X-Git-Url: http://jaekl.net/gitweb/?p=frank.git;a=blobdiff_plain;f=prod%2Fnet%2Fjaekl%2Fqd%2Futil%2FInputStreamWrapper.java;fp=prod%2Fnet%2Fjaekl%2Fqd%2Futil%2FInputStreamWrapper.java;h=f78cf613be42faed0597a3f90cebbf46a48e902c;hp=0000000000000000000000000000000000000000;hb=418e4d229a8b607b022cfb867bb702bec1765d13;hpb=d870b8b1ca2e633b0f2b58969cc042888d07db6e

diff --git a/prod/net/jaekl/qd/util/InputStreamWrapper.java b/prod/net/jaekl/qd/util/InputStreamWrapper.java
new file mode 100644
index 0000000..f78cf61
--- /dev/null
+++ b/prod/net/jaekl/qd/util/InputStreamWrapper.java
@@ -0,0 +1,47 @@
+// Copyright (C) 2014 Christian Jaekl
+
+// Wrap an inputstream, keeping a copy of the first few bytes that are read from it.
+// This is useful when passing an inputstream directly to the SAX parser, 
+// because we may want to do a post-mortem examination of the input being parsed
+// if parsing fails.
+
+package net.jaekl.qd.util;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.Arrays;
+
+public class InputStreamWrapper extends InputStream {
+	final static int HEAD_MAX = 1024;
+	
+	InputStream m_is;	// the stream being wrapped
+	byte[] m_head;		// the first (up to HEAD_MAX) bytes that were read from the wrapped stream
+	int    m_headBytes;	// number of bytes stored in m_head
+	
+	public InputStreamWrapper(InputStream is)
+	{
+		super();
+		
+		m_is = is;
+		m_head = new byte[HEAD_MAX];
+		m_headBytes = 0;
+	}
+	
+	@Override
+	public int read() throws IOException {
+		int b = m_is.read();
+		if ((-1) == b) {
+			// end-of-stream
+			return b;
+		}
+		if (m_headBytes < HEAD_MAX) {
+			m_head[m_headBytes] = (byte)b;
+			m_headBytes++;
+		}
+		return b;
+	}
+	
+	public byte[] getHeadBytes() {
+		return Arrays.copyOf(m_head, m_headBytes);
+	}
+}