1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/dom/bindings/ErrorResult.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,192 @@
1.4 +/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-*/
1.5 +/* vim: set ts=2 sw=2 et tw=79: */
1.6 +/* This Source Code Form is subject to the terms of the Mozilla Public
1.7 + * License, v. 2.0. If a copy of the MPL was not distributed with this file,
1.8 + * You can obtain one at http://mozilla.org/MPL/2.0/. */
1.9 +
1.10 +/**
1.11 + * A struct for tracking exceptions that need to be thrown to JS.
1.12 + */
1.13 +
1.14 +#ifndef mozilla_ErrorResult_h
1.15 +#define mozilla_ErrorResult_h
1.16 +
1.17 +#include <stdarg.h>
1.18 +
1.19 +#include "js/Value.h"
1.20 +#include "nscore.h"
1.21 +#include "nsStringGlue.h"
1.22 +#include "mozilla/Assertions.h"
1.23 +
1.24 +namespace mozilla {
1.25 +
1.26 +namespace dom {
1.27 +
1.28 +enum ErrNum {
1.29 +#define MSG_DEF(_name, _argc, _str) \
1.30 + _name,
1.31 +#include "mozilla/dom/Errors.msg"
1.32 +#undef MSG_DEF
1.33 + Err_Limit
1.34 +};
1.35 +
1.36 +bool
1.37 +ThrowErrorMessage(JSContext* aCx, const ErrNum aErrorNumber, ...);
1.38 +
1.39 +} // namespace dom
1.40 +
1.41 +class ErrorResult {
1.42 +public:
1.43 + ErrorResult() {
1.44 + mResult = NS_OK;
1.45 +
1.46 +#ifdef DEBUG
1.47 + // ErrorResult is extremely performance-sensitive code, where literally
1.48 + // every machine instruction matters. Initialize mMessage only to suppress
1.49 + // a debug-only warning from gcc 4.6.
1.50 + mMessage = nullptr;
1.51 + mMightHaveUnreportedJSException = false;
1.52 +#endif
1.53 + }
1.54 +
1.55 +#ifdef DEBUG
1.56 + ~ErrorResult() {
1.57 + MOZ_ASSERT_IF(IsTypeError(), !mMessage);
1.58 + MOZ_ASSERT(!mMightHaveUnreportedJSException);
1.59 + }
1.60 +#endif
1.61 +
1.62 + void Throw(nsresult rv) {
1.63 + MOZ_ASSERT(NS_FAILED(rv), "Please don't try throwing success");
1.64 + MOZ_ASSERT(rv != NS_ERROR_TYPE_ERR, "Use ThrowTypeError()");
1.65 + MOZ_ASSERT(!IsTypeError(), "Don't overwite TypeError");
1.66 + MOZ_ASSERT(rv != NS_ERROR_DOM_JS_EXCEPTION, "Use ThrowJSException()");
1.67 + MOZ_ASSERT(!IsJSException(), "Don't overwrite JS exceptions");
1.68 + MOZ_ASSERT(rv != NS_ERROR_XPC_NOT_ENOUGH_ARGS, "Use ThrowNotEnoughArgsError()");
1.69 + MOZ_ASSERT(!IsNotEnoughArgsError(), "Don't overwrite not enough args error");
1.70 + mResult = rv;
1.71 + }
1.72 +
1.73 + void ThrowTypeError(const dom::ErrNum errorNumber, ...);
1.74 + void ReportTypeError(JSContext* cx);
1.75 + void ClearMessage();
1.76 + bool IsTypeError() const { return ErrorCode() == NS_ERROR_TYPE_ERR; }
1.77 +
1.78 + // Facilities for throwing a preexisting JS exception value via this
1.79 + // ErrorResult. The contract is that any code which might end up calling
1.80 + // ThrowJSException() must call MightThrowJSException() even if no exception
1.81 + // is being thrown. Code that would call ReportJSException* or
1.82 + // StealJSException as needed must first call WouldReportJSException even if
1.83 + // this ErrorResult has not failed.
1.84 + //
1.85 + // The exn argument to ThrowJSException can be in any compartment. It does
1.86 + // not have to be in the compartment of cx. If someone later uses it, they
1.87 + // will wrap it into whatever compartment they're working in, as needed.
1.88 + void ThrowJSException(JSContext* cx, JS::Handle<JS::Value> exn);
1.89 + void ReportJSException(JSContext* cx);
1.90 + // Used to implement throwing exceptions from the JS implementation of
1.91 + // bindings to callers of the binding.
