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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.
*/
#include "DebugSession.h"
#include <AK/Assertions.h>
#include <AK/ByteBuffer.h>
#include <AK/LogStream.h>
#include <AK/StringBuilder.h>
#include <AK/kmalloc.h>
#include <LibC/sys/arch/i386/regs.h>
#include <LibCore/File.h>
#include <LibX86/Disassembler.h>
#include <LibX86/Instruction.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
static int usage()
{
printf("usage: sdb [command...]\n");
return 1;
}
OwnPtr<DebugSession> g_debug_session;
static void handle_sigint(int)
{
printf("Debugger: SIGINT\n");
// The destructor of DebugSession takes care of detaching
g_debug_session = nullptr;
}
String get_command()
{
printf("(sdb) ");
fflush(stdout);
char* line = nullptr;
size_t allocated_size = 0;
ssize_t nread = getline(&line, &allocated_size, stdin);
if (nread < 0) {
if (errno == 0) {
fprintf(stderr, "\n");
} else {
perror("getline");
exit(1);
}
}
String command(line);
free(line);
if (command.ends_with('\n'))
command = command.substring(0, command.length() - 1);
return command;
}
void handle_print_registers(const PtraceRegisters& regs)
{
printf("eax: 0x%x\n", regs.eax);
printf("ecx: 0x%x\n", regs.ecx);
printf("edx: 0x%x\n", regs.edx);
printf("ebx: 0x%x\n", regs.ebx);
printf("esp: 0x%x\n", regs.esp);
printf("ebp: 0x%x\n", regs.ebp);
printf("esi: 0x%x\n", regs.esi);
printf("edi: 0x%x\n", regs.edi);
printf("eip: 0x%x\n", regs.eip);
printf("eflags: 0x%x\n", regs.eflags);
}
bool handle_disassemble_command(const String& command, void* first_instruction)
{
auto parts = command.split(' ');
size_t number_of_instructions_to_disassemble = 5;
if (parts.size() == 2) {
bool ok;
number_of_instructions_to_disassemble = parts[1].to_uint(ok);
if (!ok)
return false;
}
// FIXME: Instead of using a fixed "dump_size",
// we can feed instructions to the disassembler one by one
constexpr size_t dump_size = 0x100;
ByteBuffer code;
for (size_t i = 0; i < dump_size / sizeof(u32); ++i) {
auto value = g_debug_session->peek(reinterpret_cast<u32*>(first_instruction) + i);
if (!value.has_value())
break;
code.append(&value, sizeof(u32));
}
X86::SimpleInstructionStream stream(code.data(), code.size());
X86::Disassembler disassembler(stream);
for (size_t i = 0; i < number_of_instructions_to_disassemble; ++i) {
auto offset = stream.offset();
auto insn = disassembler.next();
if (!insn.has_value())
break;
printf(String::format(" %08x ", offset + reinterpret_cast<size_t>(first_instruction)).characters());
printf("<+%lu>:\t", reinterpret_cast<size_t>(offset));
printf("%s\n", insn.value().to_string(offset).characters());
}
return true;
}
bool handle_breakpoint_command(const String& command)
{
auto parts = command.split(' ');
if (parts.size() != 2)
return false;
u32 breakpoint_address = strtoul(parts[1].characters(), nullptr, 16);
if (errno != 0)
return false;
bool success = g_debug_session->insert_breakpoint(reinterpret_cast<void*>(breakpoint_address));
if (!success) {
fprintf(stderr, "coult not insert breakpoint at: 0x%x\n", breakpoint_address);
return false;
}
return true;
}
void print_help()
{
printf("Options:\n"
"cont - Continue execution\n"
"regs - Print registers\n"
"dis <number of instructions> - Print disassembly\n"
"bp <address> - Insert a breakpoint\n");
}
int main(int argc, char** argv)
{
if (pledge("stdio proc exec rpath", nullptr) < 0) {
perror("pledge");
return 1;
}
if (argc == 1)
return usage();
StringBuilder command;
command.append(argv[1]);
for (int i = 2; i < argc; ++i) {
command.appendf("%s ", argv[i]);
}
auto result = DebugSession::exec_and_attach(command.to_string());
if (!result) {
fprintf(stderr, "Failed to start debugging session for: \"%s\"\n", command.to_string().characters());
exit(1);
}
g_debug_session = result.release_nonnull();
struct sigaction sa;
memset(&sa, 0, sizeof(struct sigaction));
sa.sa_handler = handle_sigint;
sigaction(SIGINT, &sa, nullptr);
bool rc = g_debug_session->insert_breakpoint(g_debug_session->get_entry_point().as_ptr());
ASSERT(rc);
g_debug_session->run([&](DebugSession::DebugBreakReason reason, Optional<PtraceRegisters> optional_regs) {
if (reason == DebugSession::DebugBreakReason::Exited) {
printf("Program exited.\n");
return DebugSession::DebugDecision::Detach;
}
ASSERT(optional_regs.has_value());
const PtraceRegisters& regs = optional_regs.value();
printf("Program is stopped at: 0x%x\n", regs.eip);
for (;;) {
auto command = get_command();
bool success = false;
if (command == "cont") {
return DebugSession::DebugDecision::Continue;
}
if (command == "regs") {
handle_print_registers(regs);
success = true;
} else if (command.starts_with("dis")) {
success = handle_disassemble_command(command, reinterpret_cast<void*>(regs.eip));
} else if (command.starts_with("bp")) {
success = handle_breakpoint_command(command);
}
if (!success)
print_help();
}
});
}
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