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thread_read_state.md

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zx_thread_read_state

SUMMARY

Read one aspect of thread state.

DECLARATION

#include <zircon/syscalls.h>

zx_status_t zx_thread_read_state(zx_handle_t handle,
                                 uint32_t kind,
                                 void* buffer,
                                 size_t buffer_size);

DESCRIPTION

zx_thread_read_state() reads one aspect of state of the thread. The thread state may only be read when the thread is halted for an exception or the thread is suspended.

The thread state is highly processor specific. See the structures in zircon/syscalls/debug.h for the contents of the structures on each platform.

STATES

ZX_THREAD_STATE_GENERAL_REGS

The buffer must point to a zx_thread_state_general_regs_t structure that contains the general registers for the current architecture.

ZX_THREAD_STATE_FP_REGS

The buffer must point to a zx_thread_state_fp_regs_t structure. On 64-bit ARM platforms, float point state is in the vector registers and this structure is empty.

ZX_THREAD_STATE_VECTOR_REGS

The buffer must point to a zx_thread_state_vector_regs_t structure.

ZX_THREAD_STATE_DEBUG_REGS

The buffer must point to a zx_thread_state_debug_regs_t structure. All input fields will be ignored and overwritten with the actual values for the thread.

ZX_THREAD_STATE_SINGLE_STEP

The buffer must point to a zx_thread_state_single_step_t value, which may contain either 0 (normal running), or 1 (single stepping enabled).

RIGHTS

handle must be of type ZX_OBJ_TYPE_THREAD and have ZX_RIGHT_READ.

RETURN VALUE

zx_thread_read_state() returns ZX_OK on success. In the event of failure, a negative error value is returned.

ERRORS

ZX_ERR_BAD_HANDLE handle is not a valid handle.

ZX_ERR_WRONG_TYPE handle is not that of a thread.

ZX_ERR_ACCESS_DENIED handle lacks ZX_RIGHT_READ.

ZX_ERR_INVALID_ARGS kind is not valid or buffer is an invalid pointer.

ZX_ERR_NO_MEMORY Failure due to lack of memory. There is no good way for userspace to handle this (unlikely) error. In a future build this error will no longer occur.

ZX_ERR_BUFFER_TOO_SMALL The buffer length buffer_size is too small to hold the data required by kind.

ZX_ERR_BAD_STATE The thread is not stopped at a point where state is available. The thread state may only be read when the thread is stopped due to an exception.

ZX_ERR_NOT_SUPPORTED kind is not supported. This can happen, for example, when trying to read a register set that is not supported by the hardware the program is currently running on.

SEE ALSO

thread_write_state.