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Revision 1.7 - (hide annotations) (download)
Mon Nov 24 10:57:06 2003 UTC (11 years ago) by liquidx
Branch: MAIN
Changes since 1.6: +3 -4 lines
use ln -sf instead of detecting symlinks

1 liquidx 1.1 # Copyright 1999-2003 Gentoo Technologies, Inc.
2     # Distributed under the terms of the GNU General Public License v2
3 liquidx 1.7 # $Header: /home/cvsroot/gentoo-x86/eclass/alternatives.eclass,v 1.6 2003/11/01 18:33:58 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 liquidx 1.6 local SYMLINK REGEX ALT myregex
51     SYMLINK=$1
52 liquidx 1.1 REGEX=$2
53 liquidx 1.6 if [ "${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 liquidx 1.1 else
59 liquidx 1.6 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 liquidx 1.1 }
67    
68     alternatives_makesym() {
69     local ALTERNATIVES=""
70 liquidx 1.6 local SYMLINK=""
71     local alt pref
72 liquidx 1.1 # usage: alternatives_makesym <resulting symlink> [alternative targets..]
73 liquidx 1.6 SYMLINK=$1
74     pref=${ROOT:0:${#ROOT}-1}
75 liquidx 1.1 shift
76     ALTERNATIVES=$@
77    
78     # step through given alternatives from first to last
79     # and if one exists, link it and finish.
80    
81     for alt in ${ALTERNATIVES}; do
82 liquidx 1.6 if [ -f "${pref}${alt}" ]; then
83     einfo "Linking ${alt} to ${pref}${SYMLINK}"
84     #are files in same directory?
85     if [ "${alt%/*}" = "${SYMLINK%/*}" ]
86     then
87     #yes; strip leading dirname from alt to create relative symlink
88 liquidx 1.7 ln -sf ${alt##*/} ${pref}${SYMLINK}
89 liquidx 1.6 else
90     #no; keep absolute path
91 liquidx 1.7 ln -sf ${pref}${alt} ${pref}${SYMLINK}
92 liquidx 1.1 fi
93     break
94     fi
95     done
96    
97     # report any errors
98 liquidx 1.6 if [ ! -L ${pref}${SYMLINK} ]; then
99     ewarn "Unable to establish ${pref}${SYMLINK} symlink"
100     else
101     # we need to check for either the target being in relative path form
102     # or absolute path form
103     if [ ! -f "`dirname ${pref}${SYMLINK}`/`readlink ${pref}${SYMLINK}`" -a \
104     ! -f "`readlink ${pref}${SYMLINK}`" ]; then
105     ewarn "${pref}${SYMLINK} is a dead symlink."
106     fi
107 liquidx 1.1 fi
108     }
109    
110     alternatives_pkg_postinst() {
111     if [ -n "${ALTERNATIVES}" -a -n "${SOURCE}" ]; then
112     alternatives_makesym ${SOURCE} ${ALTERNATIVES}
113     fi
114     }
115    
116     alternatives_pkg_postrm() {
117     if [ -n "${ALTERNATIVES}" -a -n "${SOURCE}" ]; then
118     alternatives_makesym ${SOURCE} ${ALTERNATIVES}
119     fi
120     }
121    
122     EXPORT_FUNCTIONS pkg_postinst pkg_postrm

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