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 sm_hook **hooks;
  44 static sm_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         expr = strip_expr(expr);
  56         name = expr_to_str(expr);
  57         if (!name)
  58                 return NULL;
  59
  60         state = __alloc_smatch_state(0);
  61         state->name = alloc_sname(name);
  62         free_string(name);
  63
  64         data = __alloc_modification_data(0);
  65         data->prev = prev;
  66         data->cur = expr;
  67         state->data = data;
  68
  69         return state;
  70 }
  71
  72 void add_modification_hook(int owner, sm_hook *call_back)
  73 {
  74         if (hooks[owner])
  75                 sm_fatal("multiple modification hooks for %s", check_name(owner));
  76         hooks[owner] = call_back;
  77 }
  78
  79 void add_modification_hook_late(int owner, sm_hook *call_back)
  80 {
  81         if (hooks_late[owner])
  82                 sm_fatal("multiple late modification hooks for %s", check_name(owner));
  83         hooks_late[owner] = call_back;
  84 }
  85
  86 static int shared_cnt(const char *one, const char *two)
  87 {
  88         int c = 0;
  89
  90         while (one[c] && two[c] && one[c] == two[c])
  91                 c++;
  92         return c;
  93 }
  94
  95 bool is_sub_member(const char *name, struct symbol *sym, struct sm_state *sm)
  96 {
  97         const char *sm_name;
  98         int len;
  99
 100         if (sym != sm->sym)
 101                 return false;
 102
 103         sm_name = sm->name;
 104         if (sm_name[0] == '&')
 105                 sm_name++;
 106
 107         len = shared_cnt(sm_name, name);
 108         if (name[len] == '\0') {
 109                 if (sm_name[len] == '\0')
 110                         return true;
 111                 if (sm_name[len] == '-' || sm_name[len] == '.')
 112                         return true;
 113         }
 114         if (sm_name[0] != '*')
 115                 return false;
 116         if (strncmp(sm_name + 1, name, len) == 0) {
 117                 if (sm_name[len + 1] == '\0')
 118                         return true;
 119                 if (sm_name[len + 1] == '-' || sm_name[len + 1] == '.')
 120                         return true;
 121         }
 122         return false;
 123 }
 124
 125 static void call_modification_hooks_name_sym(char *name, struct symbol *sym, struct expression *mod_expr, int late)
 126 {
 127         struct sm_state *sm;
 128         struct smatch_state *prev;
 129         int match;
 130
 131         prev = get_state(my_id, name, sym);
 132
 133         if (cur_func_sym && !__in_fake_assign)
 134                 set_state(my_id, name, sym, alloc_my_state(mod_expr, prev));
 135
 136         FOR_EACH_SM_SAFE(__get_cur_stree(), sm) {
 137                 if (sm->owner > num_checks)
 138                         continue;
 139                 if (!hooks[sm->owner] && !hooks_late[sm->owner])
 140                         continue;
 141                 match = is_sub_member(name, sym, sm);
 142                 if (!match)
 143                         continue;
 144
 145                 if (late == EARLY || late == BOTH) {
 146                         if (hooks[sm->owner])
 147                                 (hooks[sm->owner])(sm, mod_expr);
 148                 }
 149                 if (late == LATE || late == BOTH) {
 150                         if (hooks_late[sm->owner])
 151                                 (hooks_late[sm->owner])(sm, mod_expr);
 152                 }
 153         } END_FOR_EACH_SM_SAFE(sm);
 154 }
 155
 156 static void call_modification_hooks(struct expression *expr, struct expression *mod_expr, int late)
 157 {
 158         char *name;
 159         struct symbol *sym;
 160
 161         name = expr_to_known_chunk_sym(expr, &sym);
 162         if (!name)
