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arangodb/lib/Basics/Utf8Helper.cpp

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24 KiB
C++

////////////////////////////////////////////////////////////////////////////////
/// DISCLAIMER
///
/// Copyright 2014-2016 ArangoDB GmbH, Cologne, Germany
/// Copyright 2004-2014 triAGENS GmbH, Cologne, Germany
///
/// Licensed under the Apache License, Version 2.0 (the "License");
/// you may not use this file except in compliance with the License.
/// You may obtain a copy of the License at
///
/// http://www.apache.org/licenses/LICENSE-2.0
///
/// Unless required by applicable law or agreed to in writing, software
/// distributed under the License is distributed on an "AS IS" BASIS,
/// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
/// See the License for the specific language governing permissions and
/// limitations under the License.
///
/// Copyright holder is ArangoDB GmbH, Cologne, Germany
///
/// @author Frank Celler
/// @author Achim Brandt
////////////////////////////////////////////////////////////////////////////////
#include "Utf8Helper.h"
#include "Basics/StaticStrings.h"
#include "Basics/directories.h"
#include "Basics/tri-strings.h"
#include "Logger/Logger.h"
#include "unicode/brkiter.h"
#include "unicode/normalizer2.h"
#include "unicode/putil.h"
#include "unicode/ucasemap.h"
#include "unicode/uclean.h"
#include "unicode/udata.h"
#include "unicode/unorm2.h"
#include "unicode/ustdio.h"
#ifdef _WIN32
#include "Basics/win-utils.h"
#endif
using namespace arangodb::basics;
using namespace icu;
#ifdef _WIN32
std::wstring arangodb::basics::toWString(std::string const& validUTF8String) {
icu::UnicodeString utf16(validUTF8String.c_str(), validUTF8String.size());
// // probably required for newer c++ versions
// using bufferType = std::remove_pointer_t<decltype(utf16.getTerminatedBuffer())>;
// static_assert(sizeof(std::wchar_t) == sizeof(bufferType), "sizes do not match");
// return std::wstring(reinterpret_cast<wchar_t const*>(utf16.getTerminatedBuffer()), utf16.length());
return std::wstring(utf16.getTerminatedBuffer(), utf16.length());
}
std::string arangodb::basics::fromWString(wchar_t const* validUTF16String, std::size_t size) {
std::string out;
icu::UnicodeString ICUString(validUTF16String, size);
ICUString.toUTF8String<std::string>(out);
return out;
}
std::string arangodb::basics::fromWString(std::wstring const& validUTF16String) {
return arangodb::basics::fromWString(validUTF16String.data(), validUTF16String.size());
}
#endif
Utf8Helper Utf8Helper::DefaultUtf8Helper(nullptr);
Utf8Helper::Utf8Helper(std::string const& lang, void* icuDataPtr)
: _coll(nullptr) {
setCollatorLanguage(lang, icuDataPtr);
}
Utf8Helper::Utf8Helper(void* icuDataPtr) : Utf8Helper("", icuDataPtr) {}
Utf8Helper::~Utf8Helper() {
if (_coll) {
delete _coll;
if (this == &DefaultUtf8Helper) {
u_cleanup();
}
}
}
int Utf8Helper::compareUtf8(char const* left, size_t leftLength,
char const* right, size_t rightLength) const {
TRI_ASSERT(left != nullptr);
TRI_ASSERT(right != nullptr);
TRI_ASSERT(_coll);
UErrorCode status = U_ZERO_ERROR;
int result = _coll->compareUTF8(icu::StringPiece(left, (int32_t)leftLength),
icu::StringPiece(right, (int32_t)rightLength), status);
if (ADB_UNLIKELY(U_FAILURE(status))) {
TRI_ASSERT(false);
return (strncmp(left, right, leftLength < rightLength ? leftLength : rightLength));
}
return result;
}
int Utf8Helper::compareUtf16(uint16_t const* left, size_t leftLength,
uint16_t const* right, size_t rightLength) const {
TRI_ASSERT(left != nullptr);
TRI_ASSERT(right != nullptr);
TRI_ASSERT(_coll);
// ..........................................................................
// Take note here: we are assuming that the ICU type UChar is two bytes.
// There is no guarantee that this will be the case on all platforms and
// compilers.
