1 /* 2 * Copyright (C) 2011 Dan Carpenter. 3 * 4 * This program is free software; you can redistribute it and/or 5 * modify it under the terms of the GNU General Public License 6 * as published by the Free Software Foundation; either version 2 7 * of the License, or (at your option) any later version. 8 * 9 * This program is distributed in the hope that it will be useful, 10 * but WITHOUT ANY WARRANTY; without even the implied warranty of 11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 * GNU General Public License for more details. 13 * 14 * You should have received a copy of the GNU General Public License 15 * along with this program; if not, see http://www.gnu.org/copyleft/gpl.txt 16 */ 17 18 #include "smatch.h" 19 #include "smatch_slist.h" 20 21 static int my_id; 22 right_side_changes(struct expression * expr)23static int right_side_changes(struct expression *expr) 24 { 25 sval_t dummy; 26 27 if (get_value(expr->right, &dummy)) 28 return 0; 29 return 1; 30 } 31 get_iterator_set(struct statement * stmt)32static struct expression *get_iterator_set(struct statement *stmt) 33 { 34 struct expression *expr; 35 36 if (!stmt) 37 return NULL; 38 if (stmt->type != STMT_EXPRESSION) 39 return NULL; 40 expr = stmt->expression; 41 if (expr->type != EXPR_ASSIGNMENT) 42 return NULL; 43 if (expr->op != '=') 44 return NULL; 45 if (right_side_changes(expr)) 46 return NULL; 47 return expr->left; 48 } 49 get_iterator_tested(struct expression * expr)50static struct expression *get_iterator_tested(struct expression *expr) 51 { 52 if (!expr) 53 return NULL; 54 if (expr->type != EXPR_COMPARE) 55 return NULL; 56 return expr->left; 57 } 58 match_loop(struct statement * stmt)59static void match_loop(struct statement *stmt) 60 { 61 struct expression *iterator; 62 char *iter_set; 63 char *iter_tested; 64 65 if (get_macro_name(stmt->pos)) 66 return; 67 68 iterator = get_iterator_set(stmt->iterator_pre_statement); 69 iter_set = expr_to_var(iterator); 70 iterator = get_iterator_tested(stmt->iterator_pre_condition); 71 iter_tested = expr_to_var(iterator); 72 if (!iter_set || !iter_tested) 73 goto free; 74 if (strcmp(iter_set, iter_tested)) 75 goto free; 76 77 /* smatch doesn't handle loops correctly so this silences some 78 * false positives. 79 */ 80 if (right_side_changes(stmt->iterator_pre_condition)) 81 goto free; 82 83 if (implied_condition_false(stmt->iterator_pre_condition)) 84 sm_warning("we never enter this loop"); 85 86 free: 87 free_string(iter_set); 88 free_string(iter_tested); 89 } 90 check_bogus_loop(int id)91void check_bogus_loop(int id) 92 { 93 my_id = id; 94 add_hook(&match_loop, PRELOOP_HOOK); 95 } 96