asmgrader::Tracer Class Reference

A lightweight wrapper of ptrace(2) More...

#include <tracer.hpp>

Public Member Functions
	Tracer ()=default
Result< void >	begin (pid_t pid)
	Sets up tracing in parent process, then stops child immediately after exec call.
Result< RunResult >	run ()
	Run the child process. Collect syscall info each time one is executed.
Result< SyscallRecord >	execute_syscall (u64 sys_nr, std::array< std::uint64_t, 6 > args)
	Executes a syscall with the given arguments as the stopped tracee.
Result< user_regs_struct >	get_registers () const
	Get the general purpose registers of the stopped tracee IMPORTANT: this is (obviously) architecture-dependent.
Result< user_fpregs_struct >	get_fp_registers () const
Result< void >	set_registers (user_regs_struct regs) const
	Set the general purpose registers of the stopped tracee IMPORTANT: this is (obviously) architecture-dependent.
Result< void >	set_fp_registers (user_fpregs_struct regs) const
const std::vector< SyscallRecord > &	get_records () const
	Obtain records of syscalls run so far in the child process.
std::optional< int >	get_exit_code () const
	Obtain the process exit code, or nullopt if the process has not yet exited.
Result< void >	jump_to (std::uintptr_t address)
	Set the child process's instruction pointer to address
template<typename... Args>
Result< void >	setup_function_call (Args &&... args)
template<typename Ret >
Result< Ret >	process_function_ret ()
	AFTER a function has been called, inspects register values (and memory if necessary) to construct the expected return type.
MemoryIOBase &	get_memory_io ()
std::uintptr_t	get_mmapped_addr () const

Static Public Member Functions
static Result< void >	init_child ()
	Set up child process for tracing Call this within the newly-forked process.

Static Public Attributes
static constexpr std::size_t	MMAP_LENGTH = 4096
static constexpr auto	DEFAULT_TIMEOUT = std::chrono::milliseconds{10}

Detailed Description

A lightweight wrapper of ptrace(2)

Instantiate and use this class in the parent process to trace a child. In the child process, call Tracer::init_child.

Constructor & Destructor Documentation

Tracer()

asmgrader::Tracer::Tracer ( )

default

Member Function Documentation

begin()

Result< void > asmgrader::Tracer::begin

(

pid_t

pid

)

Sets up tracing in parent process, then stops child immediately after exec call.

execute_syscall()

Result< SyscallRecord > asmgrader::Tracer::execute_syscall	(	u64	sys_nr,
		std::array< std::uint64_t, 6 >	args )

Executes a syscall with the given arguments as the stopped tracee.

get_exit_code()

std::optional< int > asmgrader::Tracer::get_exit_code ( ) const

inline

Obtain the process exit code, or nullopt if the process has not yet exited.

get_fp_registers()

Result< user_fpregs_struct > asmgrader::Tracer::get_fp_registers

(

)

const

get_memory_io()

MemoryIOBase & asmgrader::Tracer::get_memory_io

(

)

get_mmapped_addr()

std::uintptr_t asmgrader::Tracer::get_mmapped_addr ( ) const

inline

get_records()

const std::vector< SyscallRecord > & asmgrader::Tracer::get_records ( ) const

inline

Obtain records of syscalls run so far in the child process.

get_registers()

Result< user_regs_struct > asmgrader::Tracer::get_registers

(

)

const

Get the general purpose registers of the stopped tracee IMPORTANT: this is (obviously) architecture-dependent.

init_child()

Result< void > asmgrader::Tracer::init_child ( )

static

Set up child process for tracing Call this within the newly-forked process.

Immediately after a call to this function should be a call to execve.

jump_to()

Result< void > asmgrader::Tracer::jump_to

(

std::uintptr_t

address

)

Set the child process's instruction pointer to address

process_function_ret()

template<typename Ret >

Result< Ret > asmgrader::Tracer::process_function_ret

(

)

AFTER a function has been called, inspects register values (and memory if necessary) to construct the expected return type.

std::nullopt is returned if it's not possible to construct return type.

run()

Result< RunResult > asmgrader::Tracer::run

(

)

Run the child process. Collect syscall info each time one is executed.

set_fp_registers()

Result< void > asmgrader::Tracer::set_fp_registers

(

user_fpregs_struct

regs

)

const

set_registers()

Result< void > asmgrader::Tracer::set_registers

(

user_regs_struct

regs

)

const

Set the general purpose registers of the stopped tracee IMPORTANT: this is (obviously) architecture-dependent.

setup_function_call()

template<typename... Args>

Result< void > asmgrader::Tracer::setup_function_call

(

Args &&...

args

)

Member Data Documentation

DEFAULT_TIMEOUT

auto asmgrader::Tracer::DEFAULT_TIMEOUT = std::chrono::milliseconds{10}

staticconstexpr

MMAP_LENGTH

std::size_t asmgrader::Tracer::MMAP_LENGTH = 4096

staticconstexpr

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The documentation for this class was generated from the following files:

• include/asmgrader/subprocess/tracer.hpp
• src/subprocess/tracer.cpp