smatch_return_to_param.c

   1 /*
   2  * Copyright (C) 2017 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 smatch_extra.c to use.  It sort of like check_assigned_expr.c but
  20  * more limited.  Say a function returns "64min-s64max[$0->data]" and the caller
  21  * does "struct whatever *p = get_data(dev);" then we want to record that p is
  22  * now the same as "dev->data".  Then if we update "p->foo" it means we can
  23  * update "dev->data->foo" as well.
  24  *
  25  */
  26
  27 #include "smatch.h"
  28 #include "smatch_slist.h"
  29 #include "smatch_extra.h"
  30
  31 static int my_id;
  32 static int link_id;
  33
  34 static struct smatch_state *alloc_my_state(const char *name, struct symbol *sym)
  35 {
  36         struct smatch_state *state;
  37
  38         state = __alloc_smatch_state(0);
  39         state->name = alloc_sname(name);
  40         state->data = sym;
  41         return state;
  42 }
  43
  44 static void undef(struct sm_state *sm, struct expression *mod_expr)
  45 {
  46         set_state(my_id, sm->name, sm->sym, &undefined);
  47 }
  48
  49 char *map_call_to_other_name_sym(const char *name, struct symbol *sym, struct symbol **new_sym)
  50 {
  51         struct smatch_state *state;
  52         int skip;
  53         char buf[256];
  54
  55         /* skip 'foo->'.  This was checked in the caller. */
  56         skip = strlen(sym->ident->name) + 2;
  57
  58         state = get_state(my_id, sym->ident->name, sym);
  59         if (!state || !state->data)
  60                 return NULL;
  61
  62         snprintf(buf, sizeof(buf), "%s->%s", state->name, name + skip);
  63         *new_sym = state->data;
  64         return alloc_string(buf);
  65 }
  66
  67 /*
  68  * Normally, we expect people to consistently refer to variables by the shortest
  69  * name.  So they use "b->a" instead of "foo->bar.a" when both point to the
  70  * same memory location.  However, when we're dealing across function boundaries
  71  * then sometimes we pass frob(foo) which sets foo->bar.a.  In that case, we
  72  * translate it to the shorter name.  Smatch extra updates the shorter name,
  73  * which in turn updates the longer name.
  74  *
  75  */
  76 char *map_long_to_short_name_sym(const char *name, struct symbol *sym, struct symbol **new_sym)
  77 {
  78         struct sm_state *sm;
  79         int len;
  80         char buf[256];
  81
  82         *new_sym = NULL;
  83
  84         FOR_EACH_MY_SM(my_id, __get_cur_stree(), sm) {
  85                 if (sm->state->data != sym)
  86                         continue;
  87                 len = strlen(sm->state->name);
  88                 if (strncmp(name, sm->state->name, len) == 0) {
  89                         if (name[len] == '.')
  90                                 continue;
  91
  92                         snprintf(buf, sizeof(buf), "%s%s", sm->name, name + len);
  93                         *new_sym = sm->sym;
  94                         return alloc_string(buf);
  95                 }
  96         } END_FOR_EACH_SM(sm);
  97
  98         return NULL;
  99 }
 100
 101 char *map_call_to_param_name_sym(struct expression *expr, struct symbol **sym)
 102 {
 103         char *name;
 104         struct smatch_state *state;
 105
 106         *sym = NULL;
 107
 108         name = expr_to_str(expr);
 109         if (!name)
 110                 return NULL;
 111         state = get_state(my_id, name, (struct symbol *)expr);
 112         if (!state || !state->data)
 113                 return NULL;
 114         *sym = state->data;
 115         return alloc_string(state->name);
 116 }
 117
 118 static void store_mapping_helper(char *left_name, struct symbol *left_sym, struct expression *call, const char *return_string)
 119 {
 120         const char *p = return_string;
 121         const char *end;
 122         int param;
 123         struct expression *arg;
 124         char *name = NULL;
 125         struct symbol *right_sym;
 126         char buf[256];
 127
 128         while (*p && *p != '[')
 129                 p++;
 130         if (!*p)
 131                 goto free;
 132         p++;
 133         if (*p != '$')
 134                 goto free;
 135         p++;
 136         param = atoi(p);
 137         p++;
 138         if (*p != '-' || *(p + 1) != '>')
 139                 goto free;
 140         end = strchr(p, ']');
 141         if (!end)
 142                 goto free;
 143
 144         arg = get_argument_from_call_expr(call->args, param);
 145         if (!arg)
 146                 goto free;
 147         name = expr_to_var_sym(arg, &right_sym);
 148         if (!name || !right_sym)
 149                 goto free;
 150         snprintf(buf, sizeof(buf), "%s", name);
 151
 152         if (end - p + strlen(buf) >= sizeof(buf))
 153                 goto free;
 154         strncat(buf, p, end - p);
 155
 156         set_state(my_id, left_name, left_sym, alloc_my_state(buf, right_sym));
 157         //set_state(my_id, buf, right_sym, alloc_my_state(left_name, left_sym));
 158
 159         store_link(link_id, buf, right_sym, left_name, left_sym);
 160
 161 free:
 162         free_string(name);
 163 }
 164
 165 void __add_return_to_param_mapping(struct expression *expr, const char *return_string)
 166 {
 167         struct expression *call;
 168         char *left_name = NULL;
 169         struct symbol *left_sym;
 170
 171         if (expr->type == EXPR_ASSIGNMENT) {
 172                 left_name = expr_to_var_sym(expr->left, &left_sym);
 173                 if (!left_name || !left_sym)
 174                         goto free;
 175
 176                 call = strip_expr(expr->right);
 177                 if (call->type != EXPR_CALL)
 178                         goto free;
 179
 180                 store_mapping_helper(left_name, left_sym, call, return_string);
 181                 goto free;
 182         }
 183
 184         if (expr->type == EXPR_CALL &&
 185             expr_get_parent_stmt(expr) &&
 186             expr_get_parent_stmt(expr)->type == STMT_RETURN) {
 187                 call = strip_expr(expr);
 188                 left_name = expr_to_str(call);
 189                 if (!left_name)
 190                         goto free;
 191
 192                 /*
 193                  * HACK ALERT: The symbol pointer is basically used as a cookie
 194                  * and not used as a pointer so we can pass expr here without
 195                  * causing an issue.
 196                  *
 197                  */
 198                 store_mapping_helper(left_name, (struct symbol *)expr, call, return_string);
 199                 goto free;
 200
 201         }
 202
 203 free:
 204         free_string(left_name);
 205 }
 206
 207 void register_return_to_param(int id)
 208 {
 209         my_id = id;
 210         add_modification_hook(my_id, &undef);
 211 }
 212
 213 void register_return_to_param_links(int id)
 214 {
 215         link_id = id;
 216         set_up_link_functions(my_id, link_id);
 217 }
 218