Prepare RawText for diff-index and diff-files

Bug: 291083
Eclipse-CQ: 3559
Change-Id: Ia02f346a96b5f1e24f8bc9676bd428b968a41222
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

org.eclipse.jgit/src/org/eclipse/jgit/diff/RawText.java

@@ -44,6 +44,8 @@
 
 package org.eclipse.jgit.diff;
 
+import java.io.File;
+import java.io.FileInputStream;
 import java.io.IOException;
 import java.io.OutputStream;
 
@@ -87,6 +89,18 @@ public class RawText implements Sequence {
 		hashes = computeHashes();
 	}
 
+	/**
+	 * Create a new sequence from a file.
+	 * <p>
+	 * The entire file contents are used.
+	 *
+	 * @param file
+	 *            the text file.
+	 */
+	public RawText(File file) throws IOException {
+		this(readFile(file));
+	}
+
 	public int size() {
 		// The line map is always 2 entries larger than the number of lines in
 		// the file. Index 0 is padded out/unused. The last index is the total
@@ -187,4 +201,16 @@ public class RawText implements Sequence {
 			hash = (hash << 5) ^ (raw[ptr] & 0xff);
 		return hash;
 	}
+
+	private static byte[] readFile(File file) throws IOException {
+		byte[] result = new byte[(int)file.length()];
+		FileInputStream in = new FileInputStream(file);
+		for (int off = 0; off < result.length; ) {
+			int read = in.read(result, off, result.length - off);
+			if (read < 0)
+				throw new IOException("Early EOF");
+			off += read;
+		}
+		return result;
+	}
 }