I have very simple client - server setup, where client connects, exchanges some messages with the server and then closes socket and exits. Everythink works OK, except when I am trying to change socket to be non-blocking AND the shell happens to be plain old Bourne. It runs no problem under ksh or bash. But when I run it under sh the program completes and then it kills the shell and kicks me out.
Below is my code, for simplicity I left the connection part of it as it is enough to highlight the problem:
Code:
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/netinet/in.h>
#include <sys/netinet/tcp.h>
#define MAXSIZE 1024
const int srvr_port = 5777;
const char *locl_addr = "127.0.0.1";
main(int argc, char *argv[])
{
struct sockaddr_in saddr;
int val;
int sh;
int sd;
int rc;
sd = socket(AF_INET, SOCK_STREAM, 0);
memset(&saddr, 0, sizeof(saddr));
saddr.sin_family = AF_INET;
saddr.sin_addr.s_addr = inet_addr(locl_addr);
saddr.sin_port = htons(srvr_port);
sh = connect(sd, (struct sockaddr *)&saddr, sizeof(saddr));
if(sh != -1)
{
printf("Connected OK\n");
val = fcntl(sh, F_GETFL);
printf("orig val=%i\n", val);
val = val | O_NONBLOCK;
printf("set val=%i\n", val);
rc = fcntl(sh, F_SETFL, val); /* if I comment out */
printf("set rc=%i\n", rc); /* the SETFL line all is OK */
}
else
{
printf("Connect Failed, errno=%i\n", errno);
return(1);
}
close(sd);
printf("sd closed\n");
return(0);
}
I run under OpenServer 5.0.7, native compiler.
To avoid having to re-login I start Bourne shell from bash, below is my run session:
Code:
bash-2.03$ sh
$
$ zx; echo "RC=$?"
Connected OK
orig val=2
set val=130
set rc=0
sd closed
RC=0
$ bash-2.03$
See, how the sh is terminated and I am back to bash
As I indicated above, if I don't do fcntl(sh, F_SETFL, val) problem disappears. The server side is not affected in any case.
If the connect call works, you're operating on file descriptor zero:
Code:
sh = connect(sd, (struct sockaddr *)&saddr, sizeof(saddr));
if(sh != -1)
{
printf("Connected OK\n");
val = fcntl(sh, F_GETFL);
printf("orig val=%i\n", val);
val = val | O_NONBLOCK;
printf("set val=%i\n", val);
rc = fcntl(sh, F_SETFL, val); /* if I comment out */
printf("set rc=%i\n", rc); /* the SETFL line all is OK */
}
The variable sh contains the status of the connect call, not the socket itself.
That should be:
Code:
sh = connect(sd, (struct sockaddr *)&saddr, sizeof(saddr));
if(sh != -1)
{
printf("Connected OK\n");
val = fcntl(sd, F_GETFL);
printf("orig val=%i\n", val);
val = val | O_NONBLOCK;
printf("set val=%i\n", val);
rc = fcntl(sd, F_SETFL, val); /* if I comment out */
printf("set rc=%i\n", rc); /* the SETFL line all is OK */
}
Good evening, friends
I'm learning with a book: Programming Linux by Kurt Wall (Prentice Hall)
The code below could run in two windows (./lockit /tmp/foo in both for example). There is not problem with the read block (first byte) but when one, apply the write block while in the other is... (1 Reply)
Hello
I have a Perl script that works on non-darwin Mac OS X environments and I think I have narrowed down the issue to a file locking problem.
In other linux environments, the flock struct is defined differently. I have adjusted this via the reference for Mac OS X fcntl(2) man page. The... (4 Replies)
I need clarification on whether it is okay to set socket options on a listening socket
simultaneously when it is being used in an accept() call?
Following is the scenario:-
-- Task 1 - is executing in a loop - polling a listen socket, lets call it 'fd', (whose file descriptor is global)... (2 Replies)
Dear Experts,
i am compiling my code in suse 4.1 which is compiling fine,
but at runtime it is showing me for socket programming error no 88
as i searched in errno.h it is telling me socket operation on non socket,
what is the meaning of this , how to deal with this error , please... (1 Reply)
Why does this socket function only read the first 1440 chars of the stream. Why not the whole stream ? I checked it with gdm and valgrind and everything seems correct...
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <string.h>
#include... (3 Replies)
Hi,
Unless I am missing some serious differences in Mac and linux in terms of C programming, I dont know why this would happen. Please take a look at the following piece of code fragment:
bool add_input_to_db(Cons *new_data) {
// Set the attributes of the lock
struct flock fl =... (3 Replies)
Hi all,
On the server side, one socket is used for listening, the others are used for communicating with the client.
My question is: if i want to set option for socket, which socket should be set on?
If either can be set, what's the different?
Again, what's the different if set option... (1 Reply)
Hi,
I was porting ipv4 application to ipv6; i was done with TCP transports. Now i am facing problem with SCTp transport at runtime.
To test SCTP transport I am using following server and client socket programs. Server program runs fine, but client program fails giving Invalid Arguments for... (0 Replies)
hi, I need to know how to lock a file. I used the following code, but after executing the program the file 'write.txt' remined empty, and I have no idea why.Maybe I'm not using the corresponding syntax for blocking a file. But I deleted then the blocking part and the problem persisted.
see to... (2 Replies)
Hello,
I actually try to make client-server program.
I'm using SCO OpenServer Release 5.0.0 and when I try to compile my code (by TELNET) I've got this error :
I'm just using this simple code :
and I get the same error if I use :
If someone can help me,
Thanks (2 Replies)
07-02-2010
