tdf#73523 support WinBMPv3-NT version of BMP files (found in Visio files)

It is a special case when there are additional 12 bytes of color bitfields
after the info header. See also the useful comments at
https://searchfox.org/mozilla-central/source/image/decoders/nsBMPDecoder.cpp#47

It turned out we generate this type of BMP files internally from EMF files,
but in that case the bfOffBits of BITMAPFILEHEADER struct points to the
pixel data. In case of Visio, bfOffBits points to the color mask. There was
no better solution than preventing jumping back in the stream.

Change-Id: I97f0fd4f184ea77beeab8b22fc98fdb78472d9bb
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/127920
Tested-by: Jenkins CollaboraOffice <jenkinscollaboraoffice@gmail.com>
Reviewed-by: Miklos Vajna <vmiklos@collabora.com>
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/127927
Tested-by: Jenkins
Reviewed-by: Andras Timar <andras.timar@collabora.com>

4 files changed, 37 insertions, 10 deletions

diff --git a/vcl/qa/cppunit/BmpFilterTest.cxx b/vcl/qa/cppunit/BmpFilterTest.cxx
index 20be739d0e98..1ab7bc2a0a4a 100644
--- a/vcl/qa/cppunit/BmpFilterTest.cxx
+++ b/vcl/qa/cppunit/BmpFilterTest.cxx
@@ -204,4 +204,17 @@ CPPUNIT_TEST_FIXTURE(BmpFilterTest, testBMP_V2)
     CPPUNIT_ASSERT_EQUAL(COL_LIGHTGREEN, aBitmap.GetPixelColor(2, 2));
 }
 
+CPPUNIT_TEST_FIXTURE(BmpFilterTest, testTdf73523)
+{
+    SvFileStream aFileStream(getFullUrl(u"tdf73523.bmp"), StreamMode::READ);
+    Graphic aGraphic;
+    CPPUNIT_ASSERT(BmpReader(aFileStream, aGraphic));
+    auto aBitmap = aGraphic.GetBitmapEx();
+    // Without the accompanying fix in place, this test would have failed with:
+    // - Expected: c[80000000]
+    // - Actual  : c[00000000]
+    // i.e. the pixel is red not black
+    CPPUNIT_ASSERT_EQUAL(COL_RED, aBitmap.GetPixelColor(0, 0));
+}
+
 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */
diff --git a/vcl/qa/cppunit/data/tdf73523.bmp b/vcl/qa/cppunit/data/tdf73523.bmp
new file mode 100644
index 000000000000..f4364ea3e841
--- /dev/null
+++ b/vcl/qa/cppunit/data/tdf73523.bmp
diff --git a/vcl/qa/cppunit/graphicfilter/data/bmp/fail/crash-1.bmp b/vcl/qa/cppunit/graphicfilter/data/bmp/pass/crash-1.bmp
index 84b6c35c87e6..84b6c35c87e6 100644
--- a/vcl/qa/cppunit/graphicfilter/data/bmp/fail/crash-1.bmp
+++ b/vcl/qa/cppunit/graphicfilter/data/bmp/pass/crash-1.bmp
diff --git a/vcl/source/bitmap/dibtools.cxx b/vcl/source/bitmap/dibtools.cxx
index 65117319afe5..96b82b9a7b86 100644
--- a/vcl/source/bitmap/dibtools.cxx
+++ b/vcl/source/bitmap/dibtools.cxx
@@ -246,8 +246,18 @@ bool ImplReadDIBInfoHeader(SvStream& rIStm, DIBV5Header& rHeader, bool& bTopDown
         readUInt32( rHeader.nV5ProfileSize );
         readUInt32( rHeader.nV5Reserved );
 
+        // Read color mask. An additional 12 bytes of color bitfields follow the info header (WinBMPv3-NT)
+        sal_uInt32 nColorMask = 0;
+        if (BITFIELDS == rHeader.nCompression && DIBINFOHEADERSIZE == rHeader.nSize)
+        {
+            rIStm.ReadUInt32( rHeader.nV5RedMask );
+            rIStm.ReadUInt32( rHeader.nV5GreenMask );
+            rIStm.ReadUInt32( rHeader.nV5BlueMask );
+            nColorMask = 12;
+        }
+
         // seek to EndPos
-        if (!checkSeek(rIStm, aStartPos + rHeader.nSize))
+        if (!checkSeek(rIStm, aStartPos + rHeader.nSize + nColorMask))
             return false;
     }
 
@@ -530,14 +540,12 @@ bool ImplReadDIBBits(SvStream& rIStm, DIBV5Header& rHeader, BitmapWriteAccess& r
     }
     else
     {
-        // Read color mask
-        if(bTCMask && BITFIELDS == rHeader.nCompression)
-        {
-            rIStm.SeekRel( -12 );
-            rIStm.ReadUInt32( nRMask );
-            rIStm.ReadUInt32( nGMask );
-            rIStm.ReadUInt32( nBMask );
-        }
+        if (rHeader.nV5RedMask > 0)
+            nRMask = rHeader.nV5RedMask;
+        if (rHeader.nV5GreenMask > 0)
+            nGMask = rHeader.nV5GreenMask;
+        if (rHeader.nV5BlueMask > 0)
+            nBMask = rHeader.nV5BlueMask;
 
         const tools::Long nWidth(rHeader.nWidth);
         const tools::Long nHeight(rHeader.nHeight);
@@ -908,7 +916,13 @@ bool ImplReadDIBBody(SvStream& rIStm, Bitmap& rBmp, AlphaMask* pBmpAlpha, sal_uI
 
     if (nOffset)
     {
-        pIStm->SeekRel(nOffset - (pIStm->Tell() - nStmPos));
+        // It is problematic to seek backwards. We are at the
+        // end of BITMAPINFOHEADER or 12 bytes further in case
+        // of WinBMPv3-NT format. It is possible to seek forward
+        // though because a gap may be there.
+        sal_Int32 nSeekRel = nOffset - (pIStm->Tell() - nStmPos);
+        if (nSeekRel > 0)
+            pIStm->SeekRel(nSeekRel);
     }
 
     const sal_Int64 nBitsPerLine (static_cast<sal_Int64>(aHeader.nWidth) * static_cast<sal_Int64>(aHeader.nBitCount));