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gecko-dev
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gecko-dev/dom/json/nsJSON.cpp

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18 KiB
C++
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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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 "jsapi.h"
#include "js/CharacterEncoding.h"
#include "nsJSON.h"
#include "nsIXPConnect.h"
#include "nsIXPCScriptable.h"
#include "nsStreamUtils.h"
#include "nsIInputStream.h"
#include "nsStringStream.h"
#include "mozilla/dom/EncodingUtils.h"
#include "nsIUnicodeEncoder.h"
#include "nsIUnicodeDecoder.h"
#include "nsXPCOMStrings.h"
#include "nsNetUtil.h"
#include "nsIURI.h"
#include "nsComponentManagerUtils.h"
#include "nsContentUtils.h"
#include "nsIScriptError.h"
#include "nsCRTGlue.h"
#include "nsAutoPtr.h"
#include "nsIScriptSecurityManager.h"
#include "nsNullPrincipal.h"
#include "mozilla/Maybe.h"
#include <algorithm>
using mozilla::dom::EncodingUtils;
#define JSON_STREAM_BUFSIZE 4096
NS_INTERFACE_MAP_BEGIN(nsJSON)
NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, nsIJSON)
NS_INTERFACE_MAP_ENTRY(nsIJSON)
NS_INTERFACE_MAP_END
NS_IMPL_ADDREF(nsJSON)
NS_IMPL_RELEASE(nsJSON)
nsJSON::nsJSON()
{
}
nsJSON::~nsJSON()
{
}
enum DeprecationWarning { EncodeWarning, DecodeWarning };
static nsresult
WarnDeprecatedMethod(DeprecationWarning warning)
{
return nsContentUtils::ReportToConsole(nsIScriptError::warningFlag,
NS_LITERAL_CSTRING("DOM Core"), nullptr,
nsContentUtils::eDOM_PROPERTIES,
warning == EncodeWarning
? "nsIJSONEncodeDeprecatedWarning"
: "nsIJSONDecodeDeprecatedWarning");
}
NS_IMETHODIMP
nsJSON::Encode(JS::Handle<JS::Value> aValue, JSContext* cx, uint8_t aArgc,
nsAString &aJSON)
{
// This function should only be called from JS.
nsresult rv = WarnDeprecatedMethod(EncodeWarning);
if (NS_FAILED(rv))
return rv;
if (aArgc == 0) {
aJSON.Truncate();
aJSON.SetIsVoid(true);
return NS_OK;
}
nsJSONWriter writer;
rv = EncodeInternal(cx, aValue, &writer);
// FIXME: bug 408838. Get exception types sorted out
if (NS_SUCCEEDED(rv) || rv == NS_ERROR_INVALID_ARG) {
rv = NS_OK;
// if we didn't consume anything, it's not JSON, so return null
if (!writer.DidWrite()) {
aJSON.Truncate();
aJSON.SetIsVoid(true);
} else {
writer.FlushBuffer();
aJSON.Append(writer.mOutputString);
}
}
return rv;
}
static const char UTF8BOM[] = "\xEF\xBB\xBF";
static const char UTF16LEBOM[] = "\xFF\xFE";
static const char UTF16BEBOM[] = "\xFE\xFF";
static nsresult CheckCharset(const char* aCharset)
{
// Check that the charset is permissible
if (!(strcmp(aCharset, "UTF-8") == 0 ||
strcmp(aCharset, "UTF-16LE") == 0 ||
strcmp(aCharset, "UTF-16BE") == 0)) {
return NS_ERROR_INVALID_ARG;
}
return NS_OK;
}
NS_IMETHODIMP
nsJSON::EncodeToStream(nsIOutputStream *aStream,
const char* aCharset,
const bool aWriteBOM,
JS::Handle<JS::Value> val,
JSContext* cx,
uint8_t aArgc)
{
// This function should only be called from JS.
NS_ENSURE_ARG(aStream);
nsresult rv;
rv = CheckCharset(aCharset);
NS_ENSURE_SUCCESS(rv, rv);
// Check to see if we have a buffered stream
nsCOMPtr<nsIOutputStream> bufferedStream;
// FIXME: bug 408514.
// NS_OutputStreamIsBuffered(aStream) asserts on file streams...
