/[gentoo-x86]/eclass/alternatives.eclass
Gentoo

Contents of /eclass/alternatives.eclass

Parent Directory Parent Directory | Revision Log Revision Log


Revision 1.14 - (show annotations) (download)
Tue May 15 15:20:59 2007 UTC (6 years, 11 months ago) by ulm
Branch: MAIN
Changes since 1.13: +3 -2 lines
Fix alternatives.eclass to remove dead symlinks.

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 1.13 2006/03/25 02:37:04 agriffis 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 "Removing dead symlink ${pref}${SYMLINK}"
108 rm -f ${pref}${SYMLINK}
109 fi
110 fi
111 }
112
113 alternatives_pkg_postinst() {
114 if [ -n "${ALTERNATIVES}" -a -n "${SOURCE}" ]; then
115 alternatives_makesym ${SOURCE} ${ALTERNATIVES}
116 fi
117 }
118
119 alternatives_pkg_postrm() {
120 if [ -n "${ALTERNATIVES}" -a -n "${SOURCE}" ]; then
121 alternatives_makesym ${SOURCE} ${ALTERNATIVES}
122 fi
123 }
124
125 EXPORT_FUNCTIONS pkg_postinst pkg_postrm

  ViewVC Help
Powered by ViewVC 1.1.20