node/src/string_bytes.cc at master · indutny/node

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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 "node.h"

#include "node_buffer.h"

#include "v8.h"

#include <assert.h>

#include <limits.h>

#include <string.h> // memcpy

// 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

namespace node {

using v8::Handle;

using v8::HandleScope;

using v8::Local;

using v8::String;

using v8::Value;

template <typename ResourceType, typename TypeName>

class ExternString: public ResourceType {

public:

~ExternString() {

delete[] data_;

node_isolate->AdjustAmountOfExternalAllocatedMemory(-length_);

}

const TypeName* data() const {

return data_;

}

size_t length() const {

return length_;

}

static Local<String> NewFromCopy(const TypeName* data, size_t length) {

HandleScope scope(node_isolate);

if (length == 0)

return scope.Close(String::Empty(node_isolate));

TypeName* new_data = new TypeName[length];

memcpy(new_data, data, length * sizeof(*new_data));

return scope.Close(ExternString<ResourceType, TypeName>::New(new_data,

length));

}

// uses "data" for external resource, and will be free'd on gc

static Local<String> New(const TypeName* data, size_t length) {

HandleScope scope(node_isolate);

if (length == 0)

return scope.Close(String::Empty(node_isolate));

ExternString* h_str = new ExternString<ResourceType, TypeName>(data,

length);

Local<String> str = String::NewExternal(h_str);

node_isolate->AdjustAmountOfExternalAllocatedMemory(length);

return scope.Close(str);

}

private:

ExternString(const TypeName* data, size_t length)

: data_(data), length_(length) { }

const TypeName* data_;

size_t length_;

};

typedef ExternString<String::ExternalAsciiStringResource,

char> ExternOneByteString;

typedef ExternString<String::ExternalStringResource,

uint16_t> ExternTwoByteString;

//// Base 64 ////

#define base64_encoded_size(size) ((size + 2 - ((size + 2) % 3)) / 3 * 4)

// Doesn't check for padding at the end. Can be 1-2 bytes over.

static inline size_t base64_decoded_size_fast(size_t size) {

size_t remainder = size % 4;

size = (size / 4) * 3;

if (remainder) {

if (size == 0 && remainder == 1) {

// special case: 1-byte input cannot be decoded

size = 0;

} else {

// non-padded input, add 1 or 2 extra bytes

size += 1 + (remainder == 3);

}

return size;

}

template <typename TypeName>

size_t base64_decoded_size(const TypeName* src, size_t size) {

if (size == 0)

return 0;

if (src[size - 1] == '=')

size--;

if (size > 0 && src[size - 1] == '=')

size--;

return base64_decoded_size_fast(size);

}

// supports regular and URL-safe base64

static const int unbase64_table[] =

{ -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

};

#define unbase64(x) unbase64_table[(uint8_t)(x)]

template <typename TypeName>

size_t base64_decode(char* buf,

size_t len,

const TypeName* src,

const size_t srcLen) {

char a, b, c, d;

char* dst = buf;

char* dstEnd = buf + len;

const TypeName* srcEnd = src + srcLen;

while (src < srcEnd && dst < dstEnd) {

int remaining = srcEnd - src;

while (unbase64(*src) < 0 && src < srcEnd)

src++, remaining--;

if (remaining == 0 || *src == '=')

break;

a = unbase64(*src++);

while (unbase64(*src) < 0 && src < srcEnd)

src++, remaining--;

if (remaining <= 1 || *src == '=')

break;

b = unbase64(*src++);

*dst++ = (a << 2) | ((b & 0x30) >> 4);

if (dst == dstEnd)

break;

while (unbase64(*src) < 0 && src < srcEnd)

src++, remaining--;

if (remaining <= 2 || *src == '=')

break;

c = unbase64(*src++);

*dst++ = ((b & 0x0F) << 4) | ((c & 0x3C) >> 2);

if (dst == dstEnd)

break;

while (unbase64(*src) < 0 && src < srcEnd)

src++, remaining--;

if (remaining <= 3 || *src == '=')

break;

d = unbase64(*src++);

