wildmatch: make /**/ match zero or more directories

"foo/**/bar" matches "foo/x/bar", "foo/x/y/bar"... but not
"foo/bar". We make a special case, when foo/**/ is detected (and
"foo/" part is already matched), try matching "bar" with the rest of
the string.

"Match one or more directories" semantics can be easily achieved using
"foo/*/**/bar".

This also makes "**/foo" match "foo" in addition to "x/foo",
"x/y/foo"..

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t3070-wildmatch.sh

@@ -63,11 +63,17 @@ match 1 1 ']' ']'
 match 0 0 'foo/baz/bar' 'foo*bar'
 match 0 0 'foo/baz/bar' 'foo**bar'
 match 0 1 'foobazbar' 'foo**bar'
+match 1 1 'foo/baz/bar' 'foo/**/bar'
+match 1 0 'foo/baz/bar' 'foo/**/**/bar'
+match 1 0 'foo/b/a/z/bar' 'foo/**/bar'
+match 1 0 'foo/b/a/z/bar' 'foo/**/**/bar'
+match 1 0 'foo/bar' 'foo/**/bar'
+match 1 0 'foo/bar' 'foo/**/**/bar'
 match 0 0 'foo/bar' 'foo?bar'
 match 0 0 'foo/bar' 'foo[/]bar'
 match 0 0 'foo/bar' 'f[^eiu][^eiu][^eiu][^eiu][^eiu]r'
 match 1 1 'foo-bar' 'f[^eiu][^eiu][^eiu][^eiu][^eiu]r'
-match 0 0 'foo' '**/foo'
+match 1 0 'foo' '**/foo'
 match 1 x '/foo' '**/foo'
 match 1 0 'bar/baz/foo' '**/foo'
 match 0 0 'bar/baz/foo' '*/foo'

wildmatch.c

@@ -90,6 +90,18 @@ static int dowild(const uchar *p, const uchar *text, int force_lower_case)
 				if ((prev_p == text || *prev_p == '/') ||
 				    (*p == '\0' || *p == '/' ||
 				     (p[0] == '\\' && p[1] == '/'))) {
+					/*
+					 * Assuming we already match 'foo/' and are at
+					 * <star star slash>, just assume it matches
+					 * nothing and go ahead match the rest of the
+					 * pattern with the remaining string. This
+					 * helps make foo/<*><*>/bar (<> because
+					 * otherwise it breaks C comment syntax) match
+					 * both foo/bar and foo/a/bar.
+					 */
+					if (p[0] == '/' &&
+					    dowild(p + 1, text, force_lower_case) == MATCH)
+						return MATCH;
 					special = TRUE;
 				} else
 					return ABORT_MALFORMED;