[src/trunk]: src/distrib/sets Add cheap implementations of basename and dirname,

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

details:   https://anonhg.NetBSD.org/src/rev/e9f23fc379aa
branches:  trunk
changeset: 586865:e9f23fc379aa
user:      apb <apb%NetBSD.org@localhost>
date:      Wed Jan 04 14:35:03 2006 +0000

description:
Add cheap implementations of basename and dirname,
using builtin printf, or using echo if printf is not a
shell builtin.

Reviewed by agc

diffstat:

 distrib/sets/sets.subr |  60 ++++++++++++++++++++++++++++++++++++++++++++++++-
 1 files changed, 58 insertions(+), 2 deletions(-)

diffs (81 lines):

diff -r 3e4a1507d132 -r e9f23fc379aa distrib/sets/sets.subr
--- a/distrib/sets/sets.subr    Wed Jan 04 14:23:22 2006 +0000
+++ b/distrib/sets/sets.subr    Wed Jan 04 14:35:03 2006 +0000
@@ -1,4 +1,4 @@
-#      $NetBSD: sets.subr,v 1.44 2006/01/04 14:23:22 apb Exp $
+#      $NetBSD: sets.subr,v 1.45 2006/01/04 14:35:03 apb Exp $
 #
 
 #
@@ -94,6 +94,62 @@
 : ${UNAME:=uname}
 : ${WC:=wc}
 
+#
+# If printf is a shell builtin command, then we can
+# implement cheaper versions of basename and dirname
+# that do not involve any fork/exec overhead.
+# If printf is not builtin, approximate it using echo,
+# and hope there are no weird file names that cause
+# some versions of echo to do the wrong thing.
+# (Converting to this version of dirname speeded up the
+# syspkgdeps script by an order of magnitude, from 68
+# seconds to 6.3 seconds on one particular host.)
+#
+# Note that naive approximations for dirname
+# using ${foo%/*} do not do the right thing in cases
+# where the result should be "/" or ".".
+#
+case "$(type printf)" in
+*builtin*)
+       basename ()
+       {
+               local bn
+               bn="${1##*/}"
+               bn="${bn%$2}"
+               printf "%s\n" "$bn"
+       }
+       dirname ()
+       {
+               local dn
+               case "$1" in
+               ?*/*)   dn="${1%/*}" ;;
+               /*)     dn=/ ;;
+               *)      dn=. ;;
+               esac
+               printf "%s\n" "$dn"
+       }
+       ;;
+*)
+       basename ()
+       {
+               local bn
+               bn="${1##*/}"
+               bn="${bn%$2}"
+               echo "$bn"
+       }
+       dirname ()
+       {
+               local dn
+               case "$1" in
+               ?*/*)   dn="${1%/*}" ;;
+               /*)     dn=/ ;;
+               *)      dn=. ;;
+               esac
+               echo "$dn"
+       }
+       ;;
+esac
+
 oIFS=$IFS
 IFS="
 "
@@ -159,7 +215,7 @@
 # In each file, a record consists of a path and a System Package name,
 # separated by whitespace. E.g.,
 #
-#      # $NetBSD: sets.subr,v 1.44 2006/01/04 14:23:22 apb Exp $
+#      # $NetBSD: sets.subr,v 1.45 2006/01/04 14:35:03 apb Exp $
 #      .                       base-sys-root   [keyword[,...]]
 #      ./altroot               base-sys-root
 #      ./bin                   base-sys-root