From e9c50fbbc3b07ef927d133da9cf2395c55611e0f Mon Sep 17 00:00:00 2001
From: offtkp <parisoplop@gmail.com>
Date: Sat, 2 Apr 2022 15:49:32 +0300
Subject: tdf#103954: Z compressed graphic formats support for EMF/WMF
MIME-Version: 1.0
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Content-Transfer-Encoding: 8bit

- Added .emz and .wmz file opening support
- Added a function to check for Z compression that
all z comp. formats can use
- Added 3 unit tests for emf/emz/wmz files
and the example files have been checked with
a different tool (File Viewer 4)
- emf/emz file detection changed from magic byte checking
to extension checking, like wmf/wmz does

Change-Id: I3e433fd23d18482648a51cd04b8f467368e97b62
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/132456
Tested-by: Jenkins
Reviewed-by: Tomaž Vajngerl <quikee@gmail.com>
---
 tools/source/zcodec/zcodec.cxx | 23 ++++++++++++++++-------
 1 file changed, 16 insertions(+), 7 deletions(-)

(limited to 'tools')

diff --git a/tools/source/zcodec/zcodec.cxx b/tools/source/zcodec/zcodec.cxx
index 97a03a463021..80daa1507a19 100644
--- a/tools/source/zcodec/zcodec.cxx
+++ b/tools/source/zcodec/zcodec.cxx
@@ -36,7 +36,7 @@
 #define GZ_COMMENT      0x10 /* bit 4 set: file comment present */
 #define GZ_RESERVED     0xE0 /* bits 5..7: reserved */
 
-const int gz_magic[2] = { 0x1f, 0x8b }; /* gzip magic header */
+constexpr sal_uInt16 GZ_MAGIC_BYTES_LE = 0x8B1F; /* gzip magic bytes, little endian */
 
 ZCodec::ZCodec( size_t nInBufSize, size_t nOutBufSize )
     : meState(STATE_INIT)
@@ -58,6 +58,16 @@ ZCodec::~ZCodec()
     delete pStream;
 }
 
+bool ZCodec::IsZCompressed( SvStream& rIStm )
+{
+    sal_uInt64 nCurPos = rIStm.Tell();
+    rIStm.Seek( 0 );
+    sal_uInt16 nFirstTwoBytes = 0;
+    rIStm.ReadUInt16( nFirstTwoBytes );
+    rIStm.Seek( nCurPos );
+    return nFirstTwoBytes == GZ_MAGIC_BYTES_LE;
+}
+
 void ZCodec::BeginCompression( int nCompressLevel, bool gzLib )
 {
     assert(meState == STATE_INIT);
@@ -272,12 +282,11 @@ void ZCodec::InitDecompress(SvStream & inStream)
     if ( mbStatus &&  mbGzLib )
     {
         sal_uInt8 j, nMethod, nFlags;
-        for (int i : gz_magic)   // gz - magic number
-        {
-            inStream.ReadUChar( j );
-            if ( j != i )
-                mbStatus = false;
-        }
+        sal_uInt16 nFirstTwoBytes;
+        inStream.Seek( 0 );
+        inStream.ReadUInt16( nFirstTwoBytes );
+        if ( nFirstTwoBytes != GZ_MAGIC_BYTES_LE )
+            mbStatus = false;
         inStream.ReadUChar( nMethod );
         inStream.ReadUChar( nFlags );
         if ( nMethod != Z_DEFLATED )
-- 
cgit