// Copyright 2021 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef INCLUDE_V8_EXCEPTION_H_
#define INCLUDE_V8_EXCEPTION_H_
#include <stddef.h>
#include "v8-local-handle.h" // NOLINT(build/include_directory)
#include "v8config.h" // NOLINT(build/include_directory)
namespace v8 {
class Context;
class Isolate;
class Message;
class StackTrace;
class String;
class Value;
namespace internal {
class Isolate;
class ThreadLocalTop;
} // namespace internal
/**
* Create new error objects by calling the corresponding error object
* constructor with the message.
*/
class V8_EXPORT Exception {
public:
static Local<Value> RangeError(Local<String> message);
static Local<Value> ReferenceError(Local<String> message);
static Local<Value> SyntaxError(Local<String> message);
static Local<Value> TypeError(Local<String> message);
static Local<Value> WasmCompileError(Local<String> message);
static Local<Value> WasmLinkError(Local<String> message);
static Local<Value> WasmRuntimeError(Local<String> message);
static Local<Value> Error(Local<String> message);
/**
* Creates an error message for the given exception.
* Will try to reconstruct the original stack trace from the exception value,
* or capture the current stack trace if not available.
*/
static Local<Message> CreateMessage(Isolate* isolate, Local<Value> exception);
/**
* Returns the original stack trace that was captured at the creation time
* of a given exception, or an empty handle if not available.
*/
static Local<StackTrace> GetStackTrace(Local<Value> exception);
};
/**
* An external exception handler.
*/
class V8_EXPORT TryCatch {
public:
/**
* Creates a new try/catch block and registers it with v8. Note that
* all TryCatch blocks should be stack allocated because the memory
* location itself is compared against JavaScript try/catch blocks.
*/
explicit TryCatch(Isolate* isolate);
/**
* Unregisters and deletes this try/catch block.
*/
~TryCatch();
/**
* Returns true if an exception has been caught by this try/catch block.
*/
bool HasCaught() const;
/**
* For certain types of exceptions, it makes no sense to continue execution.
*
* If CanContinue returns false, the correct action is to perform any C++
* cleanup needed and then return. If CanContinue returns false and
* HasTerminated returns true, it is possible to call
* CancelTerminateExecution in order to continue calling into the engine.
*/
bool CanContinue() const;
/**
* Returns true if an exception has been caught due to script execution
* being terminated.
*
* There is no JavaScript representation of an execution termination
* exception. Such exceptions are thrown when the TerminateExecution
* methods are called to terminate a long-running script.
*
* If such an exception has been thrown, HasTerminated will return true,
* indicating that it is possible to call CancelTerminateExecution in order
* to continue calling into the engine.
*/
bool HasTerminated() const;
/**
* Throws the exception caught by this TryCatch in a way that avoids
* it being caught again by this same TryCatch. As with ThrowException
* it is illegal to execute any JavaScript operations after calling
* ReThrow; the caller must return immediately to where the exception
* is caught.
*/
Local<Value> ReThrow();
/**
* Returns the exception caught by this try/catch block. If no exception has
* been caught an empty handle is returned.
*/
Local<Value> Exception() const;
/**
* Returns the .stack property of an object. If no .stack
* property is present an empty handle is returned.
*/
V8_WARN_UNUSED_RESULT static MaybeLocal<Value> StackTrace(
Local<Context> context, Local<Value> exception);
/**
* Returns the .stack property of the thrown object. If no .stack property is
* present or if this try/catch block has not caught an exception, an empty
* handle is returned.
*/
V8_WARN_UNUSED_RESULT MaybeLocal<Value> StackTrace(
Local<Context> context) const;
/**
* Returns the message associated with this exception. If there is
* no message associated an empty handle is returned.
*/
Local<v8::Message> Message() const;
/**
* Clears any exceptions that may have been caught by this try/catch block.
* After this method has been called, HasCaught() will return false. Cancels
* the scheduled exception if it is caught and ReThrow() is not called before.
*
* It is not necessary to clear a try/catch block before using it again; if
* another exception is thrown the previously caught exception will just be
* overwritten. However, it is often a good idea since it makes it easier
* to determine which operation threw a given exception.
*/
void Reset();
/**
* Set verbosity of the external exception handler.
*
* By default, exceptions that are caught by an external exception
* handler are not reported. Call SetVerbose with true on an
* external exception handler to have exceptions caught by the
* handler reported as if they were not caught.
*/
void SetVerbose(bool value);
/**
* Returns true if verbosity is enabled.
*/
bool IsVerbose() const;
/**
* Set whether or not this TryCatch should capture a Message object
* which holds source information about where the exception
* occurred. True by default.
*/
void SetCaptureMessage(bool value);
TryCatch(const TryCatch&) = delete;
void operator=(const TryCatch&) = delete;
private:
// Declaring operator new and delete as deleted is not spec compliant.
// Therefore declare them private instead to disable dynamic alloc
void* operator new(size_t size);
void* operator new[](size_t size);
void operator delete(void*, size_t);
void operator delete[](void*, size_t);
/**
* There are cases when the raw address of C++ TryCatch object cannot be
* used for comparisons with addresses into the JS stack. The cases are:
* 1) ARM, ARM64 and MIPS simulators which have separate JS stack.
* 2) Address sanitizer allocates local C++ object in the heap when
* UseAfterReturn mode is enabled.
* This method returns address that can be used for comparisons with
* addresses into the JS stack. When neither simulator nor ASAN's
* UseAfterReturn is enabled, then the address returned will be the address
* of the C++ try catch handler itself.
*/
internal::Address JSStackComparableAddressPrivate() {
return js_stack_comparable_address_;
}
void ResetInternal();
internal::Isolate* isolate_;
TryCatch* next_;
void* exception_;
void* message_obj_;
internal::Address js_stack_comparable_address_;
bool is_verbose_ : 1;
bool can_continue_ : 1;
bool capture_message_ : 1;
bool rethrow_ : 1;
bool has_terminated_ : 1;
friend class internal::Isolate;
friend class internal::ThreadLocalTop;
};
} // namespace v8
#endif // INCLUDE_V8_EXCEPTION_H_
