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         match_none = 0,
  39         match_exact,
  40         match_indirect
  41 };
  42
  43 enum {
  44         EARLY = 0,
  45         LATE = 1,
  46         BOTH = 2
  47 };
  48
  49 static modification_hook **hooks;
  50 static modification_hook **indirect_hooks;  /* parent struct modified etc */
  51 static modification_hook **hooks_late;
  52 static modification_hook **indirect_hooks_late;  /* parent struct modified etc */
  53
  54 ALLOCATOR(modification_data, "modification data");
  55
  56 static int my_id;
  57 static struct smatch_state *alloc_my_state(struct expression *expr, struct smatch_state *prev)
  58 {
  59         struct smatch_state *state;
  60         struct modification_data *data;
  61         char *name;
  62
  63         state = __alloc_smatch_state(0);
  64         expr = strip_expr(expr);
  65         name = expr_to_str(expr);
  66         state->name = alloc_sname(name);
  67         free_string(name);
  68
  69         data = __alloc_modification_data(0);
  70         data->prev = prev;
  71         data->cur = expr;
  72         state->data = data;
  73
  74         return state;
  75 }
  76
  77 void add_modification_hook(int owner, modification_hook *call_back)
  78 {
  79         hooks[owner] = call_back;
  80 }
  81
  82 void add_indirect_modification_hook(int owner, modification_hook *call_back)
  83 {
  84         indirect_hooks[owner] = call_back;
  85 }
  86
  87 void add_modification_hook_late(int owner, modification_hook *call_back)
  88 {
  89         hooks_late[owner] = call_back;
  90 }
  91
  92 void add_indirect_modification_hook_late(int owner, modification_hook *call_back)
  93 {
  94         indirect_hooks_late[owner] = call_back;
  95 }
  96
  97 static int matches(char *name, struct symbol *sym, struct sm_state *sm)
  98 {
  99         int len;
 100
 101         if (sym != sm->sym)
 102                 return match_none;
 103
 104         len = strlen(name);
 105         if (strncmp(sm->name, name, len) == 0) {
 106                 if (sm->name[len] == '\0')
 107                         return match_exact;
 108                 if (sm->name[len] == '-' || sm->name[len] == '.')
 109                         return match_indirect;
 110         }
 111         if (sm->name[0] != '*')
 112                 return match_none;
 113         if (strncmp(sm->name + 1, name, len) == 0) {
 114                 if (sm->name[len + 1] == '\0')
 115                         return match_indirect;
 116                 if (sm->name[len + 1] == '-' || sm->name[len + 1] == '.')
 117                         return match_indirect;
 118         }
 119         return match_none;
 120 }
 121
 122 static void call_modification_hooks_name_sym(char *name, struct symbol *sym, struct expression *mod_expr, int late)
 123 {
 124         struct sm_state *sm;
 125         struct smatch_state *prev;
 126         int match;
 127
 128         prev = get_state(my_id, name, sym);
 129         set_state(my_id, name, sym, alloc_my_state(mod_expr, prev));
 130
 131         FOR_EACH_SM(__get_cur_stree(), sm) {
 132                 if (sm->owner > num_checks)
 133                         continue;
 134                 match = matches(name, sym, sm);
 135                 if (!match)
 136                         continue;
 137
 138                 if (late == EARLY || late == BOTH) {
 139                         if (hooks[sm->owner])
 140                                 (hooks[sm->owner])(sm, mod_expr);
 141                         if (match == match_indirect && indirect_hooks[sm->owner])
 142                                 (indirect_hooks[sm->owner])(sm, mod_expr);
 143                 }
 144                 if (late == LATE || late == BOTH) {
 145                         if (hooks_late[sm->owner])
 146                                 (hooks_late[sm->owner])(sm, mod_expr);
 147                         if (match == match_indirect && indirect_hooks_late[sm->owner])
 148                                 (indirect_hooks_late[sm->owner])(sm, mod_expr);
 149                 }
 150
 151         } END_FOR_EACH_SM(sm);
 152 }
 153
 154 static void call_modification_hooks(struct expression *expr, struct expression *mod_expr, int late)
 155 {
 156         char *name;
 157         struct symbol *sym;
 158
 159         name = expr_to_known_chunk_sym(expr, &sym);
 160         if (!name)
 161                 goto free;
 162         call_modification_hooks_name_sym(name, sym, mod_expr, late);
