summaryrefslogtreecommitdiffstats
path: root/dom/encoding/TextDecoder.cpp
blob: c31f18ee19d6701738044bf2d34155a2be7beda3 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "mozilla/dom/TextDecoder.h"
#include "mozilla/dom/EncodingUtils.h"
#include "mozilla/dom/UnionTypes.h"
#include "mozilla/UniquePtrExtensions.h"
#include "nsContentUtils.h"
#include <stdint.h>

namespace mozilla {
namespace dom {

static const char16_t kReplacementChar = static_cast<char16_t>(0xFFFD);

void
TextDecoder::Init(const nsAString& aLabel, const bool aFatal,
                  ErrorResult& aRv)
{
  nsAutoCString encoding;
  // Let encoding be the result of getting an encoding from label.
  // If encoding is failure or replacement, throw a RangeError
  // (https://encoding.spec.whatwg.org/#dom-textdecoder).
  if (!EncodingUtils::FindEncodingForLabelNoReplacement(aLabel, encoding)) {
    nsAutoString label(aLabel);
    EncodingUtils::TrimSpaceCharacters(label);
    aRv.ThrowRangeError<MSG_ENCODING_NOT_SUPPORTED>(label);
    return;
  }
  InitWithEncoding(encoding, aFatal);
}

void
TextDecoder::InitWithEncoding(const nsACString& aEncoding, const bool aFatal)
{
  mEncoding = aEncoding;
  // If the constructor is called with an options argument,
  // and the fatal property of the dictionary is set,
  // set the internal fatal flag of the decoder object.
  mFatal = aFatal;

  // Create a decoder object for mEncoding.
  mDecoder = EncodingUtils::DecoderForEncoding(mEncoding);

  if (mFatal) {
    mDecoder->SetInputErrorBehavior(nsIUnicodeDecoder::kOnError_Signal);
  }
}

void
TextDecoder::Decode(const char* aInput, const int32_t aLength,
                    const bool aStream, nsAString& aOutDecodedString,
                    ErrorResult& aRv)
{
  aOutDecodedString.Truncate();

  // Run or resume the decoder algorithm of the decoder object's encoder.
  int32_t outLen;
  nsresult rv = mDecoder->GetMaxLength(aInput, aLength, &outLen);
  if (NS_FAILED(rv)) {
    aRv.Throw(rv);
    return;
  }
  // Need a fallible allocator because the caller may be a content
  // and the content can specify the length of the string.
  auto buf = MakeUniqueFallible<char16_t[]>(outLen + 1);
  if (!buf) {
    aRv.Throw(NS_ERROR_OUT_OF_MEMORY);
    return;
  }

  int32_t length = aLength;
  rv = mDecoder->Convert(aInput, &length, buf.get(), &outLen);
  MOZ_ASSERT(mFatal || rv != NS_ERROR_ILLEGAL_INPUT);
  buf[outLen] = 0;

  if (!aOutDecodedString.Append(buf.get(), outLen, fallible)) {
    aRv.Throw(NS_ERROR_OUT_OF_MEMORY);
    return;
  }

  // If the internal streaming flag of the decoder object is not set,
  // then reset the encoding algorithm state to the default values
  if (!aStream) {
    mDecoder->Reset();
    if (rv == NS_OK_UDEC_MOREINPUT) {
      if (mFatal) {
        aRv.ThrowTypeError<MSG_DOM_DECODING_FAILED>();
      } else {
        // Need to emit a decode error manually
        // to simulate the EOF handling of the Encoding spec.
        aOutDecodedString.Append(kReplacementChar);
      }
    }
  }

  if (NS_FAILED(rv)) {
    aRv.ThrowTypeError<MSG_DOM_DECODING_FAILED>();
  }
}

void
TextDecoder::Decode(const Optional<ArrayBufferViewOrArrayBuffer>& aBuffer,
                    const TextDecodeOptions& aOptions,
                    nsAString& aOutDecodedString,
                    ErrorResult& aRv)
{
  if (!aBuffer.WasPassed()) {
    Decode(nullptr, 0, aOptions.mStream, aOutDecodedString, aRv);
    return;
  }
  const ArrayBufferViewOrArrayBuffer& buf = aBuffer.Value();
  uint8_t* data;
  uint32_t length;
  if (buf.IsArrayBufferView()) {
    buf.GetAsArrayBufferView().ComputeLengthAndData();
    data = buf.GetAsArrayBufferView().Data();
    length = buf.GetAsArrayBufferView().Length();
  } else {
    MOZ_ASSERT(buf.IsArrayBuffer());
    buf.GetAsArrayBuffer().ComputeLengthAndData();
    data = buf.GetAsArrayBuffer().Data();
    length = buf.GetAsArrayBuffer().Length();
  }
  // The other Decode signature takes a signed int, because that's
  // what nsIUnicodeDecoder::Convert takes as the length.  Throw if
  // our length is too big.
  if (length > INT32_MAX) {
    aRv.Throw(NS_ERROR_OUT_OF_MEMORY);
    return;
  }
  Decode(reinterpret_cast<char*>(data), length, aOptions.mStream,
         aOutDecodedString, aRv);
}

void
TextDecoder::GetEncoding(nsAString& aEncoding)
{
  CopyASCIItoUTF16(mEncoding, aEncoding);
  nsContentUtils::ASCIIToLower(aEncoding);
}

} // namespace dom
} // namespace mozilla