gentoo-x86/eclass/alternatives.eclass

# 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 1.12 2005/07/11 15:08:06 swegener 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 "${pref}${SYMLINK} is a dead 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
1	# Copyright 1999-2004 Gentoo Foundation
2	# Distributed under the terms of the GNU General Public License v2
3	# $Header: /var/cvsroot/gentoo-x86/eclass/alternatives.eclass,v 1.12 2005/07/11 15:08:06 swegener Exp $
4
5	# Author : Alastair Tse <liquidx@gentoo.org> (03 Oct 2003)
6	# Short Desc: Creates symlink to the latest version of multiple slotted
7	# packages.
8	#
9	# Long Desc:
10	#
11	# When a package is SLOT'ed, very often we need to have a symlink to the
12	# latest version. However, depending on the order the user has merged them,
13	# more often than not, the symlink maybe clobbered by the older versions.
14	#
15	# This eclass provides a convenience function that needs to be given a
16	# list of alternatives (descending order of recent-ness) and the symlink.
17	# It will choose the latest version it can find installed and create
18	# the desired symlink.
19	#
20	# There are two ways to use this eclass. First is by declaring two variables
21	# $SOURCE and $ALTERNATIVES where $SOURCE is the symlink to be created and
22	# $ALTERNATIVES is a list of alternatives. Second way is the use the function
23	# alternatives_makesym() like the example below.
24	#
25	# Example:
26	#
27	# pkg_postinst() {
28	# alternatives_makesym "/usr/bin/python" "/usr/bin/python2.3" "/usr/bin/python2.2"
29	# }
30	#
31	# The above example will create a symlink at /usr/bin/python to either
32	# /usr/bin/python2.3 or /usr/bin/python2.2. It will choose python2.3 over
33	# python2.2 if both exist.
34	#
35	# Alternatively, you can use this function:
36	#
37	# pkg_postinst() {
38	# alternatives_auto_makesym "/usr/bin/python" "/usr/bin/python[0-9].[0-9]"
39	# }
40	#
41	# This will use bash pathname expansion to fill a list of alternatives it can
42	# link to. It is probably more robust against version upgrades. You should
43	# consider using this unless you are want to do something special.
44	#
45
46	# automatic deduction based on a symlink and a regex mask
47	alternatives_auto_makesym() {
48	local SYMLINK REGEX ALT myregex
49	SYMLINK=$1
50	REGEX=$2
51	if [ "${REGEX:0:1}" != "/" ]
52	then
53	#not an absolute path:
54	#inherit the root directory of our main link path for our regex search
55	myregex="${SYMLINK%/*}/${REGEX}"
56	else
57	myregex=${REGEX}
58	fi
59
60	# sort a space delimited string by converting it to a multiline list
61	# and then run sort -r over it.
62	# make sure we use ${ROOT} because otherwise stage-building will break
63	ALT="$(for i in $(echo ${ROOT}${myregex}); do echo ${i#${ROOT}}; done \| sort -r)"
64	alternatives_makesym ${SYMLINK} ${ALT}
65	}
66
67	alternatives_makesym() {
68	local ALTERNATIVES=""
69	local SYMLINK=""
70	local alt pref
71
72	# usage: alternatives_makesym <resulting symlink> [alternative targets..]
73	SYMLINK=$1
74	# this trick removes the trailing / from ${ROOT}
75	pref=$(echo ${ROOT} \| sed 's:/$::')
76	shift
77	ALTERNATIVES=$@
78
79	# step through given alternatives from first to last
80	# and if one exists, link it and finish.
81
82	for alt in ${ALTERNATIVES}; do
83	if [ -f "${pref}${alt}" ]; then
84	#are files in same directory?
85	if [ "${alt%/}" = "${SYMLINK%/}" ]
86	then
87	#yes; strip leading dirname from alt to create relative symlink
88	einfo "Linking ${alt} to ${pref}${SYMLINK} (relative)"
89	ln -sf ${alt##*/} ${pref}${SYMLINK}
90	else
91	#no; keep absolute path
92	einfo "Linking ${alt} to ${pref}${SYMLINK} (absolute)"
93	ln -sf ${pref}${alt} ${pref}${SYMLINK}
94	fi
95	break
96	fi
97	done
98
99	# report any errors
100	if [ ! -L ${pref}${SYMLINK} ]; then
101	ewarn "Unable to establish ${pref}${SYMLINK} symlink"
102	else
103	# we need to check for either the target being in relative path form
104	# or absolute path form
105	if [ ! -f "`dirname ${pref}${SYMLINK}`/`readlink ${pref}${SYMLINK}`" -a \
106	! -f "`readlink ${pref}${SYMLINK}`" ]; then
107	ewarn "${pref}${SYMLINK} is a dead symlink."
108	fi
109	fi
110	}
111
112	alternatives_pkg_postinst() {
113	if [ -n "${ALTERNATIVES}" -a -n "${SOURCE}" ]; then
114	alternatives_makesym ${SOURCE} ${ALTERNATIVES}
115	fi
116	}
117
118	alternatives_pkg_postrm() {
119	if [ -n "${ALTERNATIVES}" -a -n "${SOURCE}" ]; then
120	alternatives_makesym ${SOURCE} ${ALTERNATIVES}
121	fi
122	}
123
124	EXPORT_FUNCTIONS pkg_postinst pkg_postrm