Trim unsupported OSC sequences (#4169)

Fix #4169

src/ansi.go

@@ -98,11 +98,11 @@ func isPrint(c uint8) bool {
 	return '\x20' <= c && c <= '\x7e'
 }
 
-func matchOperatingSystemCommand(s string) int {
+func matchOperatingSystemCommand(s string, start int) int {
 	// `\x1b][0-9][;:][[:print:]]+(?:\x1b\\\\|\x07)`
-	//                        ^ match starting here
+	//                 ^ match starting here after the first printable character
 	//
-	i := 5 // prefix matched in nextAnsiEscapeSequence()
+	i := start // prefix matched in nextAnsiEscapeSequence()
 	for ; i < len(s) && isPrint(s[i]); i++ {
 	}
 	if i < len(s) {
@@ -156,7 +156,7 @@ func isCtrlSeqStart(c uint8) bool {
 // nextAnsiEscapeSequence returns the ANSI escape sequence and is equivalent to
 // calling FindStringIndex() on the below regex (which was originally used):
 //
-// "(?:\x1b[\\[()][0-9;:?]*[a-zA-Z@]|\x1b][0-9][;:][[:print:]]+(?:\x1b\\\\|\x07)|\x1b.|[\x0e\x0f]|.\x08)"
+// "(?:\x1b[\\[()][0-9;:?]*[a-zA-Z@]|\x1b][0-9]+[;:][[:print:]]+(?:\x1b\\\\|\x07)|\x1b.|[\x0e\x0f]|.\x08)"
 func nextAnsiEscapeSequence(s string) (int, int) {
 	// fast check for ANSI escape sequences
 	i := 0
@@ -191,12 +191,20 @@ Loop:
 				}
 			}
 
-			// match: `\x1b][0-9][;:][[:print:]]+(?:\x1b\\\\|\x07)`
-			if i+5 < len(s) && s[i+1] == ']' && isNumeric(s[i+2]) &&
-				(s[i+3] == ';' || s[i+3] == ':') && isPrint(s[i+4]) {
+			// match: `\x1b][0-9]+[;:][[:print:]]+(?:\x1b\\\\|\x07)`
+			if i+5 < len(s) && s[i+1] == ']' {
+				j := 2
+				// \x1b][0-9]+[;:][[:print:]]+(?:\x1b\\\\|\x07)
+				//      ------
+				for ; i+j < len(s) && isNumeric(s[i+j]); j++ {
+				}
 
-				if j := matchOperatingSystemCommand(s[i:]); j != -1 {
-					return i, i + j
+				// \x1b][0-9]+[;:][[:print:]]+(?:\x1b\\\\|\x07)
+				//            ---------------
+				if j > 2 && i+j+1 < len(s) && (s[i+j] == ';' || s[i+j] == ':') && isPrint(s[i+j+1]) {
+					if k := matchOperatingSystemCommand(s[i:], j+2); k != -1 {
+						return i, i + k
+					}
 				}
 			}
 

src/ansi_test.go

@@ -337,17 +337,25 @@ func TestExtractColor(t *testing.T) {
 	})
 
 	state = nil
+	var color24 tui.Color = (1 << 24) + (180 << 16) + (190 << 8) + 254
 	src = "\x1b[1mhello \x1b[22;1;38:2:180:190:254mworld"
 	check(func(offsets *[]ansiOffset, state *ansiState) {
 		if len(*offsets) != 2 {
 			t.Fail()
 		}
-		var color tui.Color = (1 << 24) + (180 << 16) + (190 << 8) + 254
-		if state.fg != color || state.attr != 1 {
+		if state.fg != color24 || state.attr != 1 {
 			t.Fail()
 		}
 		assert((*offsets)[0], 0, 6, -1, -1, true)
-		assert((*offsets)[1], 6, 11, color, -1, true)
+		assert((*offsets)[1], 6, 11, color24, -1, true)
+	})
+
+	src = "\x1b]133;A\x1b\\hello \x1b]133;C\x1b\\world"
+	check(func(offsets *[]ansiOffset, state *ansiState) {
+		if len(*offsets) != 1 {
+			t.Fail()
+		}
+		assert((*offsets)[0], 0, 11, color24, -1, true)
 	})
 }