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/* Tarlz - Archiver with multimember lzip compression
Copyright (C) 2013-2024 Antonio Diaz Diaz.
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 2 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/>.
*/
#define _FILE_OFFSET_BITS 64
#include <algorithm>
#include <cerrno>
#include <cstdio>
#include <unistd.h>
#include "tarlz.h"
#include "lzip_index.h"
int seek_read( const int fd, uint8_t * const buf, const int size,
const long long pos )
{
if( lseek( fd, pos, SEEK_SET ) == pos )
return readblock( fd, buf, size );
return 0;
}
namespace {
const char * bad_version( const unsigned version )
{
static char buf[80];
snprintf( buf, sizeof buf, "Version %u member format not supported.",
version );
return buf;
}
} // end namespace
bool Lzip_index::check_header( const Lzip_header & header, const bool first )
{
if( !header.check_magic() )
{ error_ = bad_magic_msg; retval_ = 2; if( first ) bad_magic_ = true;
return false; }
if( !header.check_version() )
{ error_ = bad_version( header.version() ); retval_ = 2; return false; }
if( !isvalid_ds( header.dictionary_size() ) )
{ error_ = bad_dict_msg; retval_ = 2; return false; }
return true;
}
void Lzip_index::set_errno_error( const char * const msg )
{
error_ = msg; error_ += std::strerror( errno );
retval_ = 1;
}
void Lzip_index::set_num_error( const char * const msg, unsigned long long num )
{
char buf[80];
snprintf( buf, sizeof buf, "%s%llu", msg, num );
error_ = buf;
retval_ = 2;
}
bool Lzip_index::read_header( const int fd, Lzip_header & header,
const long long pos )
{
if( seek_read( fd, header.data, header.size, pos ) != header.size )
{ set_errno_error( "Error reading member header: " ); return false; }
return true;
}
// If successful, push last member and set pos to member header.
bool Lzip_index::skip_trailing_data( const int fd, unsigned long long & pos )
{
if( pos < min_member_size ) return false;
enum { block_size = 16384,
buffer_size = block_size + Lzip_trailer::size - 1 + Lzip_header::size };
uint8_t buffer[buffer_size];
int bsize = pos % block_size; // total bytes in buffer
if( bsize <= buffer_size - block_size ) bsize += block_size;
int search_size = bsize; // bytes to search for trailer
int rd_size = bsize; // bytes to read from file
unsigned long long ipos = pos - rd_size; // aligned to block_size
while( true )
{
if( seek_read( fd, buffer, rd_size, ipos ) != rd_size )
{ set_errno_error( "Error seeking member trailer: " ); return false; }
const uint8_t max_msb = ( ipos + search_size ) >> 56;
for( int i = search_size; i >= Lzip_trailer::size; --i )
if( buffer[i-1] <= max_msb ) // most significant byte of member_size
{
const Lzip_trailer & trailer =
*(const Lzip_trailer *)( buffer + i - trailer.size );
const unsigned long long member_size = trailer.member_size();
if( member_size == 0 ) // skip trailing zeros
{ while( i > trailer.size && buffer[i-9] == 0 ) --i; continue; }
if( member_size > ipos + i || !trailer.check_consistency() ) continue;
Lzip_header header;
if( !read_header( fd, header, ipos + i - member_size ) ) return false;
if( !header.check() ) continue;
const Lzip_header & header2 = *(const Lzip_header *)( buffer + i );
const bool full_h2 = bsize - i >= header.size;
if( header2.check_prefix( bsize - i ) ) // last member
{
if( !full_h2 ) error_ = "Last member in input file is truncated.";
else if( check_header( header2, false ) )
error_ = "Last member in input file is truncated or corrupt.";
retval_ = 2; return false;
}
if( full_h2 && header2.check_corrupt() )
{ error_ = corrupt_mm_msg; retval_ = 2; return false; }
pos = ipos + i - member_size; // good member
const unsigned dictionary_size = header.dictionary_size();
if( dictionary_size_ < dictionary_size )
dictionary_size_ = dictionary_size;
member_vector.push_back( Member( 0, trailer.data_size(), pos,
member_size, dictionary_size ) );
return true;
}
if( ipos == 0 )
{ set_num_error( "Bad trailer at pos ", pos - Lzip_trailer::size );
return false; }
bsize = buffer_size;
search_size = bsize - Lzip_header::size;
rd_size = block_size;
ipos -= rd_size;
std::memcpy( buffer + rd_size, buffer, buffer_size - rd_size );
}
}
Lzip_index::Lzip_index( const int infd )
: insize( lseek( infd, 0, SEEK_END ) ), retval_( 0 ), dictionary_size_( 0 ),
bad_magic_( false )
{
if( insize < 0 )
{ set_errno_error( "Input file is not seekable: " ); return; }
if( insize < min_member_size )
{ error_ = "Input file is too short."; retval_ = 2; return; }
if( insize > INT64_MAX )
{ error_ = "Input file is too long (2^63 bytes or more).";
retval_ = 2; return; }
Lzip_header header;
if( !read_header( infd, header, 0 ) ||
!check_header( header, true ) ) return;
unsigned long long pos = insize; // always points to a header or to EOF
while( pos >= min_member_size )
{
Lzip_trailer trailer;
if( seek_read( infd, trailer.data, trailer.size, pos - trailer.size ) !=
trailer.size )
{ set_errno_error( "Error reading member trailer: " ); break; }
const unsigned long long member_size = trailer.member_size();
if( member_size > pos || !trailer.check_consistency() ) // bad trailer
{
if( member_vector.empty() )
{ if( skip_trailing_data( infd, pos ) ) continue; return; }
set_num_error( "Bad trailer at pos ", pos - trailer.size ); break;
}
if( !read_header( infd, header, pos - member_size ) ) break;
if( !header.check() ) // bad header
{
if( member_vector.empty() )
{ if( skip_trailing_data( infd, pos ) ) continue; return; }
set_num_error( "Bad header at pos ", pos - member_size ); break;
}
pos -= member_size; // good member
const unsigned dictionary_size = header.dictionary_size();
if( dictionary_size_ < dictionary_size )
dictionary_size_ = dictionary_size;
member_vector.push_back( Member( 0, trailer.data_size(), pos,
member_size, dictionary_size ) );
}
if( pos != 0 || member_vector.empty() || retval_ != 0 )
{
member_vector.clear();
if( retval_ == 0 ) { error_ = "Can't create file index."; retval_ = 2; }
return;
}
std::reverse( member_vector.begin(), member_vector.end() );
for( unsigned long i = 0; ; ++i )
{
const long long end = member_vector[i].dblock.end();
if( end < 0 || end > INT64_MAX )
{
member_vector.clear();
error_ = "Data in input file is too long (2^63 bytes or more).";
retval_ = 2; return;
}
if( i + 1 >= member_vector.size() ) break;
member_vector[i+1].dblock.pos( end );
}
}
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