smatch_modification_hooks.c

   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                 printf("multiple modification hooks for %s\n", check_name(owner));
  73                 exit(1);
  74         }
  75         hooks[owner] = call_back;
  76 }
  77
  78 void add_modification_hook_late(int owner, modification_hook *call_back)
  79 {
  80         if (hooks_late[owner]) {
  81                 printf("multiple late modification hooks for %s\n", check_name(owner));
  82                 exit(1);
  83         }
  84         hooks_late[owner] = call_back;
  85 }
  86
  87 static int matches(char *name, struct symbol *sym, struct sm_state *sm)
  88 {
  89         int len;
  90
  91         if (sym != sm->sym)
  92                 return false;
  93
  94         len = strlen(name);
  95         if (strncmp(sm->name, name, len) == 0) {
  96                 if (sm->name[len] == '\0')
  97                         return true;
  98                 if (sm->name[len] == '-' || sm->name[len] == '.')
  99                         return true;
 100         }
 101         if (sm->name[0] != '*')
 102                 return false;
 103         if (strncmp(sm->name + 1, name, len) == 0) {
 104                 if (sm->name[len + 1] == '\0')
 105                         return true;
 106                 if (sm->name[len + 1] == '-' || sm->name[len + 1] == '.')
 107                         return true;
 108         }
 109         return false;
 110 }
 111
 112 static void call_modification_hooks_name_sym(char *name, struct symbol *sym, struct expression *mod_expr, int late)
 113 {
 114         struct sm_state *sm;
 115         struct smatch_state *prev;
 116         int match;
 117
 118         prev = get_state(my_id, name, sym);
 119
 120         if (cur_func_sym && !__in_fake_assign)
 121                 set_state(my_id, name, sym, alloc_my_state(mod_expr, prev));
 122
 123         FOR_EACH_SM(__get_cur_stree(), sm) {
 124                 if (sm->owner > num_checks)
 125                         continue;
 126                 match = matches(name, sym, sm);
 127                 if (!match)
 128                         continue;
 129
 130                 if (late == EARLY || late == BOTH) {
 131                         if (hooks[sm->owner])
 132                                 (hooks[sm->owner])(sm, mod_expr);
 133                 }
 134                 if (late == LATE || late == BOTH) {
 135                         if (hooks_late[sm->owner])
 136                                 (hooks_late[sm->owner])(sm, mod_expr);
 137                 }
 138
 139         } END_FOR_EACH_SM(sm);
 140 }
 141
 142 static void call_modification_hooks(struct expression *expr, struct expression *mod_expr, int late)
 143 {
 144         char *name;
 145         struct symbol *sym;
 146
 147         if (late == LATE)
 148                 update_mtag_data(expr);
 149
 150         name = expr_to_known_chunk_sym(expr, &sym);
 151         if (!name)
 152                 goto free;
 153         call_modification_hooks_name_sym(name, sym, mod_expr, late);
 154 free:
 155         free_string(name);
 156 }
 157
 158 static void db_param_add(struct expression *expr, int param, char *key, char *value)
 159 {
 160         struct expression *arg, *gen_expr;
 161         char *name, *other_name;
 162         struct symbol *sym, *other_sym;
 163
 164         while (expr->type == EXPR_ASSIGNMENT)
 165                 expr = strip_expr(expr->right);
 166         if (expr->type != EXPR_CALL)
 167                 return;
 168
 169         arg = get_argument_from_call_expr(expr->args, param);
 170         if (!arg)
 171                 return;
 172
 173         gen_expr = gen_expression_from_key(arg, key);
 174         if (gen_expr)
 175                 update_mtag_data(gen_expr);
 176
 177         name = get_variable_from_key(arg, key, &sym);
 178         if (!name || !sym)
 179                 goto free;
 180
 181         __in_fake_assign++;
