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/* Copyright 2021 Alain Knaff.
* This file is part of mtools.
*
* Mtools 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.
*
* Mtools 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 Mtools. If not, see <http://www.gnu.org/licenses/>.
*
* Remapping shim
*/
#include "sysincludes.h"
#include "msdos.h"
#include "mtools.h"
#include "remap.h"
enum map_type_t {
DATA,
ZERO,
SKIP,
POS
};
struct map {
mt_off_t orig;
mt_off_t remapped;
enum map_type_t type;
};
typedef struct Remap_t {
struct Stream_t head;
struct map *map;
int mapSize;
mt_off_t net_offset;
} Remap_t;
static enum map_type_t remap(Remap_t *This, mt_off_t *start, size_t *len) {
int i;
for(i=0; i < This->mapSize - 1; i++)
if(*start < This->map[i+1].remapped) {
limitSizeToOffT(len, This->map[i+1].remapped - *start);
break;
}
*start = *start - This->map[i].remapped + This->map[i].orig;
return This->map[i].type;
}
static ssize_t remap_pread(Stream_t *Stream, char *buf,
mt_off_t start, size_t len)
{
DeclareThis(Remap_t);
if(remap(This, &start, &len)==DATA)
return PREADS(This->head.Next, buf, start, len);
else {
memset(buf, 0, len);
return (ssize_t) len;
}
}
static ssize_t remap_pwrite(Stream_t *Stream, char *buf,
mt_off_t start, size_t len)
{
DeclareThis(Remap_t);
if(remap(This, &start, &len)==DATA)
return PWRITES(This->head.Next, buf, start, len);
else {
unsigned int i;
/* When writing to a "zero" sector, make sure that we
indeed only write zeroes back to there. Helps catch
putting filesystems with parameters unsuitable to
the particular mapping */
for(i=0; i<len; i++) {
if(buf[i]) {
fprintf(stderr, "Bad data written to unmapped sectors\n");
errno = EFAULT;
return -1;
}
}
return (ssize_t) len;
}
}
static int remap_free(Stream_t *Stream)
{
DeclareThis(Remap_t);
if(This->map)
free(This->map);
return 0;
}
static Class_t RemapClass = {
0,
0,
remap_pread,
remap_pwrite,
0, /* flush */
remap_free, /* free */
set_geom_pass_through, /* set_geom */
0, /* get_data */
0, /* pre-allocate */
get_dosConvert_pass_through, /* dos convert */
0, /* discard */
};
static int process_map(Remap_t *This, const char *ptr,
int countOnly, char *errmsg) {
mt_off_t orig=0;
mt_off_t remapped=0;
int count=0;
int atEnd=0;
char *eptr;
while(!atEnd) {
mt_off_t len;
enum map_type_t type;
if(*ptr=='\0') {
type=DATA;
atEnd=1;
} else if(!strncmp(ptr, "skip", 4)) {
type=SKIP;
ptr+=4;
} else if(!strncmp(ptr, "zero", 4)) {
type=ZERO;
ptr+=4;
} else if(!strncmp(ptr, "pos", 3)) {
type=POS;
ptr+=3;
} else {
type=DATA;
}
len=str_to_off_with_end(ptr,&eptr);
ptr=eptr;
switch(*ptr) {
case '\0':
/* End of string */
break;
case ',':
/* Move on to next item */
ptr++;
break;
default:
sprintf(errmsg, "Bad number %s\n", ptr);
return -1;
}
if(type == POS) {
orig = len;
continue;
}
if(type != SKIP) {
if(!countOnly) {
struct map *m = This->map+count;
m->orig = orig;
m->remapped = remapped;
m->type = type;
}
remapped+=len;
count++;
}
if(type != ZERO) {
orig+=len;
}
}
This->net_offset = orig-remapped;
return count;
}
Stream_t *Remap(Stream_t *Next, struct device *dev, char *errmsg) {
Remap_t *This;
int nrItems=0;
const char *map = dev->data_map;
This = New(Remap_t);
if (!This){
printOom();
return 0;
}
memset((void*)This, 0, sizeof(Remap_t));
init_head(&This->head, &RemapClass, Next);
/* First count number of items */
nrItems=process_map(This, map, 1, errmsg);
if(nrItems < 0) {
free(This);
return NULL;
}
This->map = calloc((size_t)nrItems, sizeof(struct map));
if(!This->map) {
printOom();
goto exit_0;
}
process_map(This, map, 0, errmsg);
if(adjust_tot_sectors(dev, This->net_offset, errmsg) < 0)
goto exit_1;
This->mapSize=nrItems;
return &This->head;
exit_1:
free(This->map);
exit_0:
free(This);
printOom();
return NULL;
}
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