text: /*
   * Copyright (C) 2011 Dan Carpenter.
   *
   * This program 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 2
   * of the License, or (at your option) any later version.
   *
   * This program 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 this program; if not, see http://www.gnu.org/copyleft/gpl.txt
   */
  
  #include "smatch.h"
  #include "smatch_slist.h"
  
  static int my_id;
  
  static int right_side_changes(struct expression *expr)
  {
  	sval_t dummy;
  
  	if (get_value(expr->right, &dummy))
  		return 0;
  	return 1;
  }
  
  static struct expression *get_iterator_set(struct statement *stmt)
  {
  	struct expression *expr;
  
  	if (!stmt)
  		return NULL;
  	if (stmt->type != STMT_EXPRESSION)
  		return NULL;
  	expr = stmt->expression;
  	if (expr->type != EXPR_ASSIGNMENT)
  		return NULL;
  	if (expr->op != '=')
  		return NULL;
  	if (right_side_changes(expr))
  		return NULL;
  	return expr->left;
  }
  
  static struct expression *get_iterator_tested(struct expression *expr)
  {
  	if (!expr)
  		return NULL;
  	if (expr->type != EXPR_COMPARE)
  		return NULL;
  	return expr->left;
  }
  
  static void match_loop(struct statement *stmt)
  {
  	struct expression *iterator;
  	char *iter_set;
  	char *iter_tested;
  
  	if (get_macro_name(stmt->pos))
  		return;
  
  	iterator = get_iterator_set(stmt->iterator_pre_statement);
  	iter_set = expr_to_var(iterator);
  	iterator = get_iterator_tested(stmt->iterator_pre_condition);
  	iter_tested = expr_to_var(iterator);
  	if (!iter_set || !iter_tested)
  		goto free;
  	if (strcmp(iter_set, iter_tested))
  		goto free;
  
  	/* smatch doesn't handle loops correctly so this silences some
  	 * false positives.
  	 */
  	if (right_side_changes(stmt->iterator_pre_condition))
  		goto free;
  
  	if (implied_condition_false(stmt->iterator_pre_condition))
  		sm_warning("we never enter this loop");
  
  free:
  	free_string(iter_set);
  	free_string(iter_tested);
  }
  
  void check_bogus_loop(int id)
  {
  	my_id = id;
  	add_hook(&match_loop, PRELOOP_HOOK);
  }
  