Add methods to check to see if a given InputStream has a OOXML file header, or a OLE2 file header, so that a future factory method could figure out which class to instantiate for a given InputStraeam

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@612438 13f79535-47bb-0310-9956-ffa450edef68

3 files changed, 41 insertions, 2 deletions

diff --git a/src/java/org/apache/poi/poifs/common/POIFSConstants.java b/src/java/org/apache/poi/poifs/common/POIFSConstants.java
index bc1bf6dad5..399f52be4b 100644
--- a/src/java/org/apache/poi/poifs/common/POIFSConstants.java
+++ b/src/java/org/apache/poi/poifs/common/POIFSConstants.java
@@ -31,4 +31,7 @@ public interface POIFSConstants
     public static final int END_OF_CHAIN   = -2;
     public static final int PROPERTY_SIZE  = 0x0080;
     public static final int UNUSED_BLOCK   = -1;
+    
+    public static final byte[] OOXML_FILE_HEADER = 
+    	new byte[] { 0x50, 0x4b, 0x03, 0x04 };
 }   // end public interface POIFSConstants;
diff --git a/src/java/org/apache/poi/poifs/filesystem/POIFSFileSystem.java b/src/java/org/apache/poi/poifs/filesystem/POIFSFileSystem.java
index 981c51d39a..3d4f1aac60 100644
--- a/src/java/org/apache/poi/poifs/filesystem/POIFSFileSystem.java
+++ b/src/java/org/apache/poi/poifs/filesystem/POIFSFileSystem.java
@@ -34,6 +34,7 @@ import org.apache.poi.poifs.storage.BlockAllocationTableReader;
 import org.apache.poi.poifs.storage.BlockAllocationTableWriter;
 import org.apache.poi.poifs.storage.BlockList;
 import org.apache.poi.poifs.storage.BlockWritable;
+import org.apache.poi.poifs.storage.HeaderBlockConstants;
 import org.apache.poi.poifs.storage.HeaderBlockReader;
 import org.apache.poi.poifs.storage.HeaderBlockWriter;
 import org.apache.poi.poifs.storage.RawDataBlock;
@@ -41,6 +42,9 @@ import org.apache.poi.poifs.storage.RawDataBlockList;
 import org.apache.poi.poifs.storage.SmallBlockTableReader;
 import org.apache.poi.poifs.storage.SmallBlockTableWriter;
 import org.apache.poi.poifs.storage.SmallDocumentBlock;
+import org.apache.poi.util.IOUtils;
+import org.apache.poi.util.LongField;
+import org.apache.xmlbeans.impl.common.IOUtil;
 
 /**
  * This is the main class of the POIFS system; it manages the entire
@@ -106,6 +110,35 @@ public class POIFSFileSystem
                     .getSBATStart()), data_blocks, properties.getRoot()
                         .getChildren(), null);
     }
+    
+    /**
+     * Checks that the supplied InputStream (which MUST
+     *  support mark and reset, or be a PushbackInputStream) 
+     *  has a POIFS (OLE2) header at the start of it.
+     * If your InputStream does not support mark / reset,
+     *  then wrap it in a PushBackInputStream, then be
+     *  sure to always use that, and not the original!
+     * @param inp An InputStream which supports either mark/reset, or is a PushbackInputStream 
+     */
+    public static boolean hasPOIFSHeader(InputStream inp) throws IOException {
+    	// We want to peek at the first 8 bytes 
+    	inp.mark(8);
+
+    	byte[] header = new byte[8];
+    	IOUtils.readFully(inp, header);
+        LongField signature = new LongField(HeaderBlockConstants._signature_offset, header);
+
+        // Wind back those 8 bytes
+        if(inp instanceof PushbackInputStream) {
+        	PushbackInputStream pin = (PushbackInputStream)inp;
+        	pin.unread(header);
+        } else {
+        	inp.reset();
+        }
+    	
+    	// Did it match the signature?
+    	return (signature.get() == HeaderBlockConstants._signature);
+    }
 
     /**
      * Create a new document to be added to the root directory
diff --git a/src/java/org/apache/poi/poifs/storage/HeaderBlockReader.java b/src/java/org/apache/poi/poifs/storage/HeaderBlockReader.java
index 16c94e2c23..0d5bb817b4 100644
--- a/src/java/org/apache/poi/poifs/storage/HeaderBlockReader.java
+++ b/src/java/org/apache/poi/poifs/storage/HeaderBlockReader.java
@@ -91,8 +91,11 @@ public class HeaderBlockReader
         if (signature.get() != _signature)
         {
 			// Is it one of the usual suspects?
-			if(_data[0] == 0x50 && _data[1] == 0x4b && _data[2] == 0x03 &&
-					_data[3] == 0x04) {
+        	byte[] OOXML_FILE_HEADER = POIFSConstants.OOXML_FILE_HEADER;
+			if(_data[0] == OOXML_FILE_HEADER[0] && 
+					_data[1] == OOXML_FILE_HEADER[1] && 
+					_data[2] == OOXML_FILE_HEADER[2] &&
+					_data[3] == OOXML_FILE_HEADER[3]) {
 				throw new OfficeXmlFileException("The supplied data appears to be in the Office 2007+ XML. POI only supports OLE2 Office documents");
 			}