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Top Forums Programming Problem with signal handler and interrupted system call Post 302280302 by otheus on Monday 26th of January 2009 12:45:58 PM
Old 01-26-2009
Quote:
Code:
       retval = read(fd, &data, sizeof(unsigned long));
        if (retval == -1) {
            perror("read");
            exit(errno);
        }

That's your problem, more or less. If read() is interrupted by a system call, it returns -1, sets errno to EINTR. Your program itself does the perror and exiting, not read(). So just check if the return is -1 and errno != EINTR and restart the loop (for instance). You'll have to handle the logic for the ioctls and what not, too, or every now and then, your signal will interrupt the ioctl and exit.
 

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ln(7)							 Miscellaneous Information Manual						     ln(7)

NAME
ln - Lance Ethernet interface SYNOPSIS
config_driver ln DESCRIPTION
The ln interface provides access to a 10 Mb/s Ethernet network through the Lance controller. The host's Internet address is specified at boot time with an SIOCSIFADDR ioctl. The ln interface employs the address resolution protocol described in arp(7) to map dynamically between Internet and Ethernet addresses on the local network. The SIOCSPHYSADDR ioctl can be used to change the physical address of the Lance. The SIOCRPHYSADDR ioctl can be used to read the physical address of the Lance. The SIOCADDMULTI and SIOCDELMULTI ioctls can be used to add or delete multicast addresses. The Lance recognizes a maximum of 12 multicast addresses. The SIOCRDCTRS and SIOCRDZCTRS ioctls can be used to read or ``read and clear'' the Ethernet driver counters. The argument to these two ioctls is a pointer to a counter structure, ctrreq, found in <net/if.h>. The SIOCENABLBACK and SIOCDISABLBACK ioctls can be used to enable and disable the interface loopback mode respectively. EXAMPLES
To obtain the physical address of the adapter, use the SIOCRPHYSADDR ioctl as in the following program example: #include <stdio.h> /* standard I/O */ #include <errno.h> /* error numbers */ #include <sys/socket.h> /* socket definitions */ #include <sys/ioctl.h> /* ioctls */ #include <net/if.h> /* generic interface structures */ main() { int s,i; static struct ifdevea devea; /* Get a socket */ s = socket(AF_INET,SOCK_DGRAM,0); if (s < 0) { perror("socket"); exit(1); } strcpy(devea.ifr_name,"ln0"); if (ioctl(s,SIOCRPHYSADDR,&devea) < 0) { perror(&devea.ifr_name[0]); exit(1); } printf("Address is "); for (i = 0; i < 6; i++) printf("%X ", devea.default_pa[i] & 0xff); printf(" "); close(s); } To enable external loopback, use the SIOCENABLEBACK ioctl as in the following program example: #include <stdio.h> /* standard I/O */ #include <errno.h> /* error numbers */ #include <sys/socket.h> /* socket definitions */ #include <sys/ioctl.h> /* ioctls */ #include <net/if.h> /* generic interface structures */ main() { int s; struct ifreq data; /* Get a socket */ s = socket(AF_INET,SOCK_DGRAM,0); if (s < 0) { perror("socket"); exit(1); } strcpy(data.ifr,"ln0"); if (ioctl(s,SIOCENABLEBACK,&data) < 0) { perror("SIOCENABLEBACK:"); exit(1); } close(s); } ERRORS
The diagnostic error messages contain relevant information provided by the Lance. The interface was handed a message with addresses for- matted in an unsuitable address family, and the packet was dropped. A memory parity error has occurred. The ln driver was unable to allo- cate memory for internal data structures. The ln driver was unable to initialize the network interface. Too many multicast requests have been made. RELATED INFORMATION
arp(7), inet(7), netintro(7) delim off ln(7)
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