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/*
libparted - a library for manipulating disk partitions
Copyright (C) 2018-2022 Free Software Foundation, Inc.
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
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, see <http://www.gnu.org/licenses/>.
*/
#include <config.h>
#include <parted/parted.h>
/* Read bytes using ped_geometry_read() function */
static int read_bytes (const PedGeometry* geom, void* buffer, PedSector offset, PedSector count)
{
char* sector_buffer;
PedSector sector_offset, sector_count, buffer_offset;
sector_offset = offset / geom->dev->sector_size;
sector_count = (offset + count + geom->dev->sector_size - 1) / geom->dev->sector_size - sector_offset;
buffer_offset = offset - sector_offset * geom->dev->sector_size;
sector_buffer = alloca (sector_count * geom->dev->sector_size);
if (!ped_geometry_read (geom, sector_buffer, sector_offset, sector_count))
return 0;
memcpy (buffer, sector_buffer + buffer_offset, count);
return 1;
}
/* Scan VSR and check for UDF VSD */
static int check_vrs (const PedGeometry* geom, unsigned int vsdsize)
{
PedSector block;
PedSector offset;
unsigned char ident[5];
/* Check only first 64 blocks, but theoretically standard does not define upper limit */
for (block = 0; block < 64; block++) {
/* VRS starts at fixed offset 32kB, it is independent of block size or vsd size */
offset = 32768 + block * vsdsize;
/* Read VSD identifier, it is at offset 1 */
if (!read_bytes (geom, ident, offset + 1, 5))
return 0;
/* Check for UDF identifier */
if (memcmp (ident, "NSR02", 5) == 0 ||
memcmp (ident, "NSR03", 5) == 0)
return 1;
/* Unknown VSD identifier means end of VRS */
if (memcmp (ident, "BEA01", 5) != 0 &&
memcmp (ident, "TEA01", 5) != 0 &&
memcmp (ident, "BOOT2", 5) != 0 &&
memcmp (ident, "CD001", 5) != 0 &&
memcmp (ident, "CDW02", 5) != 0)
break;
}
return 0;
}
/* Check for UDF AVDP */
static int check_anchor (const PedGeometry* geom, unsigned int blocksize, int rel_block)
{
PedSector block;
unsigned char tag[16];
/* Negative block means relative to the end of device */
if (rel_block < 0) {
block = geom->length * geom->dev->sector_size / blocksize;
if (block <= (PedSector)(-rel_block))
return 0;
block -= (PedSector)(-rel_block);
if (block < 257)
return 0;
} else {
block = rel_block;
}
if (!read_bytes (geom, tag, block * blocksize, 16))
return 0;
/* Check for AVDP type (0x0002) */
if (((unsigned short)tag[0] | ((unsigned short)tag[1] << 8)) != 0x0002)
return 0;
/* Check that location stored in AVDP matches */
if (((unsigned long)tag[12] | ((unsigned long)tag[13] << 8) | ((unsigned long)tag[14] << 16) | ((unsigned long)tag[15] << 24)) != block)
return 0;
return 1;
}
/* Detect presence of UDF AVDP */
static int detect_anchor(const PedGeometry* geom, unsigned int blocksize)
{
/* All possible AVDP locations in preferred order */
static int anchors[] = { 256, -257, -1, 512 };
size_t i;
for (i = 0; i < sizeof (anchors)/sizeof (*anchors); i++) {
if (check_anchor (geom, blocksize, anchors[i]))
return 1;
}
return 0;
}
/* Detect UDF filesystem, it must have VRS and AVDP */
static int detect_udf (const PedGeometry* geom)
{
unsigned int blocksize;
/* VSD size is min(2048, UDF block size), check for block sizes <= 2048 */
if (check_vrs (geom, 2048)) {
for (blocksize = 512; blocksize <= 2048; blocksize *= 2) {
if (detect_anchor (geom, blocksize))
return 1;
}
}
/* Check for block sizes larger then 2048, maximal theoretical block size is 32kB */
for (blocksize = 4096; blocksize <= 32768; blocksize *= 2) {
if (!check_vrs (geom, blocksize))
continue;
if (detect_anchor (geom, blocksize))
return 1;
}
return 0;
}
PedGeometry*
udf_probe (PedGeometry* geom)
{
if (!detect_udf (geom))
return NULL;
return ped_geometry_duplicate (geom);
}
static PedFileSystemOps udf_ops = {
probe: udf_probe,
};
static PedFileSystemType udf_type = {
next: NULL,
ops: &udf_ops,
name: "udf",
};
void
ped_file_system_udf_init ()
{
ped_file_system_type_register (&udf_type);
}
void
ped_file_system_udf_done ()
{
ped_file_system_type_unregister (&udf_type);
}
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