From 20ff230b92e62deb4df36da1109818eb6c7e4a3d Mon Sep 17 00:00:00 2001
From: Sungun Park <sungunpark@google.com>
Date: Thu, 11 Jan 2024 12:47:11 -0800
Subject: [PATCH] Fix a json parsing bug (#7490)

When parsing a lexeme, we use one less byte than it's intended to be for
comparing the current string.

This results in a success in cases like:
- true and truX
- false and falsX
- null and nulX
where X means an arbitrary character.

Fix this by the full intended length.
---
 tools/matc/src/matc/JsonishLexer.cpp | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/tools/matc/src/matc/JsonishLexer.cpp b/tools/matc/src/matc/JsonishLexer.cpp
index 3cca02e560..2173693c0a 100644
--- a/tools/matc/src/matc/JsonishLexer.cpp
+++ b/tools/matc/src/matc/JsonishLexer.cpp
@@ -27,9 +27,7 @@ JsonType JsonishLexer::readIdentifier() noexcept {
         consume();
     }
 
-    const char* lexemeEnd = mCursor - 1;
-
-    size_t lexemeSize = lexemeEnd - lexemeStart;
+    size_t lexemeSize = mCursor - lexemeStart;
 
     // Check what kind of keyword we got here.
     if (strncmp("true", lexemeStart, lexemeSize) == 0) {