Set git environment variables for hooks

Set GIT_DIR and GIT_WORK_TREE when calling hooks.

Bug: 541622
Change-Id: I6153d8a6a934ec37a3a5e7319c2d0e516f539ab7
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>

org.eclipse.jgit.test/tst/org/eclipse/jgit/util/HookTest.java

@@ -199,7 +199,8 @@ public class HookTest extends RepositoryTestCase {
 		assumeSupportedPlatform();
 
 		writeHookFile(PreCommitHook.NAME,
-				"#!/bin/sh\necho \"test $1 $2\"\nread INPUT\necho $INPUT\necho 1>&2 \"stderr\"");
+				"#!/bin/sh\necho \"test $1 $2\"\nread INPUT\necho $INPUT\n"
+						+ "echo $GIT_DIR\necho $GIT_WORK_TREE\necho 1>&2 \"stderr\"");
 		ByteArrayOutputStream out = new ByteArrayOutputStream();
 		ByteArrayOutputStream err = new ByteArrayOutputStream();
 		ProcessResult res = FS.DETECTED.runHookIfPresent(db,
@@ -208,7 +209,9 @@ public class HookTest extends RepositoryTestCase {
 				"arg1", "arg2" },
 				new PrintStream(out), new PrintStream(err), "stdin");
 
-		assertEquals("unexpected hook output", "test arg1 arg2\nstdin\n",
+		assertEquals("unexpected hook output",
+				"test arg1 arg2\nstdin\n" + db.getDirectory().getAbsolutePath()
+						+ '\n' + db.getWorkTree().getAbsolutePath() + '\n',
 				out.toString("UTF-8"));
 		assertEquals("unexpected output on stderr stream", "stderr\n",
 				err.toString("UTF-8"));

org.eclipse.jgit/src/org/eclipse/jgit/util/FS.java

@@ -1110,6 +1110,13 @@ public abstract class FS {
 				hookPath);
 		ProcessBuilder hookProcess = runInShell(cmd, args);
 		hookProcess.directory(runDirectory);
+		Map<String, String> environment = hookProcess.environment();
+		environment.put(Constants.GIT_DIR_KEY,
+				repository.getDirectory().getAbsolutePath());
+		if (!repository.isBare()) {
+			environment.put(Constants.GIT_WORK_TREE_KEY,
+					repository.getWorkTree().getAbsolutePath());
+		}
 		try {
 			return new ProcessResult(runProcess(hookProcess, outRedirect,
 					errRedirect, stdinArgs), Status.OK);