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         hooks[owner] = call_back;
  72 }
  73
  74 void add_modification_hook_late(int owner, modification_hook *call_back)
  75 {
  76         hooks_late[owner] = call_back;
  77 }
  78
  79 static int matches(char *name, struct symbol *sym, struct sm_state *sm)
  80 {
  81         int len;
  82
  83         if (sym != sm->sym)
  84                 return false;
  85
  86         len = strlen(name);
  87         if (strncmp(sm->name, name, len) == 0) {
  88                 if (sm->name[len] == '\0')
  89                         return true;
  90                 if (sm->name[len] == '-' || sm->name[len] == '.')
  91                         return true;
  92         }
  93         if (sm->name[0] != '*')
  94                 return false;
  95         if (strncmp(sm->name + 1, name, len) == 0) {
  96                 if (sm->name[len + 1] == '\0')
  97                         return true;
  98                 if (sm->name[len + 1] == '-' || sm->name[len + 1] == '.')
  99                         return true;
 100         }
 101         return false;
 102 }
 103
 104 static void call_modification_hooks_name_sym(char *name, struct symbol *sym, struct expression *mod_expr, int late)
 105 {
 106         struct sm_state *sm;
 107         struct smatch_state *prev;
 108         int match;
 109
 110         prev = get_state(my_id, name, sym);
 111
 112         if (cur_func_sym && !__in_fake_assign)
 113                 set_state(my_id, name, sym, alloc_my_state(mod_expr, prev));
 114
 115         FOR_EACH_SM(__get_cur_stree(), sm) {
 116                 if (sm->owner > num_checks)
 117                         continue;
 118                 match = matches(name, sym, sm);
 119                 if (!match)
 120                         continue;
 121
 122                 if (late == EARLY || late == BOTH) {
 123                         if (hooks[sm->owner])
 124                                 (hooks[sm->owner])(sm, mod_expr);
 125                 }
 126                 if (late == LATE || late == BOTH) {
 127                         if (hooks_late[sm->owner])
 128                                 (hooks_late[sm->owner])(sm, mod_expr);
 129                 }
 130
 131         } END_FOR_EACH_SM(sm);
 132 }
 133
 134 static void call_modification_hooks(struct expression *expr, struct expression *mod_expr, int late)
 135 {
 136         char *name;
 137         struct symbol *sym;
 138
 139         if (late == LATE)
 140                 update_mtag_data(expr);
 141
 142         name = expr_to_known_chunk_sym(expr, &sym);
 143         if (!name)
 144                 goto free;
 145         call_modification_hooks_name_sym(name, sym, mod_expr, late);
 146 free:
 147         free_string(name);
 148 }
 149
 150 static void db_param_add(struct expression *expr, int param, char *key, char *value)
 151 {
 152         struct expression *arg, *gen_expr;
 153         char *name, *other_name;
 154         struct symbol *sym, *other_sym;
 155
 156         while (expr->type == EXPR_ASSIGNMENT)
 157                 expr = strip_expr(expr->right);
 158         if (expr->type != EXPR_CALL)
 159                 return;
 160
 161         arg = get_argument_from_call_expr(expr->args, param);
 162         if (!arg)
 163                 return;
 164
 165         gen_expr = gen_expression_from_key(arg, key);
 166         if (gen_expr)
 167                 update_mtag_data(gen_expr);
 168
 169         name = get_variable_from_key(arg, key, &sym);
 170         if (!name || !sym)
 171                 goto free;
 172
 173         __in_fake_assign++;
 174         call_modification_hooks_name_sym(name, sym, expr, BOTH);
 175         __in_fake_assign--;
 176
