smatch_common_functions.c

   1 /*
   2  * Copyright (C) 2013 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 #include "scope.h"
  19 #include "smatch.h"
  20 #include "smatch_extra.h"
  21
  22 static int match_strlen(struct expression *call, void *unused, struct range_list **rl)
  23 {
  24         struct expression *str;
  25         unsigned long max;
  26
  27         str = get_argument_from_call_expr(call->args, 0);
  28         if (get_implied_strlen(str, rl) && sval_is_positive(rl_min(*rl))) {
  29                 *rl = cast_rl(&ulong_ctype, *rl);
  30                 return 1;
  31         }
  32         /* smatch_strlen.c is not very complete */
  33         max = get_array_size_bytes_max(str);
  34         if (max == 0) {
  35                 *rl = alloc_rl(sval_type_val(&ulong_ctype, 0),
  36                                sval_type_val(&ulong_ctype, STRLEN_MAX_RET));
  37         } else {
  38                 max--;
  39                 *rl = alloc_rl(sval_type_val(&ulong_ctype, 0),
  40                                sval_type_val(&ulong_ctype, max));
  41         }
  42         return 1;
  43 }
  44
  45 static int match_strnlen(struct expression *call, void *unused, struct range_list **rl)
  46 {
  47         struct range_list *terminated_rl = NULL;
  48         struct expression *str, *limit;
  49         sval_t fixed;
  50         sval_t bound;
  51         sval_t ulong_max = sval_type_val(&ulong_ctype, ULONG_MAX);
  52
  53         str = get_argument_from_call_expr(call->args, 0);
  54         limit = get_argument_from_call_expr(call->args, 1);
  55         if (!str || !limit)
  56                 return 1;
  57
  58         if (is_nul_terminated(str)) {
  59                 match_strlen(call, NULL, &terminated_rl);
  60                 *rl = terminated_rl;
  61         }
  62         if (!get_implied_max(limit, &bound))
  63                 return 1;
  64         if (sval_cmp(bound, ulong_max) == 0)
  65                 return 1;
  66         if (rl_to_sval(*rl, &fixed) && sval_cmp(fixed, bound) >= 0) {
  67                 *rl = alloc_rl(bound, bound);
  68                 return 1;
  69         }
  70
  71         if (terminated_rl) {
  72                 bound.value++;
  73                 *rl = remove_range(*rl, bound, ulong_max);
  74         } else {
  75                 *rl = alloc_rl(ulong_zero, bound);
  76         }
  77
  78         return 1;
  79 }
  80
  81 static int match_sprintf(struct expression *call, void *_arg, struct range_list **rl)
  82 {
  83         int str_arg = PTR_INT(_arg);
  84         int min, max;
  85
  86         min = get_formatted_string_min_size(call, str_arg);
  87         max = get_formatted_string_size(call, str_arg);
  88         if (min < 0 || max < 0) {
  89                 *rl = alloc_whole_rl(&ulong_ctype);
  90         } else {
  91                 *rl = alloc_rl(ll_to_sval(min), ll_to_sval(max));
  92                 *rl = cast_rl(get_type(call), *rl);
  93         }
  94         return 1;
  95 }
  96
  97 void register_common_functions(int id)
  98 {
  99         /*
 100          * When you add a new function here, then don't forget to delete it from
 101          * the database and smatch_data/.
 102          */
 103         add_implied_return_hook("strlen", &match_strlen, NULL);
 104         add_implied_return_hook("__builtin_strlen", &match_strlen, NULL);
 105         add_implied_return_hook("__fortify_strlen", &match_strlen, NULL);
 106         add_implied_return_hook("strnlen", &match_strnlen, NULL);
 107         add_implied_return_hook("sprintf", &match_sprintf, INT_PTR(1));
 108         add_implied_return_hook("snprintf", &match_sprintf, INT_PTR(2));
 109 }