Use the -nt and -ot test primaries again rather than depend on GNU find

As regards the test(1) utility, the POSIX.1-2024 specification defines
the -nt and -ot primaries as standard features. Given that the
specification in question was only recently published, this would not
normally be an adequate reason for using them in gentoo-functions, in
and as of itself. However, I was already aware that the these primaries
are commonly implemented and have been so for years.

So, I decided to evaluate a number of shells and see how things stand
now. Here is a list of the ones that I tested:

- ash (busybox 1.36.1)
- dash 0.5.12
- bash 5.2.26
- ksh 93u+
- loksh 7.5
- mksh 59c
- oksh 7.5
- sh (FreeBSD 14.1)
- sh (NetBSD 10.0)
- sh (OpenBSD 7.5)
- yash 2.56.1

Of these, bash, ksh93, loksh, mksh, oksh, OpenBSD sh and yash appear to
conform with the POSIX-1.2024 specification. The remaining four fail to
conform in one particular respect, which is as follows.

$ touch existent
$ set -- existent nonexistent
$ [ "$1" -nt "$2" ]; echo "$?" # should be 0
1
$ [ "$2" -ot "$1" ]; echo "$?" # should be 0
1

To address this, I discerned a reasonably straightforward workaround
that involves testing both whether the file under consideration exists
and whether the variable keeping track of the newest/oldest file has yet
been assigned to.

As far as I am concerned, the coverage is more than adequate for both
primaries to be used by gentoo-functions. As such, this commit adjusts
the following three functions so as to do exactly that.

- is_older_than()
- newest()
- oldest()

It also removes the following functions, since they are no longer used.

- _find0()
- _select_by_mtime()

With this, GNU findutils is no longer a required runtime dependency. Of
course, should a newly introduced feature of gentoo-functions benefit
from the presence of findutils in the future, there is no reason that it
cannot be brought back in that capacity.

Signed-off-by: Kerin Millar <kfm@plushkava.net>
Signed-off-by: Sam James <sam@gentoo.org>

1 files changed, 20 insertions, 5 deletions

diff --git a/functions/rc.sh b/functions/rc.sh
index 0c14035..4eff3c8 100644
--- a/functions/rc.sh
+++ b/functions/rc.sh
@@ -1,6 +1,6 @@
 # Copyright 1999-2024 Gentoo Authors
 # Distributed under the terms of the GNU General Public License v2
-# shellcheck shell=sh disable=3043
+# shellcheck shell=sh disable=3013,3043
 
 # This file contains alternative implementations for some of the functions and
 # utilities provided by OpenRC. Please refer to ../functions.sh for coding
@@ -205,9 +205,13 @@ get_bootparam()
 # Takes the first parameter as a reference file/directory then determines
 # whether any of the following parameters refer to newer files/directories.
 #
+# The test utility is required to support the -nt primary, per POSIX-1.2024.
+# However, measures are in place to to achieve compatibility with shells that
+# implement the primary without yet fully adhering to the specification.
+#
 is_older_than()
 {
-	local ref
+	local path ref
 
 	if [ "$#" -eq 0 ]; then
 		warn "is_older_than: too few arguments (got $#, expected at least 1)"
@@ -218,9 +222,20 @@ is_older_than()
 		ref=
 	fi
 	shift
-	{ test "$#" -gt 0 && printf '%s\0' "$@"; } \
-	| _find0 -L ${ref:+-newermm} ${ref:+"${ref}"} -printf '\n' -quit \
-	| read -r _
+	for path; do
+		# The first branch addresses a conformance issue whereby
+		# [ existent -nt nonexistent ] is incorrectly false. As of
+		# August 2024, busybox ash, dash, FreeBSD sh and NetBSD sh are
+		# known to be non-conforming in this respect.
+		if [ ! "${ref}" ] && [ -e "${path}" ]; then
+			return
+		elif [ "${path}" -nt "${ref}" ]; then
+			return
+		elif [ -d "${path}" ] && is_older_than "${ref}" "${path}"/*; then
+			return
+		fi
+	done
+	false
 }
 
 #