[src/trunk]: src/bin/cp Re-order the code to short circuit all the opens and ...

[darcy <darcy%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/97a8124697bd
branches:  trunk
changeset: 320741:97a8124697bd
user:      darcy <darcy%NetBSD.org@localhost>
date:      Tue Jul 17 13:04:58 2018 +0000

description:
Re-order the code to short circuit all the opens and closes if linking.
Discussed on tech-userlevel and agreed to by christos@.
Testing suggests an order of magnitude improvement when linking.

diffstat:

 bin/cp/utils.c |  28 +++++++++++++---------------
 1 files changed, 13 insertions(+), 15 deletions(-)

diffs (56 lines):

diff -r 54e209e43d80 -r 97a8124697bd bin/cp/utils.c
--- a/bin/cp/utils.c    Tue Jul 17 12:40:00 2018 +0000
+++ b/bin/cp/utils.c    Tue Jul 17 13:04:58 2018 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: utils.c,v 1.45 2016/02/29 04:22:21 mrg Exp $ */
+/* $NetBSD: utils.c,v 1.46 2018/07/17 13:04:58 darcy Exp $ */
 
 /*-
  * Copyright (c) 1991, 1993, 1994
@@ -34,7 +34,7 @@
 #if 0
 static char sccsid[] = "@(#)utils.c    8.3 (Berkeley) 4/1/94";
 #else
-__RCSID("$NetBSD: utils.c,v 1.45 2016/02/29 04:22:21 mrg Exp $");
+__RCSID("$NetBSD: utils.c,v 1.46 2018/07/17 13:04:58 darcy Exp $");
 #endif
 #endif /* not lint */
 
@@ -99,7 +99,17 @@
        int ch, checkch, from_fd, rcount, rval, to_fd, tolnk, wcount;
        char *p;
        off_t ptotal = 0;
-       
+
+       /* if hard linking then simply link and return */
+       if (lflag) {
+               (void)unlink(to.p_path);
+               if (link(entp->fts_path, to.p_path)) {
+                       warn("%s", to.p_path);
+                       return (1);
+               }
+               return (0);
+       }
+
        if ((from_fd = open(entp->fts_path, O_RDONLY, 0)) == -1) {
                warn("%s", entp->fts_path);
                return (1);
@@ -164,18 +174,6 @@
 
        rval = 0;
 
-       /* if hard linking then simply close the open fds, link and return */
-       if (lflag) {
-               (void)close(from_fd);
-               (void)close(to_fd);
-               (void)unlink(to.p_path);
-               if (link(entp->fts_path, to.p_path)) {
-                       warn("%s", to.p_path);
-                       return (1);
-               }
-               return (0);
-       }
-
        /*
         * There's no reason to do anything other than close the file
         * now if it's empty, so let's not bother.