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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
#ifndef nsJSUtils_h__
#define nsJSUtils_h__
/**
* This is not a generated file. It contains common utility functions
* invoked from the JavaScript code generated from IDL interfaces.
* The goal of the utility functions is to cut down on the size of
* the generated code itself.
*/
#include "mozilla/Assertions.h"
#include "jsapi.h"
#include "js/CompileOptions.h"
#include "js/Conversions.h"
#include "js/String.h" // JS::{,Lossy}CopyLinearStringChars, JS::CopyStringChars, JS::Get{,Linear}StringLength, JS::MaxStringLength, JS::StringHasLatin1Chars
#include "js/Utility.h" // JS::FreePolicy
#include "nsString.h"
#include "xpcpublic.h"
class nsIScriptContext;
class nsIScriptElement;
class nsIScriptGlobalObject;
class nsXBLPrototypeBinding;
namespace JS {
class JS_PUBLIC_API EnvironmentChain;
};
namespace mozilla {
union Utf8Unit;
namespace dom {
class AutoJSAPI;
class Element;
} // namespace dom
} // namespace mozilla
class nsJSUtils {
public:
/**
* Retrieve the inner window ID based on the given JSContext.
*
* @param JSContext aContext
* The JSContext from which you want to find the inner window ID.
*
* @returns uint64_t the inner window ID.
*/
static uint64_t GetCurrentlyRunningCodeInnerWindowID(JSContext* aContext);
static nsresult CompileFunction(mozilla::dom::AutoJSAPI& jsapi,
const JS::EnvironmentChain& aEnvChain,
JS::CompileOptions& aOptions,
const nsACString& aName, uint32_t aArgCount,
const char** aArgArray,
const nsAString& aBody,
JSObject** aFunctionObject);
static nsresult UpdateFunctionDebugMetadata(
mozilla::dom::AutoJSAPI& jsapi, JS::Handle<JSObject*> aFun,
JS::CompileOptions& aOptions, JS::Handle<JSString*> aElementAttributeName,
JS::Handle<JS::Value> aPrivateValue);
static bool IsScriptable(JS::Handle<JSObject*> aEvaluationGlobal);
// Returns false if an exception got thrown on aCx. Passing a null
// aElement is allowed; that wil produce an empty aEnvChain.
static bool GetEnvironmentChainForElement(JSContext* aCx,
mozilla::dom::Element* aElement,
JS::EnvironmentChain& aEnvChain);
static void ResetTimeZone();
static bool DumpEnabled();
// A helper function that receives buffer pointer, creates ArrayBuffer, and
// convert it to Uint8Array.
// Note that the buffer needs to be created by JS_malloc (or at least can be
// freed by JS_free), as the resulting Uint8Array takes the ownership of the
// buffer.
static JSObject* MoveBufferAsUint8Array(
JSContext* aCx, size_t aSize,
mozilla::UniquePtr<uint8_t[], JS::FreePolicy> aBuffer);
};
template <typename T, typename std::enable_if_t<std::is_same<
typename T::char_type, char16_t>::value>* = nullptr>
inline bool AssignJSString(JSContext* cx, T& dest, JSString* s) {
size_t len = JS::GetStringLength(s);
static_assert(JS::MaxStringLength < (1 << 30),
"Shouldn't overflow here or in SetCapacity");
if (XPCStringConvert::MaybeAssignUCStringChars(s, len, dest)) {
return true;
}
// We don't bother checking for a dynamic-atom external string, because we'd
// just need to copy out of it anyway.
if (MOZ_UNLIKELY(!dest.SetLength(len, mozilla::fallible))) {
JS_ReportOutOfMemory(cx);
return false;
}
return JS::CopyStringChars(cx, dest.BeginWriting(), s, len);
}
// Specialization for UTF8String.
