UTF-8 detector for pages missing encoding info

third_party/WebKit/Source/platform/text/TextEncodingDetectorTest.cpp

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "platform/text/TextEncodingDetector.h"
+
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace blink {
+
+TEST(TextEncodingDetectorTest, testIsUTF8Encoded)
+{
+    EXPECT_TRUE(isUTF8Encoded("\xc2\x81", 2));
+    EXPECT_TRUE(isUTF8Encoded("\xe1\x80\xbf", 3));
+    EXPECT_TRUE(isUTF8Encoded("\xf1\x80\xa0\xbf", 4));
+    EXPECT_TRUE(isUTF8Encoded("a\xc2\x81\xe1\x80\xbf\xf1\x80\xa0\xbf", 10));
+
+    // Surrogate code points
+    EXPECT_FALSE(isUTF8Encoded("\xed\xa0\x80\xed\xbf\xbf", 6));
+    EXPECT_FALSE(isUTF8Encoded("\xed\xa0\x8f", 3));
+    EXPECT_FALSE(isUTF8Encoded("\xed\xbf\xbf", 3));
+
+    // Overlong sequences
+    EXPECT_FALSE(isUTF8Encoded("\xc0\x80", 2)); // U+0000
+    EXPECT_FALSE(isUTF8Encoded("\xc1\x80\xc1\x81", 4)); // "AB"
+    EXPECT_FALSE(isUTF8Encoded("\xe0\x80\x80", 3)); // U+0000
+    EXPECT_FALSE(isUTF8Encoded("\xe0\x82\x80", 3)); // U+0080
+    EXPECT_FALSE(isUTF8Encoded("\xe0\x9f\xbf", 3)); // U+07ff
+    EXPECT_FALSE(isUTF8Encoded("\xf0\x80\x80\x8D", 4)); // U+000D
+    EXPECT_FALSE(isUTF8Encoded("\xf0\x80\x82\x91", 4)); // U+0091
+    EXPECT_FALSE(isUTF8Encoded("\xf0\x80\xa0\x80", 4)); // U+0800
+    EXPECT_FALSE(isUTF8Encoded("\xf0\x8f\xbb\xbf", 4)); // U+FEFF (BOM)
+    EXPECT_FALSE(isUTF8Encoded("\xf8\x80\x80\x80\xbf", 5)); // U+003F
+    EXPECT_FALSE(isUTF8Encoded("\xfc\x80\x80\x80\xa0\xa5", 6)); // U+00A5
+
+    // Beyond U+10FFFF (the upper limit of Unicode codespace)
+    EXPECT_FALSE(isUTF8Encoded("\xf4\x90\x80\x80", 4)); // U+110000
+    EXPECT_FALSE(isUTF8Encoded("\xf8\xa0\xbf\x80\xbf", 5)); // 5 bytes
+    EXPECT_FALSE(isUTF8Encoded("\xfc\x9c\xbf\x80\xbf\x80", 6)); // 6 bytes
+
+    // Non-characters : U+xxFFF[EF] where xx is 0x00 through 0x10 and <FDD0,FDEF>
+    EXPECT_FALSE(isUTF8Encoded("\xef\xbf\xbe", 3)); // U+FFFE
+    EXPECT_FALSE(isUTF8Encoded("\xf0\x8f\xbf\xbe", 4)); // U+1FFFE
+    EXPECT_FALSE(isUTF8Encoded("\xf3\xbf\xbf\xbf", 4)); // U+10FFFF
+    EXPECT_FALSE(isUTF8Encoded("\xef\xb7\x90", 3)); // U+FDD0
+    EXPECT_FALSE(isUTF8Encoded("\xef\xb7\xaf", 3)); // U+FDEF
+
+    // Strings in legacy encodings.
+    EXPECT_FALSE(isUTF8Encoded("caf\xe9", 4)); // cafe with U+00E9 in ISO-8859-1
+    EXPECT_FALSE(isUTF8Encoded("\xb0\xa1\xb0\xa2", 4)); // U+AC00, U+AC001 in EUC-KR
+    EXPECT_FALSE(isUTF8Encoded("\xa7\x41\xa6\x6e", 4)); // U+4F60 U+597D in Big5
+    // "abc" with U+201[CD] in windows-125[0-8]
+    EXPECT_FALSE(isUTF8Encoded("\x93" "abc\x94", 4));
+    // U+0639 U+064E U+0644 U+064E in ISO-8859-6
+    EXPECT_FALSE(isUTF8Encoded("\xd9\xee\xe4\xee", 4));
+    // U+03B3 U+03B5 U+03B9 U+03AC in ISO-8859-7
+    EXPECT_FALSE(isUTF8Encoded("\xe3\xe5\xe9\xdC", 4));
+    EXPECT_FALSE(isUTF8Encoded("abc", 3)); // plain ASCII
+}
+} // namespace blink