Re: RFA: Sanitize deprecation messages (PR 84195)

[Nick Clifton <nickc at redhat dot com>]

Hi Martin,


> Since the class manages a resource it should ideally make sure it
> doesn't try to release the same resource multiple times.  I.e., its
> copy constructor and assignment operators should either "do the right
> thing" (whatever you think that is) or be made inaccessible (or declared deleted in C++ 11).
> 
> For example:
> 
>   {
>     escaped_string a;
>     a.escape ("foo\nbar");
> 
>     escaped_string b (a);
>     // b destroys its m_str
>     // double free in a's destructor here
>   }

I am not sure that this can happen.  First of the escaped_string
class does not have constructor that accepts a char* argument.
(Maybe in C++ this is done automatically ?  My C++-fu is very weak).

Secondly the m_owned private field is only set to true when
the m_str field is set to a string allocated by the particular
instance of the class, and memory is only freed by the destructor 
if m_owned is true.  

So even this should work:

  {
    escaped_string a,b;

    a.escape ("foo\nbar");
    b.escape ((const char *) a);
  }

The destructor for B will not free any memory, even though its
m_str field has been set to the same string as A, because its
m_owned field will be set to FALSE.

Cheers
  Nick