From e2bb5ec1e640f0c902598701c77c66a4ea31656c Mon Sep 17 00:00:00 2001
From: zima <zima@craftsman-software.com>
Date: Wed, 23 Oct 2024 17:14:49 +0900
Subject: [PATCH] Fix binary detection for text files containing emoji

---
 src/index.ts            | 14 ++++++++++----
 test/fixtures/emoji.txt |  1 +
 test/index.test.ts      |  6 ++++++
 3 files changed, 17 insertions(+), 4 deletions(-)
 create mode 100644 test/fixtures/emoji.txt

diff --git a/src/index.ts b/src/index.ts
index 36a8191..232b1dd 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -223,17 +223,23 @@ function isBinaryCheck(fileBuffer: Buffer, bytesRead: number): boolean {
       return true;
     } else if ((fileBuffer[i] < 7 || fileBuffer[i] > 14) && (fileBuffer[i] < 32 || fileBuffer[i] > 127)) {
       // UTF-8 detection
-      if (fileBuffer[i] > 193 && fileBuffer[i] < 224 && i + 1 < totalBytes) {
+      if (fileBuffer[i] >= 0xc0 && fileBuffer[i] <= 0xdf && i + 1 < totalBytes) {
         i++;
-        if (fileBuffer[i] > 127 && fileBuffer[i] < 192) {
+        if (fileBuffer[i] >= 0x80 && fileBuffer[i] <= 0xbf) {
           continue;
         }
-      } else if (fileBuffer[i] > 223 && fileBuffer[i] < 240 && i + 2 < totalBytes) {
+      } else if (fileBuffer[i] >= 0xe0 && fileBuffer[i] <= 0xef && i + 2 < totalBytes) {
         i++;
-        if (fileBuffer[i] > 127 && fileBuffer[i] < 192 && fileBuffer[i + 1] > 127 && fileBuffer[i + 1] < 192) {
+        if (fileBuffer[i] >= 0x80 && fileBuffer[i] <= 0xbf && fileBuffer[i + 1] >= 0x80 && fileBuffer[i + 1] <= 0xbf) {
           i++;
           continue;
         }
+      } else if (fileBuffer[i] >= 0xf0 && fileBuffer[i] <= 0xf7 && i + 3 < totalBytes) {
+        i++;
+        if (fileBuffer[i] >= 0x80 && fileBuffer[i] <= 0xbf && fileBuffer[i + 1] >= 0x80 && fileBuffer[i + 1] <= 0xbf && fileBuffer[i + 2] >= 0x80 && fileBuffer[i + 2] <= 0xbf) {
+          i += 2;
+          continue;
+        }
       }
 
       suspiciousBytes++;
diff --git a/test/fixtures/emoji.txt b/test/fixtures/emoji.txt
new file mode 100644
index 0000000..9eea5c2
--- /dev/null
+++ b/test/fixtures/emoji.txt
@@ -0,0 +1 @@
+UTF-8 emoji 📦
diff --git a/test/index.test.ts b/test/index.test.ts
index 08c967a..a37a1fe 100644
--- a/test/index.test.ts
+++ b/test/index.test.ts
@@ -292,3 +292,9 @@ describe('sync', () => {
     });
   });
 });
+
+it("should return false on a UTF-8 file with emoji", () => {
+  const file = path.join(FIXTURE_PATH, "emoji.txt");
+  const result = isBinaryFileSync(file);
+  expect(result).toBe(false);
+});