Re: [Sablevm-developer] Errno usage considered harmful?!

[Clark V. <cl...@CS...>]

I have some guesses, below.

-- 
ttfn,
clark
cl...@cs...


On Wed, 10 Mar 2004, Grzegorz B. Prokopski wrote:

> Hi all,
> 
> I have strange problems with compiler warnings:
> 
> 1. If I add:
>   #include <errno.h>
>   extern int errno;
> I get such warning:
>   java_lang_ProcessImpl.c:24: warning: function declaration isn't a
> prototype

It would help to know which line is line 24, but here's something that may
be worth checking:  Although the extern declaration should be fine, errno
may be declared as a macro rather than a simple variable --- particularly
with multithreaded code, where errno's exist for each separate thread.  
Try just using the include and removing the "extern int errno;" statement.

> 2. In interrupt() implementation I use a pointer to pthread_cond_t:
>   volatile pthread_cond_t *sleeping_on_cond;
> I also keep getting this warning:
>   java_lang_VMThread.c:342: warning: passing arg 1 of
>   `pthread_cond_broadcast' discards qualifiers from pointer target type
> which is such code:
>   pthread_cond_broadcast (env_other->thread.sleeping_on_cond);

The prototype for cond_broadcast doesn't expect a volatile type for the
argument, so that qualifier is being discarded when you call the function.
An explicit cast may eliminate the warning, but the problem is that the
cond_broadcast code was not compiled assuming volatile input arguments.  
If that's a problem then you'll need to re-examine why you need volatile
in sleeping_on_cond.

> Not sure how to deal with these two. Suggestions are very welcomed. [*]
> 
> Cheers,
> 
> 				Grzegorz B. Prokopski
> 
> [*] Like a good RTFM, for ex.
> 
>