Related: rhbz#761009 lp#766153 lp#892904 HandleFontOptions crash

The mpServerFont member of a ImplServerFontEntry must not be deleted while the
ImplServerFontEntry still exists

see also 39cbce55 for another reason a crash in
the same place can happen.  Its impossible from traces in crashes before
39cbce55 was fixed to distinguish those crashes
from this crash.

This crash is a regression due to 7a416820
where we went from modifying pServerFont in X11SalGraphics::setFont directly to
modifying it/a-different-one indirectly via ImplServerFontEntry

The various font caches and font thing lifecycles of LibreOffice are somewhat
confusing.

This crash had eluded me for years, to reproduce:
insert->special chars->select a font with loads of glyphs, i.e. "AR PL UKai CN"
click on the first row of glyphs and hold down page-down until you hit the
bottom, then page-up until you hit the top. Pre patch it won't survive the
whole down+up (and valgrind will moan quite a bit)

Change-Id: Ifde0cb375f487c556b04a640d77765a7dc2f0913

vcl/generic/glyphs/glyphcache.cxx

@@ -411,9 +411,22 @@ ImplServerFontEntry::ImplServerFontEntry( FontSelectPattern& rFSD )
 
 // -----------------------------------------------------------------------
 
+void ImplServerFontEntry::SetServerFont(ServerFont* p)
+{
+    if (p == mpServerFont)
+        return;
+    if (mpServerFont)
+        mpServerFont->Release();
+    mpServerFont = p;
+    if (mpServerFont)
+        mpServerFont->AddRef();
+}
+
 ImplServerFontEntry::~ImplServerFontEntry()
 {
     // TODO: remove the ServerFont here instead of in the GlyphCache
+    if (mpServerFont)
+        mpServerFont->Release();
 }
 
 // =======================================================================

vcl/inc/generic/glyphcache.hxx

@@ -225,6 +225,7 @@ public:
 private:
     friend class GlyphCache;
     friend class ServerFontLayout;
+    friend class ImplServerFontEntry;
     friend class X11SalGraphics;
 
     void                        AddRef() const      { ++mnRefCount; }
@@ -302,7 +303,7 @@ private:
 public:
                    ImplServerFontEntry( FontSelectPattern& );
     virtual        ~ImplServerFontEntry();
-    void           SetServerFont( ServerFont* p) { mpServerFont = p; }
+    void           SetServerFont(ServerFont* p);
     void           HandleFontOptions();
 };
 

vcl/unx/generic/gdi/salgdi3.cxx

@@ -194,10 +194,10 @@ bool X11SalGraphics::setFont( const FontSelectPattern *pEntry, int nFallbackLeve
 
         // apply font specific-hint settings if needed
         // TODO: also disable it for reference devices
-    if( !bPrinter_ )
-    {
-        ImplServerFontEntry* pSFE = static_cast<ImplServerFontEntry*>( pEntry->mpFontEntry );
-        pSFE->HandleFontOptions();
+        if( !bPrinter_ )
+        {
+            ImplServerFontEntry* pSFE = static_cast<ImplServerFontEntry*>( pEntry->mpFontEntry );
+            pSFE->HandleFontOptions();
         }
 
         return true;