added a select call so read doesn't fail with EWOULDBLOCK

assign to result of the read to an ssize_t instead of size_t

net/choparp/patches/patch-ac

@@ -0,0 +1,54 @@
+$NetBSD: patch-ac,v 1.3 1999/09/12 20:12:19 dbj Exp $
+
+--- choparp.c.orig	Tue Oct  7 05:29:46 1997
++++ choparp.c	Sun Sep 12 15:58:41 1999
+@@ -24,6 +24,7 @@
+ #include <netinet/if_ether.h>
+ #include <sys/param.h>
+ #include <errno.h>
++#include <assert.h>
+ 
+ #define	BPFFILENAME	"/dev/bpf%d"	/* bpf file template */
+ #ifndef	NBPFILTER			/* number of available bpf */
+@@ -217,20 +218,35 @@
+ 
+ void
+ loop(int fd, char *buf, size_t buflen){
+-    size_t  rlen;
++    ssize_t  rlen;
+     char    *p, *nextp;
+     size_t  nextlen;
+     char    *rframe;
+     size_t  rframe_len;
+     char    *sframe;
+     size_t  sframe_len;
++    fd_set fdset;
++
++    FD_ZERO(&fdset);
++    FD_SET(fd,&fdset);
+ 
+     for(;;){
+-	if ((rlen = read(fd, buf, buflen)) <= 0){
+-	    fprintf(stderr,"loop: read: %s\n", strerror(errno));
+-	    /* XXX: restart itself if daemon mode */
+-	    return;
+-	}
++      int r;
++      r = select(fd+1,&fdset, 0, 0, 0);
++      if ((r < 0) && (errno == EINTR)) continue;
++      if (r < 0) {
++	perror("select");
++	return;
++      }
++      assert(r == 1);
++
++      rlen = read(fd, buf, buflen);
++      if ((rlen < 0) && (errno = EINTR)) continue;
++      if (rlen < 0) {
++	perror("loop: read");
++	return;
++      }
++
+ 	p = buf;
+ 	while((rframe = getarp(p, rlen, &nextp, &nextlen)) != NULL){
+ 	    if (checkarp(rframe)){