smatch_strlen.c

   1 /*
   2  * smatch/smatch_strlen.c
   3  *
   4  * Copyright (C) 2013 Oracle.
   5  *
   6  * Licensed under the Open Software License version 1.1
   7  *
   8  */
   9
  10 #include <stdlib.h>
  11 #include <errno.h>
  12 #include "parse.h"
  13 #include "smatch.h"
  14 #include "smatch_slist.h"
  15 #include "smatch_extra.h"
  16
  17 static int my_strlen_id;
  18
  19 static void set_strlen_undefined(struct sm_state *sm, struct expression *mod_expr)
  20 {
  21         set_state(sm->owner, sm->name, sm->sym, &undefined);
  22 }
  23
  24 static void match_strlen(const char *fn, struct expression *expr, void *unused)
  25 {
  26         struct expression *right;
  27         struct expression *str;
  28         struct expression *len_expr;
  29         char *len_name;
  30         struct smatch_state *state;
  31
  32         right = strip_expr(expr->right);
  33         str = get_argument_from_call_expr(right->args, 0);
  34         len_expr = strip_expr(expr->left);
  35
  36         len_name = expr_to_var(len_expr);
  37         if (!len_name)
  38                 return;
  39
  40         state = __alloc_smatch_state(0);
  41         state->name = len_name;
  42         state->data = len_expr;
  43
  44         set_state_expr(my_strlen_id, str, state);
  45 }
  46
  47 int get_size_from_strlen(struct expression *expr)
  48 {
  49         struct smatch_state *state;
  50         sval_t len;
  51
  52         state = get_state_expr(my_strlen_id, expr);
  53         if (!state || !state->data)
  54                 return 0;
  55         if (!get_implied_max((struct expression *)state->data, &len))
  56                 return 0;
  57         if (sval_is_max(len))
  58                 return 0;
  59         if (len.uvalue > INT_MAX - 1 || len.value < 0)
  60                 return 0;
  61         return len.value + 1; /* add one because strlen doesn't include the NULL */
  62 }
  63
  64 void register_strlen(int id)
  65 {
  66         my_strlen_id = id;
  67         add_function_assign_hook("strlen", &match_strlen, NULL);
  68         add_modification_hook(my_strlen_id, &set_strlen_undefined);
  69 }
  70