GCC Code Coverage Report
Directory: ./ Exec Total Coverage
File: string_decoder.cc Lines: 148 153 96.7 %
Date: 2021-09-22 04:12:37 Branches: 109 132 82.6 %

Line Branch Exec Source
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#include "string_decoder.h"  // NOLINT(build/include_inline)
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#include "string_decoder-inl.h"
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4
#include "env-inl.h"
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#include "node_buffer.h"
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#include "node_errors.h"
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#include "node_external_reference.h"
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#include "string_bytes.h"
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#include "util.h"
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using v8::Array;
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using v8::ArrayBufferView;
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using v8::Context;
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using v8::FunctionCallbackInfo;
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using v8::Integer;
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using v8::Isolate;
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using v8::Local;
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using v8::MaybeLocal;
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using v8::Object;
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using v8::String;
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using v8::Value;
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namespace node {
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namespace {
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24750
MaybeLocal<String> MakeString(Isolate* isolate,
28
                              const char* data,
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                              size_t length,
30
                              enum encoding encoding) {
31
  Local<Value> error;
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  MaybeLocal<Value> ret;
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24750
  if (encoding == UTF8) {
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    MaybeLocal<String> utf8_string = String::NewFromUtf8(
35
        isolate,
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        data,
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        v8::NewStringType::kNormal,
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14494
        length);
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14494
    if (utf8_string.IsEmpty()) {
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1
      isolate->ThrowException(node::ERR_STRING_TOO_LONG(isolate));
41
1
      return MaybeLocal<String>();
42
    } else {
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14493
      return utf8_string;
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    }
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  } else {
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    ret = StringBytes::Encode(
47
        isolate,
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        data,
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        length,
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        encoding,
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10256
        &error);
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  }
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54
10256
  if (ret.IsEmpty()) {
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    CHECK(!error.IsEmpty());
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    isolate->ThrowException(error);
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  }
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  DCHECK(ret.IsEmpty() || ret.ToLocalChecked()->IsString());
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20512
  return ret.FromMaybe(Local<Value>()).As<String>();
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}
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}  // anonymous namespace
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25340
MaybeLocal<String> StringDecoder::DecodeData(Isolate* isolate,
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                                             const char* data,
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                                             size_t* nread_ptr) {
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  Local<String> prepend, body;
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25340
  size_t nread = *nread_ptr;
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35620
  if (Encoding() == UTF8 ||
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16777
      Encoding() == UCS2 ||
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42117
      Encoding() == BASE64 ||
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5771
      Encoding() == BASE64URL) {
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    // See if we want bytes to finish a character from the previous
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    // chunk; if so, copy the new bytes to the missing bytes buffer
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    // and create a small string from it that is to be prepended to the
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    // main body.
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20298
    if (MissingBytes() > 0) {
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      // There are never more bytes missing than the pre-calculated maximum.
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4019
      CHECK_LE(MissingBytes() + BufferedBytes(),
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               kIncompleteCharactersEnd);
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4019
      if (Encoding() == UTF8) {
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        // For UTF-8, we need special treatment to align with the V8 decoder:
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        // If an incomplete character is found at a chunk boundary, we use
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        // its remainder and pass it to V8 as-is.
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3296
        for (size_t i = 0; i < nread && i < MissingBytes(); ++i) {
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1844
          if ((data[i] & 0xC0) != 0x80) {
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            // This byte is not a continuation byte even though it should have
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            // been one. We stop decoding of the incomplete character at this
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            // point (but still use the rest of the incomplete bytes from this
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            // chunk) and assume that the new, unexpected byte starts a new one.
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            state_[kMissingBytes] = 0;
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            memcpy(IncompleteCharacterBuffer() + BufferedBytes(), data, i);
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            state_[kBufferedBytes] += i;
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            data += i;
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96
            nread -= i;
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96
            break;
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          }
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        }
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      }
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105
      size_t found_bytes =
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4019
          std::min(nread, static_cast<size_t>(MissingBytes()));
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4019
      memcpy(IncompleteCharacterBuffer() + BufferedBytes(),
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             data,
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             found_bytes);
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      // Adjust the two buffers.
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4019
      data += found_bytes;
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4019
      nread -= found_bytes;
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4019
      state_[kMissingBytes] -= found_bytes;
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4019
      state_[kBufferedBytes] += found_bytes;
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4019
      if (LIKELY(MissingBytes() == 0)) {
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        // If no more bytes are missing, create a small string that we
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        // will later prepend.
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3587
        if (!MakeString(isolate,
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3587
                        IncompleteCharacterBuffer(),
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3587
                        BufferedBytes(),
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10761
                        Encoding()).ToLocal(&prepend)) {
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          return MaybeLocal<String>();
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        }
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3587
        *nread_ptr += BufferedBytes();
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        // No more buffered bytes.
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3587
        state_[kBufferedBytes] = 0;
130
      }
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    }
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    // It could be that trying to finish the previous chunk already
134
    // consumed all data that we received in this chunk.
135
20298
    if (UNLIKELY(nread == 0)) {
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2766
      body = !prepend.IsEmpty() ? prepend : String::Empty(isolate);
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2287
      prepend = Local<String>();
138
    } else {
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      // If not, that means is no character left to finish at this point.
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      DCHECK_EQ(MissingBytes(), 0);
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      DCHECK_EQ(BufferedBytes(), 0);
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143
      // See whether there is a character that we may have to cut off and
144
      // finish when receiving the next chunk.
145

