1 /* 2 * Copyright (C) 2009 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 /* 19 * There are a number of ways that variables are modified: 20 * 1) assignment 21 * 2) increment/decrement 22 * 3) assembly 23 * 4) inside functions. 24 * 25 * For setting stuff inside a function then, of course, it's more accurate if 26 * you have the cross function database built. Otherwise we are super 27 * aggressive about marking things as modified and if you have "frob(foo);" then 28 * we assume "foo->bar" is modified. 29 */ 30 31 #include <stdlib.h> 32 #include <stdio.h> 33 #include "smatch.h" 34 #include "smatch_extra.h" 35 #include "smatch_slist.h" 36 37 enum { 38 EARLY = 0, 39 LATE = 1, 40 BOTH = 2 41 }; 42 43 static modification_hook **hooks; 44 static modification_hook **hooks_late; 45 46 ALLOCATOR(modification_data, "modification data"); 47 48 static int my_id; 49 static struct smatch_state *alloc_my_state(struct expression *expr, struct smatch_state *prev) 50 { 51 struct smatch_state *state; 52 struct modification_data *data; 53 char *name; 54 55 state = __alloc_smatch_state(0); 56 expr = strip_expr(expr); 57 name = expr_to_str(expr); 58 state->name = alloc_sname(name); 59 free_string(name); 60 61 data = __alloc_modification_data(0); 62 data->prev = prev; 63 data->cur = expr; 64 state->data = data; 65 66 return state; 67 } 68 69 void add_modification_hook(int owner, modification_hook *call_back) 70 { 71 if (hooks[owner]) 72 sm_fatal("multiple modification hooks for %s", check_name(owner)); 73 hooks[owner] = call_back; 74 } 75 76 void add_modification_hook_late(int owner, modification_hook *call_back) 77 { 78 if (hooks_late[owner]) 79 sm_fatal("multiple late modification hooks for %s", check_name(owner)); 80 hooks_late[owner] = call_back; 81 } 82 83 static int matches(char *name, struct symbol *sym, struct sm_state *sm) 84 { 85 int len; 86 87 if (sym != sm->sym) 88 return false; 89 90 len = strlen(name); 91 if (strncmp(sm->name, name, len) == 0) { 92 if (sm->name[len] == '\0') 93 return true; 94 if (sm->name[len] == '-' || sm->name[len] == '.') 95 return true; 96 } 97 if (sm->name[0] != '*') 98 return false; 99 if (strncmp(sm->name + 1, name, len) == 0) { 100 if (sm->name[len + 1] == '\0') 101 return true; 102 if (sm->name[len + 1] == '-' || sm->name[len + 1] == '.') 103 return true; 104 } 105 return false; 106 } 107 108 static void call_modification_hooks_name_sym(char *name, struct symbol *sym, struct expression *mod_expr, int late) 109 { 110 struct sm_state *sm; 111 struct smatch_state *prev; 112 int match; 113 114 prev = get_state(my_id, name, sym); 115 116 if (cur_func_sym && !__in_fake_assign) 117 set_state(my_id, name, sym, alloc_my_state(mod_expr, prev)); 118 119 FOR_EACH_SM(__get_cur_stree(), sm) { 120 if (sm->owner > num_checks) 121 continue; 122 match = matches(name, sym, sm); 123 if (!match) 124 continue; 125 126 if (late == EARLY || late == BOTH) { 127 if (hooks[sm->owner]) 128 (hooks[sm->owner])(sm, mod_expr); 129 } 130 if (late == LATE || late == BOTH) { 131 if (hooks_late[sm->owner]) 132 (hooks_late[sm->owner])(sm, mod_expr); 133 } 134 135 } END_FOR_EACH_SM(sm); 136 } 137 138 static void call_modification_hooks(struct expression *expr, struct expression *mod_expr, int late) 139 { 140 char *name; 141 struct symbol *sym; 142 143 if (late == LATE) 144 update_mtag_data(expr); 145 146 name = expr_to_known_chunk_sym(expr, &sym); 147 if (!name) 148 goto free; 149 call_modification_hooks_name_sym(name, sym, mod_expr, late); 150 free: 151 free_string(name); 152 } 153 154 static void db_param_add(struct expression *expr, int param, char *key, char *value) 155 { 156 struct expression *arg, *gen_expr; 157 