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sdb.c
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#include <sys/ptrace.h>
#include <sys/wait.h>
#include <sys/user.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <stdio.h>
#include "inc/disasm-tool.h"
#include "inc/command.h"
#include "inc/tracee.h"
#include "inc/vmmap.h"
#include "inc/util.h"
static int debugger_state;
int main(int argc, char *argv[])
{
char user_input[256];
char *command = NULL, *args = NULL;
int result = 0;
tracee_t tracee;
struct user_regs_struct regs;
int wait_status;
int hit = 0, hit_id = -1;
disassembler_t *disasmbler;
FSM_STATE_TRANS(debugger_state, STATE_INIT);
init_tracee(&tracee);
disasmbler = disasm_init(&tracee);
if (argc >= 2)
{
if (load_elf(&tracee, argv[1]) == 0)
{
FSM_STATE_TRANS(debugger_state, STATE_LOADED);
hit = 0;
hit_id = -1;
}
}
while (1)
{
printf("sdb> ");
memset(user_input, '\0', sizeof(user_input));
fgets(user_input, 256, stdin);
command = strtok(user_input, DELIMETER);
if (command == NULL)
continue;
if (parse_command(command, debugger_state, &result) != PARSE_OK)
{
print_command_error(result);
continue;
}
switch (result)
{
case COMMAND_BREAK:
{
if ((args = strtok(NULL, DELIMETER)) == NULL)
{
SDB_ERROR("** usage: break {instruction-address}\n");
continue;
}
// load vmmap
load_maps(&tracee, 0);
uint64_t target = strtoull(args, NULL, 0);
uint64_t code = 0;
if (debugger_state == STATE_RUNNING)
{
if (!inside_range(target, tracee.text_phaddr))
{
SDB_ERROR("** the address should be within the range specified by the text segment.\n");
continue;
}
if (set_breakpoint(&tracee, target, &code) == 0)
add_breakpoint_to_list(&tracee, target, code);
}
else // loading state
{
if (!inside_range(target, tracee.text_section_addr))
{
SDB_ERROR("** the address should be within the range specified by the text segment in the ELF file.\n");
continue;
}
add_breakpoint_to_list(&tracee, target, code);
}
break;
}
case COMMAND_RUN:
{
if (debugger_state == STATE_RUNNING)
SDB_ERROR("** program '%s' is already running.\n", tracee.program_name);
else
{
create_tracee_process(&tracee);
load_maps(&tracee, 0);
get_breakpoints_origin_code(&tracee);
enable_all_breakpoints(&tracee);
tracee.last_disasm_addr = 0;
tracee.last_dump_addr = 0;
FSM_STATE_TRANS(debugger_state, STATE_RUNNING);
SDB_ERROR("** pid %d\n", tracee.pid);
}
// no break at COMMAND_RUN case: run & continue command share the same handle logic
}
case COMMAND_CONTINUE:
{
if (hit)
{
tracee_single_step(&tracee, &wait_status);
if (is_tracee_exit(&tracee, wait_status))
{
tracee.baseaddr = 0;
FSM_STATE_TRANS(debugger_state, STATE_LOADED);
}
else
enable_all_breakpoints(&tracee);
hit = 0;
hit_id = -1;
}
ptrace(PTRACE_CONT, tracee.pid, 0, 0);
if (waitpid(tracee.pid, &wait_status, 0) > 0)
{
if (is_tracee_exit(&tracee, wait_status))
{
tracee.baseaddr = 0;
FSM_STATE_TRANS(debugger_state, STATE_LOADED);
}
else
{
get_register_values(tracee.pid, ®s);
if ((hit_id = hit_breakpoint(&tracee, regs.rip - 1)) >= 0)
{
SDB_ERROR("** breakpoint @ ");
disasm_at_break(disasmbler, hit_id);
restore_code(&tracee, ®s, hit_id, 1);
hit = 1;
}
}
}
break;
}
case COMMAND_DELETE:
{
args = strtok(NULL, DELIMETER);
if (args == NULL)
{
SDB_ERROR("** usage: delete {break-point-id}\n");
continue;
}
int id = atoi(args);
if (find_breakpoint(&tracee, id) < 0)
{
SDB_ERROR("** can not find breakpoint %d.\n", id);
continue;
}
if (hit_id == id)
{
hit = 0;
hit_id = -1;
}
else
{
if (debugger_state == STATE_RUNNING)
{
get_register_values(tracee.pid, ®s);
restore_code(&tracee, ®s, id, 0);
}
}
delete_breakpoint_from_list(&tracee, id);
break;
}
case COMMAND_DISASM:
{
unsigned long long addr;
args = strtok(NULL, DELIMETER);
if (debugger_state == STATE_LOADED)
{
if (args == NULL)
{
if (tracee.last_disasm_addr == 0)
{
SDB_ERROR("** no addr is given.\n");
continue;
}
else
{
