mirror of
https://github.com/mozilla/gecko-dev.git
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184 lines
6.5 KiB
C++
184 lines
6.5 KiB
C++
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-*/
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/* vim: set ts=2 sw=2 et tw=79: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this file,
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* You can obtain one at http://mozilla.org/MPL/2.0/. */
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/**
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* A struct for tracking exceptions that need to be thrown to JS.
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*/
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#ifndef mozilla_ErrorResult_h
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#define mozilla_ErrorResult_h
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#include <stdarg.h>
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#include "js/Value.h"
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#include "nscore.h"
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#include "nsStringGlue.h"
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#include "mozilla/Assertions.h"
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namespace mozilla {
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namespace dom {
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enum ErrNum {
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#define MSG_DEF(_name, _argc, _str) \
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_name,
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#include "mozilla/dom/Errors.msg"
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#undef MSG_DEF
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Err_Limit
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};
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bool
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ThrowErrorMessage(JSContext* aCx, const ErrNum aErrorNumber, ...);
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} // namespace dom
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class ErrorResult {
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public:
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ErrorResult() {
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mResult = NS_OK;
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#ifdef DEBUG
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mMightHaveUnreportedJSException = false;
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#endif
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}
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#ifdef DEBUG
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~ErrorResult() {
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MOZ_ASSERT_IF(IsTypeError(), !mMessage);
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MOZ_ASSERT(!mMightHaveUnreportedJSException);
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}
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#endif
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void Throw(nsresult rv) {
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MOZ_ASSERT(NS_FAILED(rv), "Please don't try throwing success");
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MOZ_ASSERT(rv != NS_ERROR_TYPE_ERR, "Use ThrowTypeError()");
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MOZ_ASSERT(!IsTypeError(), "Don't overwite TypeError");
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MOZ_ASSERT(rv != NS_ERROR_DOM_JS_EXCEPTION, "Use ThrowJSException()");
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MOZ_ASSERT(!IsJSException(), "Don't overwrite JS exceptions");
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MOZ_ASSERT(rv != NS_ERROR_XPC_NOT_ENOUGH_ARGS, "Use ThrowNotEnoughArgsError()");
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MOZ_ASSERT(!IsNotEnoughArgsError(), "Don't overwrite not enough args error");
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mResult = rv;
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}
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void ThrowTypeError(const dom::ErrNum errorNumber, ...);
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void ReportTypeError(JSContext* cx);
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void ClearMessage();
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bool IsTypeError() const { return ErrorCode() == NS_ERROR_TYPE_ERR; }
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// Facilities for throwing a preexisting JS exception value via this
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// ErrorResult. The contract is that any code which might end up calling
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// ThrowJSException() must call MightThrowJSException() even if no exception
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// is being thrown. Code that would call ReportJSException* or
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// StealJSException as needed must first call WouldReportJSException even if
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// this ErrorResult has not failed.
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void ThrowJSException(JSContext* cx, JS::Handle<JS::Value> exn);
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void ReportJSException(JSContext* cx);
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// Used to implement throwing exceptions from the JS implementation of
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// bindings to callers of the binding.
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void ReportJSExceptionFromJSImplementation(JSContext* aCx);
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bool IsJSException() const { return ErrorCode() == NS_ERROR_DOM_JS_EXCEPTION; }
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void ThrowNotEnoughArgsError() { mResult = NS_ERROR_XPC_NOT_ENOUGH_ARGS; }
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void ReportNotEnoughArgsError(JSContext* cx,
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const char* ifaceName,
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const char* memberName);
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bool IsNotEnoughArgsError() const { return ErrorCode() == NS_ERROR_XPC_NOT_ENOUGH_ARGS; }
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// StealJSException steals the JS Exception from the object. This method must
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// be called only if IsJSException() returns true. This method also resets the
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// ErrorCode() to NS_OK.
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void StealJSException(JSContext* cx, JS::MutableHandle<JS::Value> value);
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void MOZ_ALWAYS_INLINE MightThrowJSException()
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{
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#ifdef DEBUG
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mMightHaveUnreportedJSException = true;
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#endif
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}
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void MOZ_ALWAYS_INLINE WouldReportJSException()
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{
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#ifdef DEBUG
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mMightHaveUnreportedJSException = false;
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#endif
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}
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// In the future, we can add overloads of Throw that take more
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// interesting things, like strings or DOM exception types or
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// something if desired.
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// Backwards-compat to make conversion simpler. We don't call
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// Throw() here because people can easily pass success codes to
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// this.
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void operator=(nsresult rv) {
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MOZ_ASSERT(rv != NS_ERROR_TYPE_ERR, "Use ThrowTypeError()");
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MOZ_ASSERT(!IsTypeError(), "Don't overwite TypeError");
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MOZ_ASSERT(rv != NS_ERROR_DOM_JS_EXCEPTION, "Use ThrowJSException()");
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MOZ_ASSERT(!IsJSException(), "Don't overwrite JS exceptions");
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MOZ_ASSERT(rv != NS_ERROR_XPC_NOT_ENOUGH_ARGS, "Use ThrowNotEnoughArgsError()");
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MOZ_ASSERT(!IsNotEnoughArgsError(), "Don't overwrite not enough args error");
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mResult = rv;
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}
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bool Failed() const {
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return NS_FAILED(mResult);
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}
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nsresult ErrorCode() const {
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return mResult;
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}
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private:
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nsresult mResult;
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struct Message;
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// mMessage is set by ThrowTypeError and cleared (and deallocatd) by
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// ReportTypeError.
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// mJSException is set (and rooted) by ThrowJSException and unrooted
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// by ReportJSException.
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union {
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Message* mMessage; // valid when IsTypeError()
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JS::Value mJSException; // valid when IsJSException()
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};
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#ifdef DEBUG
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// Used to keep track of codepaths that might throw JS exceptions,
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// for assertion purposes.
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bool mMightHaveUnreportedJSException;
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#endif
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// Not to be implemented, to make sure people always pass this by
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// reference, not by value.
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ErrorResult(const ErrorResult&) MOZ_DELETE;
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};
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/******************************************************************************
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** Macros for checking results
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******************************************************************************/
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#define ENSURE_SUCCESS(res, ret) \
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do { \
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if (res.Failed()) { \
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nsCString msg; \
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msg.AppendPrintf("ENSURE_SUCCESS(%s, %s) failed with " \
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"result 0x%X", #res, #ret, res.ErrorCode()); \
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NS_WARNING(msg.get()); \
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return ret; \
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} \
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} while(0)
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#define ENSURE_SUCCESS_VOID(res) \
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do { \
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if (res.Failed()) { \
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nsCString msg; \
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msg.AppendPrintf("ENSURE_SUCCESS_VOID(%s) failed with " \
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"result 0x%X", #res, res.ErrorCode()); \
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NS_WARNING(msg.get()); \
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return; \
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} \
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} while(0)
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} // namespace mozilla
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#endif /* mozilla_ErrorResult_h */
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