path/path: Avoid removing wildcard in front of /..

closes golang#37552

src/path/filepath/path.go

@@ -124,10 +124,17 @@ func Clean(path string) string {
 			r += 2
 			switch {
 			case out.w > dotdot:
-				// can backtrack
-				out.w--
-				for out.w > dotdot && !os.IsPathSeparator(out.index(out.w)) {
+				// can backtrack, the first '3' in index means the length of '/..'
+				if out.path[r-3-3] == '.' && out.path[r-3-2] == '.' && out.path[r-3-1] == '.' {
+					out.append(Separator)
+					out.append('.')
+					out.append('.')
+					dotdot = out.w
+				} else {
 					out.w--
+					for out.w > dotdot && !os.IsPathSeparator(out.index(out.w)) {
+						out.w--
+					}
 				}
 			case !rooted:
 				// cannot backtrack, but not rooted, so append .. element.

src/path/filepath/path_test.go

@@ -34,6 +34,7 @@ var cleantests = []PathTest{
 	{"../../abc", "../../abc"},
 	{"/abc", "/abc"},
 	{"/", "/"},
+	{"abc/def/.../..", "abc/def/.../.."},
 
 	// Empty is current dir
 	{"", "."},

src/path/path.go

@@ -105,9 +105,16 @@ func Clean(path string) string {
 			switch {
 			case out.w > dotdot:
 				// can backtrack
-				out.w--
-				for out.w > dotdot && out.index(out.w) != '/' {
+				if out.s[r-3-3] == '.' && out.s[r-3-2] == '.' && out.s[r-3-1] == '.' {
+					out.append('/')
+					out.append('.')
+					out.append('.')
+					dotdot = out.w
+				} else {
 					out.w--
+					for out.w > dotdot && out.index(out.w) != '/' {
+						out.w--
+					}
 				}
 			case !rooted:
 				// cannot backtrack, but not rooted, so append .. element.

src/path/path_test.go

@@ -25,6 +25,7 @@ var cleantests = []PathTest{
 	{"../../abc", "../../abc"},
 	{"/abc", "/abc"},
 	{"/", "/"},
+	{"../../abc/.../..", "../../abc/.../.."},
 
 	// Remove trailing slash
 	{"abc/", "abc"},