From 28db7d06dc30de2f4121bf6e47668ca4493accfc Mon Sep 17 00:00:00 2001
From: Matthias Diester <mddiester@gmail.com>
Date: Sat, 4 Jan 2025 23:02:43 +0100
Subject: [PATCH] Fix operating system command sequence panic

Ref: https://github.com/homeport/termshot/issues/220
Ref: https://github.com/homeport/termshot/issues/102

Change skip logic to support both BEL and ST as terminator.
---
 parse.go      | 15 +++++++++++----
 parse_test.go | 12 ++++++++++++
 2 files changed, 23 insertions(+), 4 deletions(-)

diff --git a/parse.go b/parse.go
index 69b873c..f8fcbd6 100644
--- a/parse.go
+++ b/parse.go
@@ -31,6 +31,11 @@ import (
 	"strings"
 )
 
+const (
+	bel = '\a' // bel (Bell)
+	st  = '\\' // st (String Terminator)
+)
+
 var (
 	escapeSeqRegExp = regexp.MustCompile(`\x1b\[(\d+(;\d+)*)m`)
 	boldMarker      = regexp.MustCompile(`\*([^*]+?)\*`)
@@ -93,15 +98,17 @@ func ParseStream(in io.Reader, opts ...ParseOption) (*String, error) {
 		panic("failed to parse ANSI sequence")
 	}
 
-	var skipUntil = func(end rune) {
+	var skipUntil = func(ends ...rune) {
 		for {
 			r, _, err := input.ReadRune()
 			if err == io.EOF {
 				panic("reached end of file before reaching end identifier")
 			}
 
-			if r == end {
-				return
+			for _, end := range ends {
+				if r == end {
+					return
+				}
 			}
 		}
 	}
@@ -169,7 +176,7 @@ func ParseStream(in io.Reader, opts ...ParseOption) (*String, error) {
 			}
 
 		case ']':
-			skipUntil('\a')
+			skipUntil(bel, st)
 		}
 	}
 
diff --git a/parse_test.go b/parse_test.go
index 0ba8e55..3997489 100644
--- a/parse_test.go
+++ b/parse_test.go
@@ -54,6 +54,18 @@ var _ = Describe("parse input string", func() {
 			Expect(err).ToNot(HaveOccurred())
 			Expect(result.String()).To(Equal("Hello, \x1b[1mWorld\x1b[0m!"))
 		})
+
+		It("should process Operating System Command sequences that terminate on bell", func() {
+			result, err := ParseStream(strings.NewReader("\x1b]2;title\a"))
+			Expect(err).ToNot(HaveOccurred())
+			Expect(result).ToNot(BeNil())
+		})
+
+		It("should process Operating System Command sequences that terminate string terminator", func() {
+			result, err := ParseStream(strings.NewReader("\x1b]7;file://host/home/foobar/dir\x1b\\"))
+			Expect(err).ToNot(HaveOccurred())
+			Expect(result).ToNot(BeNil())
+		})
 	})
 
 	Context("parse Select Graphic Rendition (SGR) based input", func() {