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support documents without endobj for stream

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some documents declare stream objects without an endobj marker at the end of the stream. if a new obj token is encountered after reading a stream we reset the scanner to the object number token and return the stream.
This commit is contained in:
Eliot Jones
2020-01-07 15:27:01 +00:00
parent 10dc5a8eed
commit e588b2bc50
1 changed files with 31 additions and 16 deletions
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47
src/UglyToad.PdfPig/Tokenization/Scanner/PdfTokenScanner.cs
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@@ -36,9 +36,9 @@
/// </summary>
private readonly List<IToken> readTokens = new List<IToken>();
// Store the previous 2 tokens and their positions so we can backtrack to find object numbers and stream dictionaries.
private readonly long[] previousTokenPositions = new long[2];
private readonly IToken[] previousTokens = new IToken[2];
// Store the previous 3 tokens and their positions so we can backtrack to find object numbers and stream dictionaries.
private readonly long[] previousTokenPositions = new long[3];
private readonly IToken[] previousTokens = new IToken[3];
public IToken CurrentToken { get; private set; }
@@ -82,8 +82,11 @@
previousTokens[0] = previousTokens[1];
previousTokenPositions[0] = previousTokenPositions[1];
previousTokens[1] = coreTokenScanner.CurrentToken;
previousTokenPositions[1] = coreTokenScanner.CurrentTokenStart;
previousTokens[1] = previousTokens[2];
previousTokenPositions[1] = previousTokenPositions[2];
previousTokens[2] = coreTokenScanner.CurrentToken;
previousTokenPositions[2] = coreTokenScanner.CurrentTokenStart;
}
// We only read partial tokens.
@@ -92,21 +95,21 @@
return false;
}
var startPosition = previousTokenPositions[0];
var objectNumber = previousTokens[0] as NumericToken;
var generation = previousTokens[1] as NumericToken;
var startPosition = previousTokenPositions[1];
var objectNumber = previousTokens[1] as NumericToken;
var generation = previousTokens[2] as NumericToken;
if (objectNumber == null || generation == null)
{
// Handle case where the scanner correctly reads most of an object token but includes too much of the first token
// specifically %%EOF1 0 obj where scanning starts from 'F'.
if (generation != null && previousTokens[0] is OperatorToken op)
if (generation != null && previousTokens[1] is OperatorToken op)
{
var match = EndsWithNumberRegex.Match(op.Data);
if (match.Success && int.TryParse(match.Value, NumberStyles.Any, CultureInfo.InvariantCulture, out var number))
{
startPosition = previousTokenPositions[0] + match.Index;
startPosition = previousTokenPositions[1] + match.Index;
objectNumber = new NumericToken(number);
}
else
@@ -120,6 +123,7 @@
}
}
var readStream = false;
// Read all tokens between obj and endobj.
while (coreTokenScanner.MoveNext() && !Equals(coreTokenScanner.CurrentToken, OperatorToken.EndObject))
{
@@ -130,6 +134,13 @@
if (ReferenceEquals(coreTokenScanner.CurrentToken, OperatorToken.StartObject))
{
if (readStream && readTokens[0] is StreamToken streamRead)
{
readTokens.Clear();
readTokens.Add(streamRead);
coreTokenScanner.Seek(previousTokenPositions[0]);
break;
}
// This should never happen.
Debug.Assert(false, "Encountered a start object 'obj' operator before the end of the previous object.");
return false;
@@ -153,6 +164,7 @@
{
readTokens.Clear();
readTokens.Add(stream);
readStream = true;
}
}
finally
@@ -168,11 +180,14 @@
previousTokens[0] = previousTokens[1];
previousTokenPositions[0] = previousTokenPositions[1];
previousTokens[1] = coreTokenScanner.CurrentToken;
previousTokenPositions[1] = coreTokenScanner.CurrentPosition;
previousTokens[1] = previousTokens[2];
previousTokenPositions[1] = previousTokenPositions[2];
previousTokens[2] = coreTokenScanner.CurrentToken;
previousTokenPositions[2] = coreTokenScanner.CurrentTokenStart;
}
if (!ReferenceEquals(coreTokenScanner.CurrentToken, OperatorToken.EndObject))
if (!readStream && !ReferenceEquals(coreTokenScanner.CurrentToken, OperatorToken.EndObject))
{
readTokens.Clear();
return false;
@@ -495,18 +510,18 @@
private DictionaryToken GetStreamDictionary()
{
DictionaryToken streamDictionaryToken;
if (previousTokens[1] is DictionaryToken firstDictionary)
if (previousTokens[2] is DictionaryToken firstDictionary)
{
streamDictionaryToken = firstDictionary;
}
else if (previousTokens[0] is DictionaryToken secondDictionary)
else if (previousTokens[1] is DictionaryToken secondDictionary)
{
streamDictionaryToken = secondDictionary;
}
else
{
throw new PdfDocumentFormatException("No dictionary token was found prior to the 'stream' operator. Previous tokens were:" +
$" {previousTokens[1]} and {previousTokens[0]}.");
$" {previousTokens[2]} and {previousTokens[1]}.");
}
return streamDictionaryToken;