[SLUG] Non-blocking sockets
Hi All,
I'm having some trouble trying to set a TCP socket to non-blocking (code example
below). Basically fnctl is returning -1 but when I try and get the errno, it's set to
0 (which I beleive is success).
I've done a quick walk through with another hacker here but we cant' see anything
obvious.
Any ideas on what I've balls up is greatly appreciated.
Regards,
Brad
#include
#include
#include
#include
#include
#include
#include
int main()
{
int fileDescriptor = socket(AF_INET, SOCK_STREAM, 0);
if ( 0 > fileDescriptor )
printf("Unable to obtain new socket (errn = %d, text = \"%s\"\n",
errno, strerror(errno));
int currentFlags = fcntl(fileDescriptor, F_GETFL, 0);
if ( 0 > currentFlags )
printf("Unable to get current file descriptor flags\n");
int returnCode = fcntl(fileDescriptor, F_SETFL, currentFlags | O_NONBLOCK);
if ( -1 == returnCode );
printf("Unable to set file descriptor flags (errno = %d, text = \"%s\")\n",
errno, strerror(errno));
return 0;
}
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Re: [SLUG] Non-blocking sockets
On Thu, 27 May 2004 18:28:09 +1000
"Brad Douglas" <[EMAIL PROTECTED]> wrote:
> Hi All,
>
> I'm having some trouble trying to set a TCP socket to non-blocking
> (code example below).
Is that really what you want? Maybe using poll() or select() would
be a better option.
> Basically fnctl is returning -1 but when I
> try and get the errno, it's set to 0 (which I beleive is success).
I'm not sure fcntl() works on sockets, I thought you had to use an ioctl().
This link:
http://www.developerweb.net/sock-faq/detail.php?id=63
suggests that either works.
> I've done a quick walk through with another hacker here but we cant' see anything
> obvious.
>
> Any ideas on what I've balls up is greatly appreciated.
>
> Regards,
> Brad
>
> #include
> #include
> #include
> #include
> #include
> #include
> #include
>
> int main()
> {
> int fileDescriptor = socket(AF_INET, SOCK_STREAM, 0);
> if ( 0 > fileDescriptor )
> printf("Unable to obtain new socket (errn = %d, text = \"%s\"\n",
> errno, strerror(errno));
Errrm, all you have is a socket, its not connected to anything. Maybe you
could connect() or accept() on the socket before you set it to non-blocking.
Erik
--
+---+
Erik de Castro Lopo [EMAIL PROTECTED] (Yes it's valid)
+---+
A good debugger is no substitue for a good test suite.
--
--
+---+
Erik de Castro Lopo [EMAIL PROTECTED] (Yes it's valid)
+---+
A good debugger is no substitue for a good test suite.
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Re: [SLUG] Non-blocking sockets
On Thu, May 27, 2004 at 07:25:10PM +1000, Erik de Castro Lopo wrote:
> I'm not sure fcntl() works on sockets, I thought you had to use an ioctl().
fcntl() does work on sockets. I've used it.
> > int fileDescriptor = socket(AF_INET, SOCK_STREAM, 0);
> > if ( 0 > fileDescriptor )
> > printf("Unable to obtain new socket (errn = %d, text = \"%s\"\n",
> > errno, strerror(errno));
>
> Errrm, all you have is a socket, its not connected to anything. Maybe you
> could connect() or accept() on the socket before you set it to non-blocking.
I was going to wait until I got home before I answered the original
post (my Unix Network Programming books are at home), but I think
you've found the answer. From fcntl(2):
EBADFfd is not an open file descriptor, or the command
was F_SETLK or F_SETLKW and the file descriptor
open mode doesn't match with the type of lock
requested.
> --
> +---+
> Erik de Castro Lopo [EMAIL PROTECTED] (Yes it's valid)
> +---+
> A good debugger is no substitue for a good test suite.
> --
> --
> +---+
> Erik de Castro Lopo [EMAIL PROTECTED] (Yes it's valid)
> +---+
> A good debugger is no substitue for a good test suite.
CChhrrss,,
JJoohhnn
--
Trying to do *anything* industrial-strength on a NT platform is doomed to
failure - it's like the realisation that you've been allocated a bunk-space
below a confirmed bedwetter. The question is not whether you are going to
get pissed on, but when.-- Tanuki
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