/* program to demonstrate that only if siginterrupt() is called
 * for a signal are system calls interrupted by that signal on Linux.
 * Invoke with '-t' arg: siginterrupt is called and program is interrupted.
 * without it, the program hangs until it gets an unhandled signal(eg ^C),
 * even though the handler is invoked.
 */
#include <sys/types.h>
#include <unistd.h>
#include <signal.h>
#include <netinet/in.h>
#include <errno.h>

void sigalrm(int sig)
{
    write(1,"ALARM!\n",7);
}

int main(int argc, char **argv, char **envp)
{
    char buf[512];
    int r;

    signal(SIGALRM, sigalrm);
    if( (argc > 1) && (argv[1] != 0L) && (argv[1][0]=='-') && (argv[1][1]=='t'))
	siginterrupt(SIGALRM,1);
    alarm(2);
    r=read(0,buf,512);
    printf("%d %s\n",errno,strerror(errno));
}