private void RunGremlinTest(string filePath)
{
var exifReader = new ExifReader();
var sw = Stopwatch.StartNew();
var app1 = File.ReadAllBytes(filePath);
var segments = new[] { app1 };
for (var i = 0; i < app1.Length; i++)
{
if (i % 1000 == 0)
_output.WriteLine($"{i}/{app1.Length} bytes");
var original = app1[i];
for (var b = byte.MinValue; b < byte.MaxValue; b++)
{
app1[i] = b;
// ReSharper disable once ReturnValueOfPureMethodIsNotUsed
exifReader.ReadJpegSegments(segments, JpegSegmentType.App1).ToList();
}
app1[i] = original;
}
_output.WriteLine($"Finished in {sw.Elapsed.TotalSeconds:#,##0.#} seconds");
}
Extract([NotNull] SequentialReader reader, int length)
{
var directory = new PhotoshopDirectory();
var directories = new List<Directory> { directory };
// Data contains a sequence of Image Resource Blocks (IRBs):
//
// 4 bytes - Signature; mostly "8BIM" but "PHUT", "AgHg" and "DCSR" are also found
// 2 bytes - Resource identifier
// String - Pascal string, padded to make length even
// 4 bytes - Size of resource data which follows
// Data - The resource data, padded to make size even
//
// http://www.adobe.com/devnet-apps/photoshop/fileformatashtml/#50577409_pgfId-1037504
var pos = 0;
while (pos < length)
{
try
{
// 4 bytes for the signature ("8BIM", "PHUT", etc.)
var signature = reader.GetString(4);
pos += 4;
// 2 bytes for the resource identifier (tag type).
var tagType = reader.GetUInt16();
pos += 2;
// A variable number of bytes holding a pascal string (two leading bytes for length).
var descriptionLength = reader.GetByte();
pos += 1;
// Some basic bounds checking
if (descriptionLength + pos > length)
throw new ImageProcessingException("Invalid string length");
// We don't use the string value here
reader.Skip(descriptionLength);
pos += descriptionLength;
// The number of bytes is padded with a trailing zero, if needed, to make the size even.
if (pos % 2 != 0)
{
reader.Skip(1);
pos++;
}
// 4 bytes for the size of the resource data that follows.
var byteCount = reader.GetInt32();
pos += 4;
// The resource data.
var tagBytes = reader.GetBytes(byteCount);
pos += byteCount;
// The number of bytes is padded with a trailing zero, if needed, to make the size even.
if (pos % 2 != 0)
{
reader.Skip(1);
pos++;
}
// Skip any unsupported IRBs
if (signature != "8BIM")
continue;
switch (tagType)
{
case PhotoshopDirectory.TagIptc:
var iptcDirectory = new IptcReader().Extract(new SequentialByteArrayReader(tagBytes), tagBytes.Length);
iptcDirectory.Parent = directory;
directories.Add(iptcDirectory);
break;
case PhotoshopDirectory.TagIccProfileBytes:
var iccDirectory = new IccReader().Extract(new ByteArrayReader(tagBytes));
iccDirectory.Parent = directory;
directories.Add(iccDirectory);
break;
case PhotoshopDirectory.TagExifData1:
case PhotoshopDirectory.TagExifData3:
var exifDirectories = new ExifReader().Extract(new ByteArrayReader(tagBytes));
foreach (var exifDirectory in exifDirectories.Where(d => d.Parent == null))
exifDirectory.Parent = directory;
directories.AddRange(exifDirectories);
break;
case PhotoshopDirectory.TagXmpData:
var xmpDirectory = new XmpReader().Extract(tagBytes);
xmpDirectory.Parent = directory;
directories.Add(xmpDirectory);
break;
default:
directory.Set(tagType, tagBytes);
break;
}
if (tagType >= 0x0fa0 && tagType <= 0x1387)
PhotoshopDirectory.TagNameMap[tagType] = $"Plug-in {tagType - 0x0fa0 + 1} Data";
}
catch (Exception ex)
{
directory.AddError(ex.Message);
break;
}
}
return directories;
}