 177         other_name = map_long_to_short_name_sym(name, sym, &other_sym);
 178         if (other_name) {
 179                 __in_fake_assign++;
 180                 call_modification_hooks_name_sym(other_name, other_sym, expr, BOTH);
 181                 __in_fake_assign--;
 182                 free_string(other_name);
 183         }
 184
 185 free:
 186         free_string(name);
 187 }
 188
 189 static void match_assign(struct expression *expr, int late)
 190 {
 191         call_modification_hooks(expr->left, expr, late);
 192 }
 193
 194 static void unop_expr(struct expression *expr, int late)
 195 {
 196         if (expr->op != SPECIAL_DECREMENT && expr->op != SPECIAL_INCREMENT)
 197                 return;
 198
 199         call_modification_hooks(expr->unop, expr, late);
 200 }
 201
 202 static void match_call(struct expression *expr)
 203 {
 204         struct expression *arg, *tmp;
 205
 206         FOR_EACH_PTR(expr->args, arg) {
 207                 tmp = strip_expr(arg);
 208                 if (tmp->type == EXPR_PREOP && tmp->op == '&')
 209                         call_modification_hooks(tmp->unop, expr, BOTH);
 210                 else if (option_no_db)
 211                         call_modification_hooks(deref_expression(tmp), expr, BOTH);
 212         } END_FOR_EACH_PTR(arg);
 213 }
 214
 215 static void asm_expr(struct statement *stmt, int late)
 216 {
 217         struct expression *expr;
 218         int state = 0;
 219
 220         FOR_EACH_PTR(stmt->asm_outputs, expr) {
 221                 switch (state) {
 222                 case 0: /* identifier */
 223                 case 1: /* constraint */
 224                         state++;
 225                         continue;
 226                 case 2: /* expression */
 227                         state = 0;
 228                         call_modification_hooks(expr, NULL, late);
 229                         continue;
 230                 }
 231         } END_FOR_EACH_PTR(expr);
 232 }
 233
 234
 235 static void match_assign_early(struct expression *expr)
 236 {
 237         match_assign(expr, EARLY);
 238 }
 239
 240 static void unop_expr_early(struct expression *expr)
 241 {
 242         unop_expr(expr, EARLY);
 243 }
 244
 245 static void asm_expr_early(struct statement *stmt)
 246 {
 247         asm_expr(stmt, EARLY);
 248 }
 249
 250 static void match_assign_late(struct expression *expr)
 251 {
 252         match_assign(expr, LATE);
 253 }
 254
 255 static void unop_expr_late(struct expression *expr)
 256 {
 257         unop_expr(expr, LATE);
 258 }
 259
 260 static void asm_expr_late(struct statement *stmt)
 261 {
 262         asm_expr(stmt, LATE);
 263 }
 264
 265 struct smatch_state *get_modification_state(struct expression *expr)
 266 {
 267         return get_state_expr(my_id, expr);
 268 }
 269
 270 void register_modification_hooks(int id)
 271 {
 272         my_id = id;
 273
 274         hooks = malloc((num_checks + 1) * sizeof(*hooks));
 275         memset(hooks, 0, (num_checks + 1) * sizeof(*hooks));
 276         hooks_late = malloc((num_checks + 1) * sizeof(*hooks));
 277         memset(hooks_late, 0, (num_checks + 1) * sizeof(*hooks));
 278
 279         add_hook(&match_assign_early, ASSIGNMENT_HOOK);
 280         add_hook(&unop_expr_early, OP_HOOK);
 281         add_hook(&asm_expr_early, ASM_HOOK);
 282 }
 283
 284 void register_modification_hooks_late(int id)
 285 {
 286         add_hook(&match_call, FUNCTION_CALL_HOOK);
 287
 288         select_return_states_hook(PARAM_ADD, &db_param_add);
 289         select_return_states_hook(PARAM_SET, &db_param_add);
 290
 291         add_hook(&match_assign_late, ASSIGNMENT_HOOK_AFTER);
 292         add_hook(&unop_expr_late, OP_HOOK);
 293         add_hook(&asm_expr_late, ASM_HOOK);
 294 }
 295