Strings#convertGlob: fix escaping of patterns like [\[].

Originally the patterns were escaped twice leading
to wrong matching results.

Bug: 528886
Change-Id: I26e201b4b0ef51cac08f940b76f381260fa925ca
Signed-off-by: Dmitry Pavlenko <pavlenko@tmatesoft.com>
Signed-off-by: David Pursehouse <david.pursehouse@gmail.com>

org.eclipse.jgit.test/tst/org/eclipse/jgit/attributes/AttributesMatcherTest.java

@@ -382,6 +382,39 @@ public class AttributesMatcherTest {
 		assertEquals(r.getAttributes().get(2).toString(), "attribute3=value");
 	}
 
+	@Test
+	public void testBracketsInGroup() {
+		//combinations of brackets in brackets, escaped and not
+
+		String[] patterns = new String[]{"[[\\]]", "[\\[\\]]"};
+		for (String pattern : patterns) {
+			assertNotMatched(pattern, "");
+			assertNotMatched(pattern, "[]");
+			assertNotMatched(pattern, "][");
+			assertNotMatched(pattern, "[\\[]");
+			assertNotMatched(pattern, "[[]");
+			assertNotMatched(pattern, "[[]]");
+			assertNotMatched(pattern, "[\\[\\]]");
+
+			assertMatched(pattern, "[");
+			assertMatched(pattern, "]");
+		}
+
+		patterns = new String[]{"[[]]", "[\\[]]"};
+		for (String pattern : patterns) {
+			assertNotMatched(pattern, "");
+			assertMatched(pattern, "[]");
+			assertNotMatched(pattern, "][");
+			assertNotMatched(pattern, "[\\[]");
+			assertNotMatched(pattern, "[[]");
+			assertNotMatched(pattern, "[[]]");
+			assertNotMatched(pattern, "[\\[\\]]");
+
+			assertNotMatched(pattern, "[");
+			assertNotMatched(pattern, "]");
+		}
+	}
+
 	/**
 	 * Check for a match. If target ends with "/", match will assume that the
 	 * target is meant to be a directory.

org.eclipse.jgit.test/tst/org/eclipse/jgit/attributes/CGitAttributesTest.java

@@ -378,4 +378,12 @@ public class CGitAttributesTest extends RepositoryTestCase {
 		writeTrashFile(".gitattributes", "new/ bar\n");
 		assertSameAsCGit();
 	}
+
+	@Test
+	public void testBracketsInGroup() throws Exception {
+		createFiles("[", "]", "[]", "][", "[[]", "[]]", "[[]]");
+		writeTrashFile(".gitattributes", "[[]] bar1\n" + "[\\[]] bar2\n"
+				+ "[[\\]] bar3\n" + "[\\[\\]] bar4\n");
+		assertSameAsCGit();
+	}
 }

org.eclipse.jgit.test/tst/org/eclipse/jgit/ignore/CGitIgnoreTest.java

@@ -241,4 +241,31 @@ public class CGitIgnoreTest extends RepositoryTestCase {
 		assertSameAsCGit();
 	}
 
+	@Test
+	public void testUnescapedBracketsInGroup() throws Exception {
+		createFiles("[", "]", "[]", "][", "[[]", "[]]", "[[]]");
+		writeTrashFile(".gitignore", "[[]]\n");
+		assertSameAsCGit();
+	}
+
+	@Test
+	public void testEscapedFirstBracketInGroup() throws Exception {
+		createFiles("[", "]", "[]", "][", "[[]", "[]]", "[[]]");
+		writeTrashFile(".gitignore", "[\\[]]\n");
+		assertSameAsCGit();
+	}
+
+	@Test
+	public void testEscapedSecondBracketInGroup() throws Exception {
+		createFiles("[", "]", "[]", "][", "[[]", "[]]", "[[]]");
+		writeTrashFile(".gitignore", "[[\\]]\n");
+		assertSameAsCGit();
+	}
+
+	@Test
+	public void testEscapedBothBracketsInGroup() throws Exception {
+		createFiles("[", "]", "[]", "][", "[[]", "[]]", "[[]]");
+		writeTrashFile(".gitignore", "[\\[\\]]\n");
+		assertSameAsCGit();
+	}
 }

org.eclipse.jgit/src/org/eclipse/jgit/ignore/internal/Strings.java

@@ -363,7 +363,10 @@ public class Strings {
 
 			case '[':
 				if (in_brackets > 0) {
-					sb.append('\\').append('[');
+					if (!seenEscape) {
+						sb.append('\\');
+					}
+					sb.append('[');
 					ignoreLastBracket = true;
 				} else {
 					if (!seenEscape) {