if (tracee.last_disasm_addr >= tracee.text_section_addr.end)
{
SDB_ERROR("** reach the end of the text section.\n");
SDB_ERROR("** the debugger will go back to the begin of the text section and continue disassembling.\n");
tracee.last_disasm_addr = tracee.text_section_addr.begin;
}
addr = tracee.last_disasm_addr;
}
}
else
{
addr = strtoull(args, NULL, 0);
if (!inside_range(addr, tracee.text_section_addr))
{
SDB_ERROR("** the address should be within the range specified by the text segment in the ELF file\n");
continue;
}
}
unsigned long long offset = (addr - tracee.text_section_addr.begin);
tracee.last_disasm_addr = disasm(disasmbler, tracee.text + offset, tracee.text_shdr.size - offset, addr, 10);
}
else // running state
{
if (args == NULL)
{
if (tracee.last_disasm_addr == 0)
{
SDB_ERROR("** no addr is given.\n");
continue;
}
else
addr = tracee.last_disasm_addr;
}
else
addr = strtoull(args, NULL, 0);
disable_all_breakpoints(&tracee);
tracee.last_disasm_addr = disasm_in_running(disasmbler, addr);
enable_all_breakpoints(&tracee);
}
break;
}
case COMMAND_DUMP:
{
unsigned long long addr;
load_maps(&tracee, 0);
if ((args = strtok(NULL, DELIMETER)) == NULL)
{
if (tracee.last_dump_addr == 0)
{
SDB_ERROR("** no addr is given.\n");
continue;
}
else
addr = tracee.last_dump_addr;
}
else
addr = strtoull(args, NULL, 0);
tracee.last_dump_addr = dump_code(tracee.pid, addr);
break;
}
case COMMAND_EXIT:
{
disasm_finalize(disasmbler);
free_tracee(&tracee);
exit(EXIT_SUCCESS);
}
case COMMAND_GET:
{
if ((args = strtok(NULL, DELIMETER)) == NULL)
{
SDB_ERROR("** usage: get {reg}. Register names are all in lowercase\n");
continue;
}
get_register_values(tracee.pid, ®s);
print_register_value(®s, args);
break;
}
case COMMAND_GETREGS:
{
get_register_values(tracee.pid, ®s);
print_register_value(®s, NULL);
break;
}
case COMMAND_HELP:
{
help_msg();
break;
}
case COMMAND_LIST:
{
print_breakpoint_list(&tracee);
break;
}
case COMMAND_LOAD:
{
if ((args = strtok(NULL, DELIMETER)) == NULL)
{
SDB_ERROR("** usage: load {path to a program}\n");
continue;
}
init_tracee(&tracee);
if (load_elf(&tracee, args) == 0)
{
FSM_STATE_TRANS(debugger_state, STATE_LOADED);
hit = 0;
hit_id = -1;
}
break;
}
case COMMAND_VMMAP:
{
if (debugger_state == STATE_LOADED)
{
// TODO: fix access permission
SDB_ERROR("%016lx-%016lx r-x %llx\t%s\n",
tracee.text_section_addr.begin,
tracee.text_section_addr.end,
tracee.text_shdr.offset,
tracee.program_name);
}
else
load_maps(&tracee, 1);
break;
}
case COMMAND_SET:
{
// get register name
char *reg_name;
if ((reg_name = strtok(NULL, DELIMETER)) == NULL)
{
SDB_ERROR("** usage: set reg val\n");
continue;
}
// get value
if ((args = strtok(NULL, DELIMETER)) == NULL)
{
SDB_ERROR("** usage: set reg val\n");
continue;
}
unsigned long long val = strtoull(args, NULL, 0);
get_register_values(tracee.pid, ®s);
if (set_register_value(®s, reg_name, val) < 0)
{
SDB_ERROR("** no register named '%s'.\n", reg_name);
continue;
}
if (ptrace(PTRACE_SETREGS, tracee.pid, 0, ®s) < 0)
perror("set error");
break;
}
case COMMAND_SI:
{
tracee_single_step(&tracee, &wait_status);
if (is_tracee_exit(&tracee, wait_status))
{
tracee.baseaddr = 0;
FSM_STATE_TRANS(debugger_state, STATE_LOADED);
}
else
{
if (hit)
{
enable_all_breakpoints(&tracee);
hit = 0;
hit_id = -1;
}
else
{
get_register_values(tracee.pid, ®s);
if ((hit_id = hit_breakpoint(&tracee, regs.rip - 1)) >= 0)
{
SDB_INFO("** breakpoint @ ");
disasm_at_break(disasmbler, hit_id);
restore_code(&tracee, ®s, hit_id, 1);
hit = 1;
}
}
}
break;
}
case COMMAND_START:
{
create_tracee_process(&tracee);
load_maps(&tracee, 0);
get_breakpoints_origin_code(&tracee);
enable_all_breakpoints(&tracee);
tracee.last_disasm_addr = 0;
tracee.last_dump_addr = 0;
FSM_STATE_TRANS(debugger_state, STATE_RUNNING);
SDB_INFO("** pid %d\n", tracee.pid);
break;
}
}
}
return 0;
}