Code:
/ Net / Net / 3.5.50727.3053 / DEVDIV / depot / DevDiv / releases / whidbey / netfxsp / ndp / fx / src / Sys / System / IO / compression / GZipDecoder.cs / 1 / GZipDecoder.cs
namespace System.IO.Compression
{
using System;
using System.Diagnostics;
internal enum GZIPHeaderState{
// GZIP header
ReadingID1,
ReadingID2,
ReadingCM,
ReadingFLG,
ReadingMMTime, // iterates 4 times
ReadingXFL,
ReadingOS,
ReadingXLen1,
ReadingXLen2,
ReadingXLenData,
ReadingFileName,
ReadingComment,
ReadingCRC16Part1,
ReadingCRC16Part2,
Done, // done reading GZIP header
// GZIP footer
ReadingCRC, // iterates 4 times
ReadingFileSize // iterates 4 times
}
// This class decodes GZip header and footer information.
// See RFC 1952 for details about the format.
internal class GZipDecoder {
const int FileText = 1;
const int CRCFlag = 2;
const int ExtraFieldsFlag = 4;
const int FileNameFlag = 8;
const int CommentFlag= 16;
private InputBuffer input;
GZIPHeaderState gzipHeaderSubstate;
GZIPHeaderState gzipFooterSubstate;
int gzip_header_flag;
int gzip_header_xlen;
uint gzipCrc32;
uint gzipOutputStreamSize;
int loopCounter;
public GZipDecoder(InputBuffer input) {
this.input = input;
Reset();
}
public void Reset() {
gzipHeaderSubstate = GZIPHeaderState.ReadingID1;
gzipFooterSubstate = GZIPHeaderState.ReadingCRC;
gzipCrc32 = 0;
gzipOutputStreamSize = 0;
}
public uint Crc32 {
get {
return gzipCrc32;
}
}
public uint StreamSize {
get {
return gzipOutputStreamSize;
}
}
public bool ReadGzipHeader() {
while(true) {
int bits;
switch (gzipHeaderSubstate) {
case GZIPHeaderState.ReadingID1:
bits = input.GetBits(8);
if( bits < 0) {
return false;
}
if( bits != 0x1F) {
throw new InvalidDataException(SR.GetString(SR.CorruptedGZipHeader));
}
gzipHeaderSubstate = GZIPHeaderState.ReadingID2;
goto case GZIPHeaderState.ReadingID2;
case GZIPHeaderState.ReadingID2:
bits = input.GetBits(8);
if( bits < 0) {
return false;
}
if( bits != 0x8b) {
throw new InvalidDataException(SR.GetString(SR.CorruptedGZipHeader));
}
gzipHeaderSubstate = GZIPHeaderState.ReadingCM;
goto case GZIPHeaderState.ReadingCM;
case GZIPHeaderState.ReadingCM:
bits = input.GetBits(8);
if( bits < 0) {
return false;
}
if( bits != 0x8) { // compression mode must be 8 (deflate)
throw new InvalidDataException(SR.GetString(SR.UnknownCompressionMode));
}
gzipHeaderSubstate = GZIPHeaderState.ReadingFLG;;
goto case GZIPHeaderState.ReadingFLG;
case GZIPHeaderState.ReadingFLG:
bits = input.GetBits(8);
if( bits < 0) {
return false;
}
gzip_header_flag = bits;
gzipHeaderSubstate = GZIPHeaderState.ReadingMMTime;
loopCounter = 0; // 4 MMTIME bytes
goto case GZIPHeaderState.ReadingMMTime;
case GZIPHeaderState.ReadingMMTime:
bits = 0;
while(loopCounter < 4) {
bits = input.GetBits(8);
if( bits < 0) {
return false;
}
loopCounter++;
}
gzipHeaderSubstate = GZIPHeaderState.ReadingXFL;
loopCounter = 0;
goto case GZIPHeaderState.ReadingXFL;
case GZIPHeaderState.ReadingXFL: // ignore XFL
bits = input.GetBits(8);
if( bits < 0) {
return false;
}
gzipHeaderSubstate = GZIPHeaderState.ReadingOS;
goto case GZIPHeaderState.ReadingOS;
case GZIPHeaderState.ReadingOS: // ignore OS
bits = input.GetBits(8);
if( bits < 0) {
return false;
