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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/. */
+
+#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/SourceText.h"
+#include "js/String.h" // JS::{,Lossy}CopyLinearStringChars, JS::CopyStringChars, JS::Get{,Linear}StringLength, JS::MaxStringLength, JS::StringHasLatin1Chars
+#include "nsString.h"
+#include "xpcpublic.h"
+
+class nsIScriptContext;
+class nsIScriptElement;
+class nsIScriptGlobalObject;
+class nsXBLPrototypeBinding;
+
+namespace mozilla {
+union Utf8Unit;
+
+namespace dom {
+class AutoJSAPI;
+class Element;
+} // namespace dom
+} // namespace mozilla
+
+class nsJSUtils {
+ public:
+ static bool GetCallingLocation(JSContext* aContext, nsACString& aFilename,
+ uint32_t* aLineno = nullptr,
+ uint32_t* aColumn = nullptr);
+ static bool GetCallingLocation(JSContext* aContext, nsAString& aFilename,
+ uint32_t* aLineno = nullptr,
+ uint32_t* aColumn = nullptr);
+
+ /**
+ * 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,
+ JS::HandleVector<JSObject*> aScopeChain,
+ 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 aScopeChain.
+ static bool GetScopeChainForElement(
+ JSContext* aCx, mozilla::dom::Element* aElement,
+ JS::MutableHandleVector<JSObject*> aScopeChain);
+
+ 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>& aBuffer);
+};
+
+inline void AssignFromStringBuffer(nsStringBuffer* buffer, size_t len,
+ nsAString& dest) {
+ buffer->ToString(len, dest);
+}
+
+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");
+
+ const char16_t* chars;
+ if (XPCStringConvert::MaybeGetDOMStringChars(s, &chars)) {
+ // The characters represent an existing string buffer that we shared with
+ // JS. We can share that buffer ourselves if the string corresponds to the
+ // whole buffer; otherwise we have to copy.
+ if (chars[len] == '\0') {
+ AssignFromStringBuffer(
+ nsStringBuffer::FromData(const_cast<char16_t*>(chars)), len, dest);
+ return true;
+ }
+ } else if (XPCStringConvert::MaybeGetLiteralStringChars(s, &chars)) {
+ // The characters represent a literal char16_t string constant
+ // compiled into libxul; we can just use it as-is.
+ dest.AssignLiteral(chars, len);
+ 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));
+ // 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__ */