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Forgive not having Exif header in PNG text chunk (backport #3322) #3460

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Forgive not having Exif header in PNG text chunk (backport #3322) #3460

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17 changes: 9 additions & 8 deletions src/pngchunk_int.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -255,16 +255,18 @@ namespace Exiv2 {
DataBuf exifData = readRawProfile(arr,false);
long length = exifData.size_;

if (length > 0)
if (length >= 4) // length should have at least the size of TIFF header
{
// Find the position of Exif header in bytes array.

const byte exifHeader[] = { 0x45, 0x78, 0x69, 0x66, 0x00, 0x00 };
// Find the position of TIFF header in bytes array.
// Forgives the absence of the expected Exif\0 APP1 prefix.
const byte tiffHeaderLE[] = { 0x49, 0x49, 0x2A, 0x00 }; // "II*\0"
const byte tiffHeaderBE[] = { 0x4D, 0x4D, 0x00, 0x2A }; // "MM\0*"
long pos = -1;

for (long i=0 ; i < length-(long)sizeof(exifHeader) ; i++)
for (long i=0 ; i < length-(long)sizeof(tiffHeaderLE) ; i++)
{
if (memcmp(exifHeader, &exifData.pData_[i], sizeof(exifHeader)) == 0)
if ((memcmp(tiffHeaderLE, &exifData.pData_[i], sizeof(tiffHeaderLE)) == 0) ||
(memcmp(tiffHeaderBE, &exifData.pData_[i], sizeof(tiffHeaderBE)) == 0))
{
pos = i;
break;
Expand All @@ -276,9 +278,8 @@ namespace Exiv2 {
if (pos !=-1)
{
#ifdef EXIV2_DEBUG_MESSAGES
std::cout << "Exiv2::PngChunk::parseChunkContent: Exif header found at position " << pos << "\n";
std::cout << "Exiv2::PngChunk::parseChunkContent: TIFF header found at position " << pos << "\n";
#endif
pos = pos + sizeof(exifHeader);
ByteOrder bo = TiffParser::decode(pImage->exifData(),
pImage->iptcData(),
pImage->xmpData(),
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8 changes: 7 additions & 1 deletion src/pngimage.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -358,8 +358,14 @@ namespace Exiv2 {
#endif
if ( parsedBuf.size_ ) {
if ( bExif ) {
// check for expected "Exif\0\0" APP1 identifier, punt otherwise
long offset = 0;
const byte exifId[] = { 0x45, 0x78, 0x69, 0x66, 0x00, 0x00 }; // "Exif\0\0"
if (memcmp(exifId, parsedBuf.pData_, sizeof(exifId)) == 0) {
offset = 6;
}
// create memio object with the data, then print the structure
BasicIo::AutoPtr p = BasicIo::AutoPtr(new MemIo(parsedBuf.pData_+6,parsedBuf.size_-6));
BasicIo::AutoPtr p = BasicIo::AutoPtr(new MemIo(parsedBuf.pData_ + offset, parsedBuf.size_ - offset));
printTiffStructure(*p,out,option,depth);
}
if ( bIptc ) {
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