#61881 - handle invalid font names

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1817599 13f79535-47bb-0310-9956-ffa450edef68

src/scratchpad/src/org/apache/poi/hslf/record/FontEntityAtom.java

@@ -86,15 +86,39 @@ public final class FontEntityAtom extends RecordAtom {
      * @return font name
      */
     public String getFontName(){
-    	int maxLen = Math.min(_recdata.length,64);
-        for(int i = 0; i < maxLen; i+=2){
+    	final int maxLen = Math.min(_recdata.length,64);
+        for(int i = 0; i+1 < maxLen; i+=2){
             //loop until find null-terminated end of the font name
-            if(_recdata[i] == 0 && _recdata[i + 1] == 0) {
+            if(_recdata[i] == 0 && _recdata[i + 1] == 0 && !isFontNamePremature0terminated(i)) {
                 return StringUtil.getFromUnicodeLE(_recdata, 0, i/2);
             }
         }
         return null;
     }
+    
+    /**
+     * #61881: there seem to be programs out there, which write the 0-termination also
+     * at the beginning of the string. Check if the next two bytes contain a valid ascii char
+     * and correct the _recdata with a '?' char
+     */
+    private boolean isFontNamePremature0terminated(final int index) {
+        if (index > 0) {
+            // for now we only check the first char
+            return false;
+        }
+        
+        if (_recdata.length < index+4) {
+            return false;
+        }
+        
+        final int cp = LittleEndian.getShort(_recdata, index+2);
+        if (!Character.isJavaIdentifierPart(cp)) {
+            return false;
+        }
+        
+        _recdata[index] = '?';
+        return true;
+    }
 
     /**
      * Set the name of the font.

src/scratchpad/testcases/org/apache/poi/hslf/record/TestFontCollection.java

@@ -23,9 +23,12 @@ import static org.junit.Assert.assertNull;
 
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
+import java.io.InputStream;
 
+import org.apache.poi.POIDataSamples;
 import org.apache.poi.hslf.usermodel.HSLFFontInfo;
 import org.apache.poi.hslf.usermodel.HSLFFontInfoPredefined;
+import org.apache.poi.hslf.usermodel.HSLFSlideShow;
 import org.apache.poi.poifs.storage.RawDataUtil;
 import org.junit.BeforeClass;
 import org.junit.Test;
@@ -34,6 +37,8 @@ import org.junit.Test;
  * Tests {@code FontCollection} and {@code FontEntityAtom} records
  */
 public final class TestFontCollection {
+    private static final POIDataSamples _slTests = POIDataSamples.getSlideShowInstance();
+    
     // From a real file
     private static byte[] data;
     
@@ -87,4 +92,13 @@ public final class TestFontCollection {
         byte[] recdata = out.toByteArray();
         assertArrayEquals(recdata, data);
     }
+    
+    @Test
+    public void bug61881() throws IOException {
+        try (InputStream is = _slTests.openResourceAsStream("bug61881.ppt")) {
+            try (HSLFSlideShow ppt = new HSLFSlideShow(is)) {
+                assertEquals("?imes New Roman",ppt.getFont(3).getTypeface());
+            }
+        }
+    }
 }