From 452aef1bb1a5ccf986f187b6467d9827b01789f3 Mon Sep 17 00:00:00 2001
From: Gusted <postmaster@gusted.xyz>
Date: Sun, 26 Nov 2023 20:43:51 +0100
Subject: [PATCH] [GITEA] Require Latex code to have a end sequence

- Currently the parser will look for `\[` and `$$` to detect when Latex
code starts, it will look for `\]` and `$$` respectively in order to
determine the end of the code. However if no end is found the parser
assumes the rest of the input is part of the Latex code.
- Adjust the parser's behavior to not allow the case to assume the rest
of the input is part of the Latex code and requires in order to
determine if some input is Latex code that the end sequence is also
specified.
- Example: `\[hello]` would no longer be detected as Latex code with
this patch.
- Added unit tests.
- Resolves https://codeberg.org/forgejo/forgejo/issues/1817
---
 modules/markup/markdown/markdown_test.go     | 12 ++++++++++++
 modules/markup/markdown/math/block_parser.go |  5 +----
 2 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/modules/markup/markdown/markdown_test.go b/modules/markup/markdown/markdown_test.go
index 8f855f1b13..caffe0ea43 100644
--- a/modules/markup/markdown/markdown_test.go
+++ b/modules/markup/markdown/markdown_test.go
@@ -510,6 +510,18 @@ func TestMathBlock(t *testing.T) {
 			"$$a$$",
 			`<pre class="code-block is-loading"><code class="chroma language-math display">a</code></pre>` + nl,
 		},
+		{
+			`\[a b\]`,
+			`<pre class="code-block is-loading"><code class="chroma language-math display">a b</code></pre>` + nl,
+		},
+		{
+			`\[a b]`,
+			`<p>[a b]</p>` + nl,
+		},
+		{
+			`$$a`,
+			`<p>$$a</p>` + nl,
+		},
 	}
 
 	for _, test := range testcases {
diff --git a/modules/markup/markdown/math/block_parser.go b/modules/markup/markdown/math/block_parser.go
index 7f714d7239..f3262c82c0 100644
--- a/modules/markup/markdown/math/block_parser.go
+++ b/modules/markup/markdown/math/block_parser.go
@@ -55,10 +55,7 @@ func (b *blockParser) Open(parent ast.Node, reader text.Reader, pc parser.Contex
 		return node, parser.Close | parser.NoChildren
 	}
 
-	reader.Advance(segment.Len() - 1)
-	segment.Start += 2
-	node.Lines().Append(segment)
-	return node, parser.NoChildren
+	return nil, parser.NoChildren
 }
 
 // Continue parses the current line and returns a result of parsing.