Add support for PKZIP-based stpZ files

FreeCAD uses gzip-based stpZ files but many programs will compress using
the archive format of PKZIP (e.g. WinZIP).  This handles the archive
format, taking the first file from the archive, which by the standard
should be the STEP file

Fixes https://gitlab.com/kicad/code/kicad/issues/5376

plugins/3d/oce/loadmodel.cpp

@@ -33,6 +33,7 @@
 #include <wx/stdpaths.h>
 #include <wx/string.h>
 #include <wx/wfstream.h>
+#include <wx/zipstrm.h>
 
 #include <decompress.hpp>
 
@@ -473,6 +474,7 @@ bool readSTEPZ( Handle(TDocStd_Document)& m_doc, const char* aFileName )
         return false;
 
     {
+        bool success = false;
         wxFFileOutputStream ofile( outFile.GetFullPath() );
 
         if( !ofile.IsOk() )
@@ -486,17 +488,33 @@ bool readSTEPZ( Handle(TDocStd_Document)& m_doc, const char* aFileName )
         try
         {
             expanded = gzip::decompress( buffer, size );
+            success = true;
         }
         catch(...)
+        {}
+
+        if( expanded.empty() )
         {
-            delete[] buffer;
+            ifile.Reset();
-            return false;
+            ifile.SeekI( 0 );
+            wxZipInputStream izipfile( ifile );
+            std::unique_ptr<wxZipEntry> zip_file( izipfile.GetNextEntry() );
+
+            if( zip_file && !zip_file->IsDir() && izipfile.CanRead() )
+            {
+                izipfile.Read( ofile );
+                success = true;
+            }
+        }
+        else
+        {
+            ofile.Write( expanded.data(), expanded.size() );
         }
 
         delete[] buffer;
-
-        ofile.Write( expanded.data(), expanded.size() );
         ofile.Close();
+
+        return success;
     }
 
     bool retval = readSTEP( m_doc, outFile.GetFullPath().mb_str() );

utils/kicad2step/pcb/oce_utils.cpp

@@ -31,6 +31,7 @@
 #include <wx/filefn.h>
 #include <wx/stdpaths.h>
 #include <wx/wfstream.h>
+#include <wx/zipstrm.h>
 
 #include <decompress.hpp>
 
@@ -1020,14 +1021,11 @@ bool PCBMODEL::getModelLabel( const std::string& aFileName, TRIPLET aScale, TDF_
             }
 
             {
+                bool success = false;
                 wxFFileOutputStream ofile( outFile.GetFullPath() );
 
                 if( !ofile.IsOk() )
-                {
-                    ReportMessage( wxString::Format( "readSTEP() failed on filename %s\n",
-                                                     outFile.GetFullPath() ) );
                     return false;
-                }
 
                 char *buffer = new char[size];
 
@@ -1037,17 +1035,33 @@ bool PCBMODEL::getModelLabel( const std::string& aFileName, TRIPLET aScale, TDF_
                 try
                 {
                     expanded = gzip::decompress( buffer, size );
+                    success = true;
                 }
                 catch(...)
+                {}
+
+                if( expanded.empty() )
                 {
-                    delete[] buffer;
+                    ifile.Reset();
-                    return false;
+                    ifile.SeekI( 0 );
+                    wxZipInputStream izipfile( ifile );
+                    std::unique_ptr<wxZipEntry> zip_file( izipfile.GetNextEntry() );
+
+                    if( zip_file && !zip_file->IsDir() && izipfile.CanRead() )
+                    {
+                        izipfile.Read( ofile );
+                        success = true;
+                    }
+                }
+                else
+                {
+                    ofile.Write( expanded.data(), expanded.size() );
                 }
 
                 delete[] buffer;
-
-                ofile.Write( expanded.data(), expanded.size() );
                 ofile.Close();
+
+                return success;
             }
 
             return getModelLabel( outFile.GetFullPath().ToStdString(), aScale, aLabel );