asmsh/shell_cmd_breakpoint.c

/* Copyright Yann Weber <asmsh@yannweb.net>
   This file is part of asmsh.

   asmsh is free software: you can redistribute it and/or modify it under the
   terms of the GNU General Public License as published by the Free Software
   Foundation, either version 3 of the License, or any later version.
   
   asmsh is distributed in the hope that it will be useful, but WITHOUT ANY
   WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
   FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
   details.
   
   You should have received a copy of the GNU General Public License along
   with asmsh. If not, see <https://www.gnu.org/licenses/>.
*/
#include "shell_cmds.h"

/** Add a breakpoint
 * @param asmsh_t* The shell
 * @param asmsh_cmd_args_t* The command arguments
 * @param int The first argument of the expression
 * @return -1 on error else 0
 */
static int brk_add(asmsh_t *sh, asmsh_cmd_args_t *args, int expr_first);

/** Remove a breakpoint
 * @param asmsh_t* The shell
 * @param asmsh_cmd_args_t* The command arguments
 * @param int The first argument of the expression
 * @return -1 on error else 0
 */
static int brk_del(asmsh_t *sh, asmsh_cmd_args_t *args, int expr_first);

/** List all breakpoints
 * @param asmsh_t* The shell
 * @param asmsh_cmd_args_t* The command arguments
 * @param int The first argument of the expression
 * @return -1 on error else 0
 * @todo add filters arguments
 */
static int brk_ls(asmsh_t *sh, asmsh_cmd_args_t *args, int expr_first);

/** Parse a breakpoint address expression
 *
 * An expression must be of the form A [OP B] with A and B
 * an integer or '.' for current RIP value and OP one of + or -
 *
 * @param asmsh_cmd_args_t* The breakpoint command argument list
 * @param int The first argument of the address expression
 * @param const unsigned long RIP value
 * @param unsigned long* A pointer on the result address
 *
 * @returns -1 on error and 0 if ok
 */
static int parse_addr_expr(asmsh_cmd_args_t *args, int first,
		const unsigned long rip,  unsigned long *addr);

/** Utility function for @ref parse_addr_expr() that parse an expression value.
 *
 * An expression can be . for rip value or an unsigned long, possibly in hex, etc
 * @param const char* The value
 * @param unsigned long The value of RIP
 * @param unsigned long* A pointer on the result
 * @return -1 on error else 0
 */
static int addr_expr_val(const char *val, unsigned long rip, unsigned long *res);


void log_brk_usage()
{
	asmsh_log_info("Available commands are : add, a, del, d, rm, list, ls, l");
}

void log_expr_usage()
{
	asmsh_log_info("Bad argument, expected an expression of the form A + B or A - B with A and B an integer or '.' (for current RIP value)");
}


int asmsh_cmd_breakpoint(asmsh_t *sh, asmsh_cmd_args_t *args)
{
	int ret;

	if(args->argc == 0 || args->args[0][0] == '.' || \
			(args->args[0][0] >= '0' && args->args[0][0] <= '9'))
	{
		if((ret = brk_add(sh, args, 0)) < 0)
		{
			log_expr_usage();
		}
		return ret;
	}
	// At least 1 arg, 1st arg chr is not in [0-9] nor is '.'
	// Looking for specific commands argument
	if(strcmp(args->args[0], "a") == 0 || \
			strcmp(args->args[0], "add") == 0)
	{
		if((ret = brk_add(sh, args, 1)) < 0)
		{
			log_expr_usage();
		}
		return ret;
	}
	else if(strcmp(args->args[0], "d") == 0 || \
			strcmp(args->args[0], "del") == 0 || \
			strcmp(args->args[0], "rm") == 0)
	{
		ret = brk_del(sh, args, 1);
		return ret;
	}
	else if(strcmp(args->args[0], "list") == 0 || \
			strcmp(args->args[0], "ls") == 0 || \
			strcmp(args->args[0], "l") == 0)
	{
		ret = brk_ls(sh, args, 1);
		return ret;
	}
	else
	{
		asmsh_log_error("Unrecognized action '%s'", args->args[0]);
		log_brk_usage();
	}
	return -1;
}

