Attempt to cause EINTER but read is not interrupted by signal...

main.c

#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
#include <string.h>

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>


void
sigint_handler(int sig)
{
  fprintf(stderr, "signal caught\n");
	return;
}

int
make_socket(void)
{
	int		sock, port = 80;
	struct sockaddr_in serv_addr;
	struct hostent *server;

	server = gethostbyname("www.google.com");
	if (server == NULL)
		fprintf(stderr, "gethostbyname failed\n");

	sock = socket(AF_INET, SOCK_STREAM, 0);
	memset(&serv_addr, 0, sizeof(serv_addr));
	serv_addr.sin_family = AF_INET;
	memcpy(&serv_addr.sin_addr.s_addr, server->h_addr, server->h_length);
	serv_addr.sin_port = htons(port);

	if (connect(sock, (struct sockaddr *) &serv_addr, sizeof(serv_addr)) < 0)
		fprintf(stderr, "connect failed\n");

	return sock;
}

int
make_pipe(void)
{
	int		pipefd[2];

	if (pipe(pipefd) < 0)
		fprintf(stderr, "pipe failed\n");

	return pipefd[0];
}

int
main(int argc, char **argv)
{
	struct sigaction act, oact;
	int		fd;
	char	buf[512];
	int		readlen;
	int		use_socket = 1;

	act.sa_handler = sigint_handler;
	sigemptyset(&act.sa_mask);
	act.sa_flags = SA_RESTART;
	sigaction(SIGUSR1, &act, &oact);

	if (use_socket)
		fd = make_socket();
	else
		fd = make_pipe();

	readlen = read(fd, buf, 512);

	if (readlen == -1)
	{
		int		err = errno;

		fprintf(stderr, "erro = %d\n", err);
	}

	fprintf(stderr, "readlen = %d\n", readlen);

	return readlen;
}

Makefile

PROG = run
OBJS = main.o

all: $(PROG)

$(PROG): $(OBJS)
  $(CC) -o $(PROG) $(OBJS)

clean:
	rm -f $(OBJS) $(PROG)