Date: 23 Nov 2001 00:58:08 -0500 From: Arcady Genkin <antipode@thpoon.com> To: freebsd-chat@freebsd.org Subject: Reentrant readn() and writen() for socket communication Message-ID: <873d363u6n.fsf@tea.thpoon.com>
next in thread | raw e-mail | index | archive | help
Stevens' UNIX Network Programming show sample readn()[1] and writen()
functions to read/write from/to a socket.
The functions handle interrupted read()/write() system calls by
examining errno value. This approach is not thread-safe (because of
usage of errno global).
Is there a reentrant way to detect under-reads/writes, or had I better
off with just using recv() with MSG_WAITALL flag?
Footnotes:
[1] Here's the code of readn() for easy reference:
ssize_t
readn( int fd, void *vptr, size_t n )
{
size_t nleft;
ssize_t nread;
char *ptr;
ptr = vptr;
nleft = n;
while ( nleft > 0 ) {
if ( (nread = read(fd, ptr, nleft)) < 0 ) {
if (errno == EINTR)
nread = 0; /* and call read() again */
else
return (-1);
}
else if ( nread == 0 )
break; /* EOF */
nleft -= nread;
ptr += nread;
}
return (n - nleft); /* >= 0 */
}
Many thanks,
--
Arcady Genkin
i=1; while 1, hilb(i); i=i+1; end
To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-chat" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?873d363u6n.fsf>