check_passes_sizeof.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 #include "smatch.h"
  19 #include "smatch_extra.h"
  20 #include "smatch_slist.h"
  21
  22 #define NOBUF -2
  23
  24 static int my_id;
  25
  26 static int expr_equiv(struct expression *one, struct expression *two)
  27 {
  28         struct symbol *one_sym, *two_sym;
  29         char *one_name = NULL;
  30         char *two_name = NULL;
  31         int ret = 0;
  32
  33         if (!one || !two)
  34                 return 0;
  35         if (one->type != two->type)
  36                 return 0;
  37
  38         one_name = expr_to_str_sym(one, &one_sym);
  39         if (!one_name || !one_sym)
  40                 goto free;
  41         two_name = expr_to_str_sym(two, &two_sym);
  42         if (!two_name || !two_sym)
  43                 goto free;
  44         if (one_sym != two_sym)
  45                 goto free;
  46         if (strcmp(one_name, two_name) == 0)
  47                 ret = 1;
  48 free:
  49         free_string(one_name);
  50         free_string(two_name);
  51         return ret;
  52 }
  53
  54 static struct expression *get_returned_expr(struct expression *expr)
  55 {
  56         struct statement *stmt;
  57
  58         stmt = last_ptr_list((struct ptr_list *)big_statement_stack);
  59         if (!stmt || stmt->type != STMT_EXPRESSION)
  60                 return NULL;
  61         if (stmt->expression->type != EXPR_ASSIGNMENT)
  62                 return NULL;
  63         if (stmt->expression->right != expr)
  64                 return NULL;
  65         return stmt->expression->left;
  66 }
  67
  68 static struct expression *remove_dereference(struct expression *expr)
  69 {
  70         if (!expr || expr->type != EXPR_PREOP || expr->op != '*')
  71                 return expr;
  72         expr = expr->unop;
  73         if (!expr || expr->type != EXPR_PREOP || expr->op != '*')
  74                 return expr;
  75         return expr->unop;
  76 }
  77
  78 static int get_buf_number(struct expression *call, struct expression *size_arg)
  79 {
  80         struct expression *arg;
  81         int idx = -1;
  82
  83         size_arg = strip_expr(size_arg->cast_expression);
  84         size_arg = remove_dereference(size_arg);
  85
  86         arg = get_returned_expr(call);
  87         if (arg && expr_equiv(arg, size_arg))
  88                 return idx;
  89
  90         FOR_EACH_PTR(call->args, arg) {
  91                 idx++;
  92                 if (expr_equiv(arg, size_arg))
  93                         return idx;
  94         } END_FOR_EACH_PTR(arg);
  95
  96         return NOBUF;
  97 }
  98
  99 static void match_call(struct expression *call)
 100 {
 101         struct expression *arg;
 102         char *name;
 103         int buf_nr;
 104         int i = -1;
 105
 106         if (call->fn->type != EXPR_SYMBOL)
 107                 return;
 108
 109         name = expr_to_var(call->fn);
 110         FOR_EACH_PTR(call->args, arg) {
 111                 i++;
 112                 if (arg->type != EXPR_SIZEOF)
 113                         continue;
 114                 buf_nr = get_buf_number(call, arg);
 115                 if (buf_nr == NOBUF)
 116                         sm_msg("info: sizeof_param '%s' %d", name, i);
 117                 else
 118                         sm_msg("info: sizeof_param '%s' %d %d", name, i, buf_nr);
 119         } END_FOR_EACH_PTR(arg);
 120         free_string(name);
 121 }
 122
 123 void check_passes_sizeof(int id)
 124 {
 125         if (!option_info)
 126                 return;
 127
 128         my_id = id;
 129         add_hook(&match_call, FUNCTION_CALL_HOOK);
 130 }