tsai
/
ImageSharp
mirror of https://github.com/SixLabors/ImageSharp
1
0
Fork 0
Code Issues Projects Releases Wiki Activity
Browse Source

sanitize MCU processing code

af/merge-core
Anton Firszov 8 years ago
parent
1949122df4
commit
0fc9002dcc
3 changed files with 133 additions and 89 deletions
Whitespace
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
Split View
Diff Options
Show Stats Download Patch File Download Diff File
  1. 8
      src/ImageSharp/Formats/Jpeg/GolangPort/Components/Decoder/InputProcessor.cs
  2. 205
      src/ImageSharp/Formats/Jpeg/GolangPort/Components/Decoder/OrigJpegScanDecoder.cs
  3. 9
      src/ImageSharp/Formats/Jpeg/GolangPort/OrigJpegDecoderCore.cs

8
src/ImageSharp/Formats/Jpeg/GolangPort/Components/Decoder/InputProcessor.cs
View File

@ -380,5 +380,13 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
this.LastErrorCode = this.Bits.ReceiveExtendUnsafe(t, ref this, out x);
return this.LastErrorCode;
}
/// <summary>
/// Reset the Huffman decoder.
/// </summary>
public void ResetHuffmanDecoder()
{
this.Bits = default(Bits);
}
}
}

205
src/ImageSharp/Formats/Jpeg/GolangPort/Components/Decoder/OrigJpegScanDecoder.cs
View File

