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# Copyright 1999-2013 Gentoo Foundation |
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# Distributed under the terms of the GNU General Public License v2 |
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# $Header: /var/cvsroot/gentoo-x86/eclass/alternatives.eclass,v 1.17 2011/08/22 04:46:31 vapier Exp $ |
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# @ECLASS: alternatives.eclass |
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# @AUTHOR: |
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# Original author: Alastair Tse <liquidx@gentoo.org> (03 Oct 2003) |
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# @BLURB: Creates symlink to the latest version of multiple slotted packages. |
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# @DESCRIPTION: |
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# When a package is SLOT'ed, very often we need to have a symlink to the |
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# latest version. However, depending on the order the user has merged them, |
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# more often than not, the symlink maybe clobbered by the older versions. |
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# |
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# This eclass provides a convenience function that needs to be given a |
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# list of alternatives (descending order of recent-ness) and the symlink. |
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# It will choose the latest version it can find installed and create |
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# the desired symlink. |
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# |
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# There are two ways to use this eclass. First is by declaring two variables |
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# $SOURCE and $ALTERNATIVES where $SOURCE is the symlink to be created and |
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# $ALTERNATIVES is a list of alternatives. Second way is the use the function |
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# alternatives_makesym() like the example below. |
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# @EXAMPLE: |
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# pkg_postinst() { |
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# alternatives_makesym "/usr/bin/python" "/usr/bin/python2.3" "/usr/bin/python2.2" |
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# } |
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# |
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# The above example will create a symlink at /usr/bin/python to either |
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# /usr/bin/python2.3 or /usr/bin/python2.2. It will choose python2.3 over |
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# python2.2 if both exist. |
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# |
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# Alternatively, you can use this function: |
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# |
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# pkg_postinst() { |
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# alternatives_auto_makesym "/usr/bin/python" "/usr/bin/python[0-9].[0-9]" |
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# } |
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# |
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# This will use bash pathname expansion to fill a list of alternatives it can |
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# link to. It is probably more robust against version upgrades. You should |
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# consider using this unless you are want to do something special. |
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|
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# @ECLASS-VARIABLE: SOURCE |
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# @DEFAULT_UNSET |
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# @DESCRIPTION: |
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# The symlink to be created |
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|
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# @ECLASS-VARIABLE: ALTERNATIVES |
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# @DEFAULT_UNSET |
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# @DESCRIPTION: |
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# The list of alternatives |
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|
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# @FUNCTION: alternatives_auto_makesym |
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# @DESCRIPTION: |
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# automatic deduction based on a symlink and a regex mask |
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alternatives_auto_makesym() { |
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has "${EAPI:-0}" 0 1 2 && ! use prefix && EROOT="${ROOT}" |
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local SYMLINK REGEX ALT myregex |
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SYMLINK=$1 |
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REGEX=$2 |
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if [ "${REGEX:0:1}" != "/" ] |
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then |
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#not an absolute path: |
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#inherit the root directory of our main link path for our regex search |
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myregex="${SYMLINK%/*}/${REGEX}" |
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else |
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myregex=${REGEX} |
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fi |
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|
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# sort a space delimited string by converting it to a multiline list |
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# and then run sort -r over it. |
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# make sure we use ${EROOT} because otherwise stage-building will break |
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ALT="$(for i in $(echo ${EROOT}${myregex}); do echo ${i#${EROOT}}; done | sort -r)" |
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alternatives_makesym ${SYMLINK} ${ALT} |
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} |
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|
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alternatives_makesym() { |
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has "${EAPI:-0}" 0 1 2 && ! use prefix && EPREFIX= |
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local ALTERNATIVES="" |
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local SYMLINK="" |
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local alt pref |
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|
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# usage: alternatives_makesym <resulting symlink> [alternative targets..] |
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# make sure it is in the prefix, allow it already to be in the prefix |
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SYMLINK=${EPREFIX}/${1#${EPREFIX}} |
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# this trick removes the trailing / from ${ROOT} |
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pref=${ROOT%/} |
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shift |
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ALTERNATIVES=$@ |
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|
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# step through given alternatives from first to last |
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# and if one exists, link it and finish. |
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|
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for alt in ${ALTERNATIVES}; do |
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alt=${EPREFIX}/${alt#${EPREFIX}} |
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if [ -f "${pref}${alt}" ]; then |
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#are files in same directory? |
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if [ "${alt%/*}" = "${SYMLINK%/*}" ] |
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then |
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#yes; strip leading dirname from alt to create relative symlink |
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einfo "Linking ${alt} to ${pref}${SYMLINK} (relative)" |
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ln -sf ${alt##*/} ${pref}${SYMLINK} |
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else |
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#no; keep absolute path |
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einfo "Linking ${alt} to ${pref}${SYMLINK} (absolute)" |
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ln -sf ${pref}${alt} ${pref}${SYMLINK} |
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fi |
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break |
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fi |
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done |
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|
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# report any errors |
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if [ ! -L ${pref}${SYMLINK} ]; then |
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ewarn "Unable to establish ${pref}${SYMLINK} symlink" |
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else |
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# we need to check for either the target being in relative path form |
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# or absolute path form |
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if [ ! -f "`dirname ${pref}${SYMLINK}`/`readlink ${pref}${SYMLINK}`" -a \ |
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! -f "`readlink ${pref}${SYMLINK}`" ]; then |
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ewarn "Removing dead symlink ${pref}${SYMLINK}" |
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rm -f ${pref}${SYMLINK} |
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fi |
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fi |
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} |
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|
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# @FUNCTION: alernatives-pkg_postinst |
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# @DESCRIPTION: |
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# The alternatives pkg_postinst, this function will be exported |
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alternatives_pkg_postinst() { |
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if [ -n "${ALTERNATIVES}" -a -n "${SOURCE}" ]; then |
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alternatives_makesym ${SOURCE} ${ALTERNATIVES} |
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fi |
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} |
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|
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# @FUNCTION: alternatives_pkg_postrm |
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# @DESCRIPTION: |
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# The alternatives pkg_postrm, this function will be exported |
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alternatives_pkg_postrm() { |
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if [ -n "${ALTERNATIVES}" -a -n "${SOURCE}" ]; then |
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alternatives_makesym ${SOURCE} ${ALTERNATIVES} |
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fi |
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} |
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|
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EXPORT_FUNCTIONS pkg_postinst pkg_postrm |
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