Author: dteske
Date: Wed Jul 10 22:45:07 2013
New Revision: 253175
URL: http://svnweb.freebsd.org/changeset/base/253175
Log:
Introduce a new [yet unused] function for [efficiently] getting the path to
an executable by-name without forking or using externals.
In a performance benchmark of 10,000 runs on circa 2006 hardware, f_which
out-performed `which' with an average completion time of ~2.5 seconds versus
~56 seconds.
This should be handy for future use (not that I make it a habit to call
`which' in a loop 10,000 times).
Modified:
head/usr.sbin/bsdconfig/share/common.subr
Modified: head/usr.sbin/bsdconfig/share/common.subr
==============================================================================
--- head/usr.sbin/bsdconfig/share/common.subr Wed Jul 10 22:12:48 2013
(r253174)
+++ head/usr.sbin/bsdconfig/share/common.subr Wed Jul 10 22:45:07 2013
(r253175)
@@ -212,6 +212,35 @@ f_have()
f_quietly type "$@"
}
+# f_which $anything [$var_to_set]
+#
+# A fast built-in replacement for syntaxes such as foo=$( which bar ). In a
+# comparison of 10,000 runs of this function versus which, this function
+# completed in under 3 seconds, while `which' took almost a full minute.
+#
+# If $var_to_set is missing or NULL, output is (like which) to standard out.
+# Returns success if a match was found, failure otherwise.
+#
+f_which()
+{
+ local __name="$1" __var_to_set="$2"
+ case "$__name" in */*|'') return $FAILURE; esac
+ local __p IFS=":" __found=
+ for __p in $PATH; do
+ local __exec="$__p/$__name"
+ [ -f "$__exec" -a -x "$__exec" ] && __found=1 && break
+ done
+ if [ "$__found" ]; then
+ if [ "$__var_to_set" ]; then
+ setvar "$__var_to_set" "$__exec"
+ else
+ echo "$__exec"
+ fi
+ return $SUCCESS
+ fi
+ return $FAILURE
+}
+
# f_getvar $var_to_get [$var_to_set]
#
# Utility function designed to go along with the already-builtin setvar.
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