//if (!NS_OutputStreamIsBuffered(aStream)) {
rv = NS_NewBufferedOutputStream(getter_AddRefs(bufferedStream),
aStream, 4096);
NS_ENSURE_SUCCESS(rv, rv);
// aStream = bufferedStream;
//}
uint32_t ignored;
if (aWriteBOM) {
if (strcmp(aCharset, "UTF-8") == 0)
rv = aStream->Write(UTF8BOM, 3, &ignored);
else if (strcmp(aCharset, "UTF-16LE") == 0)
rv = aStream->Write(UTF16LEBOM, 2, &ignored);
else if (strcmp(aCharset, "UTF-16BE") == 0)
rv = aStream->Write(UTF16BEBOM, 2, &ignored);
NS_ENSURE_SUCCESS(rv, rv);
}
nsJSONWriter writer(bufferedStream);
rv = writer.SetCharset(aCharset);
NS_ENSURE_SUCCESS(rv, rv);
if (aArgc == 0) {
return NS_OK;
}
rv = EncodeInternal(cx, val, &writer);
NS_ENSURE_SUCCESS(rv, rv);
rv = bufferedStream->Flush();
return rv;
}
static bool
WriteCallback(const char16_t *buf, uint32_t len, void *data)
{
nsJSONWriter *writer = static_cast<nsJSONWriter*>(data);
nsresult rv = writer->Write((const char16_t*)buf, (uint32_t)len);
if (NS_FAILED(rv))
return false;
return true;
}
NS_IMETHODIMP
nsJSON::EncodeFromJSVal(JS::Value *value, JSContext *cx, nsAString &result)
{
result.Truncate();
mozilla::Maybe<JSAutoCompartment> ac;
if (value->isObject()) {
JS::Rooted<JSObject*> obj(cx, &value->toObject());
ac.emplace(cx, obj);
}
nsJSONWriter writer;
JS::Rooted<JS::Value> vp(cx, *value);
if (!JS_Stringify(cx, &vp, nullptr, JS::NullHandleValue, WriteCallback, &writer)) {
return NS_ERROR_XPC_BAD_CONVERT_JS;
}
*value = vp;
NS_ENSURE_TRUE(writer.DidWrite(), NS_ERROR_UNEXPECTED);
writer.FlushBuffer();
result.Assign(writer.mOutputString);
return NS_OK;
}
nsresult
nsJSON::EncodeInternal(JSContext* cx, const JS::Value& aValue,
nsJSONWriter* writer)
{
// Backward compatibility:
// nsIJSON does not allow to serialize anything other than objects
if (!aValue.isObject()) {
return NS_ERROR_INVALID_ARG;
}
JS::Rooted<JSObject*> obj(cx, &aValue.toObject());
/* Backward compatibility:
* Manually call toJSON if implemented by the object and check that
* the result is still an object
* Note: It is perfectly fine to not implement toJSON, so it is
* perfectly fine for GetMethod to fail
*/
JS::Rooted<JS::Value> val(cx, aValue);
JS::Rooted<JS::Value> toJSON(cx);
if (JS_GetProperty(cx, obj, "toJSON", &toJSON) &&
toJSON.isObject() && JS::IsCallable(&toJSON.toObject())) {
// If toJSON is implemented, it must not throw
if (!JS_CallFunctionValue(cx, obj, toJSON, JS::HandleValueArray::empty(), &val)) {
if (JS_IsExceptionPending(cx))
// passing NS_OK will throw the pending exception
return NS_OK;
// No exception, but still failed
return NS_ERROR_FAILURE;
}
// Backward compatibility:
// nsIJSON does not allow to serialize anything other than objects
if (val.isPrimitive())
return NS_ERROR_INVALID_ARG;
}
// GetMethod may have thrown
else if (JS_IsExceptionPending(cx))
// passing NS_OK will throw the pending exception
return NS_OK;
// Backward compatibility:
// function shall not pass, just "plain" objects and arrays
JSType type = JS_TypeOfValue(cx, val);
if (type == JSTYPE_FUNCTION)
return NS_ERROR_INVALID_ARG;
// We're good now; try to stringify
if (!JS_Stringify(cx, &val, nullptr, JS::NullHandleValue, WriteCallback, writer))
return NS_ERROR_FAILURE;
return NS_OK;
}
nsJSONWriter::nsJSONWriter() : mStream(nullptr),
mBuffer(nullptr),
mBufferCount(0),
mDidWrite(false),
mEncoder(nullptr)
{
}
nsJSONWriter::nsJSONWriter(nsIOutputStream *aStream) : mStream(aStream),
mBuffer(nullptr),
mBufferCount(0),
mDidWrite(false),