 182         call_modification_hooks_name_sym(name, sym, expr, BOTH);
 183         __in_fake_assign--;
 184
 185         other_name = map_long_to_short_name_sym(name, sym, &other_sym);
 186         if (other_name) {
 187                 __in_fake_assign++;
 188                 call_modification_hooks_name_sym(other_name, other_sym, expr, BOTH);
 189                 __in_fake_assign--;
 190                 free_string(other_name);
 191         }
 192
 193 free:
 194         free_string(name);
 195 }
 196
 197 static void match_assign(struct expression *expr, int late)
 198 {
 199         call_modification_hooks(expr->left, expr, late);
 200 }
 201
 202 static void unop_expr(struct expression *expr, int late)
 203 {
 204         if (expr->op != SPECIAL_DECREMENT && expr->op != SPECIAL_INCREMENT)
 205                 return;
 206
 207         call_modification_hooks(expr->unop, expr, late);
 208 }
 209
 210 static void match_call(struct expression *expr)
 211 {
 212         struct expression *arg, *tmp;
 213
 214         /* If we have the DB then trust the DB */
 215         if (!option_no_db)
 216                 return;
 217
 218         FOR_EACH_PTR(expr->args, arg) {
 219                 tmp = strip_expr(arg);
 220                 if (tmp->type == EXPR_PREOP && tmp->op == '&')
 221                         call_modification_hooks(tmp->unop, expr, BOTH);
 222                 else
 223                         call_modification_hooks(deref_expression(tmp), expr, BOTH);
 224         } END_FOR_EACH_PTR(arg);
 225 }
 226
 227 static void asm_expr(struct statement *stmt, int late)
 228 {
 229         struct expression *expr;
 230         int state = 0;
 231
 232         FOR_EACH_PTR(stmt->asm_outputs, expr) {
 233                 switch (state) {
 234                 case 0: /* identifier */
 235                 case 1: /* constraint */
 236                         state++;
 237                         continue;
 238                 case 2: /* expression */
 239                         state = 0;
 240                         call_modification_hooks(expr, NULL, late);
 241                         continue;
 242                 }
 243         } END_FOR_EACH_PTR(expr);
 244 }
 245
 246
 247 static void match_assign_early(struct expression *expr)
 248 {
 249         match_assign(expr, EARLY);
 250 }
 251
 252 static void unop_expr_early(struct expression *expr)
 253 {
 254         unop_expr(expr, EARLY);
 255 }
 256
 257 static void asm_expr_early(struct statement *stmt)
 258 {
 259         asm_expr(stmt, EARLY);
 260 }
 261
 262 static void match_assign_late(struct expression *expr)
 263 {
 264         match_assign(expr, LATE);
 265 }
 266
 267 static void unop_expr_late(struct expression *expr)
 268 {
 269         unop_expr(expr, LATE);
 270 }
 271
 272 static void asm_expr_late(struct statement *stmt)
 273 {
 274         asm_expr(stmt, LATE);
 275 }
 276
 277 struct smatch_state *get_modification_state(struct expression *expr)
 278 {
 279         return get_state_expr(my_id, expr);
 280 }
 281
 282 void register_modification_hooks(int id)
 283 {
 284         my_id = id;
 285
 286         hooks = malloc((num_checks + 1) * sizeof(*hooks));
 287         memset(hooks, 0, (num_checks + 1) * sizeof(*hooks));
 288         hooks_late = malloc((num_checks + 1) * sizeof(*hooks));
 289         memset(hooks_late, 0, (num_checks + 1) * sizeof(*hooks));
 290
 291         add_hook(&match_assign_early, ASSIGNMENT_HOOK);
 292         add_hook(&unop_expr_early, OP_HOOK);
 293         add_hook(&asm_expr_early, ASM_HOOK);
 294 }
 295
 296 void register_modification_hooks_late(int id)
 297 {
 298         add_hook(&match_call, FUNCTION_CALL_HOOK);
 299
 300         select_return_states_hook(PARAM_ADD, &db_param_add);
 301         select_return_states_hook(PARAM_SET, &db_param_add);
 302
 303         add_hook(&match_assign_late, ASSIGNMENT_HOOK_AFTER);
 304         add_hook(&unop_expr_late, OP_HOOK);
 305         add_hook(&asm_expr_late, ASM_HOOK);
 306 }
 307