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Date: Fri, 28 Jun 2002 14:34:16 +0200 (=?ISO-8859-1?Q?Westeurop=E4ische_Sommerzeit?=)
From: Thomas Pfaff <tpfaff AT gmx DOT net>
To: cygwin AT cygwin DOT com
Subject: 1.3.11: accept ist not interrupted by a signal
Message-ID: <Pine.WNT.4.44.0206281405210.269-100000@algeria.intern.net>
X-X-Sender: pfaff AT antarctica DOT intern DOT net
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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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