// ..........................................................................
return _coll->compare((const UChar*)left, (int32_t)leftLength,
(const UChar*)right, (int32_t)rightLength);
}
bool Utf8Helper::setCollatorLanguage(std::string const& lang, void* icuDataPointer) {
if (icuDataPointer == nullptr) {
return false;
}
UErrorCode status = U_ZERO_ERROR;
udata_setCommonData(reinterpret_cast<void*>(icuDataPointer), &status);
if (U_FAILURE(status)) {
LOG_TOPIC("2d56a", ERR, arangodb::Logger::FIXME)
<< "error while udata_setCommonData(...): " << u_errorName(status);
return false;
}
status = U_ZERO_ERROR;
if (_coll) {
ULocDataLocaleType type = ULOC_ACTUAL_LOCALE;
const icu::Locale& locale = _coll->getLocale(type, status);
if (U_FAILURE(status)) {
LOG_TOPIC("b251d", ERR, arangodb::Logger::FIXME)
<< "error in Collator::getLocale(...): " << u_errorName(status);
return false;
}
if (lang == locale.getName()) {
return true;
}
}
icu::Collator* coll;
if (lang == "") {
// get default collator for empty language
coll = icu::Collator::createInstance(status);
} else {
icu::Locale locale(lang.c_str());
coll = icu::Collator::createInstance(locale, status);
}
if (U_FAILURE(status)) {
LOG_TOPIC("d0e00", ERR, arangodb::Logger::FIXME)
<< "error in Collator::createInstance('" << lang
<< "'): " << u_errorName(status);
if (coll) {
delete coll;
}
return false;
}
// set the default attributes for sorting:
coll->setAttribute(UCOL_CASE_FIRST, UCOL_UPPER_FIRST, status); // A < a
coll->setAttribute(UCOL_NORMALIZATION_MODE, UCOL_OFF,
status); // no normalization
coll->setAttribute(UCOL_STRENGTH, UCOL_IDENTICAL,
status); // UCOL_IDENTICAL, UCOL_PRIMARY, UCOL_SECONDARY, UCOL_TERTIARY
if (U_FAILURE(status)) {
LOG_TOPIC("f0757", ERR, arangodb::Logger::FIXME)
<< "error in Collator::setAttribute(...): " << u_errorName(status);
delete coll;
return false;
}
if (_coll) {
delete _coll;
}
_coll = coll;
return true;
}
std::string Utf8Helper::getCollatorLanguage() {
if (_coll) {
UErrorCode status = U_ZERO_ERROR;
ULocDataLocaleType type = ULOC_VALID_LOCALE;
const icu::Locale& locale = _coll->getLocale(type, status);
if (U_FAILURE(status)) {
LOG_TOPIC("1d8d0", ERR, arangodb::Logger::FIXME)
<< "error in Collator::getLocale(...): " << u_errorName(status);
return "";
}
return locale.getLanguage();
}
return "";
}
std::string Utf8Helper::getCollatorCountry() {
if (_coll) {
UErrorCode status = U_ZERO_ERROR;
ULocDataLocaleType type = ULOC_VALID_LOCALE;
const icu::Locale& locale = _coll->getLocale(type, status);
if (U_FAILURE(status)) {
LOG_TOPIC("a596f", ERR, arangodb::Logger::FIXME)
<< "error in Collator::getLocale(...): " << u_errorName(status);
return "";
}
return locale.getCountry();
}
return "";
}
////////////////////////////////////////////////////////////////////////////////
/// @brief Lowercase the characters in a UTF-8 string.
////////////////////////////////////////////////////////////////////////////////
std::string Utf8Helper::toLowerCase(std::string const& src) {
int32_t utf8len = 0;
char* utf8 = tolower(src.c_str(), (int32_t)src.length(), utf8len);
if (utf8 == nullptr) {
return std::string();
}
std::string result(utf8, utf8len);
TRI_Free(utf8);
return result;
}
////////////////////////////////////////////////////////////////////////////////
/// @brief Lowercase the characters in a UTF-8 string.
