pascal/lazarus-ccr
1
0
Fork 0
Code Issues Releases Activity

fpexif: Fix crash when file with incorrectly specified segment length is written. Fix XMP metadata being lost when they coexist together with EXIF.

Browse Source 
git-svn-id: https://svn.code.sf.net/p/lazarus-ccr/svn@7965 8e941d3f-bd1b-0410-a28a-d453659cc2b4
This commit is contained in:
wp_xxyyzz
2021-01-17 18:22:28 +00:00
parent 0d703fb453
commit 85c861408a
1 changed files with 52 additions and 7 deletions
Download Patch File Download Diff File Expand all files Collapse all files

59
components/fpexif/fpemetadata.pas
View File

@ -397,11 +397,14 @@ type
end;
const
SOI_MARKER: array[0..1] of byte = ($FF, $D8);
XMP_SIGNATURE = 'http://ns.adobe.com/xap/1.0/';
var
header: TSegmentHeader;
headerSize, newHeaderSize: Word;
n, count: Int64;
savedPos: Int64;
jfif: TJpegJFIFSegment;
s: String;
begin
// Write the header segment and all metadata segments stored in TImgInfo
// to the beginning of the stream
@ -415,19 +418,61 @@ begin
while AInputStream.Position < AInputStream.Size do begin
savedPos := AInputStream.Position; // just for debugging
n := AInputStream.Read(header{%H-}, SizeOf(header));
if n <> Sizeof(header) then
if n <> SizeOf(header) then
// End of file reached, cannot read complete header
Error(rsIncompleteJpegSegmentHeader);
// Some images do not specify the segment length correctly and fill the
// space to the next segment with zero bytes.
if LongInt(header) = 0 then begin
n := 0;
while AInputStream.ReadByte = 0 do
inc(n);
AInputStream.Position := AInputStream.Position - 1;
n := AInputStream.Read(header, SizeOf(Header));
if n <> SizeOf(Header) then
Error(rsIncompleteJpegSegmentHeader);
end;
if header.Key <> $FF then
Error(rsJpegSegmentMarkerExpected);
header.Size := BEToN(header.Size);
headerSize := BEToN(header.Size);
// Save stream position before segment size value.
savedPos := AInputStream.Position - 2;
case header.Marker of
M_SOI:
header.Size := 0;
M_JFIF, M_EXIF, M_IPTC, M_COM: // these segments were already written by WriteJpeg
headerSize := 0;
M_JFIF, M_IPTC, M_COM: // These segments were already written by WriteJpeg
;
M_EXIF:
// there may be also the XMP segment which has the same key $E1.
begin
SetLength(s, Length(XMP_SIGNATURE));
AInputStream.Read(s[1], Length(XMP_SIGNATURE));
if s = XMP_SIGNATURE then
begin
// XMP segment found --> write it back as it is (needs to be fixed to write current meta data)
newHeaderSize := (Trunc(headerSize / 256) + 1) * 256 - SizeOf(header);
SetLength(s, newHeaderSize - Length(XMP_SIGNATURE));
FillChar(s[1], Length(s), 0);
AInputStream.Read(s[1], headerSize);
header.Size := NToBE(newHeaderSize);
AOutputStream.Write(header, SizeOf(Header));
AOutputStream.Write(XMP_SIGNATURE, Length(XMP_SIGNATURE));
AOutputStream.Write(s[1], Length(s));
{
AInputStream.Position := savedPos - 4;
n := AOutputStream.CopyFrom(AInputStream, Int64(header.Size) + 2);
if n <> Int64(header.Size) + 2 then
Error(rsJpegReadWriteErrorInSegment);
}
end
else
begin
// EXIF segment found. But this already has been written by WriteJpeg -> nothing to do
end;
end;
M_SOS:
begin
// this is the last segment before compressed data which don't have a marker
@ -442,11 +487,11 @@ begin
end;
else
AInputStream.Position := AInputStream.Position - 4; // go back to where the segment begins
n := AOutputStream.CopyFrom(AInputStream, Int64(header.Size) + 2);
if n <> Int64(header.Size) + 2 then
n := AOutputStream.CopyFrom(AInputStream, headerSize + 2);
if n <> Int64(headerSize) + 2 then
Error(rsJpegReadWriteErrorInSegment);
end;
AInputStream.Position := savedPos + header.Size;
AInputStream.Position := savedPos + headerSize;
end;
end;