smatch_param_set.c

   1 /*
   2  * Copyright (C) 2012 Oracle.
   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  * This is for functions like:
  20  *
  21  * int foo(int *x)
  22  * {
  23  *      if (*x == 42) {
  24  *              *x = 0;
  25  *              return 1;
  26  *      }
  27  *      return 0;
  28  * }
  29  *
  30  * If we return 1 that means the value of *x has been set to 0.  If we return
  31  * 0 then we have left *x alone.
  32  *
  33  */
  34
  35 #include "scope.h"
  36 #include "smatch.h"
  37 #include "smatch_slist.h"
  38 #include "smatch_extra.h"
  39
  40 static int my_id;
  41
  42 static struct smatch_state *unmatched_state(struct sm_state *sm)
  43 {
  44         return alloc_estate_empty();
  45 }
  46
  47 static void extra_mod_hook(const char *name, struct symbol *sym, struct smatch_state *state)
  48 {
  49         if (__in_fake_assign)
  50                 return;
  51         if (get_param_num_from_sym(sym) < 0)
  52                 return;
  53         set_state(my_id, name, sym, state);
  54 }
  55
  56 /*
  57  * This function is is a dirty hack because extra_mod_hook is giving us a NULL
  58  *  sym instead of a vsl.
  59  */
  60 static void match_array_assignment(struct expression *expr)
  61 {
  62         struct expression *array, *offset;
  63         char *name;
  64         struct symbol *sym;
  65         struct range_list *rl;
  66         sval_t sval;
  67         char buf[256];
  68
  69         if (__in_fake_assign)
  70                 return;
  71
  72         if (!is_array(expr->left))
  73                 return;
  74         array = get_array_base(expr->left);
  75         offset = get_array_offset(expr->left);
  76
  77         /* These are handled by extra_mod_hook() */
  78         if (get_value(offset, &sval))
  79                 return;
  80         name = expr_to_var_sym(array, &sym);
  81         if (!name || !sym)
  82                 goto free;
  83         if (get_param_num_from_sym(sym) < 0)
  84                 goto free;
  85         get_absolute_rl(expr->right, &rl);
  86         rl = cast_rl(get_type(expr->left), rl);
  87
  88         snprintf(buf, sizeof(buf), "*%s", name);
  89         set_state(my_id, buf, sym, alloc_estate_rl(rl));
  90 free:
  91         free_string(name);
  92 }
  93
  94 /*
  95  * This relies on the fact that these states are stored so that
  96  * foo->bar is before foo->bar->baz.
  97  */
  98 static int parent_set(struct string_list *list, const char *name)
  99 {
 100         char *tmp;
 101         int len;
 102         int ret;
 103
 104         FOR_EACH_PTR(list, tmp) {
 105                 len = strlen(tmp);
 106                 ret = strncmp(tmp, name, len);
 107                 if (ret < 0)
 108                         continue;
 109                 if (ret > 0)
 110                         return 0;
 111                 if (name[len] == '-')
 112                         return 1;
 113         } END_FOR_EACH_PTR(tmp);
 114
 115         return 0;
 116 }
 117
 118 static void print_return_value_param(int return_id, char *return_ranges, struct expression *expr)
 119 {
 120         struct stree *stree;
 121         struct sm_state *sm;
 122         struct smatch_state *extra;
 123         int param;
 124         struct range_list *rl;
 125         const char *param_name;
 126         struct string_list *set_list = NULL;
 127         char *math_str;
 128         char buf[256];
 129         sval_t sval;
 130
 131         stree = __get_cur_stree();
 132
 133         FOR_EACH_MY_SM(my_id, stree, sm) {
 134                 if (!estate_rl(sm->state))
 135                         continue;
 136                 extra = get_state(SMATCH_EXTRA, sm->name, sm->sym);
 137                 if (extra) {
 138                         rl = rl_intersection(estate_rl(sm->state), estate_rl(extra));
 139                         if (!rl)
 140                                 continue;
 141                 } else {
 142                         rl = estate_rl(sm->state);
 143                 }
 144
 145                 param = get_param_num_from_sym(sm->sym);
 146                 if (param < 0)
 147                         continue;
 148                 param_name = get_param_name(sm);
 149                 if (!param_name)
 150                         continue;
 151                 if (strcmp(param_name, "$") == 0)
 152                         continue;
 153
 154                 if (rl_to_sval(rl, &sval)) {
 155                         insert_string(&set_list, (char *)sm->name);
 156                         sql_insert_return_states(return_id, return_ranges,
 157                                         param_has_filter_data(sm) ? PARAM_ADD : PARAM_SET,
 158                                         param, param_name, show_rl(rl));
 159                         continue;
 160                 }
 161
 162                 math_str = get_value_in_terms_of_parameter_math_var_sym(sm->name, sm->sym);
 163                 if (math_str) {
 164                         snprintf(buf, sizeof(buf), "%s[%s]", show_rl(rl), math_str);
 165                         insert_string(&set_list, (char *)sm->name);
 166                         sql_insert_return_states(return_id, return_ranges,
 167                                         param_has_filter_data(sm) ? PARAM_ADD : PARAM_SET,
 168                                         param, param_name, buf);
 169                         continue;
 170                 }
 171
 172                 /* no useful information here. */
 173                 if (is_whole_rl(rl) && parent_set(set_list, sm->name))
 174                         continue;
 175                 insert_string(&set_list, (char *)sm->name);
 176
 177                 sql_insert_return_states(return_id, return_ranges,
 178                                          param_has_filter_data(sm) ? PARAM_ADD : PARAM_SET,
 179                                          param, param_name, show_rl(rl));
 180
 181         } END_FOR_EACH_SM(sm);
 182
 183         free_ptr_list((struct ptr_list **)&set_list);
 184 }
 185
 186 int param_was_set(struct expression *expr)
 187 {
 188         if (get_state_expr(my_id, expr))
 189                 return 1;
 190         return 0;
 191 }
 192
 193 void register_param_set(int id)
 194 {
 195         my_id = id;
 196
 197         add_extra_mod_hook(&extra_mod_hook);
 198         add_hook(match_array_assignment, ASSIGNMENT_HOOK);
 199         add_unmatched_state_hook(my_id, &unmatched_state);
 200         add_merge_hook(my_id, &merge_estates);
 201         add_split_return_callback(&print_return_value_param);
 202 }
 203