Hi Dominik,
this patch makes AdjustBytes search for the ByteRange filler from the
beacon position backwards.
It works for us when we add the ContentInfo key.
This was the only solution we tried.
Regards,
Pedro.
Em 08/11/2014 11:46, Dominik Seichter escreveu:
Hi Pedro
Sounds interesting. Can you provide a patch?
Regards
Dominik
Am 07.11.2014 05:09 schrieb "Pedro Lamarão"
<pedro.lama...@prodist.com.br <mailto:pedro.lama...@prodist.com.br>>:
Hello, all! I am successfully using PoDoFo to produce signed PDF
files,
many thanks to you all!
I have discovered that the AdjustByteRanges has bad synergy with the
dictionary implementation. AdjustByteRanges assume that the
Contents key
follows immediately after the ByteRange key. The dictionary
implementation orders keys in alphabetic order. Therefore if one
produces a document with the ContentInfo key in a signature field then
AdjustByteRanges assumption breaks because ByteRange < ContentInfo <
Contents.
Suggested fixes are doing a linear search or using a custom dictionary
order which always gives ByteRange < Contents < everything.
Hope this helps!
--
Pedro Lamarão
PRODIST TECHNOLOGIES
www.prodist.com.br <http://www.prodist.com.br>
Securing Critical Systems
Tel.: (21) 4062-7188
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--
Pedro Lamarão
PRODIST TECHNOLOGIES
www.prodist.com.br
Securing Critical Systems
Tel.: (21) 4062-7188
---
C:/Users/PEDRO~1.LAM/AppData/Local/Temp/2/PdfSignOutputDevice.cpp-revBASE.svn001.tmp.cpp
Sun Jul 20 17:00:29 2014
+++ P:/tmp/src/doc/PdfSignOutputDevice.cpp Mon Nov 10 10:49:47 2014
@@ -137,6 +137,9 @@ void PdfSignOutputDevice::AdjustByteRange()
PODOFO_RAISE_ERROR( ePdfError_InternalLogic );
}
+ static char * const filler = "[ 0 1234567890 1234567890 1234567890]";
+ static size_t const fillerSize = sizeof("[ 0 1234567890 1234567890
1234567890]") - 1;
+
// Get final position
size_t sFileEnd = GetLength();
PdfArray arr;
@@ -147,34 +150,27 @@ void PdfSignOutputDevice::AdjustByteRange()
std::string sPosition;
PdfVariant(arr).ToString(sPosition, ePdfWriteMode_Compact);
// Fill padding
- unsigned int sPosSize = sizeof("[ 0 1234567890 1234567890 1234567890]")-1;
- if(sPosition.size()<sPosSize)
+ if (sPosition.size() < fillerSize)
{
- // drop last ']'
- sPosition.resize(sPosition.size()-1);
- while(sPosition.size()<(sPosSize-1)) {
- sPosition+=' ';
- }
- sPosition+=']';
- }
+ sPosition.back() = ' ';
+ sPosition.resize(fillerSize, ' ');
+ sPosition.back() = ']';
+ }
- m_pRealDevice->Seek(m_sBeaconPos-sPosition.size()-9);
- char ch;
- size_t offset = m_pRealDevice->Tell();
-
- /* Sanity tests... */
- PODOFO_RAISE_LOGIC_IF( m_pRealDevice->Read(&ch, 1) != 1, "Failed to read 1
byte." );
- if (ch == '0') {
- /* probably clean write mode, whic means two more bytes back */
- m_pRealDevice->Seek(m_sBeaconPos-sPosition.size()-11);
- offset = m_pRealDevice->Tell();
- PODOFO_RAISE_LOGIC_IF( m_pRealDevice->Read(&ch, 1) != 1, "Failed to
read 1 byte." );
- }
-
- /* ...the file position should be at the '[' now */
- PODOFO_RAISE_LOGIC_IF( ch != '[', "Failed to find byte range array start
in the stream." );
-
- m_pRealDevice->Seek(offset);
+ // Note: presumes ByteRange key precedes Contents key
+
+ m_pRealDevice->Seek(m_sBeaconPos - 9 - fillerSize);
+
+ auto offset = m_pRealDevice->Tell();
+ while (true)
+ {
+ char buffer [fillerSize] = { };
+ auto read = m_pRealDevice->Read(buffer, fillerSize);
+ if (strncmp(filler, buffer, fillerSize) == 0) break;
+ if (offset == 0) PODOFO_RAISE_ERROR_INFO( ePdfError_InternalLogic,
"Failed to find byte range array start in the stream." );
+ m_pRealDevice->Seek(--offset);
+ }
+ m_pRealDevice->Seek(offset);
m_pRealDevice->Write(sPosition.c_str(), sPosition.size());
}
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