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 extra_mod_hook(const char *name, struct symbol *sym, struct expression *expr, struct smatch_state *state) 40 { 41 struct smatch_state *abs; 42 struct range_list *rl; 43 44 abs = get_state(my_id, name, sym); 45 if (!abs || !estate_rl(abs)) 46 return; 47 rl = rl_intersection(estate_rl(abs), estate_rl(state)); 48 set_state(my_id, name, sym, alloc_estate_rl(clone_rl(rl))); 49 } 50 51 static void pre_merge_hook(struct sm_state *cur, struct sm_state *other) 52 { 53 struct smatch_state *extra; 54 struct range_list *rl; 55 56 extra = get_state(SMATCH_EXTRA, cur->name, cur->sym); 57 if (!extra || !estate_rl(extra)) 58 return; 59 if (!estate_rl(cur->state)) { 60 set_state(my_id, cur->name, cur->sym, clone_estate(extra)); 61 return; 62 } 63 rl = rl_intersection(estate_rl(cur->state), estate_rl(extra)); 64 set_state(my_id, cur->name, cur->sym, alloc_estate_rl(clone_rl(rl))); 65 } 66 67 static struct smatch_state *empty_state(struct sm_state *sm) 68 { 69 return alloc_estate_empty(); 70 } 71 72 static int in_iterator_pre_statement(void) 73 { 74 struct statement *stmt; 75 76 /* 77 * we can't use __cur_stmt because that isn't set for 78 * iterator_pre_statement. Kind of a mess. 79 * 80 */ 81 82 stmt = last_ptr_list((struct ptr_list *)big_statement_stack); 83 84 if (!stmt || !stmt->parent) 85 return 0; 86 if (stmt->parent->type != STMT_ITERATOR) 87 return 0; 88 if (stmt->parent->iterator_pre_statement != stmt) 89 return 0; 90 return 1; 91 } 92 93 static void match_assign(struct expression *expr) 94 { 95 struct range_list *rl; 96 struct symbol *type; 97 sval_t sval; 98 99 if (expr->op != '=') 100 return; 101 if (is_fake_call(expr->right)) 102 return; 103 if (in_iterator_pre_statement()) 104 return; 105 106 get_real_absolute_rl(expr->right, &rl); 107 108 type = get_type(expr->left); 109 if (!type) 110 return; 111 if (type->type != SYM_PTR && type->type != SYM_BASETYPE && 112 type->type != SYM_ENUM) 113 return; 114 115 rl = cast_rl(type, rl); 116 if (is_whole_rl(rl) && !get_state_expr(my_id, expr->left)) 117 return; 118 /* These are handled by smatch_extra.c */ 119 if (rl_to_sval(rl, &sval) && !get_state_expr(my_id, expr->left)) 120 return; 121 122 set_state_expr(my_id, expr->left, alloc_estate_rl(clone_rl(rl))); 123 } 124 125 struct smatch_state *get_real_absolute_state(struct expression *expr) 126 { 127 return get_state_expr(my_id, expr); 128 } 129 130 struct smatch_state *get_real_absolute_state_var_sym(const char *name, struct symbol *sym) 131 { 132 return __get_state(my_id, name, sym); 133 } 134 135 void register_real_absolute(int id) 136 { 137 my_id = id; 138 139 set_dynamic_states(my_id); 140 add_pre_merge_hook(my_id, &pre_merge_hook); 141 add_unmatched_state_hook(my_id, &empty_state); 142 add_merge_hook(my_id, &merge_estates); 143 add_extra_mod_hook(&extra_mod_hook); 144 145 add_hook(&match_assign, ASSIGNMENT_HOOK); 146 } 147 148