1.92 + void ReportJSExceptionFromJSImplementation(JSContext* aCx);
1.93 + bool IsJSException() const { return ErrorCode() == NS_ERROR_DOM_JS_EXCEPTION; }
1.94 +
1.95 + void ThrowNotEnoughArgsError() { mResult = NS_ERROR_XPC_NOT_ENOUGH_ARGS; }
1.96 + void ReportNotEnoughArgsError(JSContext* cx,
1.97 + const char* ifaceName,
1.98 + const char* memberName);
1.99 + bool IsNotEnoughArgsError() const { return ErrorCode() == NS_ERROR_XPC_NOT_ENOUGH_ARGS; }
1.100 +
1.101 + // StealJSException steals the JS Exception from the object. This method must
1.102 + // be called only if IsJSException() returns true. This method also resets the
1.103 + // ErrorCode() to NS_OK.
1.104 + void StealJSException(JSContext* cx, JS::MutableHandle<JS::Value> value);
1.105 +
1.106 + void MOZ_ALWAYS_INLINE MightThrowJSException()
1.107 + {
1.108 +#ifdef DEBUG
1.109 + mMightHaveUnreportedJSException = true;
1.110 +#endif
1.111 + }
1.112 + void MOZ_ALWAYS_INLINE WouldReportJSException()
1.113 + {
1.114 +#ifdef DEBUG
1.115 + mMightHaveUnreportedJSException = false;
1.116 +#endif
1.117 + }
1.118 +
1.119 + // In the future, we can add overloads of Throw that take more
1.120 + // interesting things, like strings or DOM exception types or
1.121 + // something if desired.
1.122 +
1.123 + // Backwards-compat to make conversion simpler. We don't call
1.124 + // Throw() here because people can easily pass success codes to
1.125 + // this.
1.126 + void operator=(nsresult rv) {
1.127 + MOZ_ASSERT(rv != NS_ERROR_TYPE_ERR, "Use ThrowTypeError()");
1.128 + MOZ_ASSERT(!IsTypeError(), "Don't overwite TypeError");
1.129 + MOZ_ASSERT(rv != NS_ERROR_DOM_JS_EXCEPTION, "Use ThrowJSException()");
1.130 + MOZ_ASSERT(!IsJSException(), "Don't overwrite JS exceptions");
1.131 + MOZ_ASSERT(rv != NS_ERROR_XPC_NOT_ENOUGH_ARGS, "Use ThrowNotEnoughArgsError()");
1.132 + MOZ_ASSERT(!IsNotEnoughArgsError(), "Don't overwrite not enough args error");
1.133 + mResult = rv;
1.134 + }
1.135 +
1.136 + bool Failed() const {
1.137 + return NS_FAILED(mResult);
1.138 + }
1.139 +
1.140 + nsresult ErrorCode() const {
1.141 + return mResult;
1.142 + }
1.143 +
1.144 +private:
1.145 + nsresult mResult;
1.146 + struct Message;
1.147 + // mMessage is set by ThrowTypeError and cleared (and deallocatd) by
1.148 + // ReportTypeError.
1.149 + // mJSException is set (and rooted) by ThrowJSException and unrooted
1.150 + // by ReportJSException.
1.151 + union {
1.152 + Message* mMessage; // valid when IsTypeError()
1.153 + JS::Value mJSException; // valid when IsJSException()
1.154 + };
1.155 +
1.156 +#ifdef DEBUG
1.157 + // Used to keep track of codepaths that might throw JS exceptions,
1.158 + // for assertion purposes.
1.159 + bool mMightHaveUnreportedJSException;
1.160 +#endif
1.161 +
1.162 + // Not to be implemented, to make sure people always pass this by
1.163 + // reference, not by value.
1.164 + ErrorResult(const ErrorResult&) MOZ_DELETE;
1.165 +};
1.166 +
1.167 +/******************************************************************************
1.168 + ** Macros for checking results
1.169 + ******************************************************************************/
1.170 +
1.171 +#define ENSURE_SUCCESS(res, ret) \
1.172 + do { \
1.173 + if (res.Failed()) { \
1.174 + nsCString msg; \
1.175 + msg.AppendPrintf("ENSURE_SUCCESS(%s, %s) failed with " \
1.176 + "result 0x%X", #res, #ret, res.ErrorCode()); \
1.177 + NS_WARNING(msg.get()); \
1.178 + return ret; \
1.179 + } \
1.180 + } while(0)
1.181 +
1.182 +#define ENSURE_SUCCESS_VOID(res) \
1.183 + do { \
1.184 + if (res.Failed()) { \
1.185 + nsCString msg; \
1.186 + msg.AppendPrintf("ENSURE_SUCCESS_VOID(%s) failed with " \
1.187 + "result 0x%X", #res, res.ErrorCode()); \
1.188 + NS_WARNING(msg.get()); \
1.189 + return; \
1.190 + } \
1.191 + } while(0)
1.192 +
1.193 +} // namespace mozilla
1.194 +
1.195 +#endif /* mozilla_ErrorResult_h */
