Hi all,
I have attached to this e-mail the revised (and now longer) patch, a
test PDF document, the source code (using PoDoFo) to generate it, and
the source code of a kind-of "unit test" (without using libcppunit, I
don't have it installed). My rationale for the patch is as follows:
- I don't like unreachable code and I hope you don't mind it removed.
- I think that the code removed was very difficult to correct, if at
all possible
- The comment I removed doesn't apply anymore (IMO), because my changes
make the code now cover all the possible cases (IIUC) for pagefinding
- I changed some checks to make them catch previously-missed cases
- I added extensive PDF-document brokenness logging to tree traversal
So I hope that the patch now makes the method so robust that you'll
accept it, please review it, and if accepted, please apply (separately)
to the public repository.
Best regards, mabri
----- Original Message -----
From: zyx <z...@litepdf.cz>
To: podofo-users@lists.sourceforge.net
CC:
Sent: 21:03, Tuesday, 1 September 2015
Subject: Re: [Podofo-users] unreachable-code and robustness fixes in
PdfPagesTree::GetPageNode()
On Wed, 2015-08-26 at 15:59 +0000, Matthew Brincke wrote:
> What do you think?
Hi,
I do not know the exact rationale for the code being changed by your
patch. I think the best option is to have a test .pdf file(s) for it
and kind of a unit test, proving the change being right. The mix of
numKids and numDirectKids also makes things more complicated.
> + ); // TODO: perhaps log reference too?
I'd prefer to not add any new TODO, just decide and do it (or don't do
it).
Bye,
zyx
--
http://www.litePDF.cz i...@litepdf.cz
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Index: src/doc/PdfPagesTree.cpp
===================================================================
--- src/doc/PdfPagesTree.cpp (revision 1676)
+++ src/doc/PdfPagesTree.cpp (working copy)
@@ -327,9 +327,11 @@
const size_t numDirectKids = rKidsArray.size();
const size_t numKids = GetChildCount(pParent);
- if( static_cast<int>(numKids) < nPageNum )
+ // use <= since nPageNum is 0-based
+ if( static_cast<int>(numKids) <= nPageNum )
{
- PdfError::LogMessage( eLogSeverity_Critical, "Cannot retrieve page %i from a document with only %i pages.",
+ PdfError::LogMessage( eLogSeverity_Critical,
+ "Cannot retrieve page %i from a document with only %i pages.",
nPageNum, static_cast<int>(numKids) );
return NULL;
}
@@ -342,14 +344,6 @@
rLstParents.push_back( pParent );
return GetPageNodeFromArray( nPageNum, rKidsArray, rLstParents );
}
- else if( numDirectKids == numKids && static_cast<size_t>(nPageNum) < numDirectKids )
- {
- // This node has only page nodes as kids,
- // but does not contain our page,
- // skip it - this case should never occur because
- // of handling of childs in the else part below.
- return NULL;
- }
else
{
// We have to traverse the tree
@@ -356,10 +350,45 @@
while( it != rKidsArray.end() )
{
if( (*it).IsArray() )
- {
- // Fixes some broken PDFs who have trees with 1 element kids arrays
+ { // Fixes PDFs broken by having trees with arrays nested once
+
rLstParents.push_back( pParent );
- return GetPageNodeFromArray( nPageNum, (*it).GetArray(), rLstParents );
+
+ // the following code is to find the reference to log this with
+ const PdfReference & rIterArrayRef = (*it).Reference();
+ PdfReference refToLog;
+ bool isDirectObject // don't worry about 0-num. indirect ones
+ = ( !(rIterArrayRef.ObjectNumber() ) );
+ if ( isDirectObject )
+ {
+ if ( !(pObj->Reference().ObjectNumber() ) ) // rKidsArray's
+ {
+ refToLog = pParent->Reference();
+ }
+ else
+ {
+ refToLog = pObj->Reference();
+ }
+ }
+ else
+ {
+ refToLog = rIterArrayRef;
+ }
+ PdfError::LogMessage( eLogSeverity_Error,
+ "Entry in Kids array is itself an array"
+ "%s reference: %s\n", isDirectObject ? " (direct object)"
+ ", in object with" : ",", refToLog.ToString().c_str() );
+
+ const PdfArray & rIterArray = (*it).GetArray();
+
+ // is the array large enough to potentially have the page?
+ if( static_cast<size_t>(nPageNum) < rIterArray.GetSize() )
+ {
+ PdfObject* pPageNode = GetPageNodeFromArray( nPageNum,
+ rIterArray, rLstParents );
+ if ( pPageNode ) // and if not, search further
+ return pPageNode;
+ }
}
else if( (*it).IsReference() )
{
@@ -386,7 +415,7 @@
return this->GetPageNode( nPageNum, pChild, rLstParents );
}
}
- else // Type == Page
+ else if( this->IsTypePage(pChild) )
{
if( 0 == nPageNum )
{
@@ -398,6 +427,17 @@
if(nPageNum > 0 )
nPageNum--;
}
+ else
+ {
+ const PdfReference & rLogRef = pChild->Reference();
+ pdf_objnum nLogObjNum = rLogRef.ObjectNumber();
+ pdf_gennum nLogGenNum = rLogRef.GenerationNumber();
+ PdfError::LogMessage( eLogSeverity_Critical,
+ "Requesting page index %i. "
+ "Invalid datatype referenced in kids array: %s\n"
+ "Reference to invalid object: %i %i R\n", nPageNum,
+ pChild->GetDataTypeString(), nLogObjNum, nLogGenNum);
+ }
}
else
{
test-1_elem_array.pdf
Description: Adobe PDF document
#include <podofo/podofo.h>
#include <sstream>
#include <iostream> // for exception handling
using namespace PoDoFo;
#define NUM_PAGES_FIRST 3
#define NUM_PAGES_EXTRA 2
#define TEXTPOS_X 72.0
#define TEXTPOS_Y 72.0
/** Create Pages node which will be referenced from the parent of the last page
in place of the latter's reference which'll be new node's Kids' only entry.
*/
void CreatePagesNodePlacedWithLastKid(PdfDocument & doc)
{
PdfPage* pLastPage = doc.GetPage( doc.GetPageCount() - 1 ); // 0-based
PdfObject* pLastPageObj = pLastPage->GetObject();
PdfObject* pParentObj = pLastPageObj->MustGetIndirectKey( "Parent" );
PdfArray & rParentKidsArray = pParentObj->MustGetIndirectKey( "Kids" )
->GetArray();
PdfObject& pLastKidRefObj = *(rParentKidsArray.rbegin()); // num's implicit
const PdfReference & rLastKidRef = pLastKidRefObj.GetReference();
PdfVecObjects* vecObjs = doc.GetObjects();
PdfObject* pCreatedPagesNode = vecObjs->CreateObject( "Pages" ); // dict.
PdfDictionary & rLastKidDict = vecObjs->GetObject( rLastKidRef )
->GetDictionary();
rLastKidDict.AddKey( "Parent", pCreatedPagesNode->Reference() );
PdfDictionary & rCreatedPagesNodeDict = pCreatedPagesNode->GetDictionary();
rCreatedPagesNodeDict.AddKey( "Kids", PdfArray( rLastKidRef ) ); //
rCreatedPagesNodeDict.AddKey( "Count", 1LL); // PdfObject(pdf_int64) called
pLastKidRefObj = pCreatedPagesNode->Reference(); // page ref's a level down
}
void DrawSomeTextOnPage(PdfPainter & painter, PdfPage* pPage, PdfFont* pFont,
pdf_uint8 nPageNumber) // this parameter is 1-based
{
painter.SetPage( pPage );
painter.SetFont( pFont );
// Draw on the page, e.g. "Page "+page number
std::ostringstream textstream;
textstream << "Page " << nPageNumber;
painter.DrawText( TEXTPOS_X, TEXTPOS_Y, PdfString( textstream.str(),
pFont->GetEncoding() ) );
painter.FinishPage();
}
int main( int argc, const char* argv[] )
{
if (argc != 2)
{
return 1;
}
PdfMemDocument outputDoc;
PdfPainter painter;
PdfVecObjects& vecObjs = outputDoc.GetObjects();
PdfFont* pFont = PdfFontFactory::CreateBase14Font( "Helvetica", 0,
PdfEncodingFactory::GlobalWinAnsiEncodingInstance()
, &vecObjs );
for ( pdf_uint8 i = 0; i < NUM_PAGES_FIRST; i++ )
{
PdfPage* pPage = outputDoc.CreatePage( PdfPage::CreateStandardPageSize(
ePdfPageSize_A4 ));
DrawSomeTextOnPage( painter, pPage, pFont, i + 1 );
}
CreatePagesNodePlacedWithLastKid(outputDoc); // page tree 2-level ->3-level
std::vector< PdfRect > vecPageSizes;
for ( pdf_uint8 j = 0; j < NUM_PAGES_EXTRA; j++ )
{
vecPageSizes.push_back( PdfPage::CreateStandardPageSize(
ePdfPageSize_A4 ) );
}
outputDoc.CreatePages( vecPageSizes );
// Manipulate the page tree here to get a middle page in a 1-element array
const PdfObject* pDocCatalog = outputDoc.GetCatalog();
PdfObject* pPagesObj = pDocCatalog->MustGetIndirectKey( PdfName("Pages") );
PdfObject* pKidsObj = pPagesObj->MustGetIndirectKey( PdfName("Kids") );
PdfArray::iterator kidsIt = pKidsObj->GetArray().begin()
+ (NUM_PAGES_FIRST / 2);
PdfReference middlePageRef = (*kidsIt).GetReference();
*kidsIt = PdfArray(middlePageRef);
outputDoc.SetWriteMode( ePdfWriteMode_Clean ); // readable in a text editor
outputDoc.Write( argv[1] ); // Caution: if the file exists it's overwritten
return 0;
}#include <podofo/podofo.h>
#include <iostream>
using namespace PoDoFo;
#define TEST_FILE "test-1_elem_array.pdf"
#define PAGE_TO_TEST 3
int main()
{
PdfMemDocument testDoc;
testDoc.Load( TEST_FILE );
PdfPagesTree* testPagesTree = testDoc.GetPagesTree();
// GetPage argument is expected 0-based
// testPagesTree->ClearCache();
PdfPage* testPage = NULL;
try {
testPage= testPagesTree->GetPage( PAGE_TO_TEST - 1 );
} catch (PdfError & e) {
e.PrintErrorMsg();
}
if (testPage != NULL)
{
std::cerr << "SUCCESS!" << std::endl;
return 0;
}
else
{
std::cerr << "FAILURE!" << std::endl;
return 1;
}
}
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