# Copyright 1999-2004 Gentoo Foundation # Distributed under the terms of the GNU General Public License v2 # $Header: /var/cvsroot/gentoo-x86/eclass/alternatives.eclass,v 1.14 2007/05/15 15:20:59 ulm Exp $ # Author : Alastair Tse <liquidx@gentoo.org> (03 Oct 2003) # Short Desc: Creates symlink to the latest version of multiple slotted # packages. # # Long Desc: # # 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. # # automatic deduction based on a symlink and a regex mask alternatives_auto_makesym() { 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 ${ROOT} because otherwise stage-building will break ALT="$(for i in $(echo ${ROOT}${myregex}); do echo ${i#${ROOT}}; done | sort -r)" alternatives_makesym ${SYMLINK} ${ALT} } alternatives_makesym() { local ALTERNATIVES="" local SYMLINK="" local alt pref # usage: alternatives_makesym <resulting symlink> [alternative targets..] SYMLINK=$1 # this trick removes the trailing / from ${ROOT} pref=$(echo ${ROOT} | sed 's:/$::') shift ALTERNATIVES=$@ # step through given alternatives from first to last # and if one exists, link it and finish. for alt in ${ALTERNATIVES}; do if [ -f "${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 } alternatives_pkg_postinst() { if [ -n "${ALTERNATIVES}" -a -n "${SOURCE}" ]; then alternatives_makesym ${SOURCE} ${ALTERNATIVES} fi } alternatives_pkg_postrm() { if [ -n "${ALTERNATIVES}" -a -n "${SOURCE}" ]; then alternatives_makesym ${SOURCE} ${ALTERNATIVES} fi } EXPORT_FUNCTIONS pkg_postinst pkg_postrm