[ignore rules] fix for handling unmatched '[' brackets

This patch makes JGit parsing of ignore rules containing unmatched '['
bracket compatible to the Git CLI.

Since '[' starts character group, Git tries to parse the ignore rule as
a shell glob pattern and if the character group is not closed, the glob
pattern is invalid and so the ignore rule never matches anything.

See also http://article.gmane.org/gmane.comp.version-control.git/278699.

Bug: 478490
Change-Id: I734a4d14fcdd721070e3f75d57e33c2c0700d503
Signed-off-by: Andrey Loskutov <loskutov@gmx.de>

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

@@ -54,6 +54,7 @@ public class FastIgnoreRuleTest {
 
 	@Test
 	public void testSimpleCharClass() {
+		assertMatched("][a]", "]a");
 		assertMatched("[a]", "a");
 		assertMatched("][a]", "]a");
 		assertMatched("[a]", "a/");

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

@@ -768,7 +768,7 @@ public class IgnoreRuleSpecialCasesTest {
 
 	@Test
 	public void testSpecialGroupCase9() throws Exception {
-		assertMatch("][", "][", true);
+		assertMatch("][", "][", false);
 	}
 
 	@Test
@@ -968,6 +968,59 @@ public class IgnoreRuleSpecialCasesTest {
 		assertMatch("[a{}()b][a{}()b]?[a{}()b][a{}()b]", "{}x()", true);
 		assertMatch("x*{x}3", "xa{x}3", true);
 		assertMatch("a*{x}3", "axxx", false);
+
+		assertMatch("?", "[", true);
+		assertMatch("*", "[", true);
+
+		// Escaped bracket matches, but see weird things below...
+		assertMatch("\\[", "[", true);
+	}
+
+	/**
+	 * The ignore rules here <b>do not match</b> any paths because single '['
+	 * begins character group and the entire rule cannot be parsed due the
+	 * invalid glob pattern. See
+	 * http://article.gmane.org/gmane.comp.version-control.git/278699.
+	 *
+	 * @throws Exception
+	 */
+	@Test
+	public void testBracketsUnmatched1() throws Exception {
+		assertMatch("[", "[", false);
+		assertMatch("[*", "[", false);
+		assertMatch("*[", "[", false);
+		assertMatch("*[", "a[", false);
+		assertMatch("[a][", "a[", false);
+		assertMatch("*[", "a", false);
+		assertMatch("[a", "a", false);
+		assertMatch("[*", "a", false);
+		assertMatch("[*a", "a", false);
+	}
+
+	/**
+	 * Single ']' is treated here literally, not as an and of a character group
+	 *
+	 * @throws Exception
+	 */
+	@Test
+	public void testBracketsUnmatched2() throws Exception {
+		assertMatch("*]", "a", false);
+		assertMatch("]a", "a", false);
+		assertMatch("]*", "a", false);
+		assertMatch("]*a", "a", false);
+
+		assertMatch("]", "]", true);
+		assertMatch("]*", "]", true);
+		assertMatch("]*", "]a", true);
+		assertMatch("*]", "]", true);
+		assertMatch("*]", "a]", true);
+	}
+
+	@Test
+	public void testBracketsRandom() throws Exception {
+		assertMatch("[\\]", "[$0+//r4a\\d]", false);
+		assertMatch("[:]]sZX]", "[:]]sZX]", false);
+		assertMatch("[:]]:]]]", "[:]]:]]]", false);
 	}
 
 	@Test

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

@@ -141,9 +141,7 @@ public class Strings {
 	private static boolean isComplexWildcard(String pattern) {
 		int idx1 = pattern.indexOf('[');
 		if (idx1 != -1) {
-			int idx2 = pattern.indexOf(']', idx1);
-			if (idx2 > idx1)
-				return true;
+			return true;
 		}
 		if (pattern.indexOf('?') != -1) {
 			return true;