18011
      if (Encoding() == UTF8 && data[nread - 1] & 0x80) {
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        // This is UTF-8 encoded data and we ended on a non-ASCII UTF-8 byte.
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        // This means we'll need to figure out where the character to which
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        // the byte belongs begins.
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1842
        for (size_t i = nread - 1; ; --i) {
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          DCHECK_LT(i, nread);
151
1039
          state_[kBufferedBytes]++;
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2881
          if ((data[i] & 0xC0) == 0x80) {
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            // This byte does not start a character (a "trailing" byte).
154

1088
            if (state_[kBufferedBytes] >= 4 || i == 0) {
155
              // We either have more then 4 trailing bytes (which means
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              // the current character would not be inside the range for
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              // valid Unicode, and in particular cannot be represented
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              // through JavaScript's UTF-16-based approach to strings), or the
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              // current buffer does not contain the start of an UTF-8 character
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              // at all. Either way, this is invalid UTF8 and we can just
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              // let the engine's decoder handle it.
162
49
              state_[kBufferedBytes] = 0;
163
49
              break;
164
            }
165
          } else {
166
            // Found the first byte of a UTF-8 character. By looking at the
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            // upper bits we can tell how long the character *should* be.
168
1793
            if ((data[i] & 0xE0) == 0xC0) {
169
533
              state_[kMissingBytes] = 2;
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1260
            } else if ((data[i] & 0xF0) == 0xE0) {
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1117
              state_[kMissingBytes] = 3;
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143
            } else if ((data[i] & 0xF8) == 0xF0) {
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38
              state_[kMissingBytes] = 4;
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            } else {
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              // This lead byte would indicate a character outside of the
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              // representable range.
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105
              state_[kBufferedBytes] = 0;
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105
              break;
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            }
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1688
            if (BufferedBytes() >= MissingBytes()) {
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              // Received more or exactly as many trailing bytes than the lead
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              // character would indicate. In the "==" case, we have valid
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              // data and don't need to slice anything off;
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              // in the ">" case, this is invalid UTF-8 anyway.
186
384
              state_[kMissingBytes] = 0;
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384
              state_[kBufferedBytes] = 0;
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            }
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1688
            state_[kMissingBytes] -= state_[kBufferedBytes];
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1688
            break;
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          }
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        }
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16169
      } else if (Encoding() == UCS2) {
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2840
        if ((nread % 2) == 1) {
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          // We got half a codepoint, and need the second byte of it.
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1766
          state_[kBufferedBytes] = 1;
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1766
          state_[kMissingBytes] = 1;
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1074
        } else if ((data[nread - 1] & 0xFC) == 0xD8) {
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          // Half a split UTF-16 character.
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14
          state_[kBufferedBytes] = 2;
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14
          state_[kMissingBytes] = 2;
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        }
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13329
      } else if (Encoding() == BASE64 || Encoding() == BASE64URL) {
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1210
        state_[kBufferedBytes] = nread % 3;
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1210
        if (state_[kBufferedBytes] > 0)
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871
          state_[kMissingBytes] = 3 - BufferedBytes();
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      }
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18011
      if (BufferedBytes() > 0) {
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        // Copy the requested number of buffered bytes from the end of the
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        // input into the incomplete character buffer.
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3955
        nread -= BufferedBytes();
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3955
        *nread_ptr -= BufferedBytes();
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3955
        memcpy(IncompleteCharacterBuffer(), data + nread, BufferedBytes());
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      }
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18011
      if (nread > 0) {
219
31704
        if (!MakeString(isolate, data, nread, Encoding()).ToLocal(&body))
220
1
          return MaybeLocal<String>();
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      } else {
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2159
        body = String::Empty(isolate);
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      }
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    }
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20297
    if (prepend.IsEmpty()) {
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18518
      return body;
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    } else {
229
3558
      return String::Concat(isolate, prepend, body);
230
    }
231
  } else {
232


5042
    CHECK(Encoding() == ASCII || Encoding() == HEX || Encoding() == LATIN1);
233
5042
    return MakeString(isolate, data, nread, Encoding());
234
  }
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}
236
237
368
MaybeLocal<String> StringDecoder::FlushData(Isolate* isolate) {
238


368
  if (Encoding() == ASCII || Encoding() == HEX || Encoding() == LATIN1) {
239
    CHECK_EQ(MissingBytes(), 0);
240
    CHECK_EQ(BufferedBytes(), 0);
241
  }
242
243

