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Revision 1.6 - (show annotations) (download)
Sat Nov 1 18:33:58 2003 UTC (10 years, 8 months ago) by liquidx
Branch: MAIN
Changes since 1.5: +39 -24 lines
reintroducing relative linking in alternatives, this time the reverse sorting is fixed via some bash hackery. also some minor fixes in python.eclass

1 # Copyright 1999-2003 Gentoo Technologies, Inc.
2 # Distributed under the terms of the GNU General Public License v2
3 # $Header: /home/cvsroot/gentoo-x86/eclass/alternatives.eclass,v 1.4 2003/11/01 17:35:59 liquidx 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 if 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 # $ALTERNATIVES is a list of alternatives. Second way is the use the function
23 # alternatives_makesym() like the example below.
24 #
25 # Example:
26 #
27 # pkg_postinst() {
28 # alternatives_makesym "/usr/bin/python" "/usr/bin/python2.3" "/usr/bin/python2.2"
29 # }
30 #
31 # The above example will create a symlink at /usr/bin/python to either
32 # /usr/bin/python2.3 or /usr/bin/python2.2. It will choose python2.3 over
33 # python2.2 if both exist.
34 #
35 # Alternatively, you can use this function:
36 #
37 # pkg_postinst() {
38 # alternatives_auto_makesym "/usr/bin/python" "/usr/bin/python[0-9].[0-9]"
39 # }
40 #
41 # This will use bash pathname expansion to fill a list of alternatives it can
42 # link to. It is probably more robust against version upgrades. You should
43 # consider using this unless you are want to do something special.
44 #
45 ECLASS="alternatives"
46 INHERITED="$INHERITED $ECLASS"
47
48 # automatic deduction based on a symlink and a regex mask
49 alternatives_auto_makesym() {
50 local SYMLINK REGEX ALT myregex
51 SYMLINK=$1
52 REGEX=$2
53 if [ "${REGEX:0:1}" != "/" ]
54 then
55 #not an absolute path:
56 #inherit the root directory of our main link path for our regex search
57 myregex="${SYMLINK%/*}/${REGEX}"
58 else
59 myregex=${REGEX}
60 fi
61
62 # sort a space delimited string by converting it to a multiline list
63 # and then run sort -r over it.
64 ALT="$(for i in $(echo ${myregex}); do echo $i; done | sort -r)"
65 alternatives_makesym ${SYMLINK} ${ALT}
66 }
67
68 alternatives_makesym() {
69 local ALTERNATIVES=""
70 local SYMLINK=""
71 local alt pref
72 # usage: alternatives_makesym <resulting symlink> [alternative targets..]
73 SYMLINK=$1
74 pref=${ROOT:0:${#ROOT}-1}
75 shift
76 ALTERNATIVES=$@
77
78 # step through given alternatives from first to last
79 # and if one exists, link it and finish.
80
81 for alt in ${ALTERNATIVES}; do
82 if [ -f "${pref}${alt}" ]; then
83 einfo "Linking ${alt} to ${pref}${SYMLINK}"
84 [ -L "${pref}${SYMLINK}" ] && rm -f ${pref}${SYMLINK}
85 #are files in same directory?
86 if [ "${alt%/*}" = "${SYMLINK%/*}" ]
87 then
88 #yes; strip leading dirname from alt to create relative symlink
89 ln -s ${alt##*/} ${pref}${SYMLINK}
90 else
91 #no; keep absolute path
92 ln -s ${pref}${alt} ${pref}${SYMLINK}
93 fi
94 break
95 fi
96 done
97
98 # report any errors
99 if [ ! -L ${pref}${SYMLINK} ]; then
100 ewarn "Unable to establish ${pref}${SYMLINK} symlink"
101 else
102 # we need to check for either the target being in relative path form
103 # or absolute path form
104 if [ ! -f "`dirname ${pref}${SYMLINK}`/`readlink ${pref}${SYMLINK}`" -a \
105 ! -f "`readlink ${pref}${SYMLINK}`" ]; then
106 ewarn "${pref}${SYMLINK} is a dead symlink."
107 fi
108 fi
109 }
110
111 alternatives_pkg_postinst() {
112 if [ -n "${ALTERNATIVES}" -a -n "${SOURCE}" ]; then
113 alternatives_makesym ${SOURCE} ${ALTERNATIVES}
114 fi
115 }
116
117 alternatives_pkg_postrm() {
118 if [ -n "${ALTERNATIVES}" -a -n "${SOURCE}" ]; then
119 alternatives_makesym ${SOURCE} ${ALTERNATIVES}
120 fi
121 }
122
123 EXPORT_FUNCTIONS pkg_postinst pkg_postrm

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