diff options
Diffstat (limited to '')
| -rw-r--r-- | lzip.h | 40 |
1 files changed, 24 insertions, 16 deletions
@@ -1,5 +1,5 @@ /* Lzip - LZMA lossless data compressor - Copyright (C) 2008-2015 Antonio Diaz Diaz. + Copyright (C) 2008-2016 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 @@ -44,6 +44,7 @@ enum { max_dictionary_bits = 29, max_dictionary_size = 1 << max_dictionary_bits, literal_context_bits = 3, + literal_pos_state_bits = 0, // not used pos_state_bits = 2, pos_states = 1 << pos_state_bits, pos_state_mask = pos_states - 1, @@ -175,6 +176,11 @@ public: extern const CRC32 crc32; +inline bool isvalid_ds( const unsigned dictionary_size ) + { return ( dictionary_size >= min_dictionary_size && + dictionary_size <= max_dictionary_size ); } + + inline int real_bits( unsigned value ) { int bits = 0; @@ -195,9 +201,15 @@ struct File_header void set_magic() { std::memcpy( data, magic_string, 4 ); data[4] = 1; } bool verify_magic() const { return ( std::memcmp( data, magic_string, 4 ) == 0 ); } + bool verify_prefix( const int size ) const // detect truncated header + { + for( int i = 0; i < size && i < 4; ++i ) + if( data[i] != magic_string[i] ) return false; + return ( size > 0 ); + } uint8_t version() const { return data[4]; } - bool verify_version() const { return ( data[4] <= 1 ); } + bool verify_version() const { return ( data[4] == 1 ); } unsigned dictionary_size() const { @@ -209,20 +221,17 @@ struct File_header bool dictionary_size( const unsigned sz ) { - if( sz >= min_dictionary_size && sz <= max_dictionary_size ) + if( !isvalid_ds( sz ) ) return false; + data[5] = real_bits( sz - 1 ); + if( sz > min_dictionary_size ) { - data[5] = real_bits( sz - 1 ); - if( sz > min_dictionary_size ) - { - const unsigned base_size = 1 << data[5]; - const unsigned fraction = base_size / 16; - for( int i = 7; i >= 1; --i ) - if( base_size - ( i * fraction ) >= sz ) - { data[5] |= ( i << 5 ); break; } - } - return true; + const unsigned base_size = 1 << data[5]; + const unsigned fraction = base_size / 16; + for( int i = 7; i >= 1; --i ) + if( base_size - ( i * fraction ) >= sz ) + { data[5] |= ( i << 5 ); break; } } - return false; + return true; } }; @@ -233,8 +242,7 @@ struct File_trailer // 4-11 size of the uncompressed data // 12-19 member size including header and trailer - static int size( const int version = 1 ) - { return ( ( version >= 1 ) ? 20 : 12 ); } + enum { size = 20 }; unsigned data_crc() const { |