*dst++ = ((c & 0x03) << 6) | (d & 0x3F);

}

return dst - buf;

}

//// HEX ////

template <typename TypeName>

unsigned hex2bin(TypeName c) {

if (c >= '0' && c <= '9')

return c - '0';

if (c >= 'A' && c <= 'F')

return 10 + (c - 'A');

if (c >= 'a' && c <= 'f')

return 10 + (c - 'a');

return static_cast<unsigned>(-1);

}

template <typename TypeName>

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 = hex2bin(src[i * 2 + 0]);

unsigned b = hex2bin(src[i * 2 + 1]);

if (!~a || !~b)

return i;

buf[i] = a * 16 + b;

}

return i;

}

bool StringBytes::GetExternalParts(Handle<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->IsExternalAscii()) {

const String::ExternalAsciiStringResource* ext;

ext = str->GetExternalAsciiStringResource();

*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();

return true;

}

return false;

}

size_t StringBytes::Write(char* buf,

size_t buflen,

Handle<Value> val,

enum encoding encoding,

int* chars_written) {

HandleScope scope(node_isolate);

const char* data;

size_t len = 0;

bool is_extern = GetExternalParts(val, &data, &len);

Local<String> str = val.As<String>();

len = len < buflen ? len : buflen;

int flags = String::NO_NULL_TERMINATION |

String::HINT_MANY_WRITES_EXPECTED;

switch (encoding) {

case ASCII:

case BINARY:

case BUFFER:

if (is_extern)

memcpy(buf, data, len);

else

len = str->WriteOneByte(reinterpret_cast<uint8_t*>(buf),

buflen,

flags);

if (chars_written != NULL)

*chars_written = len;

break;

case UTF8:

if (is_extern)

memcpy(buf, data, len);

else

len = str->WriteUtf8(buf, buflen, chars_written, flags);

break;

case UCS2:

if (is_extern)

memcpy(buf, data, len * 2);

else

len = str->Write(reinterpret_cast<uint16_t*>(buf), 0, buflen, flags);

if (chars_written != NULL)

*chars_written = len;

len = len * sizeof(uint16_t);

break;

case BASE64:

if (is_extern) {

base64_decode(buf, buflen, data, len);

} else {

String::Value value(str);

len = base64_decode(buf, buflen, *value, value.length());

}

if (chars_written != NULL) {

*chars_written = len;

}

break;

case HEX:

if (is_extern) {

hex_decode(buf, buflen, data, len);

} else {

String::Value value(str);

len = hex_decode(buf, buflen, *value, value.length());

}

if (chars_written != NULL) {

*chars_written = len * 2;

}

break;

default:

assert(0 && "unknown encoding");

break;

}

return len;

}

bool StringBytes::IsValidString(Handle<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(Handle<Value> val, enum encoding encoding) {

HandleScope scope(node_isolate);

size_t data_size = 0;

bool is_buffer = Buffer::HasInstance(val);

if (is_buffer && (encoding == BUFFER || encoding == BINARY)) {

return Buffer::Length(val);

}

Local<String> str = val->ToString();

switch (encoding) {

case BINARY:

case BUFFER:

case ASCII:

data_size = str->Length();

break;

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:

assert(str->Length() % 2 == 0 && "invalid hex string length");

data_size = str->Length() / 2;

break;

default:

assert(0 && "unknown encoding");

break;

}

return data_size;

}

size_t StringBytes::Size(Handle<Value> val, enum encoding encoding) {

HandleScope scope(node_isolate);

size_t data_size = 0;

bool is_buffer = Buffer::HasInstance(val);

if (is_buffer && (encoding == BUFFER || encoding == BINARY))

return Buffer::Length(val);

const char* data;

if (GetExternalParts(val, &data, &data_size))

return data_size;

Local<String> str = val->ToString();

switch (encoding) {

case BINARY:

case BUFFER:

case ASCII:

data_size = str->Length();

break;

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:

assert(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(__x86_64__) || defined(_WIN64)