static int brk_add(asmsh_t *sh, asmsh_cmd_args_t *args, int expr_first)
{
	const unsigned long rip = sh->env->regs.rip;

	unsigned long addr;

	if(parse_addr_expr(args, expr_first, rip, &addr) < 0)
	{
		return -1;
	}

	int ret = asmsh_brk_add(&sh->env->brks, addr);
	if(ret < 0)
	{
		int err = errno;
		asmsh_log_error("Unable to set breakpoint @ %016lX : %s",
				addr, strerror(errno));
		errno = err;
		return -1;
	}
	else if(ret > 0)
	{
		asmsh_log_warning("Breakpoint @ %016lX allready set", addr);
		return -1;
	}
	asmsh_log_info("Set breakpoint @ %016lX", addr);
	return 0;
}

static int brk_del(asmsh_t *sh, asmsh_cmd_args_t *args, int expr_first)
{
	const unsigned long rip = sh->env->regs.rip;

	unsigned long addr;

	if(parse_addr_expr(args, expr_first, rip, &addr) < 0)
	{
		return -1;
	}

	int ret = asmsh_brk_del(&sh->env->brks, addr);
	if(ret < 0)
	{
		int err = errno;
		asmsh_log_error("Unable to remove breakpoint @ %016lX : %s",
				addr, strerror(errno));
		errno = err;
		return -1;
	}
	else if(ret > 0)
	{
		asmsh_log_warning("Breakpoint @ %016lX do not exists", addr);
		return -1;
	}
	asmsh_log_info("Removed breakpoint @ %016lX", addr);
	return 0;
}


static int brk_ls(asmsh_t *sh, asmsh_cmd_args_t *args, int expr_first)
{
	for(size_t i=0; i<sh->env->brks.sz; i++)
	{
		printf("0x%016lx\n", sh->env->brks.addrs[i]);
	}
	printf("%ld breakpoints\n", sh->env->brks.sz);
	return 0;
}

static int addr_expr_val(const char *val, unsigned long rip, unsigned long *res)
{
	if(strcmp(".", val) == 0)
	{
		*res = rip;
		return 0;
	}

	char *endptr;
	errno = 0;
	*res = strtoul(val, &endptr, 0);
	if(errno != 0)
	{
		return -1;
	}
	else if(*endptr != '\0')
	{
		errno = EINVAL;
		return -1;
	}
	return 0;
}

static int parse_addr_expr(asmsh_cmd_args_t *args, int first,
		const unsigned long rip, unsigned long *addr)
{
	char * const * argv = args->args + first;
	const int argc = args->argc - first;

	unsigned long val[2];

	switch(argc)
	{
		case 0:
			*addr = rip;
			break;
		case 1:
			if(addr_expr_val(argv[0], rip, addr) < 0)
			{
				int err = errno;
				asmsh_log_error("Invalid expression value '%s': %s",
						argv[0], strerror(errno));
				errno = err;
				return -1;
			}
			break;
		case 3:

			for(int i=0; i<2; i++)
			{
				const char *arg = i ? argv[2]:argv[0];
				if(addr_expr_val(arg, rip, &val[i]) < 0)
				{

					asmsh_log_error("Invalid value '%s' in expression '%s %s %s' : %s",
							arg,
							argv[0], argv[1], argv[2],
							strerror(errno));
					return -1;
				}
			}

			const char operator = strlen(argv[1]) == 1 ? argv[1][0]: '\0';
			switch(operator)
			{
				case '+':
					*addr = val[0] + val[1];
					break;
				case '-':
					*addr = val[0] - val[1];
					break;
				default:
					asmsh_log_error("Invalid operator '%s' in expression '%s %s %s'",
							argv[1],
							argv[0], argv[1], argv[2]);
					return -1;
			}
			break;
		default:
			//USAGE !
			asmsh_log_error("Unexexpected argument count for an expression. Expecting one of 0, 1 or 3 but got %d", argc);
			return -1;
	}
	return 0;
}