd,&stbuf) < 0)
pdie("fstat",path);
device_no = S_ISBLK(stbuf.st_mode) ? (stbuf.st_rdev >> 8) & 0xff : 0;
}
void fs_read(loff_t pos,int size,void *data)
{
CHANGE *walk;
int got;
if (llseek(fd,pos,0) != pos) pdie("Seek to %lld",pos);
if ((got = read(fd,data,size)) < 0) pdie("Read %d bytes at %lld",size,pos);
if (got != size) die("Got %d bytes instead of %d at %lld",got,size,pos);
for (walk = changes; walk; walk = walk->next) {
if (walk->pos < pos+size && walk->pos+walk->size > pos) {
if (walk->pos < pos)
memcpy(data,(char *) walk->data+pos-walk->pos,min(size,
walk->size-pos+walk->pos));
else memcpy((char *) data+walk->pos-pos,walk->data,min(walk->size,
size+pos-walk->pos));
}
}
}
int fs_test(loff_t pos,int size)
{
void *scratch;
int okay;
if (llseek(fd,pos,0) != pos) pdie("Seek to %lld",pos);
scratch = alloc(size);
okay = read(fd,scratch,size) == size;
free(scratch);
return okay;
}
void fs_write(loff_t pos,int size,void *data)
{
CHANGE *new;
int did;
if (write_immed) {
did_change = 1;
if (llseek(fd,pos,0) != pos) pdie("Seek to %lld",pos);
if ((did = write(fd,data,size)) == size) return;
if (did < 0) pdie("Write %d bytes at %lld",size,pos);
die("Wrote %d bytes instead of %d at %lld",did,size,pos);
}
new = alloc(sizeof(CHANGE));
new->pos = pos;
memcpy(new->data = alloc(new->size = size),data,size);
new->next = NULL;
if (last) last->next = new;
else changes = new;
last = new;
}
static void fs_flush(void)
{
CHANGE *this;
int size;
while (changes) {
this = changes;
changes = changes->next;
if (llseek(fd,this->pos,0) != this->pos)
fprintf(stderr,"Seek to %lld failed: %s\n Did not write %d bytes.\n",
this->pos,strerror(errno),this->size);
else if ((size = write(fd,this->data,this->size)) < 0)
fprintf(stderr,"Writing %d bytes at %lld failed: %s\n",this->size,
this->pos,strerror(errno));
else if (size != this->size)
fprintf(stderr,"Wrote %d bytes instead of %d bytes at %lld."
"\n",size,this->size,this->pos);
free(this->data);
free(this);
}
}
int fs_close(int write)
{
CHANGE *next;
int changed;
changed = !!changes;
if (write) fs_flush();
else while (changes) {
next = changes->next;
free(changes->data);
free(changes);
changes = next;
}
if (close(fd) < 0) pdie("closing file system");
return changed || did_change;
}
int fs_changed(void)
{
return !!changes || did_change;
}
/* Local Variables: */
/* tab-width: 8 */
/* End: */
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