}
gzipHeaderSubstate = GZIPHeaderState.ReadingXLen1;
goto case GZIPHeaderState.ReadingXLen1;
case GZIPHeaderState.ReadingXLen1:
if ((gzip_header_flag & ExtraFieldsFlag) == 0) {
goto case GZIPHeaderState.ReadingFileName;
}
bits = input.GetBits(8);
if( bits < 0) {
return false;
}
gzip_header_xlen = bits;
gzipHeaderSubstate = GZIPHeaderState.ReadingXLen2;
goto case GZIPHeaderState.ReadingXLen2;
case GZIPHeaderState.ReadingXLen2:
bits = input.GetBits(8);
if( bits < 0) {
return false;
}
gzip_header_xlen |= (bits << 8);
gzipHeaderSubstate = GZIPHeaderState.ReadingXLenData;
loopCounter = 0; // 0 bytes of XLEN data read so far
goto case GZIPHeaderState.ReadingXLenData;
case GZIPHeaderState.ReadingXLenData:
bits = 0;
while(loopCounter < gzip_header_xlen) {
bits = input.GetBits(8);
if( bits < 0) {
return false;
}
loopCounter++;
}
gzipHeaderSubstate = GZIPHeaderState.ReadingFileName;
loopCounter = 0;
goto case GZIPHeaderState.ReadingFileName;
case GZIPHeaderState.ReadingFileName:
if ((gzip_header_flag & FileNameFlag) == 0) {
gzipHeaderSubstate = GZIPHeaderState.ReadingComment;
goto case GZIPHeaderState.ReadingComment;
}
do {
bits = input.GetBits(8);
if( bits < 0) {
return false;
}
if( bits == 0) { // see '\0' in the file name string
break;
}
} while (true);
gzipHeaderSubstate = GZIPHeaderState.ReadingComment;
goto case GZIPHeaderState.ReadingComment;
case GZIPHeaderState.ReadingComment:
if ((gzip_header_flag & CommentFlag) == 0) {
gzipHeaderSubstate = GZIPHeaderState.ReadingCRC16Part1;
goto case GZIPHeaderState.ReadingCRC16Part1;
}
do {
bits = input.GetBits(8);
if( bits < 0) {
return false;
}
if( bits == 0) { // see '\0' in the file name string
break;
}
} while (true);
gzipHeaderSubstate = GZIPHeaderState.ReadingCRC16Part1;
goto case GZIPHeaderState.ReadingCRC16Part1;
case GZIPHeaderState.ReadingCRC16Part1:
if ((gzip_header_flag & CRCFlag) == 0) {
gzipHeaderSubstate = GZIPHeaderState.Done;
goto case GZIPHeaderState.Done;
}
bits = input.GetBits(8); // ignore crc
if( bits < 0) {
return false;
}
gzipHeaderSubstate = GZIPHeaderState.ReadingCRC16Part2;
goto case GZIPHeaderState.ReadingCRC16Part2;
case GZIPHeaderState.ReadingCRC16Part2:
bits = input.GetBits(8); // ignore crc
if( bits < 0) {
return false;
}
gzipHeaderSubstate = GZIPHeaderState.Done;
goto case GZIPHeaderState.Done;
case GZIPHeaderState.Done:
return true;
default:
Debug.Assert(false, "We should not reach unknown state!");
throw new InvalidDataException(SR.GetString(SR.UnknownState));
}
}
}
public bool ReadGzipFooter() {
input.SkipToByteBoundary();
if( gzipFooterSubstate == GZIPHeaderState.ReadingCRC) {
while (loopCounter < 4 ) {
int bits = input.GetBits(8);
if( bits < 0) {
return false;
}
gzipCrc32 |= ((uint)bits << (8*loopCounter));
loopCounter++;
}
gzipFooterSubstate = GZIPHeaderState.ReadingFileSize;
loopCounter = 0;
}
if (gzipFooterSubstate == GZIPHeaderState.ReadingFileSize) {
if (loopCounter == 0)
gzipOutputStreamSize = 0;
while (loopCounter < 4) {
int bits = input.GetBits(8);
if( bits < 0) {
return false;
}
gzipOutputStreamSize |= ((uint)bits << (8*loopCounter));
loopCounter++;
}
}
return true;
}
}
}
// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.