mEncoder(nullptr)
{
}
nsJSONWriter::~nsJSONWriter()
{
delete [] mBuffer;
}
nsresult
nsJSONWriter::SetCharset(const char* aCharset)
{
nsresult rv = NS_OK;
if (mStream) {
mEncoder = EncodingUtils::EncoderForEncoding(aCharset);
rv = mEncoder->SetOutputErrorBehavior(nsIUnicodeEncoder::kOnError_Signal,
nullptr, '\0');
NS_ENSURE_SUCCESS(rv, rv);
}
return rv;
}
nsresult
nsJSONWriter::Write(const char16_t *aBuffer, uint32_t aLength)
{
if (mStream) {
return WriteToStream(mStream, mEncoder, aBuffer, aLength);
}
if (!mDidWrite) {
mBuffer = new char16_t[JSON_STREAM_BUFSIZE];
mDidWrite = true;
}
if (JSON_STREAM_BUFSIZE <= aLength + mBufferCount) {
mOutputString.Append(mBuffer, mBufferCount);
mBufferCount = 0;
}
if (JSON_STREAM_BUFSIZE <= aLength) {
// we know mBufferCount is 0 because we know we hit the if above
mOutputString.Append(aBuffer, aLength);
} else {
memcpy(&mBuffer[mBufferCount], aBuffer, aLength * sizeof(char16_t));
mBufferCount += aLength;
}
return NS_OK;
}
bool nsJSONWriter::DidWrite()
{
return mDidWrite;
}
void
nsJSONWriter::FlushBuffer()
{
mOutputString.Append(mBuffer, mBufferCount);
}
nsresult
nsJSONWriter::WriteToStream(nsIOutputStream *aStream,
nsIUnicodeEncoder *encoder,
const char16_t *aBuffer,
uint32_t aLength)
{
nsresult rv;
int32_t srcLength = aLength;
uint32_t bytesWritten;
// The bytes written to the stream might differ from the char16_t size
int32_t aDestLength;
rv = encoder->GetMaxLength(aBuffer, srcLength, &aDestLength);
NS_ENSURE_SUCCESS(rv, rv);
// create the buffer we need
char* destBuf = (char *) moz_xmalloc(aDestLength);
if (!destBuf)
return NS_ERROR_OUT_OF_MEMORY;
rv = encoder->Convert(aBuffer, &srcLength, destBuf, &aDestLength);
if (NS_SUCCEEDED(rv))
rv = aStream->Write(destBuf, aDestLength, &bytesWritten);
free(destBuf);
mDidWrite = true;
return rv;
}
NS_IMETHODIMP
nsJSON::Decode(const nsAString& json, JSContext* cx,
JS::MutableHandle<JS::Value> aRetval)
{
nsresult rv = WarnDeprecatedMethod(DecodeWarning);
if (NS_FAILED(rv))
return rv;
const char16_t *data;
uint32_t len = NS_StringGetData(json, &data);
nsCOMPtr<nsIInputStream> stream;
rv = NS_NewByteInputStream(getter_AddRefs(stream),
reinterpret_cast<const char*>(data),
len * sizeof(char16_t),
NS_ASSIGNMENT_DEPEND);
NS_ENSURE_SUCCESS(rv, rv);
return DecodeInternal(cx, stream, len, false, aRetval);
}
NS_IMETHODIMP
nsJSON::DecodeFromStream(nsIInputStream *aStream, int32_t aContentLength,
JSContext* cx, JS::MutableHandle<JS::Value> aRetval)
{
return DecodeInternal(cx, aStream, aContentLength, true, aRetval);
}
NS_IMETHODIMP
nsJSON::DecodeToJSVal(const nsAString &str, JSContext *cx,
JS::MutableHandle<JS::Value> result)
{
if (!JS_ParseJSON(cx, static_cast<const char16_t*>(PromiseFlatString(str).get()),
str.Length(), result)) {
return NS_ERROR_UNEXPECTED;
}
return NS_OK;
}
nsresult
nsJSON::DecodeInternal(JSContext* cx,
nsIInputStream *aStream,
int32_t aContentLength,
bool aNeedsConverter,
JS::MutableHandle<JS::Value> aRetval)
{
// Consume the stream
nsCOMPtr<nsIChannel> jsonChannel;
if (!mURI) {
NS_NewURI(getter_AddRefs(mURI), NS_LITERAL_CSTRING("about:blank"), 0, 0 );
if (!mURI)
return NS_ERROR_OUT_OF_MEMORY;
}
nsresult rv;
nsCOMPtr<nsIPrincipal> nullPrincipal = nsNullPrincipal::Create();
NS_ENSURE_TRUE(nullPrincipal, NS_ERROR_FAILURE);
// The ::Decode function is deprecated [Bug 675797] and the following
// channel is never openend, so it does not matter what securityFlags
// we pass to NS_NewInputStreamChannel here.
