asmsh/src/shell_cmds_lib.c

#include "shell_cmds_lib.h"

/** Utility function for @ref asmsh_cmd_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 asmsh_log_addr_expr_usage()
{
	asmsh_log_info("Expected an address expression of the form A + B or A - B with A and B an integer or '.' (for current RIP value)");
}


int asmsh_cmd_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;
}


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;
}