nsConverterOutputStream.cpp

/* vim:set expandtab ts=4 sw=4 sts=4 cin: */
/* 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 "nsCOMPtr.h"

#include "nsIOutputStream.h"
#include "nsString.h"

#include "nsConverterOutputStream.h"
#include "mozilla/Encoding.h"
#include "mozilla/Unused.h"

using namespace mozilla;

NS_IMPL_ISUPPORTS(nsConverterOutputStream,
                  nsIUnicharOutputStream,
                  nsIConverterOutputStream)

nsConverterOutputStream::~nsConverterOutputStream()
{
    Close();
}

NS_IMETHODIMP
nsConverterOutputStream::Init(nsIOutputStream* aOutStream,
                              const char* aCharset)
{
    MOZ_ASSERT(aOutStream, "Null output stream!");

    const Encoding* encoding;
    if (!aCharset) {
      encoding = UTF_8_ENCODING;
    } else {
      encoding = Encoding::ForLabelNoReplacement(MakeStringSpan(aCharset));
      if (!encoding || encoding == UTF_16LE_ENCODING ||
          encoding == UTF_16BE_ENCODING) {
        return NS_ERROR_UCONV_NOCONV;
      }
    }

    mConverter = encoding->NewEncoder();

    mOutStream = aOutStream;

    return NS_OK;
}

NS_IMETHODIMP
nsConverterOutputStream::Write(uint32_t aCount, const char16_t* aChars,
                               bool* aSuccess)
{
    if (!mOutStream) {
        NS_ASSERTION(!mConverter, "Closed streams shouldn't have converters");
        return NS_BASE_STREAM_CLOSED;
    }
    MOZ_ASSERT(mConverter, "Must have a converter when not closed");
    uint8_t buffer[4096];
    auto dst = MakeSpan(buffer);
    auto src = MakeSpan(aChars, aCount);
    for (;;) {
      uint32_t result;
      size_t read;
      size_t written;
      bool hadErrors;
      Tie(result, read, written, hadErrors) =
        mConverter->EncodeFromUTF16(src, dst, false);
      Unused << hadErrors;
      src = src.From(read);
      uint32_t streamWritten;
      nsresult rv = mOutStream->Write(
        reinterpret_cast<char*>(dst.Elements()), written, &streamWritten);
      *aSuccess = NS_SUCCEEDED(rv) && written == streamWritten;
      if (!(*aSuccess)) {
        return rv;
      }
      if (result == kInputEmpty) {
        return NS_OK;
      }
    }
}

NS_IMETHODIMP
nsConverterOutputStream::WriteString(const nsAString& aString, bool* aSuccess)
{
    int32_t inLen = aString.Length();
    nsAString::const_iterator i;
    aString.BeginReading(i);
    return Write(inLen, i.get(), aSuccess);
}

NS_IMETHODIMP
nsConverterOutputStream::Flush()
{
    if (!mOutStream)
        return NS_OK; // Already closed.

    // If we are encoding to ISO-2022-JP, potentially
    // transition back to the ASCII state. The buffer
    // needs to be large enough for an additional NCR,
    // though.
    uint8_t buffer[12];
    auto dst = MakeSpan(buffer);
    Span<char16_t> src(nullptr);
    uint32_t result;
    size_t read;
    size_t written;
    bool hadErrors;
    Tie(result, read, written, hadErrors) =
      mConverter->EncodeFromUTF16(src, dst, true);
    Unused << hadErrors;
    MOZ_ASSERT(result == kInputEmpty);
    uint32_t streamWritten;
    if (!written) {
      return NS_OK;
    }
    return mOutStream->Write(
      reinterpret_cast<char*>(dst.Elements()), written, &streamWritten);
}

NS_IMETHODIMP
nsConverterOutputStream::Close()
{
    if (!mOutStream)
        return NS_OK; // Already closed.

    nsresult rv1 = Flush();

    nsresult rv2 = mOutStream->Close();
    mOutStream = nullptr;
    mConverter = nullptr;
    return NS_FAILED(rv1) ? rv1 : rv2;
}