rv = NS_NewInputStreamChannel(getter_AddRefs(jsonChannel),
mURI,
aStream,
nullPrincipal,
nsILoadInfo::SEC_REQUIRE_SAME_ORIGIN_DATA_IS_BLOCKED,
nsIContentPolicy::TYPE_OTHER,
NS_LITERAL_CSTRING("application/json"));
if (!jsonChannel || NS_FAILED(rv))
return NS_ERROR_FAILURE;
RefPtr<nsJSONListener> jsonListener =
new nsJSONListener(cx, aRetval.address(), aNeedsConverter);
//XXX this stream pattern should be consolidated in netwerk
rv = jsonListener->OnStartRequest(jsonChannel, nullptr);
if (NS_FAILED(rv)) {
jsonChannel->Cancel(rv);
return rv;
}
nsresult status;
jsonChannel->GetStatus(&status);
uint64_t offset = 0;
while (NS_SUCCEEDED(status)) {
uint64_t available;
rv = aStream->Available(&available);
if (rv == NS_BASE_STREAM_CLOSED) {
rv = NS_OK;
break;
}
if (NS_FAILED(rv)) {
jsonChannel->Cancel(rv);
break;
}
if (!available)
break; // blocking input stream has none available when done
if (available > UINT32_MAX)
available = UINT32_MAX;
rv = jsonListener->OnDataAvailable(jsonChannel, nullptr,
aStream,
offset,
(uint32_t)available);
if (NS_FAILED(rv)) {
jsonChannel->Cancel(rv);
break;
}
offset += available;
jsonChannel->GetStatus(&status);
}
NS_ENSURE_SUCCESS(rv, rv);
rv = jsonListener->OnStopRequest(jsonChannel, nullptr, status);
NS_ENSURE_SUCCESS(rv, rv);
return NS_OK;
}
nsresult
NS_NewJSON(nsISupports* aOuter, REFNSIID aIID, void** aResult)
{
nsJSON* json = new nsJSON();
NS_ADDREF(json);
*aResult = json;
return NS_OK;
}
nsJSONListener::nsJSONListener(JSContext *cx, JS::Value *rootVal,
bool needsConverter)
: mNeedsConverter(needsConverter),
mCx(cx),
mRootVal(rootVal)
{
}
nsJSONListener::~nsJSONListener()
{
}
NS_INTERFACE_MAP_BEGIN(nsJSONListener)
NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, nsJSONListener)
NS_INTERFACE_MAP_ENTRY(nsIRequestObserver)
NS_INTERFACE_MAP_ENTRY(nsIStreamListener)
NS_INTERFACE_MAP_END
NS_IMPL_ADDREF(nsJSONListener)
NS_IMPL_RELEASE(nsJSONListener)
NS_IMETHODIMP
nsJSONListener::OnStartRequest(nsIRequest *aRequest, nsISupports *aContext)
{
mSniffBuffer.Truncate();
mDecoder = nullptr;
return NS_OK;
}
NS_IMETHODIMP
nsJSONListener::OnStopRequest(nsIRequest *aRequest, nsISupports *aContext,
nsresult aStatusCode)
{
nsresult rv;
// This can happen with short UTF-8 messages (<4 bytes)
if (!mSniffBuffer.IsEmpty()) {
// Just consume mSniffBuffer
rv = ProcessBytes(nullptr, 0);
NS_ENSURE_SUCCESS(rv, rv);
}
JS::Rooted<JS::Value> reviver(mCx, JS::NullValue()), value(mCx);
JS::ConstTwoByteChars chars(reinterpret_cast<const char16_t*>(mBufferedChars.Elements()),
mBufferedChars.Length());
bool ok = JS_ParseJSONWithReviver(mCx, chars.start().get(),
uint32_t(mBufferedChars.Length()),
reviver, &value);
*mRootVal = value;
mBufferedChars.TruncateLength(0);
return ok ? NS_OK : NS_ERROR_FAILURE;
}
NS_IMETHODIMP
nsJSONListener::OnDataAvailable(nsIRequest *aRequest, nsISupports *aContext,
nsIInputStream *aStream,
uint64_t aOffset, uint32_t aLength)
{
nsresult rv = NS_OK;
