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 static modification_hook **hooks;
  44 static modification_hook **indirect_hooks;  /* parent struct modified etc */
  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_indirect_modification_hook(int owner, modification_hook *call_back)
  75 {
  76         indirect_hooks[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 match_none;
  85
  86         len = strlen(name);
  87         if (strncmp(sm->name, name, len) == 0) {
  88                 if (sm->name[len] == '\0')
  89                         return match_exact;
  90                 if (sm->name[len] == '-' || sm->name[len] == '.')
  91                         return match_indirect;
  92         }
  93         if (sm->name[0] != '*')
  94                 return match_none;
  95         if (strncmp(sm->name + 1, name, len) == 0) {
  96                 if (sm->name[len + 1] == '\0')
  97                         return match_indirect;
  98                 if (sm->name[len + 1] == '-' || sm->name[len + 1] == '.')
  99                         return match_indirect;
 100         }
 101         return match_none;
 102 }
 103
 104 static void call_modification_hooks_name_sym(char *name, struct symbol *sym, struct expression *mod_expr)
 105 {
 106         struct stree *stree;
 107         struct sm_state *sm;
 108         struct smatch_state *prev;
 109         int match;
 110
 111         prev = get_state(my_id, name, sym);
 112         set_state(my_id, name, sym, alloc_my_state(mod_expr, prev));
 113
 114         stree = __get_cur_stree();
 115
 116         FOR_EACH_SM(stree, sm) {
 117                 if (sm->owner > num_checks)
 118                         continue;
 119                 match = matches(name, sym, sm);
 120
 121                 if (match && hooks[sm->owner])
 122                         (hooks[sm->owner])(sm, mod_expr);
 123
 124                 if (match == match_indirect && indirect_hooks[sm->owner])
 125                         (indirect_hooks[sm->owner])(sm, mod_expr);
 126         } END_FOR_EACH_SM(sm);
 127 }
 128
 129 static void call_modification_hooks(struct expression *expr, struct expression *mod_expr)
 130 {
 131         char *name;
 132         struct symbol *sym;
 133
 134         name = expr_to_known_chunk_sym(expr, &sym);
 135         if (!name)
 136                 goto free;
 137         call_modification_hooks_name_sym(name, sym, mod_expr);
 138 free:
 139         free_string(name);
 140 }
 141
 142 static void db_param_add(struct expression *expr, int param, char *key, char *value)
 143 {
 144         struct expression *arg;
 145         char *name;
 146         struct symbol *sym;
 147
 148         while (expr->type == EXPR_ASSIGNMENT)
 149                 expr = strip_expr(expr->right);
 150         if (expr->type != EXPR_CALL)
 151                 return;
 152
 153         arg = get_argument_from_call_expr(expr->args, param);
 154         if (!arg)
 155                 return;
 156
 157         name = get_variable_from_key(arg, key, &sym);
 158         if (!name || !sym)
 159                 goto free;
 160
 161         call_modification_hooks_name_sym(name, sym, expr);
 162 free:
 163         free_string(name);
 164 }
 165
 166 static void match_assign(struct expression *expr)
 167 {
 168         call_modification_hooks(expr->left, expr);
 169 }
 170
 171 static void unop_expr(struct expression *expr)
 172 {
 173         if (expr->op != SPECIAL_DECREMENT && expr->op != SPECIAL_INCREMENT)
 174                 return;
 175
 176         call_modification_hooks(expr->unop, expr);
 177 }
 178
 179 static void match_call(struct expression *expr)
 180 {
 181         struct expression *arg, *tmp;
 182
 183         FOR_EACH_PTR(expr->args, arg) {
 184                 tmp = strip_expr(arg);
 185                 if (tmp->type == EXPR_PREOP && tmp->op == '&')
 186                         call_modification_hooks(tmp->unop, expr);
 187                 else if (option_no_db)
 188                         call_modification_hooks(deref_expression(tmp), expr);
 189         } END_FOR_EACH_PTR(arg);
 190 }
 191
 192 static void asm_expr(struct statement *stmt)
 193 {
 194         struct expression *expr;
 195         int state = 0;
 196
 197         FOR_EACH_PTR(stmt->asm_outputs, expr) {
 198                 switch (state) {
 199                 case 0: /* identifier */
 200                 case 1: /* constraint */
 201                         state++;
 202                         continue;
 203                 case 2: /* expression */
 204                         state = 0;
 205                         call_modification_hooks(expr, NULL);
 206                         continue;
 207                 }
 208         } END_FOR_EACH_PTR(expr);
 209 }
 210
 211 static void scope_end(void *_sym)
 212 {
 213         struct symbol *sym = _sym;
 214         struct expression *expr = symbol_expression(sym);
 215
 216         call_modification_hooks(expr, NULL);
 217 }
 218
 219 static void match_declaration(struct symbol *sym)
 220 {
 221         add_scope_hook(&scope_end, sym);
 222 }
 223
 224 struct smatch_state *get_modification_state(struct expression *expr)
 225 {
 226         return get_state_expr(my_id, expr);
 227 }
 228
 229 void register_modification_hooks(int id)
 230 {
 231         my_id = id;
 232
 233         hooks = malloc((num_checks + 1) * sizeof(*hooks));
 234         memset(hooks, 0, (num_checks + 1) * sizeof(*hooks));
 235         indirect_hooks = malloc((num_checks + 1) * sizeof(*hooks));
 236         memset(indirect_hooks, 0, (num_checks + 1) * sizeof(*hooks));
 237
 238         add_hook(&match_assign, ASSIGNMENT_HOOK);
 239         add_hook(&unop_expr, OP_HOOK);
 240         add_hook(&asm_expr, ASM_HOOK);
 241 }
 242
 243 void register_modification_hooks_late(int id)
 244 {
 245         add_hook(&match_call, FUNCTION_CALL_HOOK);
 246         select_return_states_hook(PARAM_ADD, &db_param_add);
 247         select_return_states_hook(PARAM_SET, &db_param_add);
 248         add_hook(&match_declaration, DECLARATION_HOOK);
 249 }
 250