===================================================================
RCS file: /cvsrepo/anoncvs/cvs/src/usr.bin/xinstall/xinstall.c,v
retrieving revision 1.49
retrieving revision 1.50
diff -u -r1.49 -r1.50
--- src/usr.bin/xinstall/xinstall.c	2009/10/27 23:59:50	1.49
+++ src/usr.bin/xinstall/xinstall.c	2012/04/11 09:27:42	1.50
@@ -1,4 +1,4 @@
-/*	$OpenBSD: xinstall.c,v 1.49 2009/10/27 23:59:50 deraadt Exp $	*/
+/*	$OpenBSD: xinstall.c,v 1.50 2012/04/11 09:27:42 espie Exp $	*/
 /*	$NetBSD: xinstall.c,v 1.9 1995/12/20 10:25:17 jonathan Exp $	*/
 
 /*
@@ -416,8 +416,10 @@
 	 * trash memory on big files.  This is really a minor hack, but it
 	 * wins some CPU back.  Sparse files need special treatment.
 	 */
-	if (!sparse && size <= 8 * 1048576) {
-		volatile size_t siz;
+	if (!size) {
+		/* nothing to do */
+	} else if (!sparse && size <= 8 * 1048576) {
+		size_t siz;
 
 		if ((p = mmap(NULL, (size_t)size, PROT_READ, MAP_PRIVATE,
 		    from_fd, (off_t)0)) == MAP_FAILED) {
@@ -425,8 +427,7 @@
 			(void)unlink(to_name);
 			errx(EX_OSERR, "%s: %s", from_name, strerror(serrno));
 		}
-		if (size)
-			madvise(p, size, MADV_SEQUENTIAL);
+		madvise(p, size, MADV_SEQUENTIAL);
 		siz = (size_t)size;
 		if ((nw = write(to_fd, p, siz)) != siz) {
 			serrno = errno;
@@ -484,8 +485,11 @@
 	off_t from_off, to_off;
 	int dfound;
 
+	if (from_len == 0 && from_len == to_len)
+		return (0);
+
 	if (from_len != to_len)
-		return(1);
+		return (1);
 
 	/*
 	 * Compare the two files being careful not to mmap