From 7c85b89aae85d397e0dafec28d7e4e384c59fa6c Mon Sep 17 00:00:00 2001
From: Mick Grove <mick.grove@mongodb.com>
Date: Wed, 8 Oct 2025 08:59:25 -0700
Subject: [PATCH] =?UTF-8?q?Fixed=20tree-sitter=20scanning=20bug=20where=20?=
 =?UTF-8?q?passing=20--no-base64=20caused=20errors=20to=20be=20printed=20w?=
 =?UTF-8?q?hen=20the=20file=20type=20couldn=E2=80=99t=20be=20determined?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 CHANGELOG.md        |  3 +++
 src/matcher.rs      | 15 +++++++++++----
 tests/int_base64.rs | 26 ++++++++++++++++++++++++++
 3 files changed, 40 insertions(+), 4 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4e1349d..1278533 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,9 @@
 
 All notable changes to this project will be documented in this file.
 
+## [v1.56.0]
+- Fixed tree-sitter scanning bug where passing --no-base64 caused errors to be printed when the file type couldn’t be determined
+
 ## [v1.55.0]
 - Added first-class Azure Repos support, including CLI commands, enumeration, and documentation updates
 - Improved performance of tree-sitter parsing
diff --git a/src/matcher.rs b/src/matcher.rs
index 08045d8..024df55 100644
--- a/src/matcher.rs
+++ b/src/matcher.rs
@@ -39,7 +39,8 @@ use crate::{
 const MAX_CHUNK_SIZE: usize = 1 << 30; // 1 GiB per scan segment
 const CHUNK_OVERLAP: usize = 64 * 1024; // 64 KiB overlap to catch boundary matches
 const BASE64_SCAN_LIMIT: usize = 64 * 1024 * 1024; // skip expensive Base64 pass on huge blobs
-const TREE_SITTER_SCAN_LIMIT: usize = 64 * 1024; // only run tree-sitter on blobs ≤64 KiB
+const TREE_SITTER_MAX_LIMIT: usize = 64 * 1024; // only run tree-sitter on blobs <= 64 KiB
+const TREE_SITTER_MIN_LIMIT: usize = 1 * 1024; // only run tree-sitter on blobs >= 1 KiB
 
 // -------------------------------------------------------------------------------------------------
 // RawMatch
@@ -324,15 +325,21 @@ impl<'a> Matcher<'a> {
         let has_raw_matches = !self.user_data.raw_matches_scratch.is_empty();
         let has_base64_items = !b64_items.is_empty();
 
-        if !has_raw_matches && !has_base64_items && !(no_base64 && lang_hint.is_some()) {
+        if !has_raw_matches && !has_base64_items {
             return Ok(ScanResult::New(Vec::new()));
         }
 
         let rules_db = self.rules_db;
         let mut seen_matches = FxHashSet::default();
         let mut previous_matches: FxHashMap<usize, Vec<OffsetSpan>> = FxHashMap::default();
-        let should_run_tree_sitter = blob.len() <= TREE_SITTER_SCAN_LIMIT
-            && (has_raw_matches || (no_base64 && lang_hint.is_some()));
+        
+        let should_run_tree_sitter = blob.len() > 0
+            && blob.len() <= TREE_SITTER_MAX_LIMIT
+            && blob.len() >= TREE_SITTER_MIN_LIMIT
+            && has_raw_matches
+            && lang_hint.is_some()
+            && !no_base64; //tree-sitter parsing is turned off when base64 scanning is disabled
+
         let tree_sitter_result = if should_run_tree_sitter {
             lang_hint.and_then(|lang_str| {
                 get_language_and_queries(lang_str).and_then(|(language, queries)| {
diff --git a/tests/int_base64.rs b/tests/int_base64.rs
index 994ce2a..c580451 100644
--- a/tests/int_base64.rs
+++ b/tests/int_base64.rs
@@ -61,6 +61,32 @@ fn skips_base64_when_disabled() -> anyhow::Result<()> {
     Ok(())
 }
 
+// Ensure disabling Base64 decoding does not trigger tree-sitter errors on empty files
+#[test]
+fn no_base64_skips_empty_files() -> anyhow::Result<()> {
+    let dir = tempdir()?;
+    let file_path = dir.path().join("empty.py");
+    fs::write(&file_path, "")?;
+
+    Command::cargo_bin("kingfisher")?
+        .args([
+            "scan",
+            dir.path().to_str().unwrap(),
+            "--no-binary",
+            "--no-base64",
+            "--confidence=low",
+            "--format",
+            "json",
+            "--no-update-check",
+        ])
+        .assert()
+        .code(0)
+        .stdout(predicate::str::contains("Source code is empty").not());
+
+    dir.close()?;
+    Ok(())
+}
+
 // Ensure tree-sitter based decoding works even when the standalone base64 scanner is disabled
 #[test]
 fn detects_base64_in_code_with_tree_sitter() -> anyhow::Result<()> {