diff --git a/packages/paszlib/examples/testgzstream.pp b/packages/paszlib/examples/testgzstream.pp new file mode 100644 index 0000000000..adb5f90393 --- /dev/null +++ b/packages/paszlib/examples/testgzstream.pp @@ -0,0 +1,41 @@ +program example; + +uses + SysUtils, ZStream, Classes; + +procedure TestGZip; +var + SS: TStringStream; + CS: TGZipCompressionStream; + FS: TFileStream; +begin + SS := TStringStream.Create('hello, hello!'); + FS := TFileStream.Create(GetTempDir+'test.gz', fmCreate); + CS := TGZipCompressionStream.Create(FS); + CS.CopyFrom(SS, 0); + CS.Free; + FS.Free; + SS.Free; +end; + +procedure TestGUnzip; +var + FS: TFileStream; + DS: TGZipDecompressionStream; + SS: TStringStream; +begin + FS := TFileStream.Create(GetTempDir+'test.gz', fmOpenRead); + DS := TGZipDecompressionStream.Create(FS); + SS := TStringStream.Create(''); + SS.CopyFrom(DS, 0); + DS.Free; + FS.Free; + WriteLn(SS.DataString); + SS.Free; +end; + +begin + TestGZip; + TestGUnZip; +end. + diff --git a/packages/paszlib/src/zstream.pp b/packages/paszlib/src/zstream.pp index 7760c0a799..675230f03f 100644 --- a/packages/paszlib/src/zstream.pp +++ b/packages/paszlib/src/zstream.pp @@ -19,6 +19,8 @@ unit ZStream; **********************************************************************} +{ GZip specs: https://datatracker.ietf.org/doc/html/rfc1952 } + {$mode objfpc} {***************************************************************************} @@ -97,6 +99,38 @@ type destructor destroy;override; end; + TGZipCompressionStream = class(TStream) + private + FLevel: TCompressionLevel; + FCrc32Val: Longword; + FUncompressedSize: Cardinal; + FDest: TStream; + FCompressionStream: TCompressionStream; + procedure WriteHeader; + procedure WriteFooter; + public + constructor Create(ADest: TStream); overload; + constructor Create(ALevel: TCompressionLevel; ADest: TStream); overload; + destructor Destroy; override; + function Write(const Buffer; Count: Longint): Longint; override; + end; + + TGZipDecompressionStream = class(TStream) + private + FCrc32Val: Longword; + FUncompressedSize: Cardinal; + FSource: TStream; + FDecompressionStream: TDecompressionStream; + procedure Assert(ACond: Boolean; AMsg: string = ''); + procedure ReadHeader; + procedure ReadFooter; + public + constructor Create(ASource: TStream); + destructor Destroy; override; + function Read(var Buffer; Count: Longint): Longint; override; + function Seek(const Offset: Int64; Origin: TSeekOrigin): Int64; override; + end; + Ezliberror=class(Estreamerror) end; @@ -117,12 +151,66 @@ uses zdeflate,zinflate; const bufsize=16384; {Size of the buffer used for temporarily storing data from the child stream.} + Crc_32_Tab : Array[0..255] of LongWord = ( + $00000000, $77073096, $ee0e612c, $990951ba, $076dc419, $706af48f, $e963a535, $9e6495a3, + $0edb8832, $79dcb8a4, $e0d5e91e, $97d2d988, $09b64c2b, $7eb17cbd, $e7b82d07, $90bf1d91, + $1db71064, $6ab020f2, $f3b97148, $84be41de, $1adad47d, $6ddde4eb, $f4d4b551, $83d385c7, + $136c9856, $646ba8c0, $fd62f97a, $8a65c9ec, $14015c4f, $63066cd9, $fa0f3d63, $8d080df5, + $3b6e20c8, $4c69105e, $d56041e4, $a2677172, $3c03e4d1, $4b04d447, $d20d85fd, $a50ab56b, + $35b5a8fa, $42b2986c, $dbbbc9d6, $acbcf940, $32d86ce3, $45df5c75, $dcd60dcf, $abd13d59, + $26d930ac, $51de003a, $c8d75180, $bfd06116, $21b4f4b5, $56b3c423, $cfba9599, $b8bda50f, + $2802b89e, $5f058808, $c60cd9b2, $b10be924, $2f6f7c87, $58684c11, $c1611dab, $b6662d3d, + $76dc4190, $01db7106, $98d220bc, $efd5102a, $71b18589, $06b6b51f, $9fbfe4a5, $e8b8d433, + $7807c9a2, $0f00f934, $9609a88e, $e10e9818, $7f6a0dbb, $086d3d2d, $91646c97, $e6635c01, + $6b6b51f4, $1c6c6162, $856530d8, $f262004e, $6c0695ed, $1b01a57b, $8208f4c1, $f50fc457, + $65b0d9c6, $12b7e950, $8bbeb8ea, $fcb9887c, $62dd1ddf, $15da2d49, $8cd37