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 void set_real_absolute(struct expression *expr, struct smatch_state *state) 40 { 41 set_state_expr(my_id, expr, clone_estate(state)); 42 } 43 44 static void extra_mod_hook(const char *name, struct symbol *sym, struct expression *expr, struct smatch_state *state) 45 { 46 struct smatch_state *abs; 47 struct range_list *rl; 48 49 abs = get_state(my_id, name, sym); 50 if (!abs || !estate_rl(abs)) 51 return; 52 rl = rl_intersection(estate_rl(abs), estate_rl(state)); 53 set_state(my_id, name, sym, alloc_estate_rl(clone_rl(rl))); 54 } 55 56 static void pre_merge_hook(struct sm_state *cur, struct sm_state *other) 57 { 58 struct smatch_state *extra; 59 struct range_list *rl; 60 61 extra = get_state(SMATCH_EXTRA, cur->name, cur->sym); 62 if (!extra || !estate_rl(extra)) 63 return; 64 if (!estate_rl(cur->state)) { 65 set_state(my_id, cur->name, cur->sym, clone_estate(extra)); 66 return; 67 } 68 rl = rl_intersection(estate_rl(cur->state), estate_rl(extra)); 69 set_state(my_id, cur->name, cur->sym, alloc_estate_rl(clone_rl(rl))); 70 } 71 72 static struct smatch_state *empty_state(struct sm_state *sm) 73 { 74 return alloc_estate_empty(); 75 } 76 77 static int in_iterator_pre_statement(void) 78 { 79 struct statement *stmt; 80 81 /* 82 * we can't use __cur_stmt because that isn't set for 83 * iterator_pre_statement. Kind of a mess. 84 * 85 */ 86 87 stmt = last_ptr_list((struct ptr_list *)big_statement_stack); 88 89 if (!stmt || !stmt->parent) 90 return 0; 91 if (stmt->parent->type != STMT_ITERATOR) 92 return 0; 93 if (stmt->parent->iterator_pre_statement != stmt) 94 return 0; 95 return 1; 96 } 97 98 static void match_assign(struct expression *expr) 99 { 100 struct range_list *rl; 101 struct symbol *type; 102 sval_t sval; 103 104 if (expr->op != '=') 105 return; 106 if (is_fake_call(expr->right)) 107 return; 108 if (in_iterator_pre_statement()) 109 return; 110 111 get_real_absolute_rl(expr->right, &rl); 112 113 type = get_type(expr->left); 114 if (!type) 115 return; 116 if (type->type != SYM_PTR && type->type != SYM_BASETYPE && 117 type->type != SYM_ENUM) 118 return; 119 120 rl = cast_rl(type, rl); 121 if (is_whole_rl(rl) && !get_state_expr(my_id, expr->left)) 122 return; 123 /* These are handled by smatch_extra.c */ 124 if (rl_to_sval(rl, &sval) && !get_state_expr(my_id, expr->left)) 125 return; 126 127 set_state_expr(my_id, expr->left, alloc_estate_rl(clone_rl(rl))); 128 } 129 130 struct smatch_state *get_real_absolute_state(struct expression *expr) 131 { 132 return get_state_expr(my_id, expr); 133 } 134 135 struct smatch_state *get_real_absolute_state_var_sym(const char *name, struct symbol *sym) 136 { 137 return __get_state(my_id, name, sym); 138 } 139 140 void register_real_absolute(int id) 141 { 142 my_id = id; 143 144 set_dynamic_states(my_id); 145 add_pre_merge_hook(my_id, &pre_merge_hook); 146 add_unmatched_state_hook(my_id, &empty_state); 147 add_merge_hook(my_id, &merge_estates); 148 add_extra_mod_hook(&extra_mod_hook); 149 150 add_hook(&match_assign, ASSIGNMENT_HOOK); 151 } 152 153