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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
* 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/. */
#ifndef vm_Xdr_h
#define vm_Xdr_h
#include "mozilla/EndianUtils.h"
#include "mozilla/TypeTraits.h"
#include "jsatom.h"
#include "jsfriendapi.h"
namespace js {
class XDRBuffer {
public:
XDRBuffer(JSContext* cx, JS::TranscodeBuffer& buffer, size_t cursor = 0)
: context_(cx), buffer_(buffer), cursor_(cursor) { }
JSContext* cx() const {
return context_;
}
const uint8_t* read(size_t n) {
MOZ_ASSERT(cursor_ < buffer_.length());
uint8_t* ptr = &buffer_[cursor_];
cursor_ += n;
return ptr;
}
const char* readCString() {
char* ptr = reinterpret_cast<char*>(&buffer_[cursor_]);
uint8_t* end = reinterpret_cast<uint8_t*>(strchr(ptr, '\0')) + 1;
MOZ_ASSERT(buffer_.begin() < end);
MOZ_ASSERT(end <= buffer_.end());
cursor_ = end - buffer_.begin();
return ptr;
}
uint8_t* write(size_t n) {
MOZ_ASSERT(n != 0);
if (!buffer_.growByUninitialized(n)) {
JS_ReportOutOfMemory(cx());
return nullptr;
}
uint8_t* ptr = &buffer_[cursor_];
cursor_ += n;
return ptr;
}
private:
JSContext* const context_;
JS::TranscodeBuffer& buffer_;
size_t cursor_;
};
/*
* XDR serialization state. All data is encoded in little endian.
*/
template <XDRMode mode>
class XDRState {
public:
XDRBuffer buf;
JS::TranscodeResult resultCode_;
XDRState(JSContext* cx, JS::TranscodeBuffer& buffer, size_t cursor = 0)
: buf(cx, buffer, cursor), resultCode_(JS::TranscodeResult_Ok) { }
JSContext* cx() const {
return buf.cx();
}
// Record logical failures of XDR.
void postProcessContextErrors(JSContext* cx);
JS::TranscodeResult resultCode() const {
return resultCode_;
}
bool fail(JS::TranscodeResult code) {
MOZ_ASSERT(resultCode_ == JS::TranscodeResult_Ok);
resultCode_ = code;
return false;
}
bool codeUint8(uint8_t* n) {
if (mode == XDR_ENCODE) {
uint8_t* ptr = buf.write(sizeof(*n));
if (!ptr)
return false;
*ptr = *n;
} else {
*n = *buf.read(sizeof(*n));
}
return true;
}
bool codeUint16(uint16_t* n) {
if (mode == XDR_ENCODE) {
uint8_t* ptr = buf.write(sizeof(*n));
if (!ptr)
return false;
mozilla::LittleEndian::writeUint16(ptr, *n);
} else {
const uint8_t* ptr = buf.read(sizeof(*n));
*n = mozilla::LittleEndian::readUint16(ptr);
}
return true;
}
bool codeUint32(uint32_t* n) {
if (mode == XDR_ENCODE) {
uint8_t* ptr = buf.write(sizeof(*n));
if (!ptr)
return false;
mozilla::LittleEndian::writeUint32(ptr, *n);
} else {
const uint8_t* ptr = buf.read(sizeof(*n));
*n = mozilla::LittleEndian::readUint32(ptr);
}
return true;
}
bool codeUint64(uint64_t* n) {
if (mode == XDR_ENCODE) {
uint8_t* ptr = buf.write(sizeof(*n));
if (!ptr)
return false;
mozilla::LittleEndian::writeUint64(ptr, *n);
} else {
const uint8_t* ptr = buf.read(sizeof(*n));
*n = mozilla::LittleEndian::readUint64(ptr);
}
return true;
}
/*
* Use SFINAE to refuse any specialization which is not an enum. Uses of
* this function do not have to specialize the type of the enumerated field
* as C++ will extract the parameterized from the argument list.
*/
template <typename T>
bool codeEnum32(T* val, typename mozilla::EnableIf<mozilla::IsEnum<T>::value, T>::Type * = NULL)
{
// Mix the enumeration value with a random magic number, such that a
// corruption with a low-ranged value (like 0) is less likely to cause a
// miss-interpretation of the XDR content and instead cause a failure.
const uint32_t MAGIC = 0xAF647BCE;
uint32_t tmp;
if (mode == XDR_ENCODE)
tmp = uint32_t(*val) ^ MAGIC;
if (!codeUint32(&tmp))
return false;
if (mode == XDR_DECODE)
*val = T(tmp ^ MAGIC);
return true;
}
bool codeDouble(double* dp) {
union DoublePun {
double d;
uint64_t u;
} pun;
if (mode == XDR_ENCODE)
pun.d = *dp;
if (!codeUint64(&pun.u))
return false;
if (mode == XDR_DECODE)
*dp = pun.d;
return true;
}
bool codeMarker(uint32_t magic) {
uint32_t actual = magic;
if (!codeUint32(&actual))
return false;
if (actual != magic) {
// Fail in debug, but only soft-fail in release
MOZ_ASSERT(false, "Bad XDR marker");
return fail(JS::TranscodeResult_Failure_BadDecode);
}
return true;
}
bool codeBytes(void* bytes, size_t len) {
if (len == 0)
return true;
if (mode == XDR_ENCODE) {
uint8_t* ptr = buf.write(len);
if (!ptr)
return false;
memcpy(ptr, bytes, len);
} else {
memcpy(bytes, buf.read(len), len);
}
return true;
}
/*
* During encoding the string is written into the buffer together with its
* terminating '\0'. During decoding the method returns a pointer into the
* decoding buffer and the caller must copy the string if it will outlive
* the decoding buffer.
*/
bool codeCString(const char** sp) {
if (mode == XDR_ENCODE) {
size_t n = strlen(*sp) + 1;
uint8_t* ptr = buf.write(n);
if (!ptr)
return false;
memcpy(ptr, *sp, n);
} else {
*sp = buf.readCString();
}
return true;
}
bool codeChars(const JS::Latin1Char* chars, size_t nchars);
bool codeChars(char16_t* chars, size_t nchars);
bool codeFunction(JS::MutableHandleFunction objp);
bool codeScript(MutableHandleScript scriptp);
bool codeConstValue(MutableHandleValue vp);
};
using XDREncoder = XDRState<XDR_ENCODE>;
using XDRDecoder = XDRState<XDR_DECODE>;
} /* namespace js */
#endif /* vm_Xdr_h */
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