template <typename T, typename std::enable_if_t<std::is_same<
typename T::char_type, char>::value>* = nullptr>
inline bool AssignJSString(JSContext* cx, T& dest, JSString* s) {
using namespace mozilla;
CheckedInt<size_t> bufLen(JS::GetStringLength(s));
if (XPCStringConvert::MaybeAssignUTF8StringChars(s, bufLen.value(), dest)) {
return true;
}
// From the contract for JS_EncodeStringToUTF8BufferPartial, to guarantee that
// the whole string is converted.
if (JS::StringHasLatin1Chars(s)) {
bufLen *= 2;
} else {
bufLen *= 3;
}
if (MOZ_UNLIKELY(!bufLen.isValid())) {
JS_ReportOutOfMemory(cx);
return false;
}
// Shouldn't really matter, but worth being safe.
const bool kAllowShrinking = true;
auto handleOrErr = dest.BulkWrite(bufLen.value(), 0, kAllowShrinking);
if (MOZ_UNLIKELY(handleOrErr.isErr())) {
JS_ReportOutOfMemory(cx);
return false;
}
auto handle = handleOrErr.unwrap();
auto maybe = JS_EncodeStringToUTF8BufferPartial(cx, s, handle.AsSpan());
if (MOZ_UNLIKELY(!maybe)) {
JS_ReportOutOfMemory(cx);
return false;
}
size_t read;
size_t written;
std::tie(read, written) = *maybe;
MOZ_ASSERT(read == JS::GetStringLength(s));
handle.Finish(written, kAllowShrinking);
return true;
}
inline void AssignJSLinearString(nsAString& dest, JSLinearString* s) {
size_t len = JS::GetLinearStringLength(s);
static_assert(JS::MaxStringLength < (1 << 30),
"Shouldn't overflow here or in SetCapacity");
dest.SetLength(len);
JS::CopyLinearStringChars(dest.BeginWriting(), s, len);
}
inline void AssignJSLinearString(nsACString& dest, JSLinearString* s) {
size_t len = JS::GetLinearStringLength(s);
static_assert(JS::MaxStringLength < (1 << 30),
"Shouldn't overflow here or in SetCapacity");
dest.SetLength(len);
JS::LossyCopyLinearStringChars(dest.BeginWriting(), s, len);
}
template <typename T>
class nsTAutoJSLinearString : public nsTAutoString<T> {
public:
explicit nsTAutoJSLinearString(JSLinearString* str) {
AssignJSLinearString(*this, str);
}
};
using nsAutoJSLinearString = nsTAutoJSLinearString<char16_t>;
using nsAutoJSLinearCString = nsTAutoJSLinearString<char>;
template <typename T>
class nsTAutoJSString : public nsTAutoString<T> {
public:
/**
* nsTAutoJSString should be default constructed, which leaves it empty
* (this->IsEmpty()), and initialized with one of the init() methods below.
*/
nsTAutoJSString() = default;
bool init(JSContext* aContext, JSString* str) {
return AssignJSString(aContext, *this, str);
}
bool init(JSContext* aContext, const JS::Value& v) {
if (v.isString()) {
return init(aContext, v.toString());
}
// Stringify, making sure not to run script.
JS::Rooted<JSString*> str(aContext);
if (v.isObject()) {
str = JS_NewStringCopyZ(aContext, "[Object]");
} else {
JS::Rooted<JS::Value> rootedVal(aContext, v);
str = JS::ToString(aContext, rootedVal);
}
return str && init(aContext, str);
}
bool init(JSContext* aContext, jsid id) {
JS::Rooted<JS::Value> v(aContext);
return JS_IdToValue(aContext, id, &v) && init(aContext, v);
}
bool init(const JS::Value& v);
~nsTAutoJSString() = default;
};
using nsAutoJSString = nsTAutoJSString<char16_t>;
// Note that this is guaranteed to be UTF-8.
using nsAutoJSCString = nsTAutoJSString<char>;
#endif /* nsJSUtils_h__ */