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dvdisaster/src/rs03-recognize.c

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/* dvdisaster: Additional error correction for optical media.
* Copyright (C) 2004-2017 Carsten Gnoerlich.
* Copyright (C) 2019-2021 The dvdisaster development team.
*
* Email: support@dvdisaster.org
*
* This file is part of dvdisaster.
*
* dvdisaster 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.
*
* dvdisaster 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 dvdisaster. If not, see <http://www.gnu.org/licenses/>.
*/
/*** src type: no GUI code ***/
#include "dvdisaster.h"
#include "udf.h"
#include "rs03-includes.h"
/*
* Aux. functions
*/
static int valid_crc_block(unsigned char *buf, guint64 sector, int image_expected)
{ CrcBlock *cb = alloca(2048);
guint32 recorded_crc, real_crc;
memcpy(cb, buf, 2048);
/* See if the magic cookie is there */
if( strncmp((char*)cb->cookie, "*dvdisaster*", 12)
|| strncmp((char*)cb->method, "RS03", 4))
return 0;
/* Examine the checksum */
recorded_crc = cb->selfCRC;
#ifdef HAVE_BIG_ENDIAN
cb->selfCRC = 0x47504c00;
#else
cb->selfCRC = 0x4c5047;
#endif
real_crc = Crc32((unsigned char*)cb, 2048);
if(real_crc != recorded_crc)
{ Verbose(".. invalid CRC block %lld\n", (unsigned long long)sector);
return 1;
}
/* If an ecc file header is found in the image (which might
rightfully contain ecc files), ignore it */
if(image_expected && (cb->methodFlags[0] & MFLAG_ECC_FILE))
{ Verbose(".. Crc block from ecc file in image - IGNORED\n");
return 1;
}
return 2;
}
/***
*** Recognize a RS03 error correction file
***/
int RS03RecognizeFile(LargeFile *ecc_file, EccHeader **eh)
{ int crc_block = 0;
int n;
Verbose("RS03RecognizeFile(): examining %s\n", ecc_file->path);
*eh = g_malloc(sizeof(EccHeader));
/*** First see whether we have a valid ecc header. */
LargeSeek(ecc_file, 0);
n = LargeRead(ecc_file, *eh, sizeof(EccHeader));
/* short read -> definitely not an ecc file */
if(n != sizeof(EccHeader))
{ g_free(*eh);
*eh=NULL;
Verbose("RS03RecognizeFile(): short read for ecc header\n");
return ECCFILE_INVALID;
}
/* Validate the header */
if(!strncmp((char*)(*eh)->cookie, "*dvdisaster*", 12))
{ guint32 recorded_crc,real_crc;
/* Examine the checksum */
recorded_crc = (*eh)->selfCRC;
#ifdef HAVE_BIG_ENDIAN
(*eh)->selfCRC = 0x47504c00;
#else
(*eh)->selfCRC = 0x4c5047;
#endif
real_crc = Crc32((unsigned char*)(*eh), 4096);
#ifdef HAVE_BIG_ENDIAN
SwapEccHeaderBytes(*eh);
#endif
if(real_crc != recorded_crc)
{ Verbose("RS03RecognizeFile(): checksum error in ecc header\n");
}
else
{ if(!strncmp((char*)(*eh)->method, "RS03", 4))
{ Verbose("RS03RecognizeFile(): ecc header found\n");
return ECCFILE_PRESENT;
}
else
{ Verbose("RS03RecognizeFile(): wrong codec\n");
g_free(*eh);
*eh=NULL;
return ECCFILE_WRONG_CODEC;
}
}
}
else Verbose("RS03RecognizeFile(): no magic cookie in header\n");
/* No ecc header found; search for CRC blocks.
