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/*
* Copyright (c) 2020, Itamar S. <itamar8910@gmail.com>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#pragma once
#include <AK/HashMap.h>
#include <AK/MappedFile.h>
#include <AK/Optional.h>
#include <AK/OwnPtr.h>
#include <AK/String.h>
#include <LibC/sys/arch/i386/regs.h>
#include <LibELF/Image.h>
#include <signal.h>
#include <stdio.h>
#include <sys/ptrace.h>
#include <sys/wait.h>
#include <unistd.h>
class DebugSession {
public:
static OwnPtr<DebugSession> exec_and_attach(const String& command);
// Has to be public for OwnPtr::make
DebugSession(int pid);
~DebugSession();
int pid() const { return m_debugee_pid; }
bool poke(u32* address, u32 data);
Optional<u32> peek(u32* address) const;
struct BreakPoint {
void* address;
u32 original_first_word;
};
bool insert_breakpoint(void* address);
void remove_breakpoint(const BreakPoint&);
Optional<BreakPoint> get_matching_breakpoint(const PtraceRegisters&) const;
PtraceRegisters get_registers() const;
void set_registers(const PtraceRegisters&);
void continue_debugee();
template<typename Callback>
void run(Callback callback);
VirtualAddress get_entry_point() const;
enum DebugDecision {
Continue,
Detach,
Kill,
};
enum DebugBreakReason {
Breakpoint,
Exited,
};
private:
// x86 breakpoint instruction "int3"
static constexpr u8 BREAKPOINT_INSTRUCTION
= 0xcc;
int m_debugee_pid { -1 };
bool m_is_debugee_dead { false };
NonnullOwnPtr<MappedFile> m_executable;
NonnullOwnPtr<ELF::Image> m_elf_image;
HashMap<void*, BreakPoint> m_breakpoints;
};
template<typename Callback>
void DebugSession::run(Callback callback)
{
for (;;) {
continue_debugee();
int wstatus = 0;
if (waitpid(m_debugee_pid, &wstatus, WSTOPPED | WEXITED) != m_debugee_pid) {
perror("waitpid");
ASSERT_NOT_REACHED();
}
// FIXME: This check actually only checks whether the debugee
// Is stopped because it hit a breakpoint or not
if (WSTOPSIG(wstatus) != SIGTRAP) {
callback(DebugBreakReason::Exited, Optional<PtraceRegisters>());
m_is_debugee_dead = true;
break;
}
auto regs = get_registers();
auto current_breakpoint = get_matching_breakpoint(regs);
if (current_breakpoint.has_value()) {
// FIXME: The current implementation removes a breakpoint
// after the first time it has been triggered.
remove_breakpoint(current_breakpoint.value());
// We need to re-execute the instruction we patched for the breakpoint,
// so we rollback the instruction pointer to the breakpoint's address
regs.eip = reinterpret_cast<u32>(current_breakpoint.value().address);
set_registers(regs);
DebugDecision decision = callback(DebugBreakReason::Breakpoint, regs);
if (decision != DebugDecision::Continue) {
// FIXME: implement detach & kill
ASSERT_NOT_REACHED();
}
}
}
}
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