EAGAIN undeclared...

Hi there, I guessing that I probably dont have some library so gcc gives this error:
erro: 'EAGAIN' undeclared (first use in this function)

Can you tell what am I doing wrong?

Thanks in advance

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#include <errno.h>

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hi again, i am doing a non-blocking server...So I put the

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accept

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inside a

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for

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and each time

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accept>0

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it creates a new thread, passing in it the socket descriptor of accepted client.

I set

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socket(PF_INET, SOCK_STREAM || SOCK_NONBLOCK, IPPROTO_TCP)

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.

Can you give me some hints to put the accept in a non-bloking mode? Probably I have to test the accept with the flag EWOULDBLOCK., but I am having some dificulties on setting this up.

Thanks in advance

PS: this is because I want to do more things inside that for...

Well is the first problem solved or not?

I would read this link (especially the bottom), and relevant man pages:
- Blocking vs. non-blocking sockets
- socket(7): socket interface - Linux man page
- fcntl(2): change file descriptor - Linux man page

One thing in particular is that all of these links mention "O_NONBLOCK", and never "SOCK_NONBLOCK".

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Originally Posted by nadroj

Well is the first problem solved or not?

I would read this link (especially the bottom), and relevant man pages:
- Blocking vs. non-blocking sockets
- socket(7): socket interface - Linux man page
- fcntl(2): change file descriptor - Linux man page

One thing in particular is that all of these links mention "O_NONBLOCK", and never "SOCK_NONBLOCK".

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Thank you. I will read it carefully. SOCK_NONSOCK is a flag mentioned in socket(2) man page

I guess i am having some troubles with error messages. In accept(2) man pages it says that SOCK_NONBLOCK flag will save extra calls to fcntl. So far so good... I set that up and now I simple dont know how to test if accept will block or not.

Any hints??

Cant you just do an "accept" and do a printf statement to see if it continues immediately after the "accept" statement and prints the message, before a client connects? Make sure to print to "stderr", so use "fprintf" to do so (because stderr is unbuffered, so all messages get printed immediately).

I havent done anything with sockets in a while now, so maybe Im just not understanding what the problem is.

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Originally Posted by tmcp

I guess i am having some troubles with error messages. In accept(2) man pages it says that SOCK_NONBLOCK flag will save extra calls to fcntl.

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Not in mine it doesn't! Please quote this. Also, there is no flags parameter to accept().

Anyway, if the socket is set NON_BLOCK, accept() will not block -- you do not have to test that.

If you want to test if the socket was successfully set non-block, just do this:

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accept(....);
puts("HEY");

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Now run the program, but don't try to connect to it. If HEY appears right away, you are in non-blocking mode. Otherwise, execution will wait for accept to accept something.

Thanks, I will probably have to use O_NONBLOCK and set it with fcntl....

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Originally Posted by MK27

Not in mine it doesn't! Please quote this. Also, there is no flags parameter to accept().

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Flags are for

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accept4()

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. A non.standard Linux system call. Linux 2.6.28. Glibc 2.10

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Originally Posted by tmcp

Thanks, I will probably have to use O_NONBLOCK and set it with fcntl....Flags are for

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accept4()

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. A non.standard Linux system call. Linux 2.6.28. Glibc 2.10

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Okay. This is very very non-standard tho, since I am running glibc 2.9 (fedora 10-64) and accept4 does not exist here, so it probably will not be available on 95%+ of linux systems. Whereas accept() and fcntl() are available anywhere you have C.

Use of fcntl() for this is pretty straightforward:

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fcntl(sock,F_SETFL,O_NONBLOCK);

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Quote:

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Originally Posted by nadroj

Cant you just do an "accept" and do a printf statement to see if it continues immediately after the "accept" statement and prints the message, before a client connects? Make sure to print to "stderr", so use "fprintf" to do so (because stderr is unbuffered, so all messages get printed immediately).

I havent done anything with sockets in a while now, so maybe Im just not understanding what the problem is.

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Thanks for the answer. Dont know that about fprintf :D! Yep, its that I am trying to do. So I guess I am doing it wrong because accept will block my other threads that are running simultaneous. As I say I maybe have to use fcntl...

Thank you again.

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Originally Posted by MK27

Okay. This is very very non-standard tho, since I am running glibc 2.9 (fedora 10-64) and accept4 does not exist here, so it probably will not be available on 95%+ of linux systems.[/code]

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Thanks you for the hints. Thats what I am going to do...I will post my results later

Problem solved...Its runnig all ok. Thanks for your help :D