The CRC block follow directly after the ecc header,
so simply continue reading in 2048 chunks until
the file ends. There is no good criterion for stopping
the read earlier since the file may be truncated and/or
contain mangled contents in many unpredictable ways. */
Verbose("RS03RecognizeFile(): exhaustive search for CRC blocks started\n");
for(;;)
{ unsigned char buf[2048];
n = LargeRead(ecc_file, buf, 2048);
if(n != 2048)
{ if(n== 0 && LargeEOF(ecc_file))
Verbose("RS03RecognizeFile(): end of file reached\n");
else Verbose("RS03RecognizeFile(): short read for CRC sector %d\n", crc_block);
g_free(*eh);
*eh=NULL;
return ECCFILE_INVALID;
}
if(valid_crc_block(buf, crc_block++, FALSE) == 2)
{ ReconstructRS03Header(*eh, (CrcBlock*)buf);
Verbose("** Success: sector %d, rediscovered format with %d roots\n",
crc_block+1, (*eh)->eccBytes);
/* Rewrite the missing ecc header if possible */
if(ecc_file->flags & O_RDWR || ecc_file->flags & O_WRONLY)
{ int success=0;
EccHeader *le_eh = *eh;
char buf[4096];
memset(buf, 0, 4096);
#ifdef HAVE_BIG_ENDIAN
/* eh contains the recovered ecc header in native endian format,
which is what we need it in, but it must be written out in
little endian. So we have to create an extra copy for writing
out when on a big endian machine. */
memcpy(buf, *eh, 4096);
le_eh = (EccHeader*)buf;
SwapEccHeaderBytes(le_eh);
le_eh->selfCRC = 0x47504c00;
le_eh->selfCRC = Crc32((unsigned char*)buf, 4096);
#endif
if(LargeSeek(ecc_file, 0))
{ if(LargeWrite(ecc_file, le_eh, 4096))
success=1;
}
if(success) Verbose("** Missing ecc header rewritten\n");
else Verbose("** Note: Could not rewrite ecc header!\n");
}
return ECCFILE_PRESENT;
}
}
/* Still nothing found. */
g_free(*eh);
*eh=NULL;
Verbose("RS03RecognizeFile(): no ecc found\n");
return ECCFILE_INVALID;
}
/***
*** Recognize RS03 error correction data in the image
***/
#if 0
static int read_fingerprint(LargeFile *file, unsigned char *fingerprint, gint64 sector)
{ struct MD5Context md5ctxt;
unsigned char buf[2048];
int n;
if(!LargeSeek(file, 2048LL*sector))
return FALSE;
n = LargeRead(file, buf, 2048);
if(n != 2048) return FALSE;
if(CheckForMissingSector(buf, sector, NULL, 0) != SECTOR_PRESENT)
return FALSE;
MD5Init(&md5ctxt);
MD5Update(&md5ctxt, buf, 2048);
MD5Final(fingerprint, &md5ctxt);
return TRUE;
}
#endif
static EccHeader* valid_header(unsigned char *buf, gint64 hdr_pos, int image_expected)
{ EccHeader *eh = (EccHeader*)buf;
guint32 recorded_crc, real_crc;
// unsigned char fingerprint[16];
/* Medium read error in ecc header? */
if( (CheckForMissingSector(buf, hdr_pos, NULL, 0) != SECTOR_PRESENT)
|| (CheckForMissingSector(buf+2048, hdr_pos+1, NULL, 0) != SECTOR_PRESENT))
return NULL;
/* See if the magic cookie is there */
if( strncmp((char*)eh->cookie, "*dvdisaster*", 12)
|| strncmp((char*)eh->method, "RS03", 4))
return NULL;
/* Examine the checksum */
recorded_crc = eh->selfCRC;
#ifdef HAVE_BIG_ENDIAN
eh->selfCRC = 0x47504c00;
#else
eh->selfCRC = 0x4c5047;
#endif
real_crc = Crc32((unsigned char*)eh, 4096);
if(real_crc != recorded_crc)
return NULL;
/* If an ecc file header is found in the image (which might
rightfully contain ecc files), ignore it */
if(image_expected && (eh->methodFlags[0] & MFLAG_ECC_FILE))
{ Verbose(".. Ecc file header in image - IGNORED\n");
return NULL;
}
/* Check the fingerprint */
eh = g_malloc(sizeof(EccHeader));
memcpy(eh, buf, sizeof(EccHeader));
#ifdef HAVE_BIG_ENDIAN
SwapEccHeaderBytes(eh);
#endif
eh->selfCRC = recorded_crc;
#if 0 //FIXME
