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Revision 1.18 - (show annotations) (download)
Sat Sep 21 01:03:42 2013 UTC (11 months ago) by ottxor
Branch: MAIN
CVS Tags: HEAD
Changes since 1.17: +10 -6 lines
added prefix support

1 # Copyright 1999-2013 Gentoo Foundation
2 # Distributed under the terms of the GNU General Public License v2
3 # $Header: /var/cvsroot/gentoo-x86/eclass/alternatives.eclass,v 1.17 2011/08/22 04:46:31 vapier Exp $
4
5 # @ECLASS: alternatives.eclass
6 # @AUTHOR:
7 # Original author: Alastair Tse <liquidx@gentoo.org> (03 Oct 2003)
8 # @BLURB: Creates symlink to the latest version of multiple slotted packages.
9 # @DESCRIPTION:
10 # When a package is SLOT'ed, very often we need to have a symlink to the
11 # latest version. However, depending on the order the user has merged them,
12 # more often than not, the symlink maybe clobbered by the older versions.
13 #
14 # This eclass provides a convenience function that needs to be given a
15 # list of alternatives (descending order of recent-ness) and the symlink.
16 # It will choose the latest version it can find installed and create
17 # the desired symlink.
18 #
19 # There are two ways to use this eclass. First is by declaring two variables
20 # $SOURCE and $ALTERNATIVES where $SOURCE is the symlink to be created and
21 # $ALTERNATIVES is a list of alternatives. Second way is the use the function
22 # alternatives_makesym() like the example below.
23 # @EXAMPLE:
24 # pkg_postinst() {
25 # alternatives_makesym "/usr/bin/python" "/usr/bin/python2.3" "/usr/bin/python2.2"
26 # }
27 #
28 # The above example will create a symlink at /usr/bin/python to either
29 # /usr/bin/python2.3 or /usr/bin/python2.2. It will choose python2.3 over
30 # python2.2 if both exist.
31 #
32 # Alternatively, you can use this function:
33 #
34 # pkg_postinst() {
35 # alternatives_auto_makesym "/usr/bin/python" "/usr/bin/python[0-9].[0-9]"
36 # }
37 #
38 # This will use bash pathname expansion to fill a list of alternatives it can
39 # link to. It is probably more robust against version upgrades. You should
40 # consider using this unless you are want to do something special.
41
42 # @ECLASS-VARIABLE: SOURCE
43 # @DEFAULT_UNSET
44 # @DESCRIPTION:
45 # The symlink to be created
46
47 # @ECLASS-VARIABLE: ALTERNATIVES
48 # @DEFAULT_UNSET
49 # @DESCRIPTION:
50 # The list of alternatives
51
52 # @FUNCTION: alternatives_auto_makesym
53 # @DESCRIPTION:
54 # automatic deduction based on a symlink and a regex mask
55 alternatives_auto_makesym() {
56 has "${EAPI:-0}" 0 1 2 && ! use prefix && EROOT="${ROOT}"
57 local SYMLINK REGEX ALT myregex
58 SYMLINK=$1
59 REGEX=$2
60 if [ "${REGEX:0:1}" != "/" ]
61 then
62 #not an absolute path:
63 #inherit the root directory of our main link path for our regex search
64 myregex="${SYMLINK%/*}/${REGEX}"
65 else
66 myregex=${REGEX}
67 fi
68
69 # sort a space delimited string by converting it to a multiline list
70 # and then run sort -r over it.
71 # make sure we use ${EROOT} because otherwise stage-building will break
72 ALT="$(for i in $(echo ${EROOT}${myregex}); do echo ${i#${EROOT}}; done | sort -r)"
73 alternatives_makesym ${SYMLINK} ${ALT}
74 }
75
76 alternatives_makesym() {
77 has "${EAPI:-0}" 0 1 2 && ! use prefix && EPREFIX=
78 local ALTERNATIVES=""
79 local SYMLINK=""
80 local alt pref
81
82 # usage: alternatives_makesym <resulting symlink> [alternative targets..]
83 # make sure it is in the prefix, allow it already to be in the prefix
84 SYMLINK=${EPREFIX}/${1#${EPREFIX}}
85 # this trick removes the trailing / from ${ROOT}
86 pref=${ROOT%/}
87 shift
88 ALTERNATIVES=$@
89
90 # step through given alternatives from first to last
91 # and if one exists, link it and finish.
92
93 for alt in ${ALTERNATIVES}; do
94 alt=${EPREFIX}/${alt#${EPREFIX}}
95 if [ -f "${pref}${alt}" ]; then
96 #are files in same directory?
97 if [ "${alt%/*}" = "${SYMLINK%/*}" ]
98 then
99 #yes; strip leading dirname from alt to create relative symlink
100 einfo "Linking ${alt} to ${pref}${SYMLINK} (relative)"
101 ln -sf ${alt##*/} ${pref}${SYMLINK}
102 else
103 #no; keep absolute path
104 einfo "Linking ${alt} to ${pref}${SYMLINK} (absolute)"
105 ln -sf ${pref}${alt} ${pref}${SYMLINK}
106 fi
107 break
108 fi
109 done
110
111 # report any errors
112 if [ ! -L ${pref}${SYMLINK} ]; then
113 ewarn "Unable to establish ${pref}${SYMLINK} symlink"
114 else
115 # we need to check for either the target being in relative path form
116 # or absolute path form
117 if [ ! -f "`dirname ${pref}${SYMLINK}`/`readlink ${pref}${SYMLINK}`" -a \
118 ! -f "`readlink ${pref}${SYMLINK}`" ]; then
119 ewarn "Removing dead symlink ${pref}${SYMLINK}"
120 rm -f ${pref}${SYMLINK}
121 fi
122 fi
123 }
124
125 # @FUNCTION: alernatives-pkg_postinst
126 # @DESCRIPTION:
127 # The alternatives pkg_postinst, this function will be exported
128 alternatives_pkg_postinst() {
129 if [ -n "${ALTERNATIVES}" -a -n "${SOURCE}" ]; then
130 alternatives_makesym ${SOURCE} ${ALTERNATIVES}
131 fi
132 }
133
134 # @FUNCTION: alternatives_pkg_postrm
135 # @DESCRIPTION:
136 # The alternatives pkg_postrm, this function will be exported
137 alternatives_pkg_postrm() {
138 if [ -n "${ALTERNATIVES}" -a -n "${SOURCE}" ]; then
139 alternatives_makesym ${SOURCE} ${ALTERNATIVES}
140 fi
141 }
142
143 EXPORT_FUNCTIONS pkg_postinst pkg_postrm

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