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unify raw byte access method

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Eliot Jones
2018-01-21 18:08:00 +00:00
parent 3172596b7c
commit 07161cef28
27 changed files with 521 additions and 910 deletions
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145
src/UglyToad.PdfPig/Parser/Parts/BruteForceSearcher.cs
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@@ -2,25 +2,26 @@
{
using System;
using System.Collections.Generic;
using System.Text;
using ContentStream;
using IO;
using Util;
using Util.JetBrains.Annotations;
/// <summary>
/// Store the results of a brute force search for all Cos Objects in the document so we only do it once.
/// Store the results of a brute force search for all objects in the document so we only do it once.
/// </summary>
internal class BruteForceSearcher
{
private const int MinimumSearchOffset = 6;
private readonly IRandomAccessRead reader;
private readonly IInputBytes bytes;
private Dictionary<IndirectReference, long> objectLocations;
public BruteForceSearcher([NotNull] IRandomAccessRead reader)
public BruteForceSearcher([NotNull] IInputBytes bytes)
{
this.reader = reader ?? throw new ArgumentNullException(nameof(reader));
this.bytes = bytes ?? throw new ArgumentNullException(nameof(bytes));
}
[NotNull]
@@ -35,70 +36,86 @@
var results = new Dictionary<IndirectReference, long>();
var originPosition = reader.GetPosition();
var originPosition = bytes.CurrentOffset;
long currentOffset = MinimumSearchOffset;
long lastObjectId = long.MinValue;
int lastGenerationId = int.MinValue;
long lastObjOffset = long.MinValue;
byte[] objString = OtherEncodings.StringAsLatin1Bytes(" obj");
byte[] endobjString = OtherEncodings.StringAsLatin1Bytes("endobj");
bool inObject = false;
bool endobjFound = false;
do
{
reader.Seek(currentOffset);
if (ReadHelper.IsString(reader, objString))
{
long tempOffset = currentOffset - 1;
reader.Seek(tempOffset);
int generationId = reader.Peek();
bytes.Seek(currentOffset);
// is the next char a digit?
if (ReadHelper.IsDigit(generationId))
if (inObject)
{
if (ReadHelper.IsString(bytes, "endobj"))
{
generationId -= 48;
tempOffset--;
reader.Seek(tempOffset);
if (ReadHelper.IsSpace(reader))
{
while (tempOffset > MinimumSearchOffset && ReadHelper.IsSpace(reader))
{
reader.Seek(--tempOffset);
}
bool objectIdFound = false;
while (tempOffset > MinimumSearchOffset && ReadHelper.IsDigit(reader))
{
reader.Seek(--tempOffset);
objectIdFound = true;
}
if (objectIdFound)
{
reader.Read();
long objectId = ObjectHelper.ReadObjectNumber(reader);
if (lastObjOffset > 0)
{
// add the former object ID only if there was a subsequent object ID
results[new IndirectReference(lastObjectId, lastGenerationId)] = lastObjOffset;
}
lastObjectId = objectId;
lastGenerationId = generationId;
lastObjOffset = tempOffset + 1;
currentOffset += objString.Length - 1;
endobjFound = false;
}
}
inObject = false;
endobjFound = true;
currentOffset += "endobj".Length;
}
else
{
currentOffset++;
}
continue;
}
else if (ReadHelper.IsString(reader, "endobj"))
if (!ReadHelper.IsString(bytes, " obj"))
{
endobjFound = true;
currentOffset += endobjString.Length - 1;
currentOffset++;
continue;
}
// Current byte is ' '[obj]
var offset = currentOffset - 1;
bytes.Seek(offset);
var generationBytes = new StringBuilder();
while (ReadHelper.IsDigit(bytes.CurrentByte) && offset >= MinimumSearchOffset)
{
generationBytes.Insert(0, (char)bytes.CurrentByte);
offset--;
bytes.Seek(offset);
}
// We should now be at the space between object and generation number.
if (!ReadHelper.IsSpace(bytes.CurrentByte))
{
continue;
}
bytes.Seek(--offset);
var objectNumberBytes = new StringBuilder();
while (ReadHelper.IsDigit(bytes.CurrentByte) && offset >= MinimumSearchOffset)
{
objectNumberBytes.Insert(0, (char)bytes.CurrentByte);
offset--;
bytes.Seek(offset);
}
if (!ReadHelper.IsWhitespace(bytes.CurrentByte))
{
continue;
}
var obj = long.Parse(objectNumberBytes.ToString());
var generation = int.Parse(generationBytes.ToString());
results[new IndirectReference(obj, generation)] = bytes.CurrentOffset + 1;
inObject = true;
endobjFound = false;
currentOffset++;
} while (currentOffset < lastEndOfFile && !reader.IsEof());
} while (currentOffset < lastEndOfFile && !bytes.IsAtEnd());
if ((lastEndOfFile < long.MaxValue || endobjFound) && lastObjOffset > 0)
{
// if the pdf wasn't cut off in the middle or if the last object ends with a "endobj" marker
@@ -107,7 +124,7 @@
}
// reestablish origin position
reader.Seek(originPosition);
bytes.Seek(originPosition);
objectLocations = results;
@@ -116,27 +133,29 @@
private long GetLastEndOfFileMarker()
{
var originalOffset = reader.GetPosition();
var originalOffset = bytes.CurrentOffset;
var searchTerm = OtherEncodings.StringAsLatin1Bytes("%%EOF");
const string searchTerm = "%%EOF";
var minimumEndOffset = reader.Length() - searchTerm.Length;
var minimumEndOffset = bytes.Length - searchTerm.Length;
reader.Seek(minimumEndOffset);
bytes.Seek(minimumEndOffset);
while (reader.GetPosition() > 0)
while (bytes.CurrentOffset > 0)
{
if (ReadHelper.IsString(reader, searchTerm))
if (ReadHelper.IsString(bytes, searchTerm))
{
var position = reader.GetPosition();
reader.Seek(originalOffset);
var position = bytes.CurrentOffset;
bytes.Seek(originalOffset);
return position;
}
reader.Seek(minimumEndOffset--);
bytes.Seek(minimumEndOffset--);
}
reader.Seek(originalOffset);
bytes.Seek(originalOffset);
return long.MaxValue;
}
}