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 void add_modification_hook(int owner, modification_hook *call_back)
  47 {
  48         hooks[owner] = call_back;
  49 }
  50
  51 void add_indirect_modification_hook(int owner, modification_hook *call_back)
  52 {
  53         indirect_hooks[owner] = call_back;
  54 }
  55
  56 static int matches(char *name, struct symbol *sym, struct sm_state *sm)
  57 {
  58         int len;
  59
  60         if (sym != sm->sym)
  61                 return match_none;
  62
  63         len = strlen(name);
  64         if (strncmp(sm->name, name, len) == 0) {
  65                 if (sm->name[len] == '\0')
  66                         return match_exact;
  67                 if (sm->name[len] == '-' || sm->name[len] == '.')
  68                         return match_indirect;
  69         }
  70         if (sm->name[0] != '*')
  71                 return match_none;
  72         if (strncmp(sm->name + 1, name, len) == 0) {
  73                 if (sm->name[len + 1] == '\0')
  74                         return match_indirect;
  75                 if (sm->name[len + 1] == '-' || sm->name[len + 1] == '.')
  76                         return match_indirect;
  77         }
  78         return match_none;
  79 }
  80
  81 static void call_modification_hooks_name_sym(char *name, struct symbol *sym, struct expression *mod_expr)
  82 {
  83         struct stree *stree;
  84         struct sm_state *sm;
  85         int match;
  86
  87         stree = __get_cur_stree();
  88
  89         FOR_EACH_SM(stree, sm) {
  90                 if (sm->owner > num_checks)
  91                         continue;
  92                 match = matches(name, sym, sm);
  93
  94                 if (match && hooks[sm->owner])
  95                         (hooks[sm->owner])(sm, mod_expr);
  96
  97                 if (match == match_indirect && indirect_hooks[sm->owner])
  98                         (indirect_hooks[sm->owner])(sm, mod_expr);
  99         } END_FOR_EACH_SM(sm);
 100 }
 101
 102 static void call_modification_hooks(struct expression *expr, struct expression *mod_expr)
 103 {
 104         char *name;
 105         struct symbol *sym;
 106
 107         name = expr_to_var_sym(expr, &sym);
 108         if (!name || !sym)
 109                 goto free;
 110         call_modification_hooks_name_sym(name, sym, mod_expr);
 111 free:
 112         free_string(name);
 113 }
 114
 115 static void db_param_add(struct expression *expr, int param, char *key, char *value)
 116 {
 117         struct expression *arg;
 118         char *name;
 119         struct symbol *sym;
 120
 121         while (expr->type == EXPR_ASSIGNMENT)
 122                 expr = strip_expr(expr->right);
 123         if (expr->type != EXPR_CALL)
 124                 return;
 125
 126         arg = get_argument_from_call_expr(expr->args, param);
 127         if (!arg)
 128                 return;
 129
 130         name = get_variable_from_key(arg, key, &sym);
 131         if (!name || !sym)
 132                 goto free;
 133
 134         call_modification_hooks_name_sym(name, sym, expr);
 135 free:
 136         free_string(name);
 137 }
 138
 139 static void match_assign(struct expression *expr)
 140 {
 141         call_modification_hooks(expr->left, expr);
 142 }
 143
 144 static void unop_expr(struct expression *expr)
 145 {
 146         if (expr->op != SPECIAL_DECREMENT && expr->op != SPECIAL_INCREMENT)
 147                 return;
 148
 149         call_modification_hooks(expr->unop, expr);
 150 }
 151
 152 static void match_call(struct expression *expr)
 153 {
 154         struct expression *arg, *tmp;
 155
 156         FOR_EACH_PTR(expr->args, arg) {
 157                 tmp = strip_expr(arg);
 158                 if (tmp->type == EXPR_PREOP && tmp->op == '&')
 159                         call_modification_hooks(tmp->unop, expr);
 160                 else if (option_no_db)
 161                         call_modification_hooks(deref_expression(tmp), expr);
 162         } END_FOR_EACH_PTR(arg);
 163 }
 164
 165 static void asm_expr(struct statement *stmt)
 166 {
 167         struct expression *expr;
 168         int state = 0;
 169
 170         FOR_EACH_PTR(stmt->asm_outputs, expr) {
 171                 switch (state) {
 172                 case 0: /* identifier */
 173                 case 1: /* constraint */
 174                         state++;
 175                         continue;
 176                 case 2: /* expression */
 177                         state = 0;
 178                         call_modification_hooks(expr, NULL);
 179                         continue;
 180                 }
 181         } END_FOR_EACH_PTR(expr);
 182 }
 183
 184 void register_modification_hooks(int id)
 185 {
 186         hooks = malloc((num_checks + 1) * sizeof(*hooks));
 187         memset(hooks, 0, (num_checks + 1) * sizeof(*hooks));
 188         indirect_hooks = malloc((num_checks + 1) * sizeof(*hooks));
 189         memset(indirect_hooks, 0, (num_checks + 1) * sizeof(*hooks));
 190
 191         add_hook(&match_assign, ASSIGNMENT_HOOK);
 192         add_hook(&unop_expr, OP_HOOK);
 193         add_hook(&asm_expr, ASM_HOOK);
 194 }
 195
 196 void register_modification_hooks_late(int id)
 197 {
 198         add_hook(&match_call, FUNCTION_CALL_HOOK);
 199         select_return_states_hook(PARAM_ADD, &db_param_add);
 200         select_return_states_hook(PARAM_SET, &db_param_add);
 201 }
 202