public bool TryParse(IRandomAccessRead source, long offset, bool isLenientParsing, CosObjectPool pool, out CrossReferenceTablePartBuilder builder)
{
builder = null;
var tableStartOffset = source.GetPosition();
if (source.Peek() != 'x')
{
return(false);
}
var xref = ReadHelper.ReadString(source);
if (!xref.Trim().Equals("xref"))
{
return(false);
}
// check for trailer after xref
var str = ReadHelper.ReadString(source);
byte[] b = OtherEncodings.StringAsLatin1Bytes(str);
source.Rewind(b.Length);
if (str.StartsWith("trailer"))
{
log.Warn("skipping empty xref table");
return(false);
}
builder = new CrossReferenceTablePartBuilder
{
Offset = offset,
XRefType = CrossReferenceType.Table
};
// Tables can have multiple sections. Each starts with a starting object id and a count.
while (true)
{
if (!TableSubsectionDefinition.TryRead(log, source, out var subsectionDefinition))
{
log.Warn($"Unexpected subsection definition in the cross-reference table at offset {offset}");
if (isLenientParsing)
{
break;
}
return(false);
}
var currentObjectId = subsectionDefinition.FirstNumber;
ReadHelper.SkipSpaces(source);
for (var i = 0; i < subsectionDefinition.Count; i++)
{
if (source.IsEof() || ReadHelper.IsEndOfName((char)source.Peek()))
{
break;
}
if (source.Peek() == 't')
{
break;
}
//Ignore table contents
var currentLine = ReadHelper.ReadLine(source);
var splitString = currentLine.Split(new[] { ' ' }, StringSplitOptions.RemoveEmptyEntries);
if (splitString.Length < 3)
{
log.Warn("invalid xref line: " + currentLine);
break;
}
// This supports the corrupt table as reported in PDFBOX-474 (XXXX XXX XX n)
if (splitString[splitString.Length - 1].Equals(InUseEntry))
{
try
{
var objectOffset = long.Parse(splitString[0]);
if (objectOffset >= tableStartOffset && objectOffset <= source.GetPosition())
{
// PDFBOX-3923: offset points inside this table - that can't be good
throw new InvalidOperationException(
$"Object offset {objectOffset} is within its own cross-reference table for object {currentObjectId}");
}
var generation = int.Parse(splitString[1]);
builder.Add(currentObjectId, generation, objectOffset);
}
catch (FormatException e)
{
throw new InvalidOperationException("Bad", e);
}
}
else if (!splitString[2].Equals(FreeEntry))
{
throw new InvalidOperationException(
$"Corrupt cross-reference table entry for object {currentObjectId}. The indicator was not 'n' or 'f' but {splitString[2]}.");
}
currentObjectId++;
ReadHelper.SkipSpaces(source);
}
ReadHelper.SkipSpaces(source);
if (!ReadHelper.IsDigit(source))
{
break;
}
}
if (!TryParseTrailer(source, isLenientParsing, pool, out var trailer))
{
throw new InvalidOperationException($"Something went wrong trying to read the XREF table at {offset}.");
}
builder.Dictionary = trailer;
builder.Previous = trailer.GetLongOrDefault(CosName.PREV);
return(true);
}
public bool TryTokenize(byte currentByte, IInputBytes inputBytes, out IToken token)
{
token = null;
if (currentByte != '/')
{
return(false);
}
var bytes = new List <byte>();
bool escapeActive = false;
int postEscapeRead = 0;
var escapedChars = new char[2];
while (inputBytes.MoveNext())
{
var b = inputBytes.CurrentByte;
if (b == '#')
{
escapeActive = true;
}
else if (escapeActive)
{
if (ReadHelper.IsHex((char)b))
{
escapedChars[postEscapeRead] = (char)b;
postEscapeRead++;
if (postEscapeRead == 2)
{
var hex = new string(escapedChars);
var characterToWrite = (byte)Convert.ToInt32(hex, 16);
bytes.Add(characterToWrite);
escapeActive = false;
postEscapeRead = 0;
}
}
else
{
bytes.Add((byte)'#');
if (postEscapeRead == 1)
{
bytes.Add((byte)escapedChars[0]);
}
if (ReadHelper.IsEndOfName(b))
{
break;
}
if (b == '#')
{
// Make it clear what's going on, we read something like #m#AE
// ReSharper disable once RedundantAssignment
escapeActive = true;
postEscapeRead = 0;
continue;
}
bytes.Add(b);
escapeActive = false;
postEscapeRead = 0;
}
}
else if (ReadHelper.IsEndOfName(b))
{
break;
}
else
{
bytes.Add(b);
}
}
byte[] byteArray = bytes.ToArray();
var str = ReadHelper.IsValidUtf8(byteArray)
? Encoding.UTF8.GetString(byteArray)
: Encoding.GetEncoding("windows-1252").GetString(byteArray);
token = NameToken.Create(str);
return(true);
}