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(__x86_64__) || defined(_WIN64)

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 base64_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.

assert(dlen >= base64_encoded_size(slen) &&

"not enough space provided for base64 encode");

dlen = base64_encoded_size(slen);

unsigned a;

unsigned b;

unsigned c;

unsigned i;

unsigned k;

unsigned n;

static const char table[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"

"abcdefghijklmnopqrstuvwxyz"

"0123456789+/";

i = 0;

k = 0;

n = slen / 3 * 3;

while (i < n) {

a = src[i + 0] & 0xff;

b = src[i + 1] & 0xff;

c = src[i + 2] & 0xff;

dst[k + 0] = table[a >> 2];

dst[k + 1] = table[((a & 3) << 4) | (b >> 4)];

dst[k + 2] = table[((b & 0x0f) << 2) | (c >> 6)];

dst[k + 3] = table[c & 0x3f];

i += 3;

k += 4;

}

if (n != slen) {

switch (slen - n) {

case 1:

a = src[i + 0] & 0xff;

dst[k + 0] = table[a >> 2];

dst[k + 1] = table[(a & 3) << 4];

dst[k + 2] = '=';

dst[k + 3] = '=';

break;

case 2:

a = src[i + 0] & 0xff;

b = src[i + 1] & 0xff;

dst[k + 0] = table[a >> 2];

dst[k + 1] = table[((a & 3) << 4) | (b >> 4)];

dst[k + 2] = table[(b & 0x0f) << 2];

dst[k + 3] = '=';

break;

}

return dlen;

}

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.

assert(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;

}

Local<Value> StringBytes::Encode(const char* buf,

size_t buflen,

enum encoding encoding) {

HandleScope scope(node_isolate);

assert(buflen <= Buffer::kMaxLength);

if (!buflen && encoding != BUFFER)

return scope.Close(String::Empty(node_isolate));

Local<String> val;

switch (encoding) {

case BUFFER:

return scope.Close(Buffer::New(buf, buflen));

case ASCII:

if (contains_non_ascii(buf, buflen)) {

char* out = new char[buflen];

force_ascii(buf, out, buflen);

if (buflen < EXTERN_APEX) {

val = OneByteString(node_isolate, out, buflen);

delete[] out;

} else {

val = ExternOneByteString::New(out, buflen);

}

} else {

if (buflen < EXTERN_APEX)

val = OneByteString(node_isolate, buf, buflen);

else

val = ExternOneByteString::NewFromCopy(buf, buflen);

}

break;

case UTF8:

val = String::NewFromUtf8(node_isolate,

buf,

String::kNormalString,

buflen);

break;

case BINARY:

if (buflen < EXTERN_APEX)

val = OneByteString(node_isolate, buf, buflen);

else

val = ExternOneByteString::NewFromCopy(buf, buflen);

break;

case BASE64: {

size_t dlen = base64_encoded_size(buflen);

char* dst = new char[dlen];

size_t written = base64_encode(buf, buflen, dst, dlen);

assert(written == dlen);

if (dlen < EXTERN_APEX) {

val = OneByteString(node_isolate, dst, dlen);

delete[] dst;

} else {

val = ExternOneByteString::New(dst, dlen);

}

break;

}

case UCS2: {

const uint16_t* out = reinterpret_cast<const uint16_t*>(buf);

if (buflen < EXTERN_APEX)

val = String::NewFromTwoByte(node_isolate,

out,

String::kNormalString,

buflen / 2);

else

val = ExternTwoByteString::NewFromCopy(out, buflen / 2);

break;

}

case HEX: {

size_t dlen = buflen * 2;

char* dst = new char[dlen];

size_t written = hex_encode(buf, buflen, dst, dlen);

assert(written == dlen);

if (dlen < EXTERN_APEX) {

val = OneByteString(node_isolate, dst, dlen);

delete[] dst;

} else {

val = ExternOneByteString::New(dst, dlen);

}

break;

}

default:

assert(0 && "unknown encoding");

break;

}

return scope.Close(val);

}

} // namespace node

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