1.3.11: accept ist not interrupted by a signal

1.3.11: accept ist not interrupted by a signal

[Thomas Pfaff]

I am a bit confused about the current signal handling in a blocking
accept call (i have not checked other system calls yet)
If the process is blocked it is not interrupted by a signal. It first
waits until a connection is made and call the signal handler afterwards.
Is this by design ? IMHO it should call the signal handler and return
EINTR.

I have attached a small testprogram.

When i press CTRL-C during accept the program will stay until i make a
connection, then the signal handler is called. If i press CTRL-C twice the
process starts to eat CPU time.

Thomas

#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <signal.h>

#define MY_PORT		(5678)

static void sig_handler( int signo );

int main( void )
{
   int listen_sock;
   int conn_sock;
   struct sockaddr_in s_local;

   struct sockaddr_in from;
   int fromlen = sizeof( from );


   signal( SIGTERM, sig_handler );
   signal( SIGINT, sig_handler );

   s_local.sin_family = AF_INET;
   s_local.sin_addr.s_addr = INADDR_ANY;
   s_local.sin_port = htons( MY_PORT );

   listen_sock = socket( AF_INET, SOCK_STREAM, 0 );
   bind( listen_sock, (struct sockaddr*) &s_local, sizeof( s_local ) );
   listen( listen_sock, 1 );
   conn_sock = accept( listen_sock, (struct sockaddr*) &from, &fromlen);
   if(conn_sock >= 0)
   {
      printf( "Got connection\n");
      close( conn_sock );
   }
   close( listen_sock );

   return 0;
}

static void sig_handler( int signo )
{
   printf("terminated\n");
   exit( 0 );
}


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Re: 1.3.11: accept ist not interrupted by a signal

[Christopher Faylor]

On Fri, Jun 28, 2002 at 02:34:16PM +0200, Thomas Pfaff wrote:
>
>I am a bit confused about the current signal handling in a blocking
>accept call (i have not checked other system calls yet)
>If the process is blocked it is not interrupted by a signal.

Yep, unfortunately that's how it works currently.

cgf

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1.3.11: accept ist not interrupted by a signal

[Franck Leray]

Hi all,

A process waiting for clients on a 'accept' statement becomes mad (eating cpu) when it receives a signal.
Not on UNIX platform.

See the message of Christopher Faylor (28 jun 2002) '1.3.11: accept ist not interrupted by a signal' for an example.

I don't want to use a non-blocking socket.

Is there an other solution ?
Is it a bug ?

Franck.


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Re: 1.3.11: accept ist not interrupted by a signal

[Thomas Pfaff]

Franck Leray wrote:
> Hi all,
> 
> A process waiting for clients on a 'accept' statement becomes mad (eating cpu) when it receives a signal.
> Not on UNIX platform.
> 
> See the message of Christopher Faylor (28 jun 2002) '1.3.11: accept ist not interrupted by a signal' for an example.
> 

This has been fixed in 1.3.12-1.

Thomas



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RE: 1.3.11: accept ist not interrupted by a signal

[lhall]

Well, you could try the latest released Cygwin DLL (1.3.14-1) or a snapshot.
If you don't have better luck, I think you can assume Chris's response is
still valid.  Oh and if that's is the case, I'm obligated to add "Patches
gratefully accepted". :-)

Sorry, I don't know of another option.

HTH,

Larry

Original Message:
-----------------
From: Franck Leray franck.leray@cheops.fr
Date: Fri, 25 Oct 2002 15:17:56 +0200
To: cygwin@cygwin.com
Subject: 1.3.11: accept ist not interrupted by a signal


Hi all,

A process waiting for clients on a 'accept' statement becomes mad (eating
cpu) when it receives a signal.
Not on UNIX platform.

See the message of Christopher Faylor (28 jun 2002) '1.3.11: accept ist not
interrupted by a signal' for an example.

I don't want to use a non-blocking socket.

Is there an other solution ?
Is it a bug ?

Franck.


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