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check that AddToTable can be done validly

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Change-Id: I0ee69279e3bb1d9871feba17b908b8307f0ec5b4
This commit is contained in:
Caolán McNamara 2014-08-17 16:21:31 +01:00
parent b9623def05
commit 43b39d3e47
2 changed files with 16 additions and 6 deletions
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20
vcl/source/filter/igif/decode.cxx
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@ -107,7 +107,7 @@ HPBYTE GIFLZWDecompressor::DecompressBlock( HPBYTE pSrc, sal_uInt8 cBufSize,
return pTarget;
}
void GIFLZWDecompressor::AddToTable( sal_uInt16 nPrevCode, sal_uInt16 nCodeFirstData )
bool GIFLZWDecompressor::AddToTable( sal_uInt16 nPrevCode, sal_uInt16 nCodeFirstData )
{
GIFLZWTableEntry* pE;
@ -116,12 +116,16 @@ void GIFLZWDecompressor::AddToTable( sal_uInt16 nPrevCode, sal_uInt16 nCodeFirst
pE = pTable + nTableSize;
pE->pPrev = pTable + nPrevCode;
pE->pFirst = pE->pPrev->pFirst;
pE->nData = pTable[ nCodeFirstData ].pFirst->nData;
GIFLZWTableEntry *pEntry = pTable[nCodeFirstData].pFirst;
if (!pEntry)
return false;
pE->nData = pEntry->nData;
nTableSize++;
if ( ( nTableSize == (sal_uInt16) (1 << nCodeSize) ) && ( nTableSize < 4096 ) )
nCodeSize++;
}
return true;
}
bool GIFLZWDecompressor::ProcessOneCode()
@ -153,17 +157,23 @@ bool GIFLZWDecompressor::ProcessOneCode()
if ( nCode < nClearCode )
{
bool bOk = true;
if ( nOldCode != 0xffff )
AddToTable( nOldCode, nCode );
bOk = AddToTable(nOldCode, nCode);
if (!bOk)
return false;
}
else if ( ( nCode > nEOICode ) && ( nCode <= nTableSize ) )
{
if ( nOldCode != 0xffff )
{
bool bOk;
if ( nCode == nTableSize )
AddToTable( nOldCode, nOldCode );
bOk = AddToTable( nOldCode, nOldCode );
else
AddToTable( nOldCode, nCode );
bOk = AddToTable( nOldCode, nCode );
if (!bOk)
return false;
}
}
else

2
vcl/source/filter/igif/decode.hxx
View file

@ -43,7 +43,7 @@ class GIFLZWDecompressor
sal_uInt8 nBlockBufSize;
sal_uInt8 nBlockBufPos;
void AddToTable(sal_uInt16 nPrevCode, sal_uInt16 nCodeFirstData);
bool AddToTable(sal_uInt16 nPrevCode, sal_uInt16 nCodeFirstData);
bool ProcessOneCode();
public: