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node/src/string_bytes.cc
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Anna Henningsen 784c6d40f8 src: use proper errors as coming from StringBytes 
The previous errors were incorrect here, as the code
only failed in situations where strings exceeded size limits or
an OOM situation was encountered, not for invalid encodings
(which aren’t even detected explicitly).

Unfortunately, these situations are hard to test for.

PR-URL: https://github.com/nodejs/node/pull/14579
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
2017-08-24 21:05:07 +02:00

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// Copyright Joyent, Inc. and other Node contributors.
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to permit
// persons to whom the Software is furnished to do so, subject to the
// following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
// USE OR OTHER DEALINGS IN THE SOFTWARE.
#include "string_bytes.h"
#include "base64.h"
#include "node.h"
#include "node_buffer.h"
#include "v8.h"
#include <limits.h>
#include <string.h> // memcpy
#include <vector>
// When creating strings >= this length v8's gc spins up and consumes
// most of the execution time. For these cases it's more performant to
// use external string resources.
#define EXTERN_APEX 0xFBEE9
// TODO(addaleax): These should all have better error messages. In particular,
// they should mention what the actual limits are.
#define SB_MALLOC_FAILED_ERROR \
v8::Exception::Error(OneByteString(isolate, "\"toString()\" failed"))
#define SB_STRING_TOO_LONG_ERROR \
v8::Exception::Error(OneByteString(isolate, "\"toString()\" failed"))
#define SB_BUFFER_CREATION_ERROR \
v8::Exception::Error(OneByteString(isolate, "\"toString()\" failed"))
#define SB_BUFFER_SIZE_EXCEEDED_ERROR \
v8::Exception::Error(OneByteString(isolate, "\"toString()\" failed"))
namespace node {
using v8::HandleScope;
using v8::Isolate;
using v8::Local;
using v8::MaybeLocal;
using v8::String;
using v8::Value;
namespace {
template <typename ResourceType, typename TypeName>
class ExternString: public ResourceType {
public:
~ExternString() override {
free(const_cast<TypeName*>(data_));
isolate()->AdjustAmountOfExternalAllocatedMemory(-byte_length());
}
const TypeName* data() const override {
return data_;
}
size_t length() const override {
return length_;
}
int64_t byte_length() const {
return length() * sizeof(*data());
}
static MaybeLocal<Value> NewFromCopy(Isolate* isolate,
const TypeName* data,
size_t length,
Local<Value>* error) {
if (length == 0)
return String::Empty(isolate);
if (length < EXTERN_APEX)
return NewSimpleFromCopy(isolate, data, length, error);
TypeName* new_data = node::UncheckedMalloc<TypeName>(length);
if (new_data == nullptr) {
*error = SB_MALLOC_FAILED_ERROR;
return MaybeLocal<Value>();
}
memcpy(new_data, data, length * sizeof(*new_data));
return ExternString<ResourceType, TypeName>::New(isolate,
new_data,
length,
error);
}
// uses "data" for external resource, and will be free'd on gc
static MaybeLocal<Value> New(Isolate* isolate,
TypeName* data,
size_t length,
Local<Value>* error) {
if (length == 0)
return String::Empty(isolate);
if (length < EXTERN_APEX) {
MaybeLocal<Value> str = NewSimpleFromCopy(isolate, data, length, error);
free(data);
return str;
}
ExternString* h_str = new ExternString<ResourceType, TypeName>(isolate,
data,
length);
MaybeLocal<Value> str = NewExternal(isolate, h_str);
isolate->AdjustAmountOfExternalAllocatedMemory(h_str->byte_length());
if (str.IsEmpty()) {
delete h_str;
*error = SB_STRING_TOO_LONG_ERROR;
return MaybeLocal<Value>();
}
return str.ToLocalChecked();
}
inline Isolate* isolate() const { return isolate_; }
private:
ExternString(Isolate* isolate, const TypeName* data, size_t length)
: isolate_(isolate), data_(data), length_(length) { }
static MaybeLocal<Value> NewExternal(Isolate* isolate,
ExternString* h_str);
// This method does not actually create ExternString instances.
static MaybeLocal<Value> NewSimpleFromCopy(Isolate* isolate,
const TypeName* data,
size_t length,
Local<Value>* error);
Isolate* isolate_;
const TypeName* data_;
size_t length_;
};
typedef ExternString<String::ExternalOneByteStringResource,
char> ExternOneByteString;
typedef ExternString<String::ExternalStringResource,
uint16_t> ExternTwoByteString;
template <>
MaybeLocal<Value> ExternOneByteString::NewExternal(
Isolate* isolate, ExternOneByteString* h_str) {
return String::NewExternalOneByte(isolate, h_str).FromMaybe(Local<Value>());
}
template <>
MaybeLocal<Value> ExternTwoByteString::NewExternal(
Isolate* isolate, ExternTwoByteString* h_str) {
return String::NewExternalTwoByte(isolate, h_str).FromMaybe(Local<Value>());
}
template <>
MaybeLocal<Value> ExternOneByteString::NewSimpleFromCopy(Isolate* isolate,
const char* data,
size_t length,
Local<Value>* error) {
MaybeLocal<String> str =
String::NewFromOneByte(isolate,
reinterpret_cast<const uint8_t*>(data),
v8::NewStringType::kNormal,
length);
if (str.IsEmpty()) {
*error = SB_STRING_TOO_LONG_ERROR;
return MaybeLocal<Value>();
}
return str.ToLocalChecked();
}
template <>
MaybeLocal<Value> ExternTwoByteString::NewSimpleFromCopy(Isolate* isolate,
const uint16_t* data,
size_t length,
Local<Value>* error) {
MaybeLocal<String> str =
String::NewFromTwoByte(isolate,
data,
v8::NewStringType::kNormal,
length);
if (str.IsEmpty()) {
*error = SB_STRING_TOO_LONG_ERROR;
return MaybeLocal<Value>();
}
return str.ToLocalChecked();
}
} // anonymous namespace
// supports regular and URL-safe base64
const int8_t unbase64_table[256] =
{ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -2, -1, -1, -2, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-2, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, 62, -1, 63,
52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1,
-1, 0, 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, -1, -1, -1, -1, 63,
-1, 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, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1
};
static const int8_t unhex_table[256] =
{ -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, -1, -1, -1, -1, -1, -1,
-1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1
};
static inline unsigned unhex(uint8_t x) {
return unhex_table[x];
}
template <typename TypeName>
static size_t hex_decode(char* buf,
size_t len,
const TypeName* src,
const size_t srcLen) {
size_t i;
for (i = 0; i < len && i * 2 + 1 < srcLen; ++i) {
unsigned a = unhex(src[i * 2 + 0]);
unsigned b = unhex(src[i * 2 + 1]);
if (!~a || !~b)
return i;
buf[i] = (a << 4) | b;
}
return i;
}
bool StringBytes::GetExternalParts(Local<Value> val,
const char** data,
size_t* len) {
if (Buffer::HasInstance(val)) {
*data = Buffer::Data(val);
*len = Buffer::Length(val);
return true;
}
if (!val->IsString())
return false;
Local<String> str = val.As<String>();
if (str->IsExternalOneByte()) {
const String::ExternalOneByteStringResource* ext;
ext = str->GetExternalOneByteStringResource();
*data = ext->data();
*len = ext->length();
return true;
} else if (str->IsExternal()) {
const String::ExternalStringResource* ext;
ext = str->GetExternalStringResource();
*data = reinterpret_cast<const char*>(ext->data());
*len = ext->length() * sizeof(*ext->data());
return true;
}
return false;
}
size_t StringBytes::WriteUCS2(char* buf,
size_t buflen,
Local<String> str,
int flags,
size_t* chars_written) {
uint16_t* const dst = reinterpret_cast<uint16_t*>(buf);
size_t max_chars = (buflen / sizeof(*dst));
size_t nchars;
size_t alignment = reinterpret_cast<uintptr_t>(dst) % sizeof(*dst);
if (alignment == 0) {
nchars = str->Write(dst, 0, max_chars, flags);
*chars_written = nchars;
return nchars * sizeof(*dst);
}
uint16_t* aligned_dst =
reinterpret_cast<uint16_t*>(buf + sizeof(*dst) - alignment);
CHECK_EQ(reinterpret_cast<uintptr_t>(aligned_dst) % sizeof(*dst), 0);
// Write all but the last char
nchars = str->Write(aligned_dst, 0, max_chars - 1, flags);
// Shift everything to unaligned-left
memmove(dst, aligned_dst, nchars * sizeof(*dst));
// One more char to be written
uint16_t last;
if (nchars == max_chars - 1 && str->Write(&last, nchars, 1, flags) != 0) {
memcpy(buf + nchars * sizeof(*dst), &last, sizeof(last));
nchars++;
}
*chars_written = nchars;
return nchars * sizeof(*dst);
}
size_t StringBytes::Write(Isolate* isolate,
char* buf,
size_t buflen,
Local<Value> val,
enum encoding encoding,
int* chars_written) {
HandleScope scope(isolate);
const char* data = nullptr;
size_t nbytes = 0;
const bool is_extern = GetExternalParts(val, &data, &nbytes);
const size_t external_nbytes = nbytes;
CHECK(val->IsString() == true);
Local<String> str = val.As<String>();
if (nbytes > buflen)
nbytes = buflen;
int flags = String::HINT_MANY_WRITES_EXPECTED |
String::NO_NULL_TERMINATION |
String::REPLACE_INVALID_UTF8;
switch (encoding) {
case ASCII:
case LATIN1:
if (is_extern && str->IsOneByte()) {
memcpy(buf, data, nbytes);
} else {
uint8_t* const dst = reinterpret_cast<uint8_t*>(buf);
nbytes = str->WriteOneByte(dst, 0, buflen, flags);
}
if (chars_written != nullptr)
*chars_written = nbytes;
break;
case BUFFER:
case UTF8:
nbytes = str->WriteUtf8(buf, buflen, chars_written, flags);
break;
case UCS2: {
size_t nchars;
if (is_extern && !str->IsOneByte()) {
memcpy(buf, data, nbytes);
nchars = nbytes / sizeof(uint16_t);
} else {
nbytes = WriteUCS2(buf, buflen, str, flags, &nchars);
}
if (chars_written != nullptr)
*chars_written = nchars;
// Node's "ucs2" encoding wants LE character data stored in
// the Buffer, so we need to reorder on BE platforms. See
// http://nodejs.org/api/buffer.html regarding Node's "ucs2"
// encoding specification
if (IsBigEndian())
SwapBytes16(buf, nbytes);
break;
}
case BASE64:
if (is_extern) {
nbytes = base64_decode(buf, buflen, data, external_nbytes);
} else {
String::Value value(str);
nbytes = base64_decode(buf, buflen, *value, value.length());
}
if (chars_written != nullptr) {
*chars_written = nbytes;
}
break;
case HEX:
if (is_extern) {
nbytes = hex_decode(buf, buflen, data, external_nbytes);
} else {
String::Value value(str);
nbytes = hex_decode(buf, buflen, *value, value.length());
}
if (chars_written != nullptr) {
*chars_written = nbytes;
}
break;
default:
CHECK(0 && "unknown encoding");
break;
}
return nbytes;
}
bool StringBytes::IsValidString(Local<String> string,
enum encoding enc) {
if (enc == HEX && string->Length() % 2 != 0)
return false;
// TODO(bnoordhuis) Add BASE64 check?
return true;
}
// Quick and dirty size calculation
// Will always be at least big enough, but may have some extra
// UTF8 can be as much as 3x the size, Base64 can have 1-2 extra bytes
size_t StringBytes::StorageSize(Isolate* isolate,
Local<Value> val,
enum encoding encoding) {
HandleScope scope(isolate);
size_t data_size = 0;
bool is_buffer = Buffer::HasInstance(val);
if (is_buffer && (encoding == BUFFER || encoding == LATIN1)) {
return Buffer::Length(val);
}
Local<String> str = val->ToString(isolate);
switch (encoding) {
case ASCII:
case LATIN1:
data_size = str->Length();
break;
case BUFFER:
case UTF8:
// A single UCS2 codepoint never takes up more than 3 utf8 bytes.
// It is an exercise for the caller to decide when a string is
// long enough to justify calling Size() instead of StorageSize()
data_size = 3 * str->Length();
break;
case UCS2:
data_size = str->Length() * sizeof(uint16_t);
break;
case BASE64:
data_size = base64_decoded_size_fast(str->Length());
break;
case HEX:
CHECK(str->Length() % 2 == 0 && "invalid hex string length");
data_size = str->Length() / 2;
break;
default:
CHECK(0 && "unknown encoding");
break;
}
return data_size;
}
size_t StringBytes::Size(Isolate* isolate,
Local<Value> val,
enum encoding encoding) {
HandleScope scope(isolate);
size_t data_size = 0;
bool is_buffer = Buffer::HasInstance(val);
if (is_buffer && (encoding == BUFFER || encoding == LATIN1))
return Buffer::Length(val);
const char* data;
if (GetExternalParts(val, &data, &data_size))
return data_size;
Local<String> str = val->ToString(isolate);
switch (encoding) {
case ASCII:
case LATIN1:
data_size = str->Length();
break;
case BUFFER:
case UTF8:
data_size = str->Utf8Length();
break;
case UCS2:
data_size = str->Length() * sizeof(uint16_t);
break;
case BASE64: {
String::Value value(str);
data_size = base64_decoded_size(*value, value.length());
break;
}
case HEX:
data_size = str->Length() / 2;
break;
default:
CHECK(0 && "unknown encoding");
break;
}
return data_size;
}
static bool contains_non_ascii_slow(const char* buf, size_t len) {
for (size_t i = 0; i < len; ++i) {
if (buf[i] & 0x80)
return true;
}
return false;
}
static bool contains_non_ascii(const char* src, size_t len) {
if (len < 16) {
return contains_non_ascii_slow(src, len);
}
const unsigned bytes_per_word = sizeof(uintptr_t);
const unsigned align_mask = bytes_per_word - 1;
const unsigned unaligned = reinterpret_cast<uintptr_t>(src) & align_mask;
if (unaligned > 0) {
const unsigned n = bytes_per_word - unaligned;
if (contains_non_ascii_slow(src, n))
return true;
src += n;
len -= n;
}
#if defined(_WIN64) || defined(_LP64)
const uintptr_t mask = 0x8080808080808080ll;
#else
const uintptr_t mask = 0x80808080l;
#endif
const uintptr_t* srcw = reinterpret_cast<const uintptr_t*>(src);
for (size_t i = 0, n = len / bytes_per_word; i < n; ++i) {
if (srcw[i] & mask)
return true;
}
const unsigned remainder = len & align_mask;
if (remainder > 0) {
const size_t offset = len - remainder;
if (contains_non_ascii_slow(src + offset, remainder))
return true;
}
return false;
}
static void force_ascii_slow(const char* src, char* dst, size_t len) {
for (size_t i = 0; i < len; ++i) {
dst[i] = src[i] & 0x7f;
}
}
static void force_ascii(const char* src, char* dst, size_t len) {
if (len < 16) {
force_ascii_slow(src, dst, len);
return;
}
const unsigned bytes_per_word = sizeof(uintptr_t);
const unsigned align_mask = bytes_per_word - 1;
const unsigned src_unalign = reinterpret_cast<uintptr_t>(src) & align_mask;
const unsigned dst_unalign = reinterpret_cast<uintptr_t>(dst) & align_mask;
if (src_unalign > 0) {
if (src_unalign == dst_unalign) {
const unsigned unalign = bytes_per_word - src_unalign;
force_ascii_slow(src, dst, unalign);
src += unalign;
dst += unalign;
len -= src_unalign;
} else {
force_ascii_slow(src, dst, len);
return;
}
}
#if defined(_WIN64) || defined(_LP64)
const uintptr_t mask = ~0x8080808080808080ll;
#else
const uintptr_t mask = ~0x80808080l;
#endif
const uintptr_t* srcw = reinterpret_cast<const uintptr_t*>(src);
uintptr_t* dstw = reinterpret_cast<uintptr_t*>(dst);
for (size_t i = 0, n = len / bytes_per_word; i < n; ++i) {
dstw[i] = srcw[i] & mask;
}
const unsigned remainder = len & align_mask;
if (remainder > 0) {
const size_t offset = len - remainder;
force_ascii_slow(src + offset, dst + offset, remainder);
}
}
static size_t hex_encode(const char* src, size_t slen, char* dst, size_t dlen) {
// We know how much we'll write, just make sure that there's space.
CHECK(dlen >= slen * 2 &&
"not enough space provided for hex encode");
dlen = slen * 2;
for (uint32_t i = 0, k = 0; k < dlen; i += 1, k += 2) {
static const char hex[] = "0123456789abcdef";
uint8_t val = static_cast<uint8_t>(src[i]);
dst[k + 0] = hex[val >> 4];
dst[k + 1] = hex[val & 15];
}
return dlen;
}
#define CHECK_BUFLEN_IN_RANGE(len) \
do { \
if ((len) > Buffer::kMaxLength) { \
*error = SB_BUFFER_SIZE_EXCEEDED_ERROR; \
return MaybeLocal<Value>(); \
} \
} while (0)
MaybeLocal<Value> StringBytes::Encode(Isolate* isolate,
const char* buf,
size_t buflen,
enum encoding encoding,
Local<Value>* error) {
CHECK_NE(encoding, UCS2);
CHECK_BUFLEN_IN_RANGE(buflen);
if (!buflen && encoding != BUFFER) {
return String::Empty(isolate);
}
MaybeLocal<String> val;
switch (encoding) {
case BUFFER:
{
auto maybe_buf = Buffer::Copy(isolate, buf, buflen);
if (maybe_buf.IsEmpty()) {
*error = SB_BUFFER_CREATION_ERROR;
return MaybeLocal<Value>();
}
return maybe_buf.ToLocalChecked();
}
case ASCII:
if (contains_non_ascii(buf, buflen)) {
char* out = node::UncheckedMalloc(buflen);
if (out == nullptr) {
*error = SB_MALLOC_FAILED_ERROR;
return MaybeLocal<Value>();
}
force_ascii(buf, out, buflen);
return ExternOneByteString::New(isolate, out, buflen, error);
} else {
return ExternOneByteString::NewFromCopy(isolate, buf, buflen, error);
}
case UTF8:
val = String::NewFromUtf8(isolate,
buf,
v8::NewStringType::kNormal,
buflen);
if (val.IsEmpty()) {
*error = SB_STRING_TOO_LONG_ERROR;
return MaybeLocal<Value>();
}
return val.ToLocalChecked();
case LATIN1:
return ExternOneByteString::NewFromCopy(isolate, buf, buflen, error);
case BASE64: {
size_t dlen = base64_encoded_size(buflen);
char* dst = node::UncheckedMalloc(dlen);
if (dst == nullptr) {
*error = SB_MALLOC_FAILED_ERROR;
return MaybeLocal<Value>();
}
size_t written = base64_encode(buf, buflen, dst, dlen);
CHECK_EQ(written, dlen);
return ExternOneByteString::New(isolate, dst, dlen, error);
}
case HEX: {
size_t dlen = buflen * 2;
char* dst = node::UncheckedMalloc(dlen);
if (dst == nullptr) {
*error = SB_MALLOC_FAILED_ERROR;
return MaybeLocal<Value>();
}
size_t written = hex_encode(buf, buflen, dst, dlen);
CHECK_EQ(written, dlen);
return ExternOneByteString::New(isolate, dst, dlen, error);
}
default:
CHECK(0 && "unknown encoding");
break;
}
UNREACHABLE();
}
MaybeLocal<Value> StringBytes::Encode(Isolate* isolate,
const uint16_t* buf,
size_t buflen,
Local<Value>* error) {
CHECK_BUFLEN_IN_RANGE(buflen);
// Node's "ucs2" encoding expects LE character data inside a
// Buffer, so we need to reorder on BE platforms. See
// http://nodejs.org/api/buffer.html regarding Node's "ucs2"
// encoding specification
std::vector<uint16_t> dst;
if (IsBigEndian()) {
dst.assign(buf, buf + buflen);
size_t nbytes = buflen * sizeof(dst[0]);
SwapBytes16(reinterpret_cast<char*>(&dst[0]), nbytes);
buf = &dst[0];
}
return ExternTwoByteString::NewFromCopy(isolate, buf, buflen, error);
}
MaybeLocal<Value> StringBytes::Encode(Isolate* isolate,
const char* buf,
enum encoding encoding,
Local<Value>* error) {
const size_t len = strlen(buf);
MaybeLocal<Value> ret;
if (encoding == UCS2) {
// In Node, UCS2 means utf16le. The data must be in little-endian
// order and must be aligned on 2-bytes. This returns an empty
// value if it's not aligned and ensures the appropriate byte order
// on big endian architectures.
const bool be = IsBigEndian();
if (len % 2 != 0)
return ret;
std::vector<uint16_t> vec(len / 2);
for (size_t i = 0, k = 0; i < len; i += 2, k += 1) {
const uint8_t hi = static_cast<uint8_t>(buf[i + 0]);
const uint8_t lo = static_cast<uint8_t>(buf[i + 1]);
vec[k] = be ?
static_cast<uint16_t>(hi) << 8 | lo
: static_cast<uint16_t>(lo) << 8 | hi;
}
ret = vec.empty() ?
static_cast< Local<Value> >(String::Empty(isolate))
: StringBytes::Encode(isolate, &vec[0], vec.size(), error);
} else {
ret = StringBytes::Encode(isolate, buf, len, encoding, error);
}
return ret;
}
} // namespace node
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