smatch_modification_hooks.c

   1 /*
   2  * sparse/smatch_modification_hooks.c
   3  *
   4  * Copyright (C) 2009 Dan Carpenter.
   5  *
   6  * Licensed under the Open Software License version 1.1
   7  *
   8  */
   9
  10 /*
  11  * There are a number of ways that variables are modified:
  12  * 1) assignment
  13  * 2) increment/decrement
  14  * 3) assembly
  15  * 4) inside functions.
  16  *
  17  * For setting stuff inside a function then, of course, it's more accurate if
  18  * you have the cross function database built.  Otherwise we are super
  19  * aggressive about marking things as modified and if you have "frob(foo);" then
  20  * we assume "foo->bar" is modified.
  21  */
  22
  23 #include <stdlib.h>
  24 #include <stdio.h>
  25 #include "smatch.h"
  26 #include "smatch_extra.h"
  27 #include "smatch_slist.h"
  28
  29 enum {
  30         match_none = 0,
  31         match_exact,
  32         match_indirect
  33 };
  34
  35 static modification_hook **hooks;
  36 static modification_hook **indirect_hooks;  /* parent struct modified etc */
  37
  38 void add_modification_hook(int owner, modification_hook *call_back)
  39 {
  40         hooks[owner] = call_back;
  41 }
  42
  43 void add_indirect_modification_hook(int owner, modification_hook *call_back)
  44 {
  45         indirect_hooks[owner] = call_back;
  46 }
  47
  48 static int matches(char *name, struct symbol *sym, struct sm_state *sm)
  49 {
  50         int len;
  51
  52         if (sym != sm->sym)
  53                 return match_none;
  54
  55         len = strlen(name);
  56         if (strncmp(sm->name, name, len) == 0) {
  57                 if (sm->name[len] == '\0')
  58                         return match_exact;
  59                 if (sm->name[len] == '-' || sm->name[len] == '.')
  60                         return match_indirect;
  61         }
  62         if (sm->name[0] != '*')
  63                 return match_none;
  64         if (strncmp(sm->name + 1, name, len) == 0) {
  65                 if (sm->name[len + 1] == '\0')
  66                         return match_indirect;
  67                 if (sm->name[len + 1] == '-' || sm->name[len + 1] == '.')
  68                         return match_indirect;
  69         }
  70         return match_none;
  71 }
  72
  73 static void call_modification_hooks_name_sym(char *name, struct symbol *sym, struct expression *mod_expr)
  74 {
  75         struct state_list *slist;
  76         struct sm_state *sm;
  77         int match;
  78
  79         slist = __get_cur_slist();
  80
  81         FOR_EACH_PTR(slist, sm) {
  82                 if (sm->owner > num_checks)
  83                         continue;
  84                 match = matches(name, sym, sm);
  85
  86                 if (match && hooks[sm->owner])
  87                         (hooks[sm->owner])(sm, mod_expr);
  88
  89                 if (match == match_indirect && indirect_hooks[sm->owner])
  90                         (indirect_hooks[sm->owner])(sm, mod_expr);
  91         } END_FOR_EACH_PTR(sm);
  92 }
  93
  94 static void call_modification_hooks(struct expression *expr, struct expression *mod_expr)
  95 {
  96         char *name;
  97         struct symbol *sym;
  98
  99         name = expr_to_var_sym(expr, &sym);
 100         if (!name || !sym)
 101                 goto free;
 102         call_modification_hooks_name_sym(name, sym, mod_expr);
 103 free:
 104         free_string(name);
 105 }
 106
 107 static void db_param_add(struct expression *expr, int param, char *key, char *value)
 108 {
 109         struct expression *arg;
 110         char *name;
 111         struct symbol *sym;
 112
 113         while (expr->type == EXPR_ASSIGNMENT)
 114                 expr = strip_expr(expr->right);
 115         if (expr->type != EXPR_CALL)
 116                 return;
 117
 118         arg = get_argument_from_call_expr(expr->args, param);
 119         if (!arg)
 120                 return;
 121
 122         name = get_variable_from_key(arg, key, &sym);
 123         if (!name || !sym)
 124                 goto free;
 125
 126         call_modification_hooks_name_sym(name, sym, expr);
 127 free:
 128         free_string(name);
 129 }
 130
 131 static void match_assign(struct expression *expr)
 132 {
 133         call_modification_hooks(expr->left, expr);
 134 }
 135
 136 static void unop_expr(struct expression *expr)
 137 {
 138         if (expr->op != SPECIAL_DECREMENT && expr->op != SPECIAL_INCREMENT)
 139                 return;
 140
 141         call_modification_hooks(expr->unop, expr);
 142 }
 143
 144 static void match_call(struct expression *expr)
 145 {
 146         struct expression *arg, *tmp;
 147
 148         FOR_EACH_PTR(expr->args, arg) {
 149                 tmp = strip_expr(arg);
 150                 if (tmp->type == EXPR_PREOP && tmp->op == '&')
 151                         call_modification_hooks(tmp->unop, expr);
 152                 else if (option_no_db)
 153                         call_modification_hooks(deref_expression(tmp), expr);
 154         } END_FOR_EACH_PTR(arg);
 155 }
 156
 157 static void asm_expr(struct statement *stmt)
 158 {
 159         struct expression *expr;
 160         int state = 0;
 161
 162         FOR_EACH_PTR(stmt->asm_outputs, expr) {
 163                 switch (state) {
 164                 case 0: /* identifier */
 165                 case 1: /* constraint */
 166                         state++;
 167                         continue;
 168                 case 2: /* expression */
 169                         state = 0;
 170                         call_modification_hooks(expr, NULL);
 171                         continue;
 172                 }
 173         } END_FOR_EACH_PTR(expr);
 174 }
 175
 176 void register_modification_hooks(int id)
 177 {
 178         hooks = malloc((num_checks + 1) * sizeof(*hooks));
 179         memset(hooks, 0, (num_checks + 1) * sizeof(*hooks));
 180         indirect_hooks = malloc((num_checks + 1) * sizeof(*hooks));
 181         memset(indirect_hooks, 0, (num_checks + 1) * sizeof(*hooks));
 182
 183         add_hook(&match_assign, ASSIGNMENT_HOOK);
 184         add_hook(&unop_expr, OP_HOOK);
 185         add_hook(&asm_expr, ASM_HOOK);
 186 }
 187
 188 void register_modification_hooks_late(int id)
 189 {
 190         add_hook(&match_call, FUNCTION_CALL_HOOK);
 191         select_return_states_hook(ADDED_VALUE, &db_param_add);
 192 }
 193