fuchsia.exception

PROTOCOLS

Handler

Defined in fuchsia.exception/handler.fidl

Protocol meant for clients interested in handling exceptions for a particular service.

OnException

This exception mirrors closely the information provided by exception channels. The design is to have clients of this API behave as closely as possible to native exception handlers that are listening to an exception channel.

exception is an exception handle, which controls the exception's lifetime. See exception zircon docs for more information.

info represents basic exception information as provided by the exception channel.

Request

Name	Type
exception	handle<exception>
info	ExceptionInfo

Response

Name	Type

ProcessLimbo

Defined in fuchsia.exception/process_limbo.fidl

Protocol meant for clients interested in obtaining processes that are suspended waiting for an exception handler (in limbo). This is the core feature that enables Just In Time (JIT) debugging.

ListProcessesWaitingOnException

Returns information on all the processes currently waiting on an exception. The information provided is intended to correctly identify an exception and determine whether the caller wants to actually handle it. To retrieve an exception, use the |GetException| call.

NOTE: The |process| and |thread| handle will only have the ZX_RIGHT_READ right, so no modification will be able to be done on them.

Request

Name	Type

Response

Name	Type
exception_list	vector<ProcessExceptionMetadata>[32]

RetrieveException

Removes the process from limbo and retrieves the exception handle and associated metadata from an exception.

Use |ListProcessesWaitingOnException| to choose a |process_koid| from the list of available exceptions.

Returns ZX_ERR_NOT_FOUND if the process is not waiting on an exception.

Request

Name	Type
process_koid	uint64

Response

Name	Type
result	ProcessLimbo_RetrieveException_Result

STRUCTS

ExceptionInfo

Defined in fuchsia.exception/handler.fidl

Basic exception information associated with a particular exception. Maps to zx_exception_info_t.

Name	Type	Description	Default
process_koid	uint64		No default
thread_koid	uint64		No default
type	ExceptionType		No default

ProcessLimbo_RetrieveException_Response

generated

Name	Type	Description	Default
process_exception	ProcessException		No default

ENUMS

ExceptionType

Type: uint32

Defined in fuchsia.exception/handler.fidl

What type of exception was triggered. Maps to the types defined in zx_excp_type_t. If zircon/syscalls/exception.h changes, this needs to be updates as well to reflect that.

Name	Value	Description
GENERAL	8
FATAL_PAGE_FAULT	264
UNDEFINED_INSTRUCTION	520
SW_BREAKPOINT	776
HW_BREAKPOINT	1032
UNALIGNED_ACCESS	1288
THREAD_STARTING	32776
THREAD_EXITING	33032
POLICY_ERROR	33288
PROCESS_STARTING	33544

TABLES

ProcessException

Defined in fuchsia.exception/handler.fidl

Generic wrapper over a thread exception. Mirrors closely the information given by an exception channel.

Ordinal	Name	Type	Description
1	exception	handle<exception>
2	info	ExceptionInfo
3	process	handle<process>
4	thread	handle<thread>

ProcessExceptionMetadata

Defined in fuchsia.exception/process_limbo.fidl

Intended to be read only metadada associated with an exception waiting in limbo. The handles provided will only have read-only access to the resource, so no modification can be done to them.

NOTE: Both |process| and |thread| will be valid if present.

Ordinal	Name	Type	Description
1	info	ExceptionInfo
2	process	handle<process>	Only has ZX_RIGHT_READ and ZX_RIGHT_GET_PROPERTY rights.
3	thread	handle<thread>	The thread that generated the exception. The process may have other threads that are not reflected here. Only has ZX_RIGHT_READ and ZX_RIGHT_GET_PROPERTY rights.

UNIONS

ProcessLimbo_RetrieveException_Result

generated

Name	Type	Description
response	ProcessLimbo_RetrieveException_Response
err	int32

CONSTANTS

Name	Value	Type	Description
MAX_EXCEPTIONS_PER_CALL	32	uint64	The maximum amount of exceptions that will be listed at any given time by a call to |ListProcessesWaitingOnException|.