1 /* 2 * Copyright (C) 2015 Oracle. 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 /* 19 * Say we have a line like: 20 * foo = bar / 8; 21 * Assume we don't know anything about bar. Well, now we know that foo is less 22 * than UINT_MAX / 8. Which might be useful, but it probably is misleading 23 * useless knowledge. Up to now we have ignored those but now we have said to 24 * store them. 25 * 26 * It also works if you have something like "foo = (int)(char)unknown_var;". 27 * 28 * I feel like this data doesn't have to be perfect, it just has to be better 29 * than nothing and that will help eliminate some false positives. 30 * 31 */ 32 33 #include "smatch.h" 34 #include "smatch_slist.h" 35 #include "smatch_extra.h" 36 37 static int my_id; 38 39 static void pre_merge_hook(struct sm_state *sm) 40 { 41 struct smatch_state *abs; 42 struct smatch_state *extra; 43 struct range_list *rl; 44 45 extra = get_state(SMATCH_EXTRA, sm->name, sm->sym); 46 if (!extra || !estate_rl(extra)) 47 return; 48 abs = get_state(my_id, sm->name, sm->sym); 49 if (!abs || !estate_rl(abs)) { 50 set_state(my_id, sm->name, sm->sym, clone_estate(extra)); 51 return; 52 } 53 rl = rl_intersection(estate_rl(abs), estate_rl(extra)); 54 set_state(my_id, sm->name, sm->sym, alloc_estate_rl(clone_rl(rl))); 55 } 56 57 static struct smatch_state *empty_state(struct sm_state *sm) 58 { 59 return alloc_estate_empty(); 60 } 61 62 static void reset(struct sm_state *sm, struct expression *mod_expr) 63 { 64 set_state(my_id, sm->name, sm->sym, alloc_estate_whole(estate_type(sm->state))); 65 } 66 67 static int in_iterator_pre_statement(void) 68 { 69 struct statement *stmt; 70 71 /* 72 * we can't use __cur_stmt because that isn't set for 73 * iterator_pre_statement. Kind of a mess. 74 * 75 */ 76 77 stmt = last_ptr_list((struct ptr_list *)big_statement_stack); 78 79 if (!stmt || !stmt->parent) 80 return 0; 81 if (stmt->parent->type != STMT_ITERATOR) 82 return 0; 83 if (stmt->parent->iterator_pre_statement != stmt) 84 return 0; 85 return 1; 86 } 87 88 static void match_assign(struct expression *expr) 89 { 90 struct range_list *rl; 91 struct symbol *type; 92 sval_t sval; 93 94 if (expr->op != '=') 95 return; 96 if (is_fake_call(expr->right)) 97 return; 98 if (in_iterator_pre_statement()) 99 return; 100 101 get_real_absolute_rl(expr->right, &rl); 102 103 type = get_type(expr->left); 104 if (!type) 105 return; 106 107 rl = cast_rl(type, rl); 108 if (is_whole_rl(rl) && !get_state_expr(my_id, expr->left)) 109 return; 110 /* These are handled by smatch_extra.c */ 111 if (rl_to_sval(rl, &sval) && !get_state_expr(my_id, expr->left)) 112 return; 113 114 set_state_expr(my_id, expr->left, alloc_estate_rl(clone_rl(rl))); 115 } 116 117 struct smatch_state *get_real_absolute_state(struct expression *expr) 118 { 119 return get_state_expr(my_id, expr); 120 } 121 122 struct smatch_state *get_real_absolute_state_var_sym(const char *name, struct symbol *sym) 123 { 124 return get_state(my_id, name, sym); 125 } 126 127 void register_real_absolute(int id) 128 { 129 my_id = id; 130 131 add_pre_merge_hook(my_id, &pre_merge_hook); 132 add_unmatched_state_hook(my_id, &empty_state); 133 add_merge_hook(my_id, &merge_estates); 134 add_modification_hook(my_id, &reset); 135 136 add_hook(&match_assign, ASSIGNMENT_HOOK); 137 } 138 139