 163                 goto free;
 164         call_modification_hooks_name_sym(name, sym, mod_expr, late);
 165 free:
 166         free_string(name);
 167 }
 168
 169 static void db_param_add(struct expression *expr, int param, char *key, char *value)
 170 {
 171         struct expression *arg;
 172         char *name, *other_name;
 173         struct symbol *sym, *other_sym;
 174
 175         while (expr->type == EXPR_ASSIGNMENT)
 176                 expr = strip_expr(expr->right);
 177         if (expr->type != EXPR_CALL)
 178                 return;
 179
 180         arg = get_argument_from_call_expr(expr->args, param);
 181         if (!arg)
 182                 return;
 183
 184         name = get_variable_from_key(arg, key, &sym);
 185         if (!name || !sym)
 186                 goto free;
 187
 188         __in_fake_assign++;
 189         call_modification_hooks_name_sym(name, sym, expr, BOTH);
 190         __in_fake_assign--;
 191
 192         other_name = get_other_name_sym(name, sym, &other_sym);
 193         if (other_name) {
 194                 __in_fake_assign++;
 195                 call_modification_hooks_name_sym(other_name, other_sym, expr, BOTH);
 196                 __in_fake_assign--;
 197                 free_string(other_name);
 198         }
 199
 200 free:
 201         free_string(name);
 202 }
 203
 204 static void match_assign(struct expression *expr, int late)
 205 {
 206         if (__in_fake_parameter_assign)
 207                 return;
 208         if (expr->left->smatch_flags & Fake)
 209                 return;
 210         call_modification_hooks(expr->left, expr, late);
 211 }
 212
 213 static void unop_expr(struct expression *expr, int late)
 214 {
 215         if (expr->op != SPECIAL_DECREMENT && expr->op != SPECIAL_INCREMENT)
 216                 return;
 217
 218         call_modification_hooks(expr->unop, expr, late);
 219 }
 220
 221 static void match_call(struct expression *expr)
 222 {
 223         struct expression *arg, *tmp;
 224
 225         /* If we have the DB then trust the DB */
 226         if (!option_no_db)
 227                 return;
 228
 229         FOR_EACH_PTR(expr->args, arg) {
 230                 tmp = strip_expr(arg);
 231                 if (tmp->type == EXPR_PREOP && tmp->op == '&')
 232                         call_modification_hooks(tmp->unop, expr, BOTH);
 233                 else
 234                         call_modification_hooks(deref_expression(tmp), expr, BOTH);
 235         } END_FOR_EACH_PTR(arg);
 236 }
 237
 238 static void asm_expr(struct statement *stmt, int late)
 239 {
 240         struct asm_operand *op;
 241
 242         FOR_EACH_PTR(stmt->asm_outputs, op) {
 243                 call_modification_hooks(op->expr, NULL, late);
 244         } END_FOR_EACH_PTR(op);
 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 allocate_modification_hooks(void)
 283 {
 284         hooks = malloc(num_checks * sizeof(*hooks));
 285         memset(hooks, 0, num_checks * sizeof(*hooks));
 286         hooks_late = malloc(num_checks * sizeof(*hooks));
 287         memset(hooks_late, 0, num_checks * sizeof(*hooks));
 288 }
 289
 290 void register_modification_hooks(int id)
 291 {
 292         my_id = id;
 293
 294         set_dynamic_states(my_id);
 295
 296         add_hook(&match_assign_early, ASSIGNMENT_HOOK);
 297         add_hook(&unop_expr_early, OP_HOOK);
 298         add_hook(&asm_expr_early, ASM_HOOK);
 299 }
 300
 301 void register_modification_hooks_late(int id)
 302 {
 303         add_hook(&match_call, FUNCTION_CALL_HOOK);
 304
 305         select_return_states_hook(PARAM_ADD, &db_param_add);
 306         select_return_states_hook(PARAM_SET, &db_param_add);
 307
 308         add_hook(&match_assign_late, ASSIGNMENT_HOOK_AFTER);
 309         add_hook(&unop_expr_late, OP_HOOK);
 310         add_hook(&asm_expr_late, ASM_HOOK);
 311 }
 312