namespace System.IO.Compression
{
using System;
using System.Diagnostics;
internal enum GZIPHeaderState{
// GZIP header
ReadingID1,
ReadingID2,
ReadingCM,
ReadingFLG,
ReadingMMTime, // iterates 4 times
ReadingXFL,
ReadingOS,
ReadingXLen1,
ReadingXLen2,
ReadingXLenData,
ReadingFileName,
ReadingComment,
ReadingCRC16Part1,
ReadingCRC16Part2,
Done, // done reading GZIP header
// GZIP footer
ReadingCRC, // iterates 4 times
ReadingFileSize // iterates 4 times
}
// This class decodes GZip header and footer information.
// See RFC 1952 for details about the format.
internal class GZipDecoder {
const int FileText = 1;
const int CRCFlag = 2;
const int ExtraFieldsFlag = 4;
const int FileNameFlag = 8;
const int CommentFlag= 16;
private InputBuffer input;
GZIPHeaderState gzipHeaderSubstate;
GZIPHeaderState gzipFooterSubstate;
int gzip_header_flag;
int gzip_header_xlen;
uint gzipCrc32;
uint gzipOutputStreamSize;
int loopCounter;
public GZipDecoder(InputBuffer input) {
this.input = input;
Reset();
}
public void Reset() {
gzipHeaderSubstate = GZIPHeaderState.ReadingID1;
gzipFooterSubstate = GZIPHeaderState.ReadingCRC;
gzipCrc32 = 0;
gzipOutputStreamSize = 0;
}
public uint Crc32 {
get {
return gzipCrc32;
}
}
public uint StreamSize {
get {
return gzipOutputStreamSize;
}
}
public bool ReadGzipHeader() {
while(true) {
int bits;
switch (gzipHeaderSubstate) {
case GZIPHeaderState.ReadingID1:
bits = input.GetBits(8);
if( bits < 0) {
return false;
}
if( bits != 0x1F) {
throw new InvalidDataException(SR.GetString(SR.CorruptedGZipHeader));
}
gzipHeaderSubstate = GZIPHeaderState.ReadingID2;
goto case GZIPHeaderState.ReadingID2;
case GZIPHeaderState.ReadingID2:
bits = input.GetBits(8);
if( bits < 0) {
return false;
}
if( bits != 0x8b) {
throw new InvalidDataException(SR.GetString(SR.CorruptedGZipHeader));
}
gzipHeaderSubstate = GZIPHeaderState.ReadingCM;
goto case GZIPHeaderState.ReadingCM;
case GZIPHeaderState.ReadingCM:
bits = input.GetBits(8);
if( bits < 0) {
return false;
}
if( bits != 0x8) { // compression mode must be 8 (deflate)
throw new InvalidDataException(SR.GetString(SR.UnknownCompressionMode));
}
gzipHeaderSubstate = GZIPHeaderState.ReadingFLG;;
goto case GZIPHeaderState.ReadingFLG;
case GZIPHeaderState.ReadingFLG:
bits = input.GetBits(8);
if( bits < 0) {
return false;
}
gzip_header_flag = bits;
gzipHeaderSubstate = GZIPHeaderState.ReadingMMTime;
loopCounter = 0; // 4 MMTIME bytes
goto case GZIPHeaderState.ReadingMMTime;
case GZIPHeaderState.ReadingMMTime:
bits = 0;
while(loopCounter < 4) {
bits = input.GetBits(8);
if( bits < 0) {
return false;
}
loopCounter++;
}
gzipHeaderSubstate = GZIPHeaderState.ReadingXFL;
loopCounter = 0;
goto case GZIPHeaderState.ReadingXFL;
case GZIPHeaderState.ReadingXFL: // ignore XFL
bits = input.GetBits(8);
if( bits < 0) {
return false;
}
gzipHeaderSubstate = GZIPHeaderState.ReadingOS;
goto case GZIPHeaderState.ReadingOS;
case GZIPHeaderState.ReadingOS: // ignore OS
bits = input.GetBits(8);
if( bits < 0) {
return false;
}
gzipHeaderSubstate = GZIPHeaderState.ReadingXLen1;
goto case GZIPHeaderState.ReadingXLen1;
case GZIPHeaderState.ReadingXLen1:
