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Revision 1.15 - (show annotations) (download)
Wed Sep 10 08:10:31 2008 UTC (5 years, 10 months ago) by pva
Branch: MAIN
Changes since 1.14: +54 -41 lines
Make eclass-manpages ready, bug #210058, thank mren for report.

1 # Copyright 1999-2008 Gentoo Foundation
2 # Distributed under the terms of the GNU General Public License v2
3 # $Header: /var/cvsroot/gentoo-x86/eclass/alternatives.eclass,v 1.14 2007/05/15 15:20:59 ulm Exp $
4
5 # @ECLASS: alternatives.eclass
6 # @MAINTAINER:
7 #
8 # Original author : Alastair Tse <liquidx@gentoo.org> (03 Oct 2003)
9 # @BLURB: Creates symlink to the latest version of multiple slotted packages.
10 # @DESCRIPTION:
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 # @EXAMPLE:
25 # pkg_postinst() {
26 # alternatives_makesym "/usr/bin/python" "/usr/bin/python2.3" "/usr/bin/python2.2"
27 # }
28 #
29 # The above example will create a symlink at /usr/bin/python to either
30 # /usr/bin/python2.3 or /usr/bin/python2.2. It will choose python2.3 over
31 # python2.2 if both exist.
32 #
33 # Alternatively, you can use this function:
34 #
35 # pkg_postinst() {
36 # alternatives_auto_makesym "/usr/bin/python" "/usr/bin/python[0-9].[0-9]"
37 # }
38 #
39 # This will use bash pathname expansion to fill a list of alternatives it can
40 # link to. It is probably more robust against version upgrades. You should
41 # consider using this unless you are want to do something special.
42
43 # @ECLASS-VARIABLE: SOURCE
44 # @DESCRIPTION:
45 # The symlink to be created
46
47 # @ECLASS-VARIABLE: ALTERNATIVES
48 # @DESCRIPTION:
49 # The list of alternatives
50
51 # @FUNCTION: alternatives_auto_makesym
52 # @DESCRIPTION:
53 # automatic deduction based on a symlink and a regex mask
54 alternatives_auto_makesym() {
55 local SYMLINK REGEX ALT myregex
56 SYMLINK=$1
57 REGEX=$2
58 if [ "${REGEX:0:1}" != "/" ]
59 then
60 #not an absolute path:
61 #inherit the root directory of our main link path for our regex search
62 myregex="${SYMLINK%/*}/${REGEX}"
63 else
64 myregex=${REGEX}
65 fi
66
67 # sort a space delimited string by converting it to a multiline list
68 # and then run sort -r over it.
69 # make sure we use ${ROOT} because otherwise stage-building will break
70 ALT="$(for i in $(echo ${ROOT}${myregex}); do echo ${i#${ROOT}}; done | sort -r)"
71 alternatives_makesym ${SYMLINK} ${ALT}
72 }
73
74 alternatives_makesym() {
75 local ALTERNATIVES=""
76 local SYMLINK=""
77 local alt pref
78
79 # usage: alternatives_makesym <resulting symlink> [alternative targets..]
80 SYMLINK=$1
81 # this trick removes the trailing / from ${ROOT}
82 pref=$(echo ${ROOT} | sed 's:/$::')
83 shift
84 ALTERNATIVES=$@
85
86 # step through given alternatives from first to last
87 # and if one exists, link it and finish.
88
89 for alt in ${ALTERNATIVES}; do
90 if [ -f "${pref}${alt}" ]; then
91 #are files in same directory?
92 if [ "${alt%/*}" = "${SYMLINK%/*}" ]
93 then
94 #yes; strip leading dirname from alt to create relative symlink
95 einfo "Linking ${alt} to ${pref}${SYMLINK} (relative)"
96 ln -sf ${alt##*/} ${pref}${SYMLINK}
97 else
98 #no; keep absolute path
99 einfo "Linking ${alt} to ${pref}${SYMLINK} (absolute)"
100 ln -sf ${pref}${alt} ${pref}${SYMLINK}
101 fi
102 break
103 fi
104 done
105
106 # report any errors
107 if [ ! -L ${pref}${SYMLINK} ]; then
108 ewarn "Unable to establish ${pref}${SYMLINK} symlink"
109 else
110 # we need to check for either the target being in relative path form
111 # or absolute path form
112 if [ ! -f "`dirname ${pref}${SYMLINK}`/`readlink ${pref}${SYMLINK}`" -a \
113 ! -f "`readlink ${pref}${SYMLINK}`" ]; then
114 ewarn "Removing dead symlink ${pref}${SYMLINK}"
115 rm -f ${pref}${SYMLINK}
116 fi
117 fi
118 }
119
120 # @FUNCTION: alernatives-pkg_postinst
121 # @DESCRIPTION:
122 # The alternatives pkg_postinst, this function will be exported
123 alternatives_pkg_postinst() {
124 if [ -n "${ALTERNATIVES}" -a -n "${SOURCE}" ]; then
125 alternatives_makesym ${SOURCE} ${ALTERNATIVES}
126 fi
127 }
128
129 # @FUNCTION: alternatives_pkg_postrm
130 # @DESCRIPTION:
131 # The alternatives pkg_postrm, this function will be exported
132 alternatives_pkg_postrm() {
133 if [ -n "${ALTERNATIVES}" -a -n "${SOURCE}" ]; then
134 alternatives_makesym ${SOURCE} ${ALTERNATIVES}
135 fi
136 }
137
138 EXPORT_FUNCTIONS pkg_postinst pkg_postrm

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