TCP socket I/O from the kernel

Question

We've been working on extending our filesystem support from UDP to TCP,
and have run into an apparent roadblock. We'd like to know whether
Sun is aware of the problem that we're seeing, and if so, if there
is something else we should be doing to avoid it.
We've been using the "sockfs" module to create sockets [where
sockfs_xxx is found using modlookup("sockfs", "xxx")]:
avp = sockfs_solookup(AF_INET, SOCK_STREAM, 0, "/dev/tcp", &rc);
sop = sockfs_socreate(avp, AF_INET, SOCK_STREAM, 0,
SOV_DEFAULT, NULL, &rc);
binding, and setting some socket ops:
sockfs_sobind(sop, (struct sockaddr *)&client_addr,
sizeof(client_addr), 0, 0);
sockfs_sosetsockopt(sop, SOL_SOCKET, ... );
and connecting:
sockfs_soconnect(sop, (struct sockaddr *)&server_addr,
sizeof(server_addr), 0, 0);
We're able to send data successfully with:
sockfs_sosendmsg(sop, &nmsg, &uio);
where uio.uio_segflg = UIO_SYSSPACE;
But when we try to receive with a similar
sockfs_sorcvmsg(sop, &nmsg, &uio);
we regularly receive EFAULT errors.
[This same sequence works fine for both send and receive if we use
/dev/udp instead.]
As we trace through the call, we see that TCP uses a special UIO
function (uioipcopyout) that simply returns EFAULT for any
UIO_SYSSPACE move. The use of this function appears to be driven by
queue settings (STRUIOT_IP) in the TCP stream queue initializers.
So, our questions are:
Is there a way to override this behavior (safely)?
Should we be using another interface to do socket I/O
from the kernel? (At first glance, that wouldn't help
us here, as this deeply rooted in the TCP implementation.)
Are there any code examples (published or otherwise)
that would help us here?
Thanks for any help you can offer us!

Answer 1

you can do this in Java 5.0 using jline (must be around version 0.9.91) it must be running on linux/unix/mac though. i think in the future jline may support windowsTerminal also. however with java 6.0 you may wonder what's the point
public static String readPassword(String prompt) {
try {
Terminal t = Terminal.getTerminal();
if(t instanceof jline.UnixTerminal){
UnixTerminal ut = (UnixTerminal) t;
ConsoleReader reader = new ConsoleReader();
//ConsoleReaderInputStream cris = new ConsoleReaderInputStream(reader);
Character mask = new Character((char) 0);
//reader.setEchoCharacter(new Character('0'));
String line = null;
do {
line = reader.readLine(prompt,mask) ;
if (line != null){
//reader.setEchoCharacter(null);
reader.flushConsole();
ut.restoreTerminal();
return line;
} while(line != null && line.length() > 0);
} catch (Exception e){}
return null;
}