Respect UTF-8 detection result for local file resources

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

 /*
  * Copyright (C) 2008, 2009 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 12 matching lines @@
  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #include "platform/text/TextEncodingDetector.h"
 
+#include "platform/weborigin/KURL.h"
 #include "third_party/ced/src/compact_enc_det/compact_enc_det.h"
 #include "wtf/text/TextEncoding.h"
 
 namespace blink {
 
 bool detectTextEncoding(const char* data,
                         size_t length,
                         const char* hintEncodingName,
                         const char* hintUrl,
                         const char* hintUserLanguage,
                         WTF::TextEncoding* detectedEncoding) {
   *detectedEncoding = WTF::TextEncoding();
   Language language;
   LanguageFromCode(hintUserLanguage, &language);
   int consumedBytes;
   bool isReliable;
   Encoding encoding = CompactEncDet::DetectEncoding(
       data, length, hintUrl, nullptr, nullptr,
       EncodingNameAliasToEncoding(hintEncodingName), language,
       CompactEncDet::WEB_CORPUS,
       false,  // Include 7-bit encodings to detect ISO-2022-JP
       &consumedBytes, &isReliable);
 
   // Should return false if the detected encoding is UTF8. This helps prevent
   // modern web sites from neglecting proper encoding labelling and simply
   // relying on browser-side encoding detection. Encoding detection is supposed
-  // to work for web sites with legacy encoding only. Detection failure leads
-  // |TextResourceDecoder| to use its default encoding determined from system
-  // locale or TLD.
-  if (encoding == UNKNOWN_ENCODING || encoding == UTF8)
+  // to work for web sites with legacy encoding only (so this doesn't have to
+  // be applied to local file resources).
+  // Detection failure leads |TextResourceDecoder| to use its default encoding
+  // determined from system locale or TLD.
+  String protocol = hintUrl ? KURL(ParsedURLString, hintUrl).protocol() : "";
+  if (encoding == UNKNOWN_ENCODING || (protocol != "file" && encoding == UTF8))
     return false;
 
   // Map all the Shift-JIS variants to Shift-JIS.
   if (hintUserLanguage && !strncmp(hintUserLanguage, "ja", 2) &&
       IsShiftJisOrVariant(encoding)) {
     encoding = JAPANESE_SHIFT_JIS;
   }
 
   // 7-bit encodings (except ISO-2022-JP), and some obscure encodings not
   // supported in WHATWG encoding standard are marked as ASCII to keep the raw
@@ skipping 33 matching lines @@
       encoding = ASCII_7BIT;
       break;
     default:
       break;
   }
   *detectedEncoding = WTF::TextEncoding(MimeEncodingName(encoding));
   return true;
 }
 
 }  // namespace blink