////////////////////////////////////////////////////////////////////////////////
char* Utf8Helper::tolower(char const* src, int32_t srcLength, int32_t& dstLength) {
char* utf8_dest = nullptr;
if (src == nullptr || srcLength == 0) {
utf8_dest = (char*)TRI_Allocate(sizeof(char));
if (utf8_dest != nullptr) {
utf8_dest[0] = '\0';
}
dstLength = 0;
return utf8_dest;
}
uint32_t options = U_FOLD_CASE_DEFAULT;
UErrorCode status = U_ZERO_ERROR;
std::string locale = getCollatorLanguage();
icu::LocalUCaseMapPointer csm(ucasemap_open(locale.c_str(), options, &status));
if (U_FAILURE(status)) {
LOG_TOPIC("12bc5", ERR, arangodb::Logger::FIXME)
<< "error in ucasemap_open(...): " << u_errorName(status);
} else {
utf8_dest = (char*)TRI_Allocate((srcLength + 1) * sizeof(char));
if (utf8_dest == nullptr) {
return nullptr;
}
dstLength = ucasemap_utf8ToLower(csm.getAlias(), utf8_dest, srcLength + 1,
src, srcLength, &status);
if (status == U_BUFFER_OVERFLOW_ERROR) {
status = U_ZERO_ERROR;
TRI_Free(utf8_dest);
utf8_dest = (char*)TRI_Allocate((dstLength + 1) * sizeof(char));
if (utf8_dest == nullptr) {
return nullptr;
}
dstLength = ucasemap_utf8ToLower(csm.getAlias(), utf8_dest, dstLength + 1,
src, srcLength, &status);
}
if (U_FAILURE(status)) {
LOG_TOPIC("d7295", ERR, arangodb::Logger::FIXME)
<< "error in ucasemap_utf8ToLower(...): " << u_errorName(status);
TRI_Free(utf8_dest);
} else {
return utf8_dest;
}
}
utf8_dest = TRI_LowerAsciiString(src);
if (utf8_dest != nullptr) {
dstLength = (int32_t)strlen(utf8_dest);
}
return utf8_dest;
}
////////////////////////////////////////////////////////////////////////////////
/// @brief Uppercase the characters in a UTF-8 string.
////////////////////////////////////////////////////////////////////////////////
std::string Utf8Helper::toUpperCase(std::string const& src) {
int32_t utf8len = 0;
char* utf8 = toupper(src.c_str(), (int32_t)src.length(), utf8len);
if (utf8 == nullptr) {
return std::string();
}
std::string result(utf8, utf8len);
TRI_Free(utf8);
return result;
}
////////////////////////////////////////////////////////////////////////////////
/// @brief Lowercase the characters in a UTF-8 string.
////////////////////////////////////////////////////////////////////////////////
char* Utf8Helper::toupper(char const* src, int32_t srcLength, int32_t& dstLength) {
char* utf8_dest = nullptr;
if (src == nullptr || srcLength == 0) {
utf8_dest = (char*)TRI_Allocate(sizeof(char));
if (utf8_dest != nullptr) {
utf8_dest[0] = '\0';
}
dstLength = 0;
return utf8_dest;
}
uint32_t options = U_FOLD_CASE_DEFAULT;
UErrorCode status = U_ZERO_ERROR;
std::string locale = getCollatorLanguage();
LocalUCaseMapPointer csm(ucasemap_open(locale.c_str(), options, &status));
if (U_FAILURE(status)) {
LOG_TOPIC("10333", ERR, arangodb::Logger::FIXME)
<< "error in ucasemap_open(...): " << u_errorName(status);
} else {
utf8_dest = (char*)TRI_Allocate((srcLength + 1) * sizeof(char));
if (utf8_dest == nullptr) {
return nullptr;
}
dstLength = ucasemap_utf8ToUpper(csm.getAlias(), utf8_dest, srcLength, src,
srcLength, &status);
if (status == U_BUFFER_OVERFLOW_ERROR) {
status = U_ZERO_ERROR;
TRI_Free(utf8_dest);
utf8_dest = (char*)TRI_Allocate((dstLength + 1) * sizeof(char));
if (utf8_dest == nullptr) {
return nullptr;
}
dstLength = ucasemap_utf8ToUpper(csm.getAlias(), utf8_dest, dstLength + 1,
src, srcLength, &status);
}
if (U_FAILURE(status)) {
LOG_TOPIC("cafe4", ERR, arangodb::Logger::FIXME)
<< "error in ucasemap_utf8ToUpper(...): " << u_errorName(status);
TRI_Free(utf8_dest);
} else {
return utf8_dest;
}
}
utf8_dest = TRI_UpperAsciiString(src);
if (utf8_dest != nullptr) {
dstLength = (int32_t)strlen(utf8_dest);
}
return utf8_dest;
}
////////////////////////////////////////////////////////////////////////////////
/// @brief Extract the words from a UTF-8 string.
////////////////////////////////////////////////////////////////////////////////
bool Utf8Helper::tokenize(std::set<std::string>& words,
arangodb::velocypack::StringRef const& text,
size_t minimalLength, size_t maximalLength, bool lowerCase) {
UErrorCode status = U_ZERO_ERROR;
UnicodeString word;
if (text.empty()) {
return true;
}
size_t textLength = text.size();
if (textLength < minimalLength) {
// input text is shorter than required minimum length
return true;
}
size_t textUtf16Length = 0;
UChar* textUtf16 = nullptr;
if (lowerCase) {
// lower case string
int32_t lowerLength = 0;
char* lower = tolower(text.data(), (int32_t)textLength, lowerLength);
if (lower == nullptr) {
// out of memory
return false;
}
if (lowerLength == 0) {
TRI_Free(lower);
return false;
}
textUtf16 = TRI_Utf8ToUChar(lower, lowerLength, &textUtf16Length);
TRI_Free(lower);
} else {
textUtf16 = TRI_Utf8ToUChar(text.data(), (int32_t)textLength, &textUtf16Length);
}
if (textUtf16 == nullptr) {
return false;
}
ULocDataLocaleType type = ULOC_VALID_LOCALE;
const icu::Locale& locale = _coll->getLocale(type, status);
if (U_FAILURE(status)) {
TRI_Free(textUtf16);
LOG_TOPIC("0e8cb", ERR, arangodb::Logger::FIXME)
<< "error in Collator::getLocale(...): " << u_errorName(status);
return false;
}
UChar* tempUtf16 = (UChar*)TRI_Allocate((textUtf16Length + 1) * sizeof(UChar));
if (tempUtf16 == nullptr) {
TRI_Free(textUtf16);
return false;
}
BreakIterator* wordIterator = BreakIterator::createWordInstance(locale, status);
TRI_ASSERT(wordIterator != nullptr);
UnicodeString utext(textUtf16);
wordIterator->setText(utext);
int32_t start = wordIterator->first();
for (int32_t end = wordIterator->next(); end != BreakIterator::DONE;
start = end, end = wordIterator->next()) {
size_t tempUtf16Length = (size_t)(end - start);
// end - start = word length
if (tempUtf16Length >= minimalLength) {
size_t chunkLength = tempUtf16Length;
if (chunkLength > maximalLength) {
chunkLength = maximalLength;
}
utext.extractBetween(start, (int32_t)(start + chunkLength), tempUtf16, 0);
size_t utf8WordLength;
char* utf8Word = TRI_UCharToUtf8(tempUtf16, chunkLength, &utf8WordLength);
if (utf8Word != nullptr) {
words.emplace(utf8Word, utf8WordLength);
TRI_Free(utf8Word);
}
}
}
delete wordIterator;
TRI_Free(textUtf16);
TRI_Free(tempUtf16);
return true;
}
////////////////////////////////////////////////////////////////////////////////
/// @brief builds a regex matcher for the specified pattern
////////////////////////////////////////////////////////////////////////////////
icu::RegexMatcher* Utf8Helper::buildMatcher(std::string const& pattern) {
UErrorCode status = U_ZERO_ERROR;
auto matcher =
std::make_unique<icu::RegexMatcher>(icu::UnicodeString::fromUTF8(pattern), 0, status);
if (U_FAILURE(status)) {
return nullptr;
}
return matcher.release();
}
////////////////////////////////////////////////////////////////////////////////
/// @brief whether or not value matches a regex
////////////////////////////////////////////////////////////////////////////////
bool Utf8Helper::matches(icu::RegexMatcher* matcher, char const* value,
size_t valueLength, bool partial, bool& error) {
TRI_ASSERT(value != nullptr);
icu::UnicodeString v =
icu::UnicodeString::fromUTF8(icu::StringPiece(value, static_cast<int32_t>(valueLength)));
matcher->reset(v);
UErrorCode status = U_ZERO_ERROR;
error = false;
TRI_ASSERT(matcher != nullptr);
UBool result;
if (partial) {
// partial match
result = matcher->find(status);
} else {
// full match
result = matcher->matches(status);
}
if (U_FAILURE(status)) {
error = true;
}
return (result ? true : false);
}
////////////////////////////////////////////////////////////////////////////////
/// @brief replace value using a regex
////////////////////////////////////////////////////////////////////////////////
std::string Utf8Helper::replace(icu::RegexMatcher* matcher, char const* value,
size_t valueLength, char const* replacement,
size_t replacementLength, bool partial, bool& error) {
TRI_ASSERT(value != nullptr);
icu::UnicodeString v =
icu::UnicodeString::fromUTF8(icu::StringPiece(value, static_cast<int32_t>(valueLength)));
icu::UnicodeString r = icu::UnicodeString::fromUTF8(
icu::StringPiece(replacement, static_cast<int32_t>(replacementLength)));
matcher->reset(v);
UErrorCode status = U_ZERO_ERROR;
error = false;
TRI_ASSERT(matcher != nullptr);
icu::UnicodeString result;
if (partial) {
// partial match
result = matcher->replaceFirst(r, status);
} else {
// full match
result = matcher->replaceAll(r, status);
}
if (U_FAILURE(status)) {
error = true;
return StaticStrings::Empty;
}
std::string utf8;
result.toUTF8String(utf8);
return utf8;
}
////////////////////////////////////////////////////////////////////////////////
/// @brief Lowercase the characters in a UTF-8 string (implemented in
/// Basic/Utf8Helper.cpp)
////////////////////////////////////////////////////////////////////////////////
char* TRI_tolower_utf8(char const* src, int32_t srcLength, int32_t* dstLength) {
return Utf8Helper::DefaultUtf8Helper.tolower(src, srcLength, *dstLength);
}
////////////////////////////////////////////////////////////////////////////////
/// @brief convert a utf-8 string to a uchar (utf-16)
////////////////////////////////////////////////////////////////////////////////
UChar* TRI_Utf8ToUChar(char const* utf8, size_t inLength,
UChar* buffer, size_t bufferSize, size_t* outLength) {
UErrorCode status = U_ZERO_ERROR;
// 1. convert utf8 string to utf16
// calculate utf16 string length
int32_t utf16Length;
u_strFromUTF8(nullptr, 0, &utf16Length, utf8, (int32_t)inLength, &status);
if (status != U_BUFFER_OVERFLOW_ERROR) {
return nullptr;
}
UChar* utf16;
if (utf16Length + 1 <= (int32_t) bufferSize) {
// use local buffer
utf16 = buffer;
} else {
// dynamic memory
utf16 = (UChar*)TRI_Allocate((utf16Length + 1) * sizeof(UChar));
if (utf16 == nullptr) {
return nullptr;
}
}
// now convert
status = U_ZERO_ERROR;
// the +1 will append a 0 byte at the end
u_strFromUTF8(utf16, utf16Length + 1, nullptr, utf8, (int32_t)inLength, &status);
if (status != U_ZERO_ERROR) {
TRI_Free(utf16);
return nullptr;
}
*outLength = (size_t)utf16Length;
return utf16;
}
UChar* TRI_Utf8ToUChar(char const* utf8, size_t inLength, size_t* outLength) {
int32_t utf16Length;
// 1. convert utf8 string to utf16
// calculate utf16 string length
UErrorCode status = U_ZERO_ERROR;
u_strFromUTF8(nullptr, 0, &utf16Length, utf8, (int32_t)inLength, &status);
if (status != U_BUFFER_OVERFLOW_ERROR) {
return nullptr;
}
UChar* utf16 = (UChar*)TRI_Allocate((utf16Length + 1) * sizeof(UChar));
if (utf16 == nullptr) {
return nullptr;
}
// now convert
status = U_ZERO_ERROR;
// the +1 will append a 0 byte at the end
u_strFromUTF8(utf16, utf16Length + 1, nullptr, utf8, (int32_t)inLength, &status);
if (status != U_ZERO_ERROR) {
TRI_Free(utf16);
return nullptr;
}
*outLength = (size_t)utf16Length;
return utf16;
}
////////////////////////////////////////////////////////////////////////////////
/// @brief convert a uchar (utf-16) to a utf-8 string
////////////////////////////////////////////////////////////////////////////////
char* TRI_UCharToUtf8(UChar const* uchar, size_t inLength, size_t* outLength) {
int32_t utf8Length;
// calculate utf8 string length
UErrorCode status = U_ZERO_ERROR;
u_strToUTF8(nullptr, 0, &utf8Length, uchar, (int32_t)inLength, &status);
if (status != U_ZERO_ERROR && status != U_BUFFER_OVERFLOW_ERROR) {
return nullptr;
}
char* utf8 = static_cast<char*>(TRI_Allocate(utf8Length + 1));
if (utf8 == nullptr) {
return nullptr;
}
// convert to utf8
status = U_ZERO_ERROR;
// the +1 will append a 0 byte at the end
u_strToUTF8(utf8, utf8Length + 1, nullptr, uchar, (int32_t)inLength, &status);
if (status != U_ZERO_ERROR) {
TRI_Free(utf8);
return nullptr;
}
*outLength = (size_t)utf8Length;
return utf8;
}
////////////////////////////////////////////////////////////////////////////////
/// @brief normalize an utf8 string (NFC)
////////////////////////////////////////////////////////////////////////////////
char* TRI_normalize_utf8_to_NFC(char const* utf8, size_t inLength, size_t* outLength) {
*outLength = 0;
if (inLength == 0) {
char* utf8Dest = static_cast<char*>(TRI_Allocate(sizeof(char)));
if (utf8Dest != nullptr) {
utf8Dest[0] = '\0';
}
return utf8Dest;
}
size_t utf16Length;
// use this buffer and pass it to TRI_Utf8ToUChar so we can avoid dynamic memory
// allocation for shorter strings
UChar buffer[128];
UChar* utf16 = TRI_Utf8ToUChar(utf8, inLength, &buffer[0], sizeof(buffer) / sizeof(UChar), &utf16Length);
if (utf16 == nullptr) {
return nullptr;
}
// continue in TR_normalize_utf16_to_NFC
char* utf8Dest = TRI_normalize_utf16_to_NFC((uint16_t const*)utf16,
(int32_t)utf16Length, outLength);
if (utf16 != &buffer[0]) {
// TRI_Utf8ToUChar dynamically allocated memory
TRI_Free(utf16);
}
return utf8Dest;
}
////////////////////////////////////////////////////////////////////////////////
/// @brief normalize an utf8 string (NFC)
////////////////////////////////////////////////////////////////////////////////
char* TRI_normalize_utf16_to_NFC(uint16_t const* utf16, size_t inLength, size_t* outLength) {
*outLength = 0;
if (inLength == 0) {
char* utf8Dest = static_cast<char*>(TRI_Allocate(sizeof(char)));
if (utf8Dest != nullptr) {
utf8Dest[0] = '\0';
}
return utf8Dest;
}
UErrorCode status = U_ZERO_ERROR;
UNormalizer2 const* norm2 = unorm2_getInstance(nullptr, "nfc", UNORM2_COMPOSE, &status);
if (status != U_ZERO_ERROR) {
return nullptr;
}
// normalize UChar (UTF-16)
UChar* utf16Dest;
bool mustFree;
char buffer[512];
if (inLength < sizeof(buffer) / sizeof(UChar)) {
// use a static buffer
utf16Dest = (UChar*)&buffer[0];
mustFree = false;
} else {
// use dynamic memory
utf16Dest = (UChar*)TRI_Allocate((inLength + 1) * sizeof(UChar));
if (utf16Dest == nullptr) {
return nullptr;
}
mustFree = true;
}
size_t overhead = 0;
int32_t utf16DestLength;
while (true) {
status = U_ZERO_ERROR;
utf16DestLength = unorm2_normalize(norm2, (UChar*)utf16, (int32_t)inLength, utf16Dest,
(int32_t)(inLength + overhead + 1), &status);
if (status == U_ZERO_ERROR) {
break;
}
if (status == U_BUFFER_OVERFLOW_ERROR || status == U_STRING_NOT_TERMINATED_WARNING) {
// output buffer was too small. now re-try with a bigger buffer (inLength
// + overhead size)
if (mustFree) {
// free original buffer first so we don't leak
TRI_Free(utf16Dest);
mustFree = false;
}
if (overhead == 0) {
// set initial overhead size
if (inLength < 256) {
overhead = 16;
} else if (inLength < 4096) {
overhead = 128;
} else {
overhead = 256;
}
} else {
// use double buffer size
overhead += overhead;
if (overhead >= 1024 * 1024) {
// enough is enough
return nullptr;
}
}
utf16Dest = (UChar*)TRI_Allocate((inLength + overhead + 1) * sizeof(UChar));
if (utf16Dest != nullptr) {
// got new memory. now try again with the adjusted, bigger buffer
mustFree = true;
continue;
}
// intentionally falls through
}
if (mustFree) {
TRI_Free(utf16Dest);
}
return nullptr;
}
// Convert data back from UChar (UTF-16) to UTF-8
char* utf8Dest = TRI_UCharToUtf8(utf16Dest, (size_t)utf16DestLength, outLength);
if (mustFree) {
TRI_Free(utf16Dest);
}
return utf8Dest;
}