if ((gzip_header_flag & ExtraFieldsFlag) == 0) {
goto case GZIPHeaderState.ReadingFileName;
}
bits = input.GetBits(8);
if( bits < 0) {
return false;
}
gzip_header_xlen = bits;
gzipHeaderSubstate = GZIPHeaderState.ReadingXLen2;
goto case GZIPHeaderState.ReadingXLen2;
case GZIPHeaderState.ReadingXLen2:
bits = input.GetBits(8);
if( bits < 0) {
return false;
}
gzip_header_xlen |= (bits << 8);
gzipHeaderSubstate = GZIPHeaderState.ReadingXLenData;
loopCounter = 0; // 0 bytes of XLEN data read so far
goto case GZIPHeaderState.ReadingXLenData;
case GZIPHeaderState.ReadingXLenData:
bits = 0;
while(loopCounter < gzip_header_xlen) {
bits = input.GetBits(8);
if( bits < 0) {
return false;
}
loopCounter++;
}
gzipHeaderSubstate = GZIPHeaderState.ReadingFileName;
loopCounter = 0;
goto case GZIPHeaderState.ReadingFileName;
case GZIPHeaderState.ReadingFileName:
if ((gzip_header_flag & FileNameFlag) == 0) {
gzipHeaderSubstate = GZIPHeaderState.ReadingComment;
goto case GZIPHeaderState.ReadingComment;
}
do {
bits = input.GetBits(8);
if( bits < 0) {
return false;
}
if( bits == 0) { // see '\0' in the file name string
break;
}
} while (true);
gzipHeaderSubstate = GZIPHeaderState.ReadingComment;
goto case GZIPHeaderState.ReadingComment;
case GZIPHeaderState.ReadingComment:
if ((gzip_header_flag & CommentFlag) == 0) {
gzipHeaderSubstate = GZIPHeaderState.ReadingCRC16Part1;
goto case GZIPHeaderState.ReadingCRC16Part1;
}
do {
bits = input.GetBits(8);
if( bits < 0) {
return false;
}
if( bits == 0) { // see '\0' in the file name string
break;
}
} while (true);
gzipHeaderSubstate = GZIPHeaderState.ReadingCRC16Part1;
goto case GZIPHeaderState.ReadingCRC16Part1;
case GZIPHeaderState.ReadingCRC16Part1:
if ((gzip_header_flag & CRCFlag) == 0) {
gzipHeaderSubstate = GZIPHeaderState.Done;
goto case GZIPHeaderState.Done;
}
bits = input.GetBits(8); // ignore crc
if( bits < 0) {
return false;
}
gzipHeaderSubstate = GZIPHeaderState.ReadingCRC16Part2;
goto case GZIPHeaderState.ReadingCRC16Part2;
case GZIPHeaderState.ReadingCRC16Part2:
bits = input.GetBits(8); // ignore crc
if( bits < 0) {
return false;
}
gzipHeaderSubstate = GZIPHeaderState.Done;
goto case GZIPHeaderState.Done;
case GZIPHeaderState.Done:
return true;
default:
Debug.Assert(false, "We should not reach unknown state!");
throw new InvalidDataException(SR.GetString(SR.UnknownState));
}
}
}
public bool ReadGzipFooter() {
input.SkipToByteBoundary();
if( gzipFooterSubstate == GZIPHeaderState.ReadingCRC) {
while (loopCounter < 4 ) {
int bits = input.GetBits(8);
if( bits < 0) {
return false;
}
gzipCrc32 |= ((uint)bits << (8*loopCounter));
loopCounter++;
}
gzipFooterSubstate = GZIPHeaderState.ReadingFileSize;
loopCounter = 0;
}
if (gzipFooterSubstate == GZIPHeaderState.ReadingFileSize) {
if (loopCounter == 0)
gzipOutputStreamSize = 0;
while (loopCounter < 4) {
int bits = input.GetBits(8);
if( bits < 0) {
return false;
}
gzipOutputStreamSize |= ((uint)bits << (8*loopCounter));
loopCounter++;
}
}
return true;
}
}
}
// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.
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