status = read_fingerprint(file, fingerprint, eh->fpSector);
if(!status) /* be optimistic if fingerprint sector is unreadable */
return eh;
if(!memcmp(fingerprint, eh->mediumFP, 16)) /* good fingerprint */
{ printf("RS03 header found\n");
return eh;
}
g_free(eh);
#endif
return eh;
}
EccHeader* FindRS03HeaderInImage(Image *image)
{ EccHeader *eh = NULL;
gint64 hdr_pos;
IsoInfo *ii;
unsigned char buf[4096];
switch(image->type)
{ case IMAGE_FILE:
Verbose("FindRS03HeaderInImage: file %s\n", image->file->path);
break;
case IMAGE_MEDIUM:
Verbose("FindRS03HeaderInImage: medium %s\n", image->dh->device);
break;
default:
Verbose("FindRS03HeaderInImage: unknown type %d\n", image->type);
break;
}
/*** Try to find the header behind the ISO image */
ii = image->isoInfo;
if(!ii) Verbose(" . NO ISO structures found!\n");
if(ii)
{ hdr_pos = ii->volumeSize;
if(ImageReadSectors(image, buf, hdr_pos, 2) == 2)
{ eh = valid_header(buf, hdr_pos, TRUE);
if(eh)
{ Verbose("FindRS03HeaderInImage(): Header found at pos +0\n");
return eh;
}
}
hdr_pos = ii->volumeSize - 150;
if(ImageReadSectors(image, buf, hdr_pos, 2) == 2)
{ eh = valid_header(buf, hdr_pos, TRUE);
if(eh)
{ Verbose("FindRS03HeaderInImage(): Header found at pos -150\n");
return eh;
}
}
}
return NULL;
}
typedef struct
{ AlignedBuffer *layer[256];
AlignedBuffer *ab;
RS03Layout *layout[256];
int layer_checked[256];
} recognize_context;
static void free_recognize_context(recognize_context *rc)
{ int i;
if(rc->ab) FreeAlignedBuffer(rc->ab);
for(i=0; i<255; i++)
{ if(rc->layer[i])
FreeAlignedBuffer(rc->layer[i]);
if(rc->layout[i])
g_free(rc->layout[i]);
}
g_free(rc);
}
int RS03RecognizeImage(Image *image)
{ recognize_context *rc = g_malloc0(sizeof(recognize_context));
guint64 image_sectors;
guint64 layer_size;
gint64 trynumber;
gint64 maxtries;
int untested_layers;
int layer, layer_sector;
int i;
switch(image->type)
{ case IMAGE_FILE:
Verbose("RS03RecognizeImage: file %s\n", image->file->path);
if(image->eccFile)
Stop("Internal error: RS03RecognizeImage() called with ecc file\n");
image_sectors = image->sectorSize;
break;
case IMAGE_MEDIUM:
Verbose("RS03RecognizeImage: medium %s\n", image->dh->device);
image_sectors = MAX(image->dh->readCapacity, image->dh->userAreaSize);
break;
default:
Verbose("RS03RecognizeImage: unknown type %d\n", image->type);
free_recognize_context(rc);
return FALSE;
break;
}
/* Easy shot: Locate the ecc header in the image */
if (!Closure->debugMode || !Closure->ignoreRS03header)
{ image->eccHeader = FindRS03HeaderInImage(image);
if(image->eccHeader)
{ free_recognize_context(rc);
return TRUE;
}
}
/* This concludes the non-exhaustive search, where we tried to look for
an ECC header signature on the sector right after the end of the ISO
data. This doesn't always work, as some software tend to add some sectors
after the end of the ISO (ImgBurn does this), or because the medium doesn't
have any ISO9600 structure at all (some have only UDF for example), in that
case the above quick search just does nothing.
By default, we don't launch an exhaustive search unless asked for.
For example on the medium-info page, we won't do it unless enabled in the options,
as the inserted medium might not have RS02 nor RS03 at all.
Of course, when doing verify or repair, as it implies the user knows there is
some ECC correction available on the medium, our caller will always require
an exhaustive search. It's also always enabled if we're not reading from a
drive but from a file on the hard drive, as seeking is very fast.
