Add support for built-in smudge filters

JGit supports smudge filters defined in repository configuration. The
filters are implemented as external programs filtering content by
accepting the original content (as seen in git's object database) on
stdin and which emit the filtered content on stdout. This content is
then written to the file in the working tree. To run such a filter JGit
has to start an external process and pump data into/from this process.

This commit adds support for built-in smudge filters which are
implemented in Java and which are executed by jgit's main thread. When a
filter is defined in the configuration as
"jgit://builtin/<filterDriverName>/smudge" then JGit will lookup in a
static map whether a builtin filter is registered under this name. If
found such a filter is called to do the filtering.

The functionality in this commit requires that a program using JGit
explicitly calls the JGit API to register built-in implementations for
specific smudge filters. In follow-up commits configuration parameters
will be added which trigger such registrations.

Change-Id: Ia743aa0dbed795e71e5792f35ae55660e0eb3c24

1 files changed, 94 insertions, 0 deletions

diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/util/FilterCommandsTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/util/FilterCommandsTest.java
index 5fb894e911..0d31811257 100644
--- a/org.eclipse.jgit.test/tst/org/eclipse/jgit/util/FilterCommandsTest.java
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/util/FilterCommandsTest.java
@@ -154,4 +154,98 @@ public class FilterCommandsTest extends RepositoryTestCase {
 		config.setString("filter", "test", "clean", null);
 		config.save();
 	}
+
+	@Test
+	public void testBuiltinSmudgeFilter() throws IOException, GitAPIException {
+		String builtinCommandName = "jgit://builtin/test/smudge";
+		FilterCommandRegistry.register(builtinCommandName,
+				new TestCommandFactory('s'));
+		StoredConfig config = git.getRepository().getConfig();
+		config.setString("filter", "test", "smudge", builtinCommandName);
+		config.save();
+
+		writeTrashFile(".gitattributes", "*.txt filter=test");
+		git.add().addFilepattern(".gitattributes").call();
+		git.commit().setMessage("add filter").call();
+
+		writeTrashFile("Test.txt", "Hello again");
+		git.add().addFilepattern("Test.txt").call();
+		assertEquals(
+				"[.gitattributes, mode:100644, content:*.txt filter=test][Test.txt, mode:100644, content:Hello again]",
+				indexState(CONTENT));
+		assertEquals("Hello again", read("Test.txt"));
+		deleteTrashFile("Test.txt");
+		git.checkout().addPath("Test.txt").call();
+		assertEquals("sHseslslsos sasgsasisn", read("Test.txt"));
+
+		writeTrashFile("Test.bin", "Hello again");
+		git.add().addFilepattern("Test.bin").call();
+		assertEquals(
+				"[.gitattributes, mode:100644, content:*.txt filter=test][Test.bin, mode:100644, content:Hello again][Test.txt, mode:100644, content:Hello again]",
+				indexState(CONTENT));
+		deleteTrashFile("Test.bin");
+		git.checkout().addPath("Test.bin").call();
+		assertEquals("Hello again", read("Test.bin"));
+
+		config.setString("filter", "test", "clean", null);
+		config.save();
+
+		git.add().addFilepattern("Test.txt").call();
+		assertEquals(
+				"[.gitattributes, mode:100644, content:*.txt filter=test][Test.bin, mode:100644, content:Hello again][Test.txt, mode:100644, content:sHseslslsos sasgsasisn]",
+				indexState(CONTENT));
+
+		config.setString("filter", "test", "clean", null);
+		config.save();
+	}
+
+	@Test
+	public void testBuiltinCleanAndSmudgeFilter() throws IOException, GitAPIException {
+		String builtinCommandPrefix = "jgit://builtin/test/";
+		FilterCommandRegistry.register(builtinCommandPrefix + "smudge",
+				new TestCommandFactory('s'));
+		FilterCommandRegistry.register(builtinCommandPrefix + "clean",
+				new TestCommandFactory('c'));
+		StoredConfig config = git.getRepository().getConfig();
+		config.setString("filter", "test", "smudge", builtinCommandPrefix+"smudge");
+		config.setString("filter", "test", "clean",
+				builtinCommandPrefix + "clean");
+		config.save();
+
+		writeTrashFile(".gitattributes", "*.txt filter=test");
+		git.add().addFilepattern(".gitattributes").call();
+		git.commit().setMessage("add filter").call();
+
+		writeTrashFile("Test.txt", "Hello again");
+		git.add().addFilepattern("Test.txt").call();
+		assertEquals(
+				"[.gitattributes, mode:100644, content:*.txt filter=test][Test.txt, mode:100644, content:cHceclclcoc cacgcacicn]",
+				indexState(CONTENT));
+		assertEquals("Hello again", read("Test.txt"));
+		deleteTrashFile("Test.txt");
+		git.checkout().addPath("Test.txt").call();
+		assertEquals("scsHscsescslscslscsoscs scsascsgscsascsiscsn",
+				read("Test.txt"));
+
+		writeTrashFile("Test.bin", "Hello again");
+		git.add().addFilepattern("Test.bin").call();
+		assertEquals(
+				"[.gitattributes, mode:100644, content:*.txt filter=test][Test.bin, mode:100644, content:Hello again][Test.txt, mode:100644, content:cHceclclcoc cacgcacicn]",
+				indexState(CONTENT));
+		deleteTrashFile("Test.bin");
+		git.checkout().addPath("Test.bin").call();
+		assertEquals("Hello again", read("Test.bin"));
+
+		config.setString("filter", "test", "clean", null);
+		config.save();
+
+		git.add().addFilepattern("Test.txt").call();
+		assertEquals(
+				"[.gitattributes, mode:100644, content:*.txt filter=test][Test.bin, mode:100644, content:Hello again][Test.txt, mode:100644, content:scsHscsescslscslscsoscs scsascsgscsascsiscsn]",
+				indexState(CONTENT));
+
+		config.setString("filter", "test", "clean", null);
+		config.save();
+	}
+
 }