From 4f2d7949f03e1c198bc888f2d05f421d35c57e21 Mon Sep 17 00:00:00 2001
From: V3n3RiX <venerix@redcorelinux.org>
Date: Mon, 9 Oct 2017 18:53:29 +0100
Subject: reinit the tree, so we can have metadata

---
 eclass/alternatives.eclass | 142 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 142 insertions(+)
 create mode 100644 eclass/alternatives.eclass

(limited to 'eclass/alternatives.eclass')

diff --git a/eclass/alternatives.eclass b/eclass/alternatives.eclass
new file mode 100644
index 000000000000..fd99bd85acdb
--- /dev/null
+++ b/eclass/alternatives.eclass
@@ -0,0 +1,142 @@
+# Copyright 1999-2013 Gentoo Foundation
+# Distributed under the terms of the GNU General Public License v2
+
+# @ECLASS: alternatives.eclass
+# @AUTHOR:
+# Original author: Alastair Tse <liquidx@gentoo.org> (03 Oct 2003)
+# @BLURB: Creates symlink to the latest version of multiple slotted packages.
+# @DESCRIPTION:
+# When a package is SLOT'ed, very often we need to have a symlink to the
+# latest version. However, depending on the order the user has merged them,
+# more often than not, the symlink maybe clobbered by the older versions.
+#
+# This eclass provides a convenience function that needs to be given a
+# list of alternatives (descending order of recent-ness) and the symlink.
+# It will choose the latest version it can find installed and create
+# the desired symlink.
+#
+# There are two ways to use this eclass. First is by declaring two variables
+# $SOURCE and $ALTERNATIVES where $SOURCE is the symlink to be created and
+# $ALTERNATIVES is a list of alternatives. Second way is the use the function
+# alternatives_makesym() like the example below.
+# @EXAMPLE:
+# pkg_postinst() {
+#     alternatives_makesym "/usr/bin/python" "/usr/bin/python2.3" "/usr/bin/python2.2"
+# }
+#
+# The above example will create a symlink at /usr/bin/python to either
+# /usr/bin/python2.3 or /usr/bin/python2.2. It will choose python2.3 over
+# python2.2 if both exist.
+#
+# Alternatively, you can use this function:
+#
+# pkg_postinst() {
+#    alternatives_auto_makesym "/usr/bin/python" "/usr/bin/python[0-9].[0-9]"
+# }
+#
+# This will use bash pathname expansion to fill a list of alternatives it can
+# link to. It is probably more robust against version upgrades. You should
+# consider using this unless you are want to do something special.
+
+# @ECLASS-VARIABLE: SOURCE
+# @DEFAULT_UNSET
+# @DESCRIPTION:
+# The symlink to be created
+
+# @ECLASS-VARIABLE: ALTERNATIVES
+# @DEFAULT_UNSET
+# @DESCRIPTION:
+# The list of alternatives
+
+# @FUNCTION: alternatives_auto_makesym
+# @DESCRIPTION:
+# automatic deduction based on a symlink and a regex mask
+alternatives_auto_makesym() {
+	has "${EAPI:-0}" 0 1 2 && ! use prefix && EROOT="${ROOT}"
+	local SYMLINK REGEX ALT myregex
+	SYMLINK=$1
+	REGEX=$2
+	if [ "${REGEX:0:1}" != "/" ]
+	then
+		#not an absolute path:
+		#inherit the root directory of our main link path for our regex search
+		myregex="${SYMLINK%/*}/${REGEX}"
+	else
+		myregex=${REGEX}
+	fi
+
+	# sort a space delimited string by converting it to a multiline list
+	# and then run sort -r over it.
+	# make sure we use ${EROOT} because otherwise stage-building will break
+	ALT="$(for i in $(echo ${EROOT}${myregex}); do echo ${i#${EROOT}}; done | sort -r)"
+	alternatives_makesym ${SYMLINK} ${ALT}
+}
+
+alternatives_makesym() {
+	has "${EAPI:-0}" 0 1 2 && ! use prefix && EPREFIX=
+	local ALTERNATIVES=""
+	local SYMLINK=""
+	local alt pref
+
+	# usage: alternatives_makesym <resulting symlink> [alternative targets..]
+	# make sure it is in the prefix, allow it already to be in the prefix
+	SYMLINK=${EPREFIX}/${1#${EPREFIX}}
+	# this trick removes the trailing / from ${ROOT}
+	pref=${ROOT%/}
+	shift
+	ALTERNATIVES=$@
+
+	# step through given alternatives from first to last
+	# and if one exists, link it and finish.
+
+	for alt in ${ALTERNATIVES}; do
+		alt=${EPREFIX}/${alt#${EPREFIX}}
+		if [ -f "${pref}${alt}" ]; then
+			#are files in same directory?
+			if [ "${alt%/*}" = "${SYMLINK%/*}" ]
+			then
+				#yes; strip leading dirname from alt to create relative symlink
+				einfo "Linking ${alt} to ${pref}${SYMLINK} (relative)"
+				ln -sf ${alt##*/} ${pref}${SYMLINK}
+			else
+				#no; keep absolute path
+				einfo "Linking ${alt} to ${pref}${SYMLINK} (absolute)"
+				ln -sf ${pref}${alt} ${pref}${SYMLINK}
+			fi
+			break
+		fi
+	done
+
+	# report any errors
+	if [ ! -L ${pref}${SYMLINK} ]; then
+		ewarn "Unable to establish ${pref}${SYMLINK} symlink"
+	else
+		# we need to check for either the target being in relative path form
+		# or absolute path form
+		if [ ! -f "`dirname ${pref}${SYMLINK}`/`readlink ${pref}${SYMLINK}`" -a \
+			 ! -f "`readlink ${pref}${SYMLINK}`" ]; then
+			ewarn "Removing dead symlink ${pref}${SYMLINK}"
+			rm -f ${pref}${SYMLINK}
+		fi
+	fi
+}
+
+# @FUNCTION: alernatives-pkg_postinst
+# @DESCRIPTION:
+# The alternatives pkg_postinst, this function will be exported
+alternatives_pkg_postinst() {
+	if [ -n "${ALTERNATIVES}" -a -n "${SOURCE}" ]; then
+		alternatives_makesym ${SOURCE} ${ALTERNATIVES}
+	fi
+}
+
+# @FUNCTION: alternatives_pkg_postrm
+# @DESCRIPTION:
+# The alternatives pkg_postrm, this function will be exported
+alternatives_pkg_postrm() {
+	if [ -n "${ALTERNATIVES}" -a -n "${SOURCE}" ]; then
+		alternatives_makesym ${SOURCE} ${ALTERNATIVES}
+	fi
+}
+
+EXPORT_FUNCTIONS pkg_postinst pkg_postrm
-- 
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