dom/encoding/TextDecoder.cpp

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #include "mozilla/dom/TextDecoder.h"
   8 #include "mozilla/dom/UnionTypes.h"
   9 #include "mozilla/Encoding.h"
  10 #include "mozilla/UniquePtrExtensions.h"
  11 #include "nsContentUtils.h"
  12 #include <stdint.h>
  13
  14 namespace mozilla::dom {
  15
  16 void TextDecoder::Init(const nsAString& aLabel,
  17                        const TextDecoderOptions& aOptions, ErrorResult& aRv) {
  18   // Let encoding be the result of getting an encoding from label.
  19   // If encoding is failure or replacement, throw a RangeError
  20   // (https://encoding.spec.whatwg.org/#dom-textdecoder).
  21   const Encoding* encoding = Encoding::ForLabelNoReplacement(aLabel);
  22   if (!encoding) {
  23     NS_ConvertUTF16toUTF8 label(aLabel);
  24     label.Trim(" \t\n\f\r");
  25     aRv.ThrowRangeError<MSG_ENCODING_NOT_SUPPORTED>(label);
  26     return;
  27   }
  28   InitWithEncoding(WrapNotNull(encoding), aOptions);
  29 }
  30
  31 void TextDecoder::InitWithEncoding(NotNull<const Encoding*> aEncoding,
  32                                    const TextDecoderOptions& aOptions) {
  33   aEncoding->Name(mEncoding);
  34   // Store the flags passed via our options dictionary.
  35   mFatal = aOptions.mFatal;
  36   mIgnoreBOM = aOptions.mIgnoreBOM;
  37
  38   // Create a decoder object for mEncoding.
  39   if (mIgnoreBOM) {
  40     mDecoder = aEncoding->NewDecoderWithoutBOMHandling();
  41   } else {
  42     mDecoder = aEncoding->NewDecoderWithBOMRemoval();
  43   }
  44 }
  45
  46 void TextDecoder::Decode(Span<const uint8_t> aInput, const bool aStream,
  47                          nsAString& aOutDecodedString, ErrorResult& aRv) {
  48   aOutDecodedString.Truncate();
  49
  50   CheckedInt<size_t> needed = mDecoder->MaxUTF16BufferLength(aInput.Length());
  51   if (!needed.isValid() ||
  52       needed.value() > std::numeric_limits<nsAString::size_type>::max()) {
  53     aRv.Throw(NS_ERROR_OUT_OF_MEMORY);
  54     return;
  55   }
  56
  57   if (!aOutDecodedString.SetLength(needed.value(), fallible)) {
  58     aRv.Throw(NS_ERROR_OUT_OF_MEMORY);
  59     return;
  60   }
  61
  62   uint32_t result;
  63   size_t read;
  64   size_t written;
  65   bool hadErrors;
  66   if (mFatal) {
  67     Tie(result, read, written) = mDecoder->DecodeToUTF16WithoutReplacement(
  68         aInput, aOutDecodedString, !aStream);
  69     if (result != kInputEmpty) {
  70       aRv.ThrowTypeError<MSG_DOM_DECODING_FAILED>();
  71       return;
  72     }
  73   } else {
  74     Tie(result, read, written, hadErrors) =
  75         mDecoder->DecodeToUTF16(aInput, aOutDecodedString, !aStream);
  76   }
  77   MOZ_ASSERT(result == kInputEmpty);
  78   MOZ_ASSERT(read == aInput.Length());
  79   MOZ_ASSERT(written <= aOutDecodedString.Length());
  80   Unused << hadErrors;
  81
  82   if (!aOutDecodedString.SetLength(written, fallible)) {
  83     aRv.Throw(NS_ERROR_OUT_OF_MEMORY);
  84     return;
  85   }
  86
  87   // If the internal streaming flag of the decoder object is not set,
  88   // then reset the encoding algorithm state to the default values
  89   if (!aStream) {
  90     if (mIgnoreBOM) {
  91       mDecoder->Encoding()->NewDecoderWithoutBOMHandlingInto(*mDecoder);
  92     } else {
  93       mDecoder->Encoding()->NewDecoderWithBOMRemovalInto(*mDecoder);
  94     }
  95   }
  96 }
  97
  98 void TextDecoder::Decode(const Optional<ArrayBufferViewOrArrayBuffer>& aBuffer,
  99                          const TextDecodeOptions& aOptions,
 100                          nsAString& aOutDecodedString, ErrorResult& aRv) {
 101   if (!aBuffer.WasPassed()) {
 102     Decode(nullptr, aOptions.mStream, aOutDecodedString, aRv);
 103     return;
 104   }
 105   const ArrayBufferViewOrArrayBuffer& buf = aBuffer.Value();
 106   uint8_t* data;
 107   uint32_t length;
 108   if (buf.IsArrayBufferView()) {
 109     buf.GetAsArrayBufferView().ComputeState();
 110     data = buf.GetAsArrayBufferView().Data();
 111     length = buf.GetAsArrayBufferView().Length();
 112   } else {
 113     MOZ_ASSERT(buf.IsArrayBuffer());
 114     buf.GetAsArrayBuffer().ComputeState();
 115     data = buf.GetAsArrayBuffer().Data();
 116     length = buf.GetAsArrayBuffer().Length();
 117   }
 118   Decode(Span(data, length), aOptions.mStream, aOutDecodedString, aRv);
 119 }
 120
 121 void TextDecoder::GetEncoding(nsAString& aEncoding) {
 122   CopyASCIItoUTF16(mEncoding, aEncoding);
 123   nsContentUtils::ASCIIToLower(aEncoding);
 124 }
 125
 126 }  // namespace mozilla::dom