 163 free:
 164         free_string(name);
 165 }
 166
 167 static void db_param_add(struct expression *expr, int param, char *key, char *value)
 168 {
 169         struct expression *arg;
 170         char *name;
 171         struct symbol *sym;
 172
 173         while (expr->type == EXPR_ASSIGNMENT)
 174                 expr = strip_expr(expr->right);
 175         if (expr->type != EXPR_CALL)
 176                 return;
 177
 178         arg = get_argument_from_call_expr(expr->args, param);
 179         if (!arg)
 180                 return;
 181
 182         name = get_variable_from_key(arg, key, &sym);
 183         if (!name || !sym)
 184                 goto free;
 185
 186         call_modification_hooks_name_sym(name, sym, expr, BOTH);
 187 free:
 188         free_string(name);
 189 }
 190
 191 static void match_assign(struct expression *expr, int late)
 192 {
 193         call_modification_hooks(expr->left, expr, late);
 194 }
 195
 196 static void unop_expr(struct expression *expr, int late)
 197 {
 198         if (expr->op != SPECIAL_DECREMENT && expr->op != SPECIAL_INCREMENT)
 199                 return;
 200
 201         call_modification_hooks(expr->unop, expr, late);
 202 }
 203
 204 static void match_call(struct expression *expr)
 205 {
 206         struct expression *arg, *tmp;
 207
 208         FOR_EACH_PTR(expr->args, arg) {
 209                 tmp = strip_expr(arg);
 210                 if (tmp->type == EXPR_PREOP && tmp->op == '&')
 211                         call_modification_hooks(tmp->unop, expr, BOTH);
 212                 else if (option_no_db)
 213                         call_modification_hooks(deref_expression(tmp), expr, BOTH);
 214         } END_FOR_EACH_PTR(arg);
 215 }
 216
 217 static void asm_expr(struct statement *stmt, int late)
 218 {
 219         struct expression *expr;
 220         int state = 0;
 221
 222         FOR_EACH_PTR(stmt->asm_outputs, expr) {
 223                 switch (state) {
 224                 case 0: /* identifier */
 225                 case 1: /* constraint */
 226                         state++;
 227                         continue;
 228                 case 2: /* expression */
 229                         state = 0;
 230                         call_modification_hooks(expr, NULL, late);
 231                         continue;
 232                 }
 233         } END_FOR_EACH_PTR(expr);
 234 }
 235
 236
 237 static void match_assign_early(struct expression *expr)
 238 {
 239         match_assign(expr, EARLY);
 240 }
 241
 242 static void unop_expr_early(struct expression *expr)
 243 {
 244         unop_expr(expr, EARLY);
 245 }
 246
 247 static void asm_expr_early(struct statement *stmt)
 248 {
 249         asm_expr(stmt, EARLY);
 250 }
 251
 252 static void match_assign_late(struct expression *expr)
 253 {
 254         match_assign(expr, LATE);
 255 }
 256
 257 static void unop_expr_late(struct expression *expr)
 258 {
 259         unop_expr(expr, LATE);
 260 }
 261
 262 static void asm_expr_late(struct statement *stmt)
 263 {
 264         asm_expr(stmt, LATE);
 265 }
 266
 267 struct smatch_state *get_modification_state(struct expression *expr)
 268 {
 269         return get_state_expr(my_id, expr);
 270 }
 271
 272 void register_modification_hooks(int id)
 273 {
 274         my_id = id;
 275
 276         hooks = malloc((num_checks + 1) * sizeof(*hooks));
 277         memset(hooks, 0, (num_checks + 1) * sizeof(*hooks));
 278         indirect_hooks = malloc((num_checks + 1) * sizeof(*hooks));
 279         memset(indirect_hooks, 0, (num_checks + 1) * sizeof(*hooks));
 280         hooks_late = malloc((num_checks + 1) * sizeof(*hooks));
 281         memset(hooks_late, 0, (num_checks + 1) * sizeof(*hooks));
 282         indirect_hooks_late = malloc((num_checks + 1) * sizeof(*hooks));
 283         memset(indirect_hooks_late, 0, (num_checks + 1) * sizeof(*hooks));
 284
 285         add_hook(&match_assign_early, ASSIGNMENT_HOOK);
 286         add_hook(&unop_expr_early, OP_HOOK);
 287         add_hook(&asm_expr_early, ASM_HOOK);
 288 }
 289
 290 void register_modification_hooks_late(int id)
 291 {
 292         add_hook(&match_call, FUNCTION_CALL_HOOK);
 293
 294         add_hook(&match_assign_late, ASSIGNMENT_HOOK);
 295         add_hook(&unop_expr_late, OP_HOOK);
 296         add_hook(&asm_expr_late, ASM_HOOK);
 297
 298         select_return_states_hook(PARAM_ADD, &db_param_add);
 299         select_return_states_hook(PARAM_SET, &db_param_add);
 300 }
 301