--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/org/tmatesoft/hg/internal/ProcessExecHelper.java	Wed Mar 21 20:40:28 2012 +0100
@@ -0,0 +1,96 @@
+/*
+ * Copyright (c) 2012 TMate Software Ltd
+ *  
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * For information on how to redistribute this software under
+ * the terms of a license other than GNU General Public License
+ * contact TMate Software at support@hg4j.com
+ */
+package org.tmatesoft.hg.internal;
+
+import java.io.File;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.nio.CharBuffer;
+import java.util.Arrays;
+import java.util.LinkedList;
+import java.util.List;
+
+/**
+ * Utility to run shell commands. Not thread-safe.
+ * Beware of memory overcommitment issue on Linux - suprocess get allocated virtual memory of parent process size
+ * @see http://developers.sun.com/solaris/articles/subprocess/subprocess.html
+ * 
+ * @author Artem Tikhomirov
+ * @author Tmate Software Ltd.
+ */
+public class ProcessExecHelper {
+	private File dir;
+	private int exitValue;
+	private ProcessBuilder pb;
+	
+	public ProcessExecHelper() {
+	}
+	
+	protected List<String> prepareCommand(List<String> cmd) {
+		return cmd;
+	}
+	
+	public CharSequence exec(String... command) throws IOException, InterruptedException {
+		return exec(Arrays.asList(command));
+	}
+
+	public CharSequence exec(List<String> command) throws IOException, InterruptedException {
+		List<String> cmd = prepareCommand(command);
+		if (pb == null) {
+			pb = new ProcessBuilder(cmd).directory(dir).redirectErrorStream(true);
+		} else {
+			pb.command(cmd); // dir and redirect are set
+		}
+		Process p = pb.start();
+		InputStreamReader stdOut = new InputStreamReader(p.getInputStream());
+		LinkedList<CharBuffer> l = new LinkedList<CharBuffer>();
+		int r = -1;
+		CharBuffer b = null;
+		do {
+			if (b == null || b.remaining() < b.capacity() / 3) {
+				b = CharBuffer.allocate(512);
+				l.add(b);
+			}
+			r = stdOut.read(b);
+		} while (r != -1);
+		int total = 0;
+		for (CharBuffer cb : l) {
+			total += cb.position();
+			cb.flip();
+		}
+		CharBuffer res = CharBuffer.allocate(total);
+		for (CharBuffer cb : l) {
+			res.put(cb);
+		}
+		res.flip();
+		p.waitFor();
+		exitValue = p.exitValue();
+		return res;
+	}
+	
+	public int exitValue() {
+		return exitValue;
+	}
+
+	public ProcessExecHelper cwd(File wd) {
+		dir = wd;
+		if (pb != null) {
+			pb.directory(dir);
+		}
+		return this;
+	}
+}