From 3f1965ea27570732c9e905ae9ed79636f16dcad1 Mon Sep 17 00:00:00 2001
From: Nick Burch <nick@apache.org>
Date: Tue, 25 Oct 2016 09:15:02 +0000
Subject: [PATCH] Work in progress - v5 pointer containers

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1766487 13f79535-47bb-0310-9956-ffa450edef68
---
 .../poi/hdgf/pointers/PointerFactory.java     | 38 +++++++++++++++++++
 .../hdgf/streams/PointerContainingStream.java | 23 +++++++----
 2 files changed, 53 insertions(+), 8 deletions(-)

diff --git a/src/scratchpad/src/org/apache/poi/hdgf/pointers/PointerFactory.java b/src/scratchpad/src/org/apache/poi/hdgf/pointers/PointerFactory.java
index ddb519cef..640396cf5 100644
--- a/src/scratchpad/src/org/apache/poi/hdgf/pointers/PointerFactory.java
+++ b/src/scratchpad/src/org/apache/poi/hdgf/pointers/PointerFactory.java
@@ -17,6 +17,7 @@
 
 package org.apache.poi.hdgf.pointers;
 
+import org.apache.poi.hdgf.streams.PointerContainingStream;
 import org.apache.poi.util.LittleEndian;
 
 /**
@@ -54,4 +55,41 @@ public final class PointerFactory {
 			throw new IllegalArgumentException("Visio files with versions below 5 are not supported, yours was " + version);
 		}
 	}
+	
+	/**
+	 * In a {@link PointerContainingStream}, where would the
+	 *  number of child pointers be stored for this kind of Pointer?
+	 */
+	public int identifyNumPointersOffset(Pointer pointer, byte[] data) {
+	    if (pointer instanceof PointerV6) {
+	        // V6 stores it as the first value in the stream
+	        return (int)LittleEndian.getUInt(data, 0);
+	    } else if (pointer instanceof PointerV5) {
+	        // V5 uses fixed offsets
+	        switch (pointer.type) {
+    	         case 0x1d:
+    	         case 0x4e:
+    	            return 0x24-6;
+    	         case 0x1e:
+    	            return 0x3c-6;
+                 case 0x14:
+                     return 0x88-6;
+	        }
+	        return 10;
+	    } else {
+            throw new IllegalArgumentException("Unsupported Pointer type " + pointer);
+	    }
+	}
+	
+	public int identifyNumPointers(Pointer pointer, int offset, byte[] data) {
+        if (pointer instanceof PointerV6) {
+            // V6 stores it a 32 bit number at the offset
+            return (int)LittleEndian.getUInt(data, offset);
+        } else if (pointer instanceof PointerV5) {
+            // V5 stores it as a 16 bit number at the offset
+            return LittleEndian.getShort(data, offset);
+        } else {
+            throw new IllegalArgumentException("Unsupported Pointer type " + pointer);
+        }
+	}
 }
diff --git a/src/scratchpad/src/org/apache/poi/hdgf/streams/PointerContainingStream.java b/src/scratchpad/src/org/apache/poi/hdgf/streams/PointerContainingStream.java
index ff8da5e98..d07aa0450 100644
--- a/src/scratchpad/src/org/apache/poi/hdgf/streams/PointerContainingStream.java
+++ b/src/scratchpad/src/org/apache/poi/hdgf/streams/PointerContainingStream.java
@@ -20,6 +20,7 @@ package org.apache.poi.hdgf.streams;
 import org.apache.poi.hdgf.chunks.ChunkFactory;
 import org.apache.poi.hdgf.pointers.Pointer;
 import org.apache.poi.hdgf.pointers.PointerFactory;
+import org.apache.poi.hdgf.pointers.PointerV6;
 import org.apache.poi.util.LittleEndian;
 
 /**
@@ -40,20 +41,26 @@ public class PointerContainingStream extends Stream { // TODO - instantiable sup
 		this.pointerFactory = pointerFactory;
 
 		// Find the offset to the number of child pointers we have
-		// This ought to be the first thing stored in us
-		numPointersLocalOffset = (int)LittleEndian.getUInt(
-				store.getContents(), 0
+		numPointersLocalOffset = pointerFactory.identifyNumPointersOffset(
+				pointer, store.getContents()
 		);
 
 		// Generate the objects for the pointers we contain
-		int numPointers = (int)LittleEndian.getUInt(
-				store.getContents(), numPointersLocalOffset
+		int numPointers = pointerFactory.identifyNumPointers(
+				pointer, numPointersLocalOffset, store.getContents()
 		);
 		childPointers = new Pointer[numPointers];
+		
+		// Prepare to read the children
+        int pos = numPointersLocalOffset;
 
-		// After the number of pointers is another (unknown)
-		//  4 byte value
-		int pos = numPointersLocalOffset + 4 + 4;
+        // v5 only has another (unknown) 4 byte value
+        // TODO Should this logic go into PointerFactory?
+        if (pointer instanceof PointerV6) {
+            pos += 4 + 4;
+        } else {
+            pos += 2;
+        }
 
 		// Now create the pointer objects
 		for(int i=0; i<numPointers; i++) {