client-server programming

[Stelios Bounanos]

In message <81FBBA8C21B9D311A6E500508B6144AA11DBEB at eupalinos.aegean.gr>,
    Gousios Georgios <cs98011 at icsd.aegean.gr> wrote:

> Geia sas
> Ayth thn epoxh asxoloymai, logo panephsthmiou, me client server programming.
> Exv tis parakato apories:
> 
> a)Mhpos yparxei kapia synarthsh san thn fflush pou na katharizei oti exei
> "perisepsei" se ena socket meta apo read?

Ftiakse mia poy na kanei non-blocking reads kai meta na epistrefei (des b))

> b)Yparxei tropos na kanoyme thn read na mhn "kollaei" se kapoio socket otan
> den briskei dedomena?

Nai, setareis to O_NONBLOCK me thn fcntl:

#include <unistd.h>
#include <fcntl.h>
#include ...

int sockfd, sockflags;
...

sockflags=fcntl(sockfd, F_GETFL, 0);
if ( sockflags < 0 )
     handle_error_func("fcntl GETFL error");

sockflags |= O_NONBLOCK;
if ( fcntl(sockfd, F_SETFL, sockflags) < 0 )
     handle_error_func("fcntl SETFL error");

Twra h read() 8a epistrefei -1 kai 8a to errno 8a ginetai EAGAIN
('h EWOULDBLOCK se orismena systhmata) an den yparxei tipota gia
diabasma.


> c)Oi signal handlers (px signal(SIGCHLD,func)) prepei na kaloyntai synexos
> se ena brogxo gia na doylepsoyn h apla ftanei na kleithoyn mia fora sthn
> arxh kai tha pianoyn ta signals otan ayta emfanistoyn?
> 

Uhm, eksartatai apo to systhma soy, opote des ta manpages. 
An exei thn sigaction(2), tote xrhsimopoihse aythn anti gia th signal
kai de 8a xreiazetai na ksanasetareis ton handler ka8e fora.

> Kathe boithia kalodexoymenh
> George 
> 

Rgds,
/-sb.
-- 

Stelios Bounanos <sb at dial.pipex.com>
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