private long GetLastEndOfFileMarker()
{
var originalOffset = reader.GetPosition();
var searchTerm = OtherEncodings.StringAsLatin1Bytes("%%EOF");
var minimumEndOffset = reader.Length() - searchTerm.Length;
reader.Seek(minimumEndOffset);
while (reader.GetPosition() > 0)
{
if (ReadHelper.IsString(reader, searchTerm))
{
var position = reader.GetPosition();
reader.Seek(originalOffset);
return(position);
}
reader.Seek(minimumEndOffset--);
}
reader.Seek(originalOffset);
return(long.MaxValue);
}
private bool validateStreamLength(IRandomAccessRead source, long streamLength, long fileLength)
{
bool streamLengthIsValid = true;
long originOffset = source.GetPosition();
long expectedEndOfStream = originOffset + streamLength;
if (expectedEndOfStream > fileLength)
{
streamLengthIsValid = false;
//LOG.warn("The end of the stream is out of range, using workaround to read the stream, "
// + "stream start position: " + originOffset + ", length: " + streamLength
// + ", expected end position: " + expectedEndOfStream);
}
else
{
source.Seek(expectedEndOfStream);
ReadHelper.SkipSpaces(source);
if (!ReadHelper.IsString(source, "endstream"))
{
streamLengthIsValid = false;
//LOG.warn("The end of the stream doesn't point to the correct offset, using workaround to read the stream, "
// + "stream start position: " + originOffset + ", length: " + streamLength
// + ", expected end position: " + expectedEndOfStream);
}
source.Seek(originOffset);
}
return(streamLengthIsValid);
}
public IReadOnlyDictionary <CosObjectKey, long> GetObjectLocations()
{
if (objectLocations != null)
{
return(objectLocations);
}
var lastEndOfFile = GetLastEndOfFileMarker();
var results = new Dictionary <CosObjectKey, long>();
var originPosition = reader.GetPosition();
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 endobjFound = false;
do
{
reader.Seek(currentOffset);
if (ReadHelper.IsString(reader, objString))
{
long tempOffset = currentOffset - 1;
reader.Seek(tempOffset);
int generationId = reader.Peek();
// is the next char a digit?
if (ReadHelper.IsDigit(generationId))
{
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 CosObjectKey(lastObjectId, lastGenerationId)] = lastObjOffset;
}
lastObjectId = objectId;
lastGenerationId = generationId;
lastObjOffset = tempOffset + 1;
currentOffset += objString.Length - 1;
endobjFound = false;
}
}
}
}
else if (ReadHelper.IsString(reader, "endobj"))
{
endobjFound = true;
currentOffset += endobjString.Length - 1;
}
currentOffset++;
} while (currentOffset < lastEndOfFile && !reader.IsEof());
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
// the last object id has to be added here so that it can't get lost as there isn't any subsequent object id
results[new CosObjectKey(lastObjectId, lastGenerationId)] = lastObjOffset;
}
// reestablish origin position
reader.Seek(originPosition);
objectLocations = results;
return(objectLocations);
}
