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Revision 1.2 - (hide annotations) (download)
Tue Oct 7 20:26:50 2003 UTC (10 years, 9 months ago) by liquidx
Branch: MAIN
Changes since 1.1: +6 -3 lines
fixed issues with ${ROOT} on auto_makesym

1 liquidx 1.1 # Copyright 1999-2003 Gentoo Technologies, Inc.
2     # Distributed under the terms of the GNU General Public License v2
3 liquidx 1.2 # $Header: /home/cvsroot/gentoo-x86/eclass/alternatives.eclass,v 1.1 2003/10/07 17:21:40 liquidx Exp $
4 liquidx 1.1
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 SOURCE REGEX ALT
51     local unsorted
52     SOURCE=$1
53     REGEX=$2
54    
55 liquidx 1.2 ALT="`ls -1 --color=never ${ROOT}${REGEX} | sed -e "s:^${ROOT}::" | sort -r | xargs`"
56     einfo "alternatives: $ROOT $REGEX $ALT"
57 liquidx 1.1 if [ -n "${ALT}" ]; then
58     alternatives_makesym ${SOURCE} ${ALT}
59     else
60     eerror "regex ${REGEX} doesn't match any files."
61     fi
62     }
63    
64     alternatives_makesym() {
65     local ALTERNATIVES=""
66     local SOURCE=""
67    
68     # usage: alternatives_makesym <resulting symlink> [alternative targets..]
69     SOURCE=$1
70     shift
71     ALTERNATIVES=$@
72    
73     # step through given alternatives from first to last
74     # and if one exists, link it and finish.
75    
76     for alt in ${ALTERNATIVES}; do
77     if [ -f "${ROOT}${alt}" ]; then
78     if [ -L "${ROOT}${SOURCE}" ]; then
79     rm -f ${ROOT}${SOURCE}
80     fi
81     einfo "Linking ${alt} to ${SOURCE}"
82 liquidx 1.2 # we do this instead of ${ROOT}${SOURCE} because if
83     # ROOT=/, then a symlink to //usr/bin/python confuses distutils
84     cd ${ROOT}; ln -s ${alt} ${SOURCE}
85 liquidx 1.1 break
86     fi
87     done
88    
89     # report any errors
90     if [ ! -L ${ROOT}${SOURCE} ]; then
91     ewarn "Unable to establish ${SOURCE} symlink"
92     elif [ ! -f "`readlink ${ROOT}${SOURCE}`" -a ! -f "${ROOT}`readlink ${ROOT}${SOURE}`" ]; then
93     ewarn "${SOURCE} is a dead symlink."
94     fi
95     }
96    
97     alternatives_pkg_postinst() {
98     if [ -n "${ALTERNATIVES}" -a -n "${SOURCE}" ]; then
99     alternatives_makesym ${SOURCE} ${ALTERNATIVES}
100     fi
101     }
102    
103     alternatives_pkg_postrm() {
104     if [ -n "${ALTERNATIVES}" -a -n "${SOURCE}" ]; then
105     alternatives_makesym ${SOURCE} ${ALTERNATIVES}
106     fi
107     }
108    
109     EXPORT_FUNCTIONS pkg_postinst pkg_postrm

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