cf3, $fbd44c65, + $4db26158, $3ab551ce, $a3bc0074, $d4bb30e2, $4adfa541, $3dd895d7, $a4d1c46d, $d3d6f4fb, + $4369e96a, $346ed9fc, $ad678846, $da60b8d0, $44042d73, $33031de5, $aa0a4c5f, $dd0d7cc9, + $5005713c, $270241aa, $be0b1010, $c90c2086, $5768b525, $206f85b3, $b966d409, $ce61e49f, + $5edef90e, $29d9c998, $b0d09822, $c7d7a8b4, $59b33d17, $2eb40d81, $b7bd5c3b, $c0ba6cad, + $edb88320, $9abfb3b6, $03b6e20c, $74b1d29a, $ead54739, $9dd277af, $04db2615, $73dc1683, + $e3630b12, $94643b84, $0d6d6a3e, $7a6a5aa8, $e40ecf0b, $9309ff9d, $0a00ae27, $7d079eb1, + $f00f9344, $8708a3d2, $1e01f268, $6906c2fe, $f762575d, $806567cb, $196c3671, $6e6b06e7, + $fed41b76, $89d32be0, $10da7a5a, $67dd4acc, $f9b9df6f, $8ebeeff9, $17b7be43, $60b08ed5, + $d6d6a3e8, $a1d1937e, $38d8c2c4, $4fdff252, $d1bb67f1, $a6bc5767, $3fb506dd, $48b2364b, + $d80d2bda, $af0a1b4c, $36034af6, $41047a60, $df60efc3, $a867df55, $316e8eef, $4669be79, + $cb61b38c, $bc66831a, $256fd2a0, $5268e236, $cc0c7795, $bb0b4703, $220216b9, $5505262f, + $c5ba3bbe, $b2bd0b28, $2bb45a92, $5cb36a04, $c2d7ffa7, $b5d0cf31, $2cd99e8b, $5bdeae1d, + $9b64c2b0, $ec63f226, $756aa39c, $026d930a, $9c0906a9, $eb0e363f, $72076785, $05005713, + $95bf4a82, $e2b87a14, $7bb12bae, $0cb61b38, $92d28e9b, $e5d5be0d, $7cdcefb7, $0bdbdf21, + $86d3d2d4, $f1d4e242, $68ddb3f8, $1fda836e, $81be16cd, $f6b9265b, $6fb077e1, $18b74777, + $88085ae6, $ff0f6a70, $66063bca, $11010b5c, $8f659eff, $f862ae69, $616bffd3, $166ccf45, + $a00ae278, $d70dd2ee, $4e048354, $3903b3c2, $a7672661, $d06016f7, $4969474d, $3e6e77db, + $aed16a4a, $d9d65adc, $40df0b66, $37d83bf0, $a9bcae53, $debb9ec5, $47b2cf7f, $30b5ffe9, + $bdbdf21c, $cabac28a, $53b39330, $24b4a3a6, $bad03605, $cdd70693, $54de5729, $23d967bf, + $b3667a2e, $c4614ab8, $5d681b02, $2a6f2b94, $b40bbe37, $c30c8ea1, $5a05df1b, $2d02ef8d + ); resourcestring Sgz_open_error='Could not open gzip compressed file %s.'; Sgz_read_only='Gzip compressed file was opened for reading.'; Sgz_write_only='Gzip compressed file was opened for writing.'; + Sgz_invalid_header='Invalid GZip header'; + Sgz_invalid_algorithm='Invalid compression algorithm'; + Sgz_invalid_crc32='Invalid crc32 checksum'; + Sgz_invalid_output_size='Invalid output size'; Sseek_failed='Seek in deflate compressed stream failed.'; +function UpdateCrc32(Crc: Longword; const Buffer; Count: Longint): Longword; +var + PBuf: PByte; + i: Longint; +begin + PBuf := @Buffer; + + Result := Crc xor $FFFFFFFF; + for i := 1 to Count do + begin + Result := Crc_32_Tab[(Result xor PBuf^) and $ff] xor (Result shr 8); + Inc(PBuf); + end; + Result := Result xor $FFFFFFFF; +end; + constructor Tcustomzlibstream.create(stream:Tstream); begin @@ -413,4 +501,175 @@ begin inherited destroy; end; +{ TGZipCompressionStream } + +constructor TGZipCompressionStream.Create(ADest: TStream); +begin + Create(clDefault, ADest); +end; + +constructor TGZipCompressionStream.Create(ALevel: TCompressionLevel; ADest: TStream); +begin + inherited Create; + FLevel := ALevel; + FCrc32Val := 0; + FUncompressedSize := 0; + FDest := ADest; + WriteHeader; + FCompressionStream := TCompressionStream.Create(FLevel, FDest, True); +end; + +destructor TGZipCompressionStream.Destroy; +begin + FCompressionStream.Flush; + FCompressionStream.Free; + WriteFooter; + inherited; +end; + +procedure TGZipCompressionStream.WriteHeader; +begin + FDest.WriteByte($1f); // signature 1 of 2 + FDest.WriteByte($8b); // signature 2 of 2 + FDest.WriteByte($08); // deflate algorithm + FDest.WriteByte($00); // no flags + FDest.WriteDWord($00); // modification time unknown. Source is stream, not a file + if FLevel = clmax then // XFL = extra flags = compression level + FDest.WriteByte($02) + else if FLevel = clfastest then + FDest.WriteByte($04) + else + FDest.WriteByte($00); + FDest.WriteByte($ff); // OS file system unknown. Source is stream, not a file +end; + +procedure TGZipCompressionStream.WriteFooter; +var + i: Integer; +begin + // write crc32 in 4 bytes, least significant byte first + for i := 1 to 4 do + begin + FDest.WriteByte(FCrc32Val and $ff); + FCrc32Val := FCrc32Val shr 8; + end; + + // write uncompressed size in 4 bytes, least significant byte first + for i := 1 to 4 do + begin + FDest.WriteByte(FUncompressedSize and $ff); + FUncompressedSize := FUncompressedSize shr 8; + end; +end; + +function TGZipCompressionStream.Write(const Buffer; Count: Longint): Longint; +begin + FCrc32Val := UpdateCrc32(FCrc32Val, Buffer, Count); + Inc(FUncompressedSize, Count); + Result := FCompressionStream.Write(Buffer, Count); +end; + +{ TGZipDecompressionStream } + +constructor TGZipDecompressionStream.Create(ASource: TStream); +begin + inherited Create; + FSource := ASource; + FCrc32Val := 0; + FUncompressedSize := 0; + ReadHeader; + FDecompressionStream := TDecompressionStream.Create(FSource, True); +end; + +destructor TGZipDecompressionStream.Destroy; +begin + FDecompressionStream.Free; + inherited; +end; + +procedure TGZipDecompressionStream.Assert(ACond: Boolean; AMsg: string = ''); +begin + if not ACond then + raise EDecompressionError.Create(AMsg); +end; + +procedure TGZipDecompressionStream.ReadHeader; +var + Flags: Byte; + XLEN: Cardinal; +begin + Assert(FSource.ReadByte = $1f, Sgz_invalid_header); + Assert(FSource.ReadByte = $8b, Sgz_invalid_header); + Assert(FSource.ReadByte = $08, Sgz_invalid_algorithm); + Flags := FSource.ReadByte; + FSource.ReadDWord; // skip modification time. Dest is stream, not a file + FSource.ReadByte; // skip compression level, is not needed + FSource.ReadByte; // skip OS file system. Dest is stream, not a file + + if (Flags and $4) <> 0 then // FLG.FEXTRA + begin + XLEN := FSource.ReadByte + FSource.ReadByte shl 8; // least significant byte first + while XLEN > 0 do + begin + FSource.ReadByte; + Dec(XLEN); + end; + end; + + if (Flags and $8) <> 0 then // FLG.FNAME + begin + repeat + until FSource.ReadByte = 0; // zero-terminated file name + end; + + if (Flags and $10) <> 0 then // FLG.FCOMMENT + begin + repeat + until FSource.ReadByte = 0; // zero-terminated file comment + end; + + if (Flags and $2) <> 0 then // FLG.FHCRC + FSource.ReadWord; // skip CRC16, check not implemented +end; + +procedure TGZipDecompressionStream.ReadFooter; +var + Crc32: Longword; + OrigSize: Longword; +begin + // The TDecompressionStream reads in buffers, so the footer + // may already be skipped. Therefore, we need to Seek to the footer. + // If FSource is non-seekable, we skip checking Crc32 and OrigSize. + try + FSource.Seek(-8, soEnd); + except + Exit; // skip Crc32 and OrigSize checking + end; + + Crc32 := FSource.ReadByte + FSource.ReadByte shl 8 + FSource.ReadByte shl 16 + FSource.ReadByte shl 24; + Assert(FCrc32Val = Crc32, Sgz_invalid_crc32); + OrigSize := FSource.ReadByte + FSource.ReadByte shl 8 + FSource.ReadByte shl 16 + FSource.ReadByte shl 24; + Assert(FUncompressedSize = OrigSize, Sgz_invalid_output_size); +end; + +function TGZipDecompressionStream.Read(var Buffer; Count: Longint): Longint; +begin + Result := FDecompressionStream.Read(Buffer, Count); + Inc(FUncompressedSize, Result); + FCrc32Val := UpdateCrc32(FCrc32Val, Buffer, Result); + + if Result < Count then + ReadFooter; +end; + +function TGZipDecompressionStream.Seek(const Offset: Int64; Origin: TSeekOrigin): Int64; +begin + // accept Seek(0, soBeginning) if nothing read yet + // this is needed for the TStream.CopyFrom() method + if (Offset = 0) and (Origin = TSeekOrigin.soBeginning) and (FUncompressedSize = 0) then + Result := 0 + else + Result := inherited Seek(Offset, Origin); +end; + end.