[Mono-list] InteropServices: DllNotFoundException...?

[Simon Ask Ulsnes]

*sigh*
Hooray for Managed Code! ;-)

Could you please give a short example of a C++ library function that 
returns a string for use in a managed application? (with proper memory 
hygiene ;-)

- Simon

Jonathan Pryor wrote:

>Inline...
>
>On Sun, 2004-05-23 at 10:56, Simon Ask Ulsnes wrote:
><snip/>
>  
>
>>>Furthermore, if you do something like this:
>>>
>>>	const char*
>>>	get_my_string()
>>>	{
>>>		std::string s ("this is my string");
>>>		return s.c_str();
>>>	}
>>>
>>>You're *asking* for trouble, as the std::string destructor will free the
>>>memory used to hold the string, so the string returned by
>>>get_my_string() will be pointing to invalid memory.
>>>      
>>>
>>  
>>And guess what, that's actually what I'm doing (basically) - so far, it 
>>works, I haven't detected any memory leaks (haven't checked very 
>>thoroughly, though).
>>But you say using marshalling and IntPtr's is the best way to do it?
>>    
>>
>
>The above situation isn't a memory leak, so it won't be detected as a
>memory leak.  It's instead a "use after free".  It's akin to doing this:
>
>	char *mem = malloc (20);                 // allocate
>	strcpy(mem, "some string");              // initialize
>	free (mem);                              // free
>	printf ("this is my string: %s\n", mem); // use?!  bad.
>
>It's not safe to use memory after it's freed.  Especially in a
>multi-threaded environment -- the memory could have been re-allocated by
>another thread and initialized with different data.
>
>So this isn't a memory corruption bug or a memory leak, it's just bad
>memory hygiene.
>
> - Jon
>
>
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