368
  if (Encoding() == UCS2 && BufferedBytes() % 2 == 1) {
244
    // Ignore a single trailing byte, like the JS decoder does.
245
100
    state_[kMissingBytes]--;
246
100
    state_[kBufferedBytes]--;
247
  }
248
249
368
  if (BufferedBytes() == 0)
250
99
    return String::Empty(isolate);
251
252
  MaybeLocal<String> ret =
253
      MakeString(isolate,
254
269
                 IncompleteCharacterBuffer(),
255
269
                 BufferedBytes(),
256
538
                 Encoding());
257
258
269
  state_[kMissingBytes] = 0;
259
269
  state_[kBufferedBytes] = 0;
260
261
269
  return ret;
262
}
263
264
namespace {
265
266
25340
void DecodeData(const FunctionCallbackInfo<Value>& args) {
267
  StringDecoder* decoder =
268
25340
      reinterpret_cast<StringDecoder*>(Buffer::Data(args[0]));
269
25340
  CHECK_NOT_NULL(decoder);
270
271
25340
  CHECK(args[1]->IsArrayBufferView());
272
50680
  ArrayBufferViewContents<char> content(args[1].As<ArrayBufferView>());
273
25340
  size_t length = content.length();
274
275
  MaybeLocal<String> ret =
276
50680
      decoder->DecodeData(args.GetIsolate(), content.data(), &length);
277
25340
  if (!ret.IsEmpty())
278
50678
    args.GetReturnValue().Set(ret.ToLocalChecked());
279
25340
}
280
281
368
void FlushData(const FunctionCallbackInfo<Value>& args) {
282
  StringDecoder* decoder =
283
368
      reinterpret_cast<StringDecoder*>(Buffer::Data(args[0]));
284
368
  CHECK_NOT_NULL(decoder);
285
368
  MaybeLocal<String> ret = decoder->FlushData(args.GetIsolate());
286
368
  if (!ret.IsEmpty())
287
736
    args.GetReturnValue().Set(ret.ToLocalChecked());
288
368
}
289
290
625
void InitializeStringDecoder(Local<Object> target,
291
                             Local<Value> unused,
292
                             Local<Context> context,
293
                             void* priv) {
294
625
  Environment* env = Environment::GetCurrent(context);
295
625
  Isolate* isolate = env->isolate();
296
297
#define SET_DECODER_CONSTANT(name)                                            \
298
  target->Set(context,                                                        \
299
              FIXED_ONE_BYTE_STRING(isolate, #name),                          \
300
              Integer::New(isolate, StringDecoder::name)).FromJust()
301
302
2500
  SET_DECODER_CONSTANT(kIncompleteCharactersStart);
303
2500
  SET_DECODER_CONSTANT(kIncompleteCharactersEnd);
304
2500
  SET_DECODER_CONSTANT(kMissingBytes);
305
2500
  SET_DECODER_CONSTANT(kBufferedBytes);
306
2500
  SET_DECODER_CONSTANT(kEncodingField);
307
1875
  SET_DECODER_CONSTANT(kNumFields);
308
309
625
  Local<Array> encodings = Array::New(isolate);
310
#define ADD_TO_ENCODINGS_ARRAY(cname, jsname)                                 \
311
  encodings->Set(context,                                                     \
312
                 static_cast<int32_t>(cname),                                 \
313
                 FIXED_ONE_BYTE_STRING(isolate, jsname)).FromJust()
314
1875
  ADD_TO_ENCODINGS_ARRAY(ASCII, "ascii");
315
1875
  ADD_TO_ENCODINGS_ARRAY(UTF8, "utf8");
316
1875
  ADD_TO_ENCODINGS_ARRAY(BASE64, "base64");
317
1875
  ADD_TO_ENCODINGS_ARRAY(BASE64URL, "base64url");
318
1875
  ADD_TO_ENCODINGS_ARRAY(UCS2, "utf16le");
319
1875
  ADD_TO_ENCODINGS_ARRAY(HEX, "hex");
320
1875
  ADD_TO_ENCODINGS_ARRAY(BUFFER, "buffer");
321
1875
  ADD_TO_ENCODINGS_ARRAY(LATIN1, "latin1");
322
323
625
  target->Set(context,
324
              FIXED_ONE_BYTE_STRING(isolate, "encodings"),
325
1875
              encodings).Check();
326
327
625
  target->Set(context,
328
              FIXED_ONE_BYTE_STRING(isolate, "kSize"),
329
1875
              Integer::New(isolate, sizeof(StringDecoder))).Check();
330
331
625
  env->SetMethod(target, "decode", DecodeData);
332
625
  env->SetMethod(target, "flush", FlushData);
333
625
}
334
335
}  // anonymous namespace
336
337
4853
void RegisterStringDecoderExternalReferences(
338
    ExternalReferenceRegistry* registry) {
339
4853
  registry->Register(DecodeData);
340
4853
  registry->Register(FlushData);
341
4853
}
342
343
}  // namespace node
344
345
4926
NODE_MODULE_CONTEXT_AWARE_INTERNAL(string_decoder,
346
                                   node::InitializeStringDecoder)
347
4853
NODE_MODULE_EXTERNAL_REFERENCE(string_decoder,
348
                               node::RegisterStringDecoderExternalReferences)