From 992a11007fff6cfd40b952150ab8d30410c4a20a Mon Sep 17 00:00:00 2001
From: Jakob Krigovsky <jakob@krigovsky.com>
Date: Tue, 6 Nov 2018 19:10:49 +0100
Subject: [PATCH] Return null if no charset matches

Fixes a segmentation fault if no charset matches. According to http://icu-project.org/apiref/icu4c/ucsdet_8h.html#aff2633b5055d472cff4108d94f97cf7d, ucsdet_detect() may return NULL if no charset matches.

Fixes: #15
Co-authored-by: chenzhip <letme2010@gmail.com>
---
 README.md      | 2 ++
 icuWrapper.cpp | 6 ++++++
 test/index.js  | 4 ++++
 3 files changed, 12 insertions(+)

diff --git a/README.md b/README.md
index 80ace35e..7cf48de6 100644
--- a/README.md
+++ b/README.md
@@ -27,6 +27,8 @@ console.log(charsetMatch);
 // }
 ```
 
+detect-character-encoding may return `null` if no charset matches.
+
 ## Supported operating systems
 
 - macOS High Sierra
diff --git a/icuWrapper.cpp b/icuWrapper.cpp
index a228fe06..78282d51 100644
--- a/icuWrapper.cpp
+++ b/icuWrapper.cpp
@@ -40,6 +40,12 @@ NAN_METHOD(DetectCharacterEncoding) {
 		return;
 	}
 
+	if(charsetMatch == NULL) {
+		info.GetReturnValue().Set(Nan::Null());
+		ucsdet_close(charsetDetector);
+		return;
+	}
+
 	const char *charsetName = ucsdet_getName(charsetMatch, &errorCode);
 
 	if(U_FAILURE(errorCode)) {
diff --git a/test/index.js b/test/index.js
index ea484e66..a9554799 100644
--- a/test/index.js
+++ b/test/index.js
@@ -18,6 +18,10 @@ it('should return a confidence value', () => {
 	assert(typeof detectCharacterEncoding(getFixture('utf-8.txt')).confidence === 'number');
 });
 
+it('should return null if no charset matches', () => {
+	assert.strictEqual(detectCharacterEncoding(Buffer.from([0xAB])), null);
+});
+
 it('should throw a TypeError if argument is not a buffer', () => {
 	assert.throws(() => {
 		detectCharacterEncoding('string');