Re: [Xenomai-help] writing from NRT to a rt_pipe

[Philippe Gerum <rpm@xenomai.org>]

On Thu, 2007-06-07 at 13:57 -0500, NZG wrote:
> When writing from NRT to a real time pile (open, write, close).
> Are message boundaries preserved based upon the length of the write call?
> 

It should yes, that's the main difference between this interface and
other RT fifo implementations. rt_pipe_stream() works the other way,
though (i.e. bytestream mode).

> It's not working for me. The code below returns success, but calling 
> 
> err = rt_pipe_read(comp,k,sizeof(kommand_t),TM_NONBLOCK);
> or
> err = rt_pipe_read(comp,k,sizeof(kommand_t),100);
> 
> from RT space on the same pipe never returns any data
> 
> err = rt_pipe_read(comp,k,sizeof(kommand_t),TM_NONBLOCK); 
> always returns err 
> 0x0b,  Resource temporarily unavailable
> 
>  err = rt_pipe_read(comp,k,sizeof(kommand_t),100);
> always returns err:
> 0x6e, Connection timed out
> 

Please send a compilable standalone test, so that we get a clear view of
what fails, and of the current runtime conditions when that fails.

> NZG
> 
> code specifics follow...............
> 
> 		int err;
> 		kommand_t k = {
> 		.type = KILLCYCLE,	
> 		};
> 	   
> 	    int cfd = open(COMMANDPIPE, O_WRONLY|O_SYNC);
> 	   
> 	   if(cfd<0){
> 	   	printf("can't open %s (%s)\n",COMMANDPIPE, strerror(-cfd));
> 	   	fflush(stdout);
> 	   	return;
> 	   }
> 	   	
> 	   printf("sizeof kommand_t = %u\n",sizeof(kommand_t));
> 	   
>        err=write(cfd,&k,sizeof(kommand_t));
>        	
>        if(err>=0)printf("wrote %u bytes to %s\n",err,COMMANDPIPE); 
>        	
>        if(err<0)printf("err writing to %s (%s)\n",COMMANDPIPE, 
> strerror(errno));
>        
>        
>        if(close(cfd)<0)printf("couldn't close %s\n",COMMANDPIPE);
> 
> 
>  
> 
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-- 
Philippe.