char *name, *other_name; 158 struct symbol *sym, *other_sym; 159 160 while (expr->type == EXPR_ASSIGNMENT) 161 expr = strip_expr(expr->right); 162 if (expr->type != EXPR_CALL) 163 return; 164 165 arg = get_argument_from_call_expr(expr->args, param); 166 if (!arg) 167 return; 168 169 gen_expr = gen_expression_from_key(arg, key); 170 if (gen_expr) 171 update_mtag_data(gen_expr); 172 173 name = get_variable_from_key(arg, key, &sym); 174 if (!name || !sym) 175 goto free; 176 177 __in_fake_assign++; 178 call_modification_hooks_name_sym(name, sym, expr, BOTH); 179 __in_fake_assign--; 180 181 other_name = map_long_to_short_name_sym(name, sym, &other_sym); 182 if (other_name) { 183 __in_fake_assign++; 184 call_modification_hooks_name_sym(other_name, other_sym, expr, BOTH); 185 __in_fake_assign--; 186 free_string(other_name); 187 } 188 189 free: 190 free_string(name); 191 } 192 193 static void match_assign(struct expression *expr, int late) 194 { 195 call_modification_hooks(expr->left, expr, late); 196 } 197 198 static void unop_expr(struct expression *expr, int late) 199 { 200 if (expr->op != SPECIAL_DECREMENT && expr->op != SPECIAL_INCREMENT) 201 return; 202 203 call_modification_hooks(expr->unop, expr, late); 204 } 205 206 static void match_call(struct expression *expr) 207 { 208 struct expression *arg, *tmp; 209 210 /* If we have the DB then trust the DB */ 211 if (!option_no_db) 212 return; 213 214 FOR_EACH_PTR(expr->args, arg) { 215 tmp = strip_expr(arg); 216 if (tmp->type == EXPR_PREOP && tmp->op == '&') 217 call_modification_hooks(tmp->unop, expr, BOTH); 218 else 219 call_modification_hooks(deref_expression(tmp), expr, BOTH); 220 } END_FOR_EACH_PTR(arg); 221 } 222 223 static void asm_expr(struct statement *stmt, int late) 224 { 225 struct expression *expr; 226 int state = 0; 227 228 FOR_EACH_PTR(stmt->asm_outputs, expr) { 229 switch (state) { 230 case 0: /* identifier */ 231 case 1: /* constraint */ 232 state++; 233 continue; 234 case 2: /* expression */ 235 state = 0; 236 call_modification_hooks(expr, NULL, late); 237 continue; 238 } 239 } END_FOR_EACH_PTR(expr); 240 } 241 242 243 static void match_assign_early(struct expression *expr) 244 { 245 match_assign(expr, EARLY); 246 } 247 248 static void unop_expr_early(struct expression *expr) 249 { 250 unop_expr(expr, EARLY); 251 } 252 253 static void asm_expr_early(struct statement *stmt) 254 { 255 asm_expr(stmt, EARLY); 256 } 257 258 static void match_assign_late(struct expression *expr) 259 { 260 match_assign(expr, LATE); 261 } 262 263 static void unop_expr_late(struct expression *expr) 264 { 265 unop_expr(expr, LATE); 266 } 267 268 static void asm_expr_late(struct statement *stmt) 269 { 270 asm_expr(stmt, LATE); 271 } 272 273 struct smatch_state *get_modification_state(struct expression *expr) 274 { 275 return get_state_expr(my_id, expr); 276 } 277 278 void register_modification_hooks(int id) 279 { 280 my_id = id; 281 282 hooks = malloc((num_checks + 1) * sizeof(*hooks)); 283 memset(hooks, 0, (num_checks + 1) * sizeof(*hooks)); 284 hooks_late = malloc((num_checks + 1) * sizeof(*hooks)); 285 memset(hooks_late, 0, (num_checks + 1) * sizeof(*hooks)); 286 287 add_hook(&match_assign_early, ASSIGNMENT_HOOK); 288 add_hook(&unop_expr_early, OP_HOOK); 289 add_hook(&asm_expr_early, ASM_HOOK); 290 } 291 292 void register_modification_hooks_late(int id) 293 { 294 add_hook(&match_call, FUNCTION_CALL_HOOK); 295 296 select_return_states_hook(PARAM_ADD, &db_param_add); 297 select_return_states_hook(PARAM_SET, &db_param_add); 298 299 add_hook(&match_assign_late, ASSIGNMENT_HOOK_AFTER); 300 add_hook(&unop_expr_late, OP_HOOK); 301 add_hook(&asm_expr_late, ASM_HOOK); 302 } 303 304