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 int parent_is_set(const char *name, struct symbol *sym, struct smatch_state *state)
  48 {
  49         struct expression *faked;
  50         char *left_name;
  51         int ret = 0;
  52         int len;
  53
  54         if (!__in_fake_assign)
  55                 return 0;
  56         if (!is_whole_rl(estate_rl(state)))
  57                 return 0;
  58         if (get_state(my_id, name, sym))
  59                 return 0;
  60
  61         faked = get_faked_expression();
  62         if (!faked || faked->type != EXPR_ASSIGNMENT)
  63                 return 0;
  64
  65         left_name = expr_to_var(faked->left);
  66         if (!left_name)
  67                 return 0;
  68
  69         len = strlen(left_name);
  70         if (strncmp(name, left_name, len) == 0 && name[len] == '-')
  71                 ret = 1;
  72         free_string(left_name);
  73
  74         return ret;
  75 }
  76
  77 static void extra_mod_hook(const char *name, struct symbol *sym, struct expression *expr, struct smatch_state *state)
  78 {
  79         if (parent_is_set(name, sym, state))
  80                 return;
  81         if (get_param_num_from_sym(sym) < 0)
  82                 return;
  83         set_state(my_id, name, sym, state);
  84 }
  85
  86 /*
  87  * This function is is a dirty hack because extra_mod_hook is giving us a NULL
  88  *  sym instead of a vsl.
  89  */
  90 static void match_array_assignment(struct expression *expr)
  91 {
  92         struct expression *array, *offset;
  93         char *name;
  94         struct symbol *sym;
  95         struct range_list *rl;
  96         sval_t sval;
  97         char buf[256];
  98
  99         if (__in_fake_assign)
 100                 return;
 101
 102         if (!is_array(expr->left))
 103                 return;
 104         array = get_array_base(expr->left);
 105         offset = get_array_offset(expr->left);
 106
 107         /* These are handled by extra_mod_hook() */
 108         if (get_value(offset, &sval))
 109                 return;
 110         name = expr_to_var_sym(array, &sym);
 111         if (!name || !sym)
 112                 goto free;
 113         if (get_param_num_from_sym(sym) < 0)
 114                 goto free;
 115         get_absolute_rl(expr->right, &rl);
 116         rl = cast_rl(get_type(expr->left), rl);
 117
 118         snprintf(buf, sizeof(buf), "*%s", name);
 119         set_state(my_id, buf, sym, alloc_estate_rl(rl));
 120 free:
 121         free_string(name);
 122 }
 123
 124 /*
 125  * This relies on the fact that these states are stored so that
 126  * foo->bar is before foo->bar->baz.
 127  */
 128 static int parent_set(struct string_list *list, const char *name)
 129 {
 130         char *tmp;
 131         int len;
 132         int ret;
 133
 134         FOR_EACH_PTR(list, tmp) {
 135                 len = strlen(tmp);
 136                 ret = strncmp(tmp, name, len);
 137                 if (ret < 0)
 138                         continue;
 139                 if (ret > 0)
 140                         return 0;
 141                 if (name[len] == '-')
 142                         return 1;
 143         } END_FOR_EACH_PTR(tmp);
 144
 145         return 0;
 146 }
 147
 148 static void print_return_value_param(int return_id, char *return_ranges, struct expression *expr)
 149 {
 150         struct sm_state *sm;
 151         struct smatch_state *extra;
 152         int param;
 153         struct range_list *rl;
 154         const char *param_name;
 155         struct string_list *set_list = NULL;
 156         char *math_str;
 157         char buf[256];
 158         sval_t sval;
 159
 160         FOR_EACH_MY_SM(my_id, __get_cur_stree(), sm) {
 161                 if (!estate_rl(sm->state))
 162                         continue;
 163                 extra = get_state(SMATCH_EXTRA, sm->name, sm->sym);
 164                 if (extra) {
 165                         rl = rl_intersection(estate_rl(sm->state), estate_rl(extra));
 166                         if (!rl)
 167                                 continue;
 168                 } else {
 169                         rl = estate_rl(sm->state);
 170                 }
 171
 172                 param = get_param_num_from_sym(sm->sym);
 173                 if (param < 0)
 174                         continue;
 175                 param_name = get_param_name(sm);
 176                 if (!param_name)
 177                         continue;
 178                 if (strcmp(param_name, "$") == 0)
 179                         continue;
 180
 181                 if (rl_to_sval(rl, &sval)) {
 182                         insert_string(&set_list, (char *)sm->name);
 183                         sql_insert_return_states(return_id, return_ranges,
 184                                         param_has_filter_data(sm) ? PARAM_ADD : PARAM_SET,
 185                                         param, param_name, show_rl(rl));
 186                         continue;
 187                 }
 188
 189                 math_str = get_value_in_terms_of_parameter_math_var_sym(sm->name, sm->sym);
 190                 if (math_str) {
 191                         snprintf(buf, sizeof(buf), "%s[%s]", show_rl(rl), math_str);
 192                         insert_string(&set_list, (char *)sm->name);
 193                         sql_insert_return_states(return_id, return_ranges,
 194                                         param_has_filter_data(sm) ? PARAM_ADD : PARAM_SET,
 195                                         param, param_name, buf);
 196                         continue;
 197                 }
 198
 199                 /* no useful information here. */
 200                 if (is_whole_rl(rl) && parent_set(set_list, sm->name))
 201                         continue;
 202                 insert_string(&set_list, (char *)sm->name);
 203
 204                 sql_insert_return_states(return_id, return_ranges,
 205                                          param_has_filter_data(sm) ? PARAM_ADD : PARAM_SET,
 206                                          param, param_name, show_rl(rl));
 207
 208         } END_FOR_EACH_SM(sm);
 209
 210         free_ptr_list((struct ptr_list **)&set_list);
 211 }
 212
 213 int param_was_set_var_sym(const char *name, struct symbol *sym)
 214 {
 215         struct sm_state *sm;
 216         int len;
 217
 218         FOR_EACH_MY_SM(my_id, __get_cur_stree(), sm) {
 219                 if (sm->sym != sym)
 220                         continue;
 221                 len = strlen(sm->name);
 222                 if (strncmp(sm->name, name, len) != 0)
 223                         continue;
 224                 if (name[len] == '\0' ||
 225                     name[len] == '-')
 226                         return 1;
 227         } END_FOR_EACH_SM(sm);
 228
 229         return 0;
 230 }
 231
 232 int param_was_set(struct expression *expr)
 233 {
 234         char *name;
 235         struct symbol *sym;
 236         int ret = 0;
 237
 238         name = expr_to_var_sym(expr, &sym);
 239         if (!name || !sym)
 240                 goto free;
 241
 242         ret = param_was_set_var_sym(name, sym);
 243 free:
 244         free_string(name);
 245         return ret;
 246 }
 247
 248 void register_param_set(int id)
 249 {
 250         my_id = id;
 251
 252         add_extra_mod_hook(&extra_mod_hook);
 253         add_hook(match_array_assignment, ASSIGNMENT_HOOK);
 254         add_unmatched_state_hook(my_id, &unmatched_state);
 255         add_merge_hook(my_id, &merge_estates);
 256         add_split_return_callback(&print_return_value_param);
 257 }
 258