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         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, modification_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, modification_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 static int matches(char *name, struct symbol *sym, struct sm_state *sm)
  96 {
  97         int len;
  98
  99         if (sym != sm->sym)
 100                 return false;
 101
 102         len = shared_cnt(sm->name, name);
 103         if (name[len] == '\0') {
 104                 if (sm->name[len] == '\0')
 105                         return true;
 106                 if (sm->name[len] == '-' || sm->name[len] == '.')
 107                         return true;
 108         }
 109         if (sm->name[0] != '*')
 110                 return false;
 111         if (strncmp(sm->name + 1, name, len) == 0) {
 112                 if (sm->name[len + 1] == '\0')
 113                         return true;
 114                 if (sm->name[len + 1] == '-' || sm->name[len + 1] == '.')
 115                         return true;
 116         }
 117         return false;
 118 }
 119
 120 static void call_modification_hooks_name_sym(char *name, struct symbol *sym, struct expression *mod_expr, int late)
 121 {
 122         struct sm_state *sm;
 123         struct smatch_state *prev;
 124         int match;
 125
 126         prev = get_state(my_id, name, sym);
 127
 128         if (cur_func_sym && !__in_fake_assign)
 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                 if (!hooks[sm->owner] && !hooks_late[sm->owner])
 135                         continue;
 136                 match = matches(name, sym, sm);
 137                 if (!match)
 138                         continue;
 139
 140                 if (late == EARLY || late == BOTH) {
 141                         if (hooks[sm->owner])
 142                                 (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                 }
 148
 149         } END_FOR_EACH_SM(sm);
 150 }
 151
 152 static void call_modification_hooks(struct expression *expr, struct expression *mod_expr, int late)
 153 {
 154         char *name;
 155         struct symbol *sym;
 156
 157         name = expr_to_known_chunk_sym(expr, &sym);
 158         if (!name)
 159                 goto free;
 160         call_modification_hooks_name_sym(name, sym, mod_expr, late);
 161 free:
 162         free_string(name);
 163 }
 164
 165 static void db_param_add(struct expression *expr, int param, char *key, char *value)
 166 {
 167         struct expression *arg;
 168         char *name, *other_name;
 169         struct symbol *sym, *other_sym;
 170
 171         while (expr->type == EXPR_ASSIGNMENT)
 172                 expr = strip_expr(expr->right);
 173         if (expr->type != EXPR_CALL)
 174                 return;
 175
 176         arg = get_argument_from_call_expr(expr->args, param);
 177         if (!arg)
 178                 return;
 179
 180         name = get_variable_from_key(arg, key, &sym);
 181         if (!name || !sym)
 182                 goto free;
 183
 184         __in_fake_assign++;
 185         call_modification_hooks_name_sym(name, sym, expr, BOTH);
 186         __in_fake_assign--;
 187
 188         other_name = get_other_name_sym(name, sym, &other_sym);
 189         if (other_name) {
 190                 __in_fake_assign++;
 191                 call_modification_hooks_name_sym(other_name, other_sym, expr, BOTH);
 192                 __in_fake_assign--;
 193                 free_string(other_name);
 194         }
 195
 196 free:
 197         free_string(name);
 198 }
 199
 200 static void match_assign(struct expression *expr, int late)
 201 {
 202         if (expr->left->smatch_flags & Fake)
 203                 return;
 204         call_modification_hooks(expr->left, expr, late);
 205 }
 206
 207 static void unop_expr(struct expression *expr, int late)
 208 {
 209         if (expr->op != SPECIAL_DECREMENT && expr->op != SPECIAL_INCREMENT)
 210                 return;
 211
 212         call_modification_hooks(expr->unop, expr, late);
 213 }
 214
 215 static void match_call(struct expression *expr)
 216 {
 217         struct expression *arg, *tmp;
 218
 219         /* If we have the DB then trust the DB */
 220         if (!option_no_db)
 221                 return;
 222
 223         FOR_EACH_PTR(expr->args, arg) {
 224                 tmp = strip_expr(arg);
 225                 if (tmp->type == EXPR_PREOP && tmp->op == '&')
 226                         call_modification_hooks(tmp->unop, expr, BOTH);
 227                 else
 228                         call_modification_hooks(deref_expression(tmp), expr, BOTH);
 229         } END_FOR_EACH_PTR(arg);
 230 }
 231
 232 static void asm_expr(struct statement *stmt, int late)
 233 {
 234         struct asm_operand *op;
 235
 236         FOR_EACH_PTR(stmt->asm_outputs, op) {
 237                 call_modification_hooks(op->expr, NULL, late);
 238         } END_FOR_EACH_PTR(op);
 239 }
 240
 241 static void match_assign_early(struct expression *expr)
 242 {
 243         match_assign(expr, EARLY);
 244 }
 245
 246 static void unop_expr_early(struct expression *expr)
 247 {
 248         unop_expr(expr, EARLY);
 249 }
 250
 251 static void asm_expr_early(struct statement *stmt)
 252 {
 253         asm_expr(stmt, EARLY);
 254 }
 255
 256 static void match_assign_late(struct expression *expr)
 257 {
 258         match_assign(expr, LATE);
 259 }
 260
 261 static void unop_expr_late(struct expression *expr)
 262 {
 263         unop_expr(expr, LATE);
 264 }
 265
 266 static void asm_expr_late(struct statement *stmt)
 267 {
 268         asm_expr(stmt, LATE);
 269 }
 270
 271 struct smatch_state *get_modification_state(struct expression *expr)
 272 {
 273         return get_state_expr(my_id, expr);
 274 }
 275
 276 void register_modification_hooks(int id)
 277 {
 278         my_id = id;
 279
 280         set_dynamic_states(my_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