However even if not asked for an exhaustive search, and due to what has been
explained in the first paragraph, we'll always try to read at least 3 sectors
using the exhaustive search mechanism. On most images having ECC data, we'll
find the header on the first try, at least on easy cases. This is a tradeoff
to avoid having to display "no ECC data" on the medium-info page just because
we didn't bother looking for it too hard, without bringing in the full
exhaustive search which can take seconds or minutes on an optical drive with
a medium that, in the end, doesn't have any ECC data.
*/
if(!Closure->examineRS03 && image->type == IMAGE_MEDIUM)
{ maxtries = 3; /* no exhaustive search asked and reading from optical drive */
Verbose("RS03RecognizeImage: quick RS03 search, attempting up to %" PRId64" sector reads max\n", maxtries);
}
else
{ maxtries = -1; /* infinity */
Verbose("RS03RecognizeImage: No EH, entering exhaustive search\n");
}
/* Determine image size in augmented case. */
if(Closure->debugMode && Closure->mediumSize > 170)
{ layer_size = Closure->mediumSize/GF_FIELDMAX;
Verbose("Warning: image size set to %" PRId64 " for debugging!\n", Closure->mediumSize);
}
else
{
const guint64 bd_sl_sz = (Closure->noBdrDefectManagement ? BD_SL_SIZE_NODM : BD_SL_SIZE);
const guint64 bd_dl_sz = (Closure->noBdrDefectManagement ? BD_DL_SIZE_NODM : BD_DL_SIZE);
const guint64 bd_tl_sz = (Closure->noBdrDefectManagement ? BDXL_TL_SIZE_NODM : BDXL_TL_SIZE);
const guint64 bd_ql_sz = (Closure->noBdrDefectManagement ? BDXL_QL_SIZE_NODM : BDXL_QL_SIZE);
if(image_sectors < CDR_SIZE) layer_size = CDR_SIZE/GF_FIELDMAX;
else if(image_sectors < DVD_SL_SIZE) layer_size = DVD_SL_SIZE/GF_FIELDMAX;
else if(image_sectors < DVD_DL_SIZE) layer_size = DVD_DL_SIZE/GF_FIELDMAX;
else if(image_sectors < bd_sl_sz)
layer_size = bd_sl_sz/GF_FIELDMAX;
else if(image_sectors < bd_dl_sz)
layer_size = bd_dl_sz/GF_FIELDMAX;
else if(image_sectors < bd_tl_sz)
layer_size = bd_tl_sz/GF_FIELDMAX;
else layer_size = bd_ql_sz/GF_FIELDMAX;
}
Verbose(".. trying layer size %" PRId64 "\n", layer_size);
/*
* Try a quick scan for the CRC sectors in order
* to re-discover the layout.
*/
Verbose("Scanning layers for signatures.\n");
/* Prepare layout for all possible cases (8..170 roots) */
for(i=84; i<=247; i++) /* allowed range of ndata */
{ RS03Layout *lay;
rc->layout[i] = lay = g_malloc0(sizeof(RS03Layout));
lay->eh = NULL;
lay->dataSectors = (i-1)*layer_size-2;
lay->dataPadding = 0;
lay->totalSectors = GF_FIELDMAX*layer_size;
lay->sectorsPerLayer = layer_size;
lay->mediumCapacity = 0;
lay->eccHeaderPos = lay->dataSectors;
lay->firstCrcPos = (i-1)*layer_size;
lay->firstEccPos = i*layer_size;
lay->nroots = GF_FIELDMAX-i;
lay->ndata = i;
lay->inLast = 2048;
lay->target = ECC_IMAGE;
}
untested_layers = 247-84+1;
trynumber = 0;
rc->ab = CreateAlignedBuffer(2048);
for(layer_sector = 0; layer_sector < layer_size; layer_sector++)
{ CrcBlock *cb = (CrcBlock*)rc->ab->buf;
Verbose("- layer slice %d\n", layer_sector);
for(layer = 84; layer <= 247; layer++)
{ if(!rc->layer_checked[layer])
{ gint64 sector;
int crc_state;
sector = RS03SectorIndex(rc->layout[layer], layer, layer_sector);
/* reading beyond the image won't yield anything */
if(sector >= image_sectors)
