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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 "vm/Xdr.h"
#include "mozilla/Assertions.h" // MOZ_ASSERT, MOZ_ASSERT_IF
#include "mozilla/EndianUtils.h" // mozilla::NativeEndian, MOZ_LITTLE_ENDIAN
#include "mozilla/Result.h" // mozilla::{Result, Ok, Err}, MOZ_TRY
#include "mozilla/Utf8.h" // mozilla::Utf8Unit
#include <algorithm> // std::transform
#include <stddef.h> // size_t
#include <stdint.h> // uint8_t, uint32_t, uintptr_t
#include <string> // std::char_traits
#include <type_traits> // std::is_same_v
#include <utility> // std::move
#include "frontend/FrontendContext.h" // FrontendContext
#include "js/Transcoding.h" // JS::TranscodeResult, JS::TranscodeBuffer, JS::TranscodeRange
#include "js/UniquePtr.h" // UniquePtr
#include "js/Utility.h" // JS::FreePolicy, js_delete
#include "vm/JSContext.h" // JSContext, ReportAllocationOverflow
#include "vm/StringType.h" // JSString
using namespace js;
using mozilla::Utf8Unit;
#ifdef DEBUG
bool XDRCoderBase::validateResultCode(JSContext* cx, FrontendContext* fc,
JS::TranscodeResult code) const {
// NOTE: This function is called to verify that we do not have a pending
// exception on the JSContext at the same time as a TranscodeResult failure.
if (cx->isHelperThreadContext()) {
return true;
}
// NOTE: Errors during XDR encode/decode are supposed to be reported to
// FrontendContext, instead of JSContext.
// This branch is for covering remaining consumer of JSContext for
// error reporting (e.g. memory allocation).
// TODO: Remove this once JSContext is removed from frontend and all errors
// are reported to FrontendContext.
if (cx->isExceptionPending()) {
return bool(code == JS::TranscodeResult::Throw);
}
return fc->hadErrors() == bool(code == JS::TranscodeResult::Throw);
}
#endif
template <XDRMode mode>
XDRResult XDRState<mode>::codeChars(char* chars, size_t nchars) {
return codeBytes(chars, nchars);
}
template <XDRMode mode>
XDRResult XDRState<mode>::codeChars(Latin1Char* chars, size_t nchars) {
static_assert(sizeof(Latin1Char) == 1,
"Latin1Char must be 1 byte for nchars below to be the "
"proper count of bytes");
static_assert(std::is_same_v<Latin1Char, unsigned char>,
"Latin1Char must be unsigned char to C++-safely reinterpret "
"the bytes generically copied below as Latin1Char");
return codeBytes(chars, nchars);
}
template <XDRMode mode>
XDRResult XDRState<mode>::codeChars(Utf8Unit* units, size_t count) {
if (count == 0) {
return Ok();
}
if (mode == XDR_ENCODE) {
uint8_t* ptr = buf->write(count);
if (!ptr) {
return fail(JS::TranscodeResult::Throw);
}
std::transform(units, units + count, ptr,
[](const Utf8Unit& unit) { return unit.toUint8(); });
} else {
const uint8_t* ptr = buf->read(count);
if (!ptr) {
return fail(JS::TranscodeResult::Failure_BadDecode);
}
std::transform(ptr, ptr + count, units,
[](const uint8_t& value) { return Utf8Unit(value); });
}
return Ok();
}
template <XDRMode mode>
XDRResult XDRState<mode>::codeChars(char16_t* chars, size_t nchars) {
if (nchars == 0) {
return Ok();
}
size_t nbytes = nchars * sizeof(char16_t);
if (mode == XDR_ENCODE) {
uint8_t* ptr = buf->write(nbytes);
if (!ptr) {
return fail(JS::TranscodeResult::Throw);
}
// |mozilla::NativeEndian| correctly handles writing into unaligned |ptr|.
mozilla::NativeEndian::copyAndSwapToLittleEndian(ptr, chars, nchars);
} else {
const uint8_t* ptr = buf->read(nbytes);
if (!ptr) {
return fail(JS::TranscodeResult::Failure_BadDecode);
}
// |mozilla::NativeEndian| correctly handles reading from unaligned |ptr|.
mozilla::NativeEndian::copyAndSwapFromLittleEndian(chars, ptr, nchars);
}
return Ok();
}
template <XDRMode mode, typename CharT>
static XDRResult XDRCodeCharsZ(XDRState<mode>* xdr,
XDRTranscodeString<CharT>& buffer) {
MOZ_ASSERT_IF(mode == XDR_ENCODE, !buffer.empty());
MOZ_ASSERT_IF(mode == XDR_DECODE, buffer.empty());
using OwnedString = js::UniquePtr<CharT[], JS::FreePolicy>;
OwnedString owned;
static_assert(JSString::MAX_LENGTH <= INT32_MAX,
"String length must fit in int32_t");
uint32_t length = 0;
CharT* chars = nullptr;
if (mode == XDR_ENCODE) {
chars = const_cast<CharT*>(buffer.template ref<const CharT*>());
// Set a reasonable limit on string length.
size_t lengthSizeT = std::char_traits<CharT>::length(chars);
if (lengthSizeT > JSString::MAX_LENGTH) {
ReportAllocationOverflow(xdr->cx());
return xdr->fail(JS::TranscodeResult::Throw);
}
length = static_cast<uint32_t>(lengthSizeT);
}
MOZ_TRY(xdr->codeUint32(&length));
if (mode == XDR_DECODE) {
owned = xdr->cx()->template make_pod_array<CharT>(length + 1);
if (!owned) {
return xdr->fail(JS::TranscodeResult::Throw);
}
chars = owned.get();
}
MOZ_TRY(xdr->codeChars(chars, length));
if (mode == XDR_DECODE) {
// Null-terminate and transfer ownership to caller.
owned[length] = '\0';
buffer.template construct<OwnedString>(std::move(owned));
}
return Ok();
}
template <XDRMode mode>
XDRResult XDRState<mode>::codeCharsZ(XDRTranscodeString<char>& buffer) {
return XDRCodeCharsZ(this, buffer);
}
template <XDRMode mode>
XDRResult XDRState<mode>::codeCharsZ(XDRTranscodeString<char16_t>& buffer) {
return XDRCodeCharsZ(this, buffer);
}
template class js::XDRState<XDR_ENCODE>;
template class js::XDRState<XDR_DECODE>;
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