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 expression *expr, struct smatch_state *state)
  48 {
  49         if (get_param_num_from_sym(sym) < 0)
  50                 return;
  51         set_state(my_id, name, sym, state);
  52 }
  53
  54 /*
  55  * This function is is a dirty hack because extra_mod_hook is giving us a NULL
  56  *  sym instead of a vsl.
  57  */
  58 static void match_array_assignment(struct expression *expr)
  59 {
  60         struct expression *array, *offset;
  61         char *name;
  62         struct symbol *sym;
  63         struct range_list *rl;
  64         sval_t sval;
  65         char buf[256];
  66
  67         if (__in_fake_assign)
  68                 return;
  69
  70         if (!is_array(expr->left))
  71                 return;
  72         array = get_array_base(expr->left);
  73         offset = get_array_offset(expr->left);
  74
  75         /* These are handled by extra_mod_hook() */
  76         if (get_value(offset, &sval))
  77                 return;
  78         name = expr_to_var_sym(array, &sym);
  79         if (!name || !sym)
  80                 goto free;
  81         if (get_param_num_from_sym(sym) < 0)
  82                 goto free;
  83         get_absolute_rl(expr->right, &rl);
  84         rl = cast_rl(get_type(expr->left), rl);
  85
  86         snprintf(buf, sizeof(buf), "*%s", name);
  87         set_state(my_id, buf, sym, alloc_estate_rl(rl));
  88 free:
  89         free_string(name);
  90 }
  91
  92 /*
  93  * This relies on the fact that these states are stored so that
  94  * foo->bar is before foo->bar->baz.
  95  */
  96 static int parent_set(struct string_list *list, const char *name)
  97 {
  98         char *tmp;
  99         int len;
 100         int ret;
 101
 102         FOR_EACH_PTR(list, tmp) {
 103                 len = strlen(tmp);
 104                 ret = strncmp(tmp, name, len);
 105                 if (ret < 0)
 106                         continue;
 107                 if (ret > 0)
 108                         return 0;
 109                 if (name[len] == '-')
 110                         return 1;
 111         } END_FOR_EACH_PTR(tmp);
 112
 113         return 0;
 114 }
 115
 116 static void print_return_value_param(int return_id, char *return_ranges, struct expression *expr)
 117 {
 118         struct sm_state *sm;
 119         struct smatch_state *extra;
 120         int param;
 121         struct range_list *rl;
 122         const char *param_name;
 123         struct string_list *set_list = NULL;
 124         char *math_str;
 125         char buf[256];
 126         sval_t sval;
 127
 128         FOR_EACH_MY_SM(my_id, __get_cur_stree(), sm) {
 129                 if (!estate_rl(sm->state))
 130                         continue;
 131                 extra = get_state(SMATCH_EXTRA, sm->name, sm->sym);
 132                 if (extra) {
 133                         rl = rl_intersection(estate_rl(sm->state), estate_rl(extra));
 134                         if (!rl)
 135                                 continue;
 136                 } else {
 137                         rl = estate_rl(sm->state);
 138                 }
 139
 140                 param = get_param_num_from_sym(sm->sym);
 141                 if (param < 0)
 142                         continue;
 143                 param_name = get_param_name(sm);
 144                 if (!param_name)
 145                         continue;
 146                 if (strcmp(param_name, "$") == 0)
 147                         continue;
 148
 149                 if (rl_to_sval(rl, &sval)) {
 150                         insert_string(&set_list, (char *)sm->name);
 151                         sql_insert_return_states(return_id, return_ranges,
 152                                         param_has_filter_data(sm) ? PARAM_ADD : PARAM_SET,
 153                                         param, param_name, show_rl(rl));
 154                         continue;
 155                 }
 156
 157                 math_str = get_value_in_terms_of_parameter_math_var_sym(sm->name, sm->sym);
 158                 if (math_str) {
 159                         snprintf(buf, sizeof(buf), "%s[%s]", show_rl(rl), math_str);
 160                         insert_string(&set_list, (char *)sm->name);
 161                         sql_insert_return_states(return_id, return_ranges,
 162                                         param_has_filter_data(sm) ? PARAM_ADD : PARAM_SET,
 163                                         param, param_name, buf);
 164                         continue;
 165                 }
 166
 167                 /* no useful information here. */
 168                 if (is_whole_rl(rl) && parent_set(set_list, sm->name))
 169                         continue;
 170                 insert_string(&set_list, (char *)sm->name);
 171
 172                 sql_insert_return_states(return_id, return_ranges,
 173                                          param_has_filter_data(sm) ? PARAM_ADD : PARAM_SET,
 174                                          param, param_name, show_rl(rl));
 175
 176         } END_FOR_EACH_SM(sm);
 177
 178         free_ptr_list((struct ptr_list **)&set_list);
 179 }
 180
 181 int param_was_set_var_sym(const char *name, struct symbol *sym)
 182 {
 183         struct sm_state *sm;
 184         int len;
 185
 186         FOR_EACH_MY_SM(my_id, __get_cur_stree(), sm) {
 187                 if (sm->sym != sym)
 188                         continue;
 189                 len = strlen(sm->name);
 190                 if (strncmp(sm->name, name, len) != 0)
 191                         continue;
 192                 if (name[len] == '\0' ||
 193                     name[len] == '-')
 194                         return 1;
 195         } END_FOR_EACH_SM(sm);
 196
 197         return 0;
 198 }
 199
 200 int param_was_set(struct expression *expr)
 201 {
 202         char *name;
 203         struct symbol *sym;
 204         int ret = 0;
 205
 206         name = expr_to_var_sym(expr, &sym);
 207         if (!name || !sym)
 208                 goto free;
 209
 210         ret = param_was_set_var_sym(name, sym);
 211 free:
 212         free_string(name);
 213         return ret;
 214 }
 215
 216 void register_param_set(int id)
 217 {
 218         my_id = id;
 219
 220         add_extra_mod_hook(&extra_mod_hook);
 221         add_hook(match_array_assignment, ASSIGNMENT_HOOK);
 222         add_unmatched_state_hook(my_id, &unmatched_state);
 223         add_merge_hook(my_id, &merge_estates);
 224         add_split_return_callback(&print_return_value_param);
 225 }
 226