if (mNeedsConverter && mSniffBuffer.Length() < 4) {
uint32_t readCount = (aLength < 4) ? aLength : 4;
rv = NS_ConsumeStream(aStream, readCount, mSniffBuffer);
NS_ENSURE_SUCCESS(rv, rv);
if (mSniffBuffer.Length() < 4)
return NS_OK;
}
char buffer[JSON_STREAM_BUFSIZE];
unsigned long bytesRemaining = aLength - mSniffBuffer.Length();
while (bytesRemaining) {
unsigned int bytesRead;
rv = aStream->Read(buffer,
std::min((unsigned long)sizeof(buffer), bytesRemaining),
&bytesRead);
NS_ENSURE_SUCCESS(rv, rv);
rv = ProcessBytes(buffer, bytesRead);
NS_ENSURE_SUCCESS(rv, rv);
bytesRemaining -= bytesRead;
}
return rv;
}
nsresult
nsJSONListener::ProcessBytes(const char* aBuffer, uint32_t aByteLength)
{
nsresult rv;
// Check for BOM, or sniff charset
nsAutoCString charset;
if (mNeedsConverter && !mDecoder) {
if (!nsContentUtils::CheckForBOM((const unsigned char*) mSniffBuffer.get(),
mSniffBuffer.Length(), charset)) {
// OK, found no BOM, sniff the first character to see what this is
// See section 3 of RFC4627 for details on why this works.
const char *buffer = mSniffBuffer.get();
if (mSniffBuffer.Length() >= 4) {
if (buffer[0] == 0x00 && buffer[1] != 0x00 &&
buffer[2] == 0x00 && buffer[3] != 0x00) {
charset = "UTF-16BE";
} else if (buffer[0] != 0x00 && buffer[1] == 0x00 &&
buffer[2] != 0x00 && buffer[3] == 0x00) {
charset = "UTF-16LE";
} else if (buffer[0] != 0x00 && buffer[1] != 0x00 &&
buffer[2] != 0x00 && buffer[3] != 0x00) {
charset = "UTF-8";
}
} else {
// Not enough bytes to sniff, assume UTF-8
charset = "UTF-8";
}
}
// We should have a unicode charset by now
rv = CheckCharset(charset.get());
NS_ENSURE_SUCCESS(rv, rv);
mDecoder = EncodingUtils::DecoderForEncoding(charset);
// consume the sniffed bytes
rv = ConsumeConverted(mSniffBuffer.get(), mSniffBuffer.Length());
NS_ENSURE_SUCCESS(rv, rv);
mSniffBuffer.Truncate();
}
if (!aBuffer)
return NS_OK;
if (mNeedsConverter) {
rv = ConsumeConverted(aBuffer, aByteLength);
} else {
uint32_t unichars = aByteLength / sizeof(char16_t);
rv = Consume((char16_t *) aBuffer, unichars);
}
return rv;
}
nsresult
nsJSONListener::ConsumeConverted(const char* aBuffer, uint32_t aByteLength)
{
nsresult rv;
int32_t unicharLength = 0;
int32_t srcLen = aByteLength;
rv = mDecoder->GetMaxLength(aBuffer, srcLen, &unicharLength);
NS_ENSURE_SUCCESS(rv, rv);
char16_t* endelems = mBufferedChars.AppendElements(unicharLength);
int32_t preLength = unicharLength;
rv = mDecoder->Convert(aBuffer, &srcLen, endelems, &unicharLength);
if (NS_FAILED(rv))
return rv;
MOZ_ASSERT(preLength >= unicharLength, "GetMaxLength lied");
if (preLength > unicharLength)
mBufferedChars.TruncateLength(mBufferedChars.Length() - (preLength - unicharLength));
return NS_OK;
}
nsresult
nsJSONListener::Consume(const char16_t* aBuffer, uint32_t aByteLength)
{
if (!mBufferedChars.AppendElements(aBuffer, aByteLength))
return NS_ERROR_FAILURE;
return NS_OK;
}
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