src/base/iconv.cc

// Copyright 2010-2015, Google Inc.
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#ifndef OS_WIN
#include <iconv.h>
#else
#include <windows.h>
#include <memory>
#endif

#include <string>
#include "base/logging.h"
#include "base/util.h"

#ifdef OS_WIN
using std::unique_ptr;
#endif  // OS_WIN

namespace {

#ifndef OS_WIN

bool IconvHelper(iconv_t ic, const string &input, string *output) {
  size_t ilen = input.size();
  size_t olen = ilen * 4;
  string tmp;
  tmp.reserve(olen);
  char *ibuf = const_cast<char *>(input.data());
  char *obuf_org = const_cast<char *>(tmp.data());
  char *obuf = obuf_org;
  fill(obuf, obuf + olen, 0);
  size_t olen_org = olen;
  iconv(ic, 0, &ilen, 0, &olen);  // reset iconv state
  while (ilen != 0) {
    if (iconv(ic, reinterpret_cast<char **>(&ibuf), &ilen, &obuf, &olen)
        == static_cast<size_t>(-1)) {
      return false;
    }
  }
  output->assign(obuf_org, olen_org - olen);
  return true;
}

inline bool Convert(const char *from, const char *to,
                    const string &input, string *output) {
  iconv_t ic = iconv_open(to, from);   // note the order
  if (ic == reinterpret_cast<iconv_t>(-1)) {
    LOG(WARNING) << "iconv_open failed";
    *output = input;
    return false;
  }
  bool result = IconvHelper(ic, input, output);
  iconv_close(ic);
  return result;
}
#else
// Returns the code-page identifier for the specified encoding string.
// This function scans a list of mappings from an encoding name to a
// code-page identifier of Windows according to the encoding name.
// If the given encoding string does not have any matching code-page
// identifiers, this function returns 0.
// To add a mapping from an encoding name to its code-page identifier:
// 1. Read the list of code-page identifiers supported by Windows (*1), and;
// 2. Find a code-page identifier matching to the encoding name:
// (*1) "http://msdn.microsoft.com/en-us/library/ms776446(VS.85).aspx".
static int GetCodepage(const char* name) {
  static const struct {
    const char* name;
    int codepage;
  } kCodePageMap[] = {
    { "UTF8",      CP_UTF8 },  // Unicode UTF-8
    { "SJIS",      932     },  // ANSI/OEM - Japanese, Shift-JIS
    { "EUC-JP-MS", 51932   },  // EUC - Japanese
    { "JIS",       20932   },  // JIS X 0208-1990 & 0212-1990
  };

  for (size_t i = 0; i < arraysize(kCodePageMap); i++) {
    if (strcmp(kCodePageMap[i].name, name) == 0) {
      return kCodePageMap[i].codepage;
    }
  }
  return 0;
}

// Converts the encoding of the specified string.
// This function firstly converts the source string to create a temporary
// UTF-16 string, and encodes the UTF-16 string with the destination encoding.
inline bool Convert(const char *from, const char *to,
                    const string &input, string *output) {
  const int codepage_from = GetCodepage(from);
  const int codepage_to = GetCodepage(to);
  if (codepage_from == 0 || codepage_to == 0) {
    return false;
  }

  const int wide_length = MultiByteToWideChar(codepage_from, 0, input.c_str(),
                                              -1, NULL, 0);
  if (wide_length == 0) {
    return false;
  }

  unique_ptr<wchar_t[]> wide(new wchar_t[wide_length + 1]);
  if (wide.get() == NULL) {
    return false;
  }

  if (MultiByteToWideChar(codepage_from, 0, input.c_str(), -1,
                          wide.get(), wide_length + 1) == 0)
    return false;

  const int output_length = WideCharToMultiByte(codepage_to, 0, wide.get(), -1,
                                                NULL, 0, NULL, NULL);
  if (output_length == 0) {
    return false;
  }

  unique_ptr<char[]> multibyte(new char[output_length + 1]);
  if (multibyte.get() == NULL) {
    return false;
  }

  const int result = WideCharToMultiByte(codepage_to, 0, wide.get(),
                                         wide_length, multibyte.get(),
                                         output_length + 1, NULL, NULL);
  if (result == 0) {
    return false;
  }

  output->assign(multibyte.get());
  return true;
}

#endif
}   // namespace

namespace mozc {

#ifndef OS_WIN
// The following functions don't work on Windows
void Util::UTF8ToEUC(const string &input, string *output) {
  Convert("UTF8", "EUC-JP-MS", input, output);
}

void Util::EUCToUTF8(const string &input, string *output) {
  Convert("EUC-JP-MS", "UTF8", input, output);
}
#endif

void Util::UTF8ToSJIS(const string &input, string *output) {
  Convert("UTF8", "SJIS", input, output);
}

void Util::SJISToUTF8(const string &input, string *output) {
  Convert("SJIS", "UTF8", input, output);
}
}  // namespace mozc