check_passes_sizeof.c

   1 /*
   2  * smatch/check_passes_sizeof.c
   3  *
   4  * Copyright (C) 2012 Oracle.
   5  *
   6  * Licensed under the Open Software License version 1.1
   7  *
   8  */
   9
  10 #include "smatch.h"
  11 #include "smatch_extra.h"
  12 #include "smatch_slist.h"
  13
  14 #define NOBUF -2
  15
  16 static int my_id;
  17
  18 static int expr_equiv(struct expression *one, struct expression *two)
  19 {
  20         struct symbol *one_sym, *two_sym;
  21         char *one_name = NULL;
  22         char *two_name = NULL;
  23         int ret = 0;
  24
  25         if (!one || !two)
  26                 return 0;
  27         if (one->type != two->type)
  28                 return 0;
  29
  30         one_name = get_variable_from_expr_complex(one, &one_sym);
  31         if (!one_name || !one_sym)
  32                 goto free;
  33         two_name = get_variable_from_expr_complex(two, &two_sym);
  34         if (!two_name || !two_sym)
  35                 goto free;
  36         if (one_sym != two_sym)
  37                 goto free;
  38         if (strcmp(one_name, two_name) == 0)
  39                 ret = 1;
  40 free:
  41         free_string(one_name);
  42         free_string(two_name);
  43         return ret;
  44 }
  45
  46 static struct expression *get_returned_expr(struct expression *expr)
  47 {
  48         struct statement *stmt;
  49
  50         stmt = last_ptr_list((struct ptr_list *)big_statement_stack);
  51         if (!stmt || stmt->type != STMT_EXPRESSION)
  52                 return NULL;
  53         if (stmt->expression->type != EXPR_ASSIGNMENT)
  54                 return NULL;
  55         if (stmt->expression->right != expr)
  56                 return NULL;
  57         return stmt->expression->left;
  58 }
  59
  60 static struct expression *remove_dereference(struct expression *expr)
  61 {
  62         if (!expr || expr->type != EXPR_PREOP || expr->op != '*')
  63                 return expr;
  64         expr = expr->unop;
  65         if (!expr || expr->type != EXPR_PREOP || expr->op != '*')
  66                 return expr;
  67         return expr->unop;
  68 }
  69
  70 static int get_buf_number(struct expression *call, struct expression *size_arg)
  71 {
  72         struct expression *arg;
  73         int idx = -1;
  74
  75         size_arg = strip_expr(size_arg->cast_expression);
  76         size_arg = remove_dereference(size_arg);
  77
  78         arg = get_returned_expr(call);
  79         if (arg && expr_equiv(arg, size_arg))
  80                 return idx;
  81
  82         FOR_EACH_PTR(call->args, arg) {
  83                 idx++;
  84                 if (expr_equiv(arg, size_arg))
  85                         return idx;
  86         } END_FOR_EACH_PTR(arg);
  87
  88         return NOBUF;
  89 }
  90
  91 static void match_call(struct expression *call)
  92 {
  93         struct expression *arg;
  94         char *name;
  95         int buf_nr;
  96         int i = -1;
  97
  98         if (call->fn->type != EXPR_SYMBOL)
  99                 return;
 100
 101         name = get_variable_from_expr(call->fn, NULL);
 102         FOR_EACH_PTR(call->args, arg) {
 103                 i++;
 104                 if (arg->type != EXPR_SIZEOF)
 105                         continue;
 106                 buf_nr = get_buf_number(call, arg);
 107                 if (buf_nr == NOBUF)
 108                         sm_msg("info: sizeof_param '%s' %d", name, i);
 109                 else
 110                         sm_msg("info: sizeof_param '%s' %d %d", name, i, buf_nr);
 111         } END_FOR_EACH_PTR(arg);
 112         free_string(name);
 113 }
 114
 115 void check_passes_sizeof(int id)
 116 {
 117         if (!option_info)
 118                 return;
 119
 120         my_id = id;
 121         add_hook(&match_call, FUNCTION_CALL_HOOK);
 122 }