PDFBOX-6146: don't load duplicate content (helps avoiding broken content but also saves space), as suggested by james

git-svn-id: https://svn.apache.org/repos/asf/pdfbox/trunk@1931302 13f79535-47bb-0310-9956-ffa450edef68

Author: THausherr

fontbox/src/main/java/org/apache/fontbox/ttf/GlyphSubstitutionTable.java

@@ -179,6 +179,11 @@ private Map<String, ScriptTable> readScriptList(TTFDataStream data, long offset)
         }
         for (int i = 0; i < scriptCount; i++)
         {
+            if (resultScriptList.get(scriptTags[i]) != null)
+            {
+                // PDFBOX-6146
+                continue;
+            }
             ScriptTable scriptTable = readScriptTable(data, offset + scriptOffsets[i]);
             resultScriptList.put(scriptTags[i], scriptTable);
         }
@@ -315,9 +320,16 @@ else if (offset + lookups[i] > data.getOriginalDataSize())
             }
         }
         LookupTable[] lookupTables = new LookupTable[lookupCount];
+        Map<Integer, LookupTable> lookupTableMap = new HashMap<>(); // PDFBOX-6146
         for (int i = 0; i < lookupCount; i++)
         {
-            lookupTables[i] = readLookupTable(data, offset + lookups[i]);
+            LookupTable lookupTable = lookupTableMap.get(lookups[i]);
+            if (lookupTable == null)
+            {
+                lookupTable = readLookupTable(data, offset + lookups[i]);
+                lookupTableMap.put(lookups[i], lookupTable);
+            }
+            lookupTables[i] = lookupTable;
         }
         return new LookupListTable(lookupCount, lookupTables);
     }