@ -94,6 +94,21 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
/// </summary>
private int eobRun;
/// <summary>
/// The block counter
/// </summary>
private int blockCounter;
/// <summary>
/// The MCU counter
/// </summary>
private int mcuCounter;
/// <summary>
/// The expected RST marker value
/// </summary>
private byte expectedRst;
/// <summary>
/// Initializes a default-constructed <see cref="OrigJpegScanDecoder"/> instance for reading data from <see cref="OrigJpegDecoderCore"/>-s stream.
/// </summary>
@ -139,124 +154,136 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
{
decoder.InputProcessor.ResetErrorState();
int blockCount = 0;
int mcu = 0;
byte expectedRst = OrigJpegConstants.Markers.RST0;
this.blockCounter = 0;
this.mcuCounter = 0;
this.expectedRst = OrigJpegConstants.Markers.RST0;
for (int my = 0; my < decoder.MCUCountY; my++)
{
for (int mx = 0; mx < decoder.MCUCountX; mx++)
{
for (int scanIndex = 0; scanIndex < this.componentScanCount; scanIndex++)
{
this.ComponentIndex = this.pointers.ComponentScan[scanIndex].ComponentIndex;
OrigComponent component = decoder.Components[this.ComponentIndex];
this.DecodeBlocksAtMcuIndex(decoder, mx, my);
this.hi = component.HorizontalSamplingFactor;
int vi = component.VerticalSamplingFactor;
for (int j = 0; j < this.hi * vi; j++)
{
if (this.componentScanCount != 1)
{
this.bx = (this.hi * mx) + (j % this.hi);
this.by = (vi * my) + (j / this.hi);
}
else
{
int q = decoder.MCUCountX * this.hi;
this.bx = blockCount % q;
this.by = blockCount / q;
blockCount++;
if (this.bx * 8 >= decoder.ImageWidth || this.by * 8 >= decoder.ImageHeight)
{
continue;
}
}
this.mcuCounter++;
// Find the block at (bx,by) in the component's buffer:
ref Block8x8 blockRefOnHeap = ref component.GetBlockReference(this.bx, this.by);
// Handling restart intervals
// Useful info: https://stackoverflow.com/a/8751802
if (decoder.IsAtRestartInterval(this.mcuCounter))
{
this.ProcessRSTMarker(decoder);
this.Reset(decoder);
}
}
}
}
// Copy block to stack
this.data.Block = blockRefOnHeap;
private void DecodeBlocksAtMcuIndex(OrigJpegDecoderCore decoder, int mx, int my)
{
for (int scanIndex = 0; scanIndex < this.componentScanCount; scanIndex++)
{
this.ComponentIndex = this.pointers.ComponentScan[scanIndex].ComponentIndex;
OrigComponent component = decoder.Components[this.ComponentIndex];
if (!decoder.InputProcessor.ReachedEOF)
{
this.DecodeBlock(decoder, scanIndex);
}
this.hi = component.HorizontalSamplingFactor;
int vi = component.VerticalSamplingFactor;
// Store the result block:
blockRefOnHeap = this.data.Block;
for (int j = 0; j < this.hi * vi; j++)
{
if (this.componentScanCount != 1)
{
this.bx = (this.hi * mx) + (j % this.hi);
this.by = (vi * my) + (j / this.hi);
}
else
{
int q = decoder.MCUCountX * this.hi;
this.bx = this.blockCounter % q;
this.by = this.blockCounter / q;
this.blockCounter++;
if (this.bx * 8 >= decoder.ImageWidth || this.by * 8 >= decoder.ImageHeight)
{
continue;
}
}
// Find the block at (bx,by) in the component's buffer:
ref Block8x8 blockRefOnHeap = ref component.GetBlockReference(this.bx, this.by);
// for j
// Copy block to stack
this.data.Block = blockRefOnHeap;
if (!decoder.InputProcessor.ReachedEOF)
{
this.DecodeBlock(decoder, scanIndex);
}
// for i
mcu++;
// Store the result block:
blockRefOnHeap = this.data.Block;
}
}
}
if (decoder.RestartInterval > 0 && mcu % decoder.RestartInterval == 0 && mcu < decoder.TotalMCUCount)
private void ProcessRSTMarker(OrigJpegDecoderCore decoder)
{
// Attempt to look for RST[0-7] markers to resynchronize from corrupt input.
if (!decoder.InputProcessor.ReachedEOF)
{
decoder.InputProcessor.ReadFullUnsafe(decoder.Temp, 0, 2);
if (decoder.InputProcessor.CheckEOFEnsureNoError())
{
if (decoder.Temp[0] != 0xFF || decoder.Temp[1] != this.expectedRst)
{
// Attempt to look for RST[0-7] markers to resynchronize from corrupt input.
if (!decoder.InputProcessor.ReachedEOF)
bool invalidRst = true;
// Most jpeg's containing well-formed input will have a RST[0-7] marker following immediately
// but some, see Issue #481, contain padding bytes "0xFF" before the RST[0-7] marker.
// If we identify that case we attempt to read until we have bypassed the padded bytes.
// We then check again for our RST marker and throw if invalid.
// No other methods are attempted to resynchronize from corrupt input.
if (decoder.Temp[0] == 0xFF && decoder.Temp[1] == 0xFF)
{
decoder.InputProcessor.ReadFullUnsafe(decoder.Temp, 0, 2);
if (decoder.InputProcessor.CheckEOFEnsureNoError())
while (decoder.Temp[0] == 0xFF && decoder.InputProcessor.CheckEOFEnsureNoError())
{
if (decoder.Temp[0] != 0xFF || decoder.Temp[1] != expectedRst)
{
bool invalidRst = true;
// Most jpeg's containing well-formed input will have a RST[0-7] marker following immediately
// but some, see Issue #481, contain padding bytes "0xFF" before the RST[0-7] marker.
// If we identify that case we attempt to read until we have bypassed the padded bytes.
// We then check again for our RST marker and throw if invalid.
// No other methods are attempted to resynchronize from corrupt input.
if (decoder.Temp[0] == 0xFF && decoder.Temp[1] == 0xFF)
{
while (decoder.Temp[0] == 0xFF && decoder.InputProcessor.CheckEOFEnsureNoError())
{
decoder.InputProcessor.ReadFullUnsafe(decoder.Temp, 0, 1);
if (!decoder.InputProcessor.CheckEOFEnsureNoError())
{
break;
}
}
// Have we found a valid restart marker?
invalidRst = decoder.Temp[0] != expectedRst;
}
if (invalidRst)
{
throw new ImageFormatException("Bad RST marker");
}
}
expectedRst++;
if (expectedRst == OrigJpegConstants.Markers.RST7 + 1)
decoder.InputProcessor.ReadFullUnsafe(decoder.Temp, 0, 1);
if (!decoder.InputProcessor.CheckEOFEnsureNoError())
{
expectedRst = OrigJpegConstants.Markers.RST0;
break;
}
}
}
// Reset the Huffman decoder.
decoder.InputProcessor.Bits = default(Bits);
// Have we found a valid restart marker?
invalidRst = decoder.Temp[0] != this.expectedRst;
}
// Reset the DC components, as per section F.2.1.3.1.
this.ResetDc();
if (invalidRst)
{
throw new ImageFormatException("Bad RST marker");
}
}
// Reset the progressive decoder state, as per section G.1.2.2.
this.eobRun = 0;
this.expectedRst++;
if (this.expectedRst == OrigJpegConstants.Markers.RST7 + 1)
{
this.expectedRst = OrigJpegConstants.Markers.RST0;
}
}
// for mx
}
}
private void ResetDc()
private void Reset(OrigJpegDecoderCore decoder)
{
decoder.InputProcessor.ResetHuffmanDecoder();
this.ResetDcValues();
// Reset the progressive decoder state, as per section G.1.2.2.
this.eobRun = 0;
}
/// <summary>
/// Reset the DC components, as per section F.2.1.3.1.
/// </summary>
private void ResetDcValues()
{
Unsafe.InitBlock(this.pointers.Dc, default(byte), sizeof(int) * OrigJpegDecoderCore.MaxComponents);
}

9
src/ImageSharp/Formats/Jpeg/GolangPort/OrigJpegDecoderCore.cs
View File

@ -411,6 +411,15 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort
this.InitDerivedMetaDataProperties();
}
/// <summary>
/// Returns true if 'mcuCounter' is at restart interval
/// </summary>
public bool IsAtRestartInterval(int mcuCounter)
{
return this.RestartInterval > 0 && mcuCounter % this.RestartInterval == 0
&& mcuCounter < this.TotalMCUCount;
}
/// <summary>
/// Assigns derived metadata properties to <see cref="MetaData"/>, eg. horizontal and vertical resolution if it has a JFIF header.
/// </summary>

Write Preview
Loading…
Cancel
Save