goto mark_invalid_layer;
if (++trynumber > maxtries && maxtries > 0) {
Verbose("RS03: max tries reached, stopping search\n");
free_recognize_context(rc);
return FALSE;
}
Verbose("RS03: %s = %" PRId64 ", reading sector %" PRId64 "\n",
maxtries < 0 ? "try number" : "tries left",
maxtries < 0 ? trynumber : maxtries - trynumber,
sector);
switch(image->type)
{ case IMAGE_FILE:
RS03ReadSectors(image, rc->layout[layer], rc->ab->buf,
layer, layer_sector, 1, RS03_READ_ALL);
if(CheckForMissingSector(rc->ab->buf, sector, NULL, 0) != SECTOR_PRESENT)
continue; /* unreadble -> can't decide */
break;
case IMAGE_MEDIUM:
{ int n;
n = ImageReadSectors(image, rc->ab->buf, sector, 1);
if(!n)
continue; /* unreadble -> can't decide */
}
}
/* CRC header found? */
crc_state = valid_crc_block(rc->ab->buf, sector, TRUE);
if(crc_state)
{ int nroots=255-layer-1;
if(crc_state == 1) /* corrupted crc header, try this layer again later */
continue;
Verbose("** Success: sector %" PRId64 ", rediscovered format with %d roots\n",
sector, nroots);
image->eccHeader = g_malloc(sizeof(EccHeader));
ReconstructRS03Header(image->eccHeader, cb);
/* Note: Rewriting the missing ecc header makes no sense here
as we do not have access to the image written in the reading
functions, and the error correction will restore it anyways.
(contrary to the situation with ecc files) */
free_recognize_context(rc);
return TRUE;
}
/* Sector readable but not a CRC header -> skip this layer */
mark_invalid_layer:
if(!rc->layer_checked[layer])
{ rc->layer_checked[layer] = 1;
untested_layers--;
}
if(untested_layers <= 0)
{ Verbose("** All layers tested -> no RS03 data found\n");
free_recognize_context(rc);
return FALSE;
}
}
}
Verbose("-> %d untested layers remaining\n", untested_layers);
}
Verbose("-- whole medium/image scanned; %d layers remain untested\n", untested_layers);
Verbose("-- giving now up as ecc-based search is not yet implemented\n");
free_recognize_context(rc);
return FALSE;
/*
* TODO: Assemble all ecc blocks and see whether the error corrction
* succeeds for a certain number of roots
*/
#if 0
for(i=0; i<255; i++)
rc->layer[i] = CreateAlignedBuffer(2048);
for(ecc_block=0; ecc_block<layer_size; ecc_block++)
{ Verbose("Assembling ecc block %d\n", ecc_block);
/* Assemble the ecc block */
for(i=0; i<255; i++)
{ gint64 sector = rc->bidx[i]++;
int n;
if(!LargeSeek(ecc_file, (gint64)(2048*sector)))
Stop(_("Failed seeking to sector %lld in image: %s"),
sector, strerror(errno));
n = LargeRead(ecc_file, rc->layer[i], 2048);
if(n != 2048)
Stop(_("Failed reading sector %lld in image: %s"),sector,strerror(errno));
}
/* Experimentally apply the RS code */
for(ndata=255-8; ndata >=85; ndata--)
{ CrcBlock *cb = (CrcBlock*)rc->layer[ndata];
/* Do the real decode here */
/* See if we have decoded a CRC block */
if( !memcmp(cb->cookie, "*dvdisaster*", 12)
||!memcmp(cb->method, "RS03", 4))
{
nroots = 255-ndata-1;
Verbose(".. Success: rediscovered format with %d roots\n", nroots);
image->eccHeader = g_malloc(sizeof(EccHeader));
ReconstructRS03Header(image->eccHeader, cb);
//FIXME: endianess okay?
free_recognize_context(rc);
return TRUE;
}
}
}
#endif
free_recognize_context(rc);
return FALSE;
}
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