From 1bfacb8fe9720cc690d73c69a99febd40d1ddfad Mon Sep 17 00:00:00 2001
From: Shadowfacts <me@shadowfacts.net>
Date: Tue, 6 Feb 2024 18:53:47 -0500
Subject: [PATCH] Fix crash when converting malformed HTML with unmatched
 closing tag

---
 Sources/HTMLStreamer/AttributedStringConverter.swift      | 8 +++++---
 Sources/HTMLStreamer/TextConverter.swift                  | 8 +++++---
 .../AttributedStringConverterTests.swift                  | 4 ++++
 Tests/HTMLStreamerTests/TextConverterTests.swift          | 4 ++++
 4 files changed, 18 insertions(+), 6 deletions(-)

diff --git a/Sources/HTMLStreamer/AttributedStringConverter.swift b/Sources/HTMLStreamer/AttributedStringConverter.swift
index 7dd826f..5375086 100644
--- a/Sources/HTMLStreamer/AttributedStringConverter.swift
+++ b/Sources/HTMLStreamer/AttributedStringConverter.swift
@@ -75,10 +75,12 @@ public struct AttributedStringConverter<Callbacks: HTMLConversionCallbacks> {
             case .endTag(let name):
                 handleEndTag(name)
                 // if we have a non-default action for the current element, the run finishes here
-                if actionStack.last != .default {
-                    finishRun()
+                if let action = actionStack.last {
+                    if action != .default {
+                        finishRun()
+                    }
+                    actionStack.removeLast()
                 }
-                actionStack.removeLast()
             case .doctype:
                 // ignored
                 continue
diff --git a/Sources/HTMLStreamer/TextConverter.swift b/Sources/HTMLStreamer/TextConverter.swift
index b302582..8271aa6 100644
--- a/Sources/HTMLStreamer/TextConverter.swift
+++ b/Sources/HTMLStreamer/TextConverter.swift
@@ -55,10 +55,12 @@ public struct TextConverter<Callbacks: HTMLConversionCallbacks> {
                 handleStartTag(name, selfClosing: selfClosing, attributes: attributes)
             case .endTag(let name):
                 handleEndTag(name)
-                if actionStack.last != .default {
-                    finishRun()
+                if let action = actionStack.last {
+                    if action != .default {
+                        finishRun()
+                    }
+                    actionStack.removeLast()
                 }
-                actionStack.removeLast()
             case .comment, .doctype:
                 break
             }
diff --git a/Tests/HTMLStreamerTests/AttributedStringConverterTests.swift b/Tests/HTMLStreamerTests/AttributedStringConverterTests.swift
index e574a31..6df0da9 100644
--- a/Tests/HTMLStreamerTests/AttributedStringConverterTests.swift
+++ b/Tests/HTMLStreamerTests/AttributedStringConverterTests.swift
@@ -352,4 +352,8 @@ final class AttributedStringConverterTests: XCTestCase {
         XCTAssertEqual(convert(#"<a href="https://example.com"><span class="invisible">https://</span><span>example.com</span><span class="invisible"></span></a>"#, callbacks: Callbacks.self), result)
     }
     
+    func testMalformedOnlyClosingTag() {
+        XCTAssertEqual(convert("</span>"), .init())
+    }
+    
 }
diff --git a/Tests/HTMLStreamerTests/TextConverterTests.swift b/Tests/HTMLStreamerTests/TextConverterTests.swift
index 09858f9..0ad8ff1 100644
--- a/Tests/HTMLStreamerTests/TextConverterTests.swift
+++ b/Tests/HTMLStreamerTests/TextConverterTests.swift
@@ -83,4 +83,8 @@ final class TextConverterTests: XCTestCase {
         XCTAssertEqual(convert(#"<a href="https://example.com"><span class="invisible">https://</span><span>example.com</span><span class="invisible"></span></a>"#, callbacks: Callbacks.self), "example.com")
     }
     
+    func testMalformedOnlyClosingTag() {
+        XCTAssertEqual(convert("</span>"), "")
+    }
+    
 }