utils/update-alternatives

   1 #!/bin/sh
   2 # update-alternatives
   3 #
   4 # Copyright (C) 2001 Carl D. Worth
   5 #
   6 # This program was inspired by the Debian update-alternatives program
   7 # which is Copyright (C) 1995 Ian Jackson. This version of
   8 # update-alternatives is command-line compatible with Debian's for a
   9 # subset of the options, (only --install, --remove, and --help)
  10 #
  11 # This program is free software; you can redistribute it and/or modify
  12 # it under the terms of the GNU General Public License as published by
  13 # the Free Software Foundation; either version 2, or (at your option)
  14 # any later version.
  15 #
  16 # This program is distributed in the hope that it will be useful,
  17 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  18 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19 # GNU General Public License for more details.
  20
  21 set -e
  22
  23 # admin dir
  24 ad="$OPKG_OFFLINE_ROOT/usr/lib/opkg/alternatives"
  25
  26 usage() {
  27         echo "update-alternatives: $*
  28
  29 Usage: update-alternatives --install <link> <name> <path> <priority>
  30        update-alternatives --remove <name> <path>
  31        update-alternatives --help
  32 <link> is the link pointing to the provided path (ie. /usr/bin/foo).
  33 <name> is the name in $ad/alternatives (ie. foo)
  34 <path> is the name referred to (ie. /usr/bin/foo-extra-spiffy)
  35 <priority> is an integer; options with higher numbers are chosen.
  36 " >&2
  37         exit 2
  38 }
  39
  40 quit() {
  41         echo "update-alternatives: $*" >&2
  42         exit 2
  43 }
  44
  45 register_alt() {
  46         [ $# -lt 2 ] && return 1
  47         local name="$1"
  48         local link="$2"
  49
  50         if [ ! -d $ad ]; then
  51                 mkdir -p $ad
  52         fi
  53
  54         if [ -e "$ad/$name" ]; then
  55                 local olink=`head -n 1 $ad/$name`
  56                 if [ "$link" != "$olink" ]; then
  57                         echo "update-alternatives: Error: cannot register alternative $name to $link since it is already registered to $olink" >&2
  58                         return 1
  59                 fi
  60         else
  61                 echo "$link" > "$ad/$name"
  62         fi
  63
  64         return 0
  65 }
  66
  67 protect_slashes() {
  68         sed -e 's/\//\\\//g'
  69 }
  70
  71 remove_alt() {
  72         [ $# -lt 2 ] && return 1
  73         local name="$1"
  74         local path="$2"
  75
  76         [ ! -f $ad/$name ] && return 0
  77
  78         path=`echo $path | protect_slashes`
  79         sed -ne "/^$path\>.*/!p" $ad/$name > $ad/$name.new
  80         mv $ad/$name.new $ad/$name
  81 }
  82
  83 add_alt() {
  84         [ $# -lt 3 ] && return 1
  85         local name="$1"
  86         local path="$2"
  87         local priority="$3"
  88         remove_alt $name $path
  89         echo "$path $priority" >> $ad/$name
  90 }
  91
  92 find_best_alt() {
  93         [ $# -lt 1 ] && return 1
  94         [ ! -f $ad/$name ] && return 0
  95
  96         link=$OPKG_OFFLINE_ROOT/`head -n 1 $ad/$name`
  97
  98 ##      path=`sed -ne "1!p" $ad/$name | sort -nr -k2 | head -1 | sed 's/ .*//'`
  99 ## busybox safe:
 100         path=`sed -ne "1!p" $ad/$name | sed -e "s/\(.*\) \(.*\)/\2 \1/g" | sort -nr | head -n 1 | sed 's/[^ ]* //'`
 101         if [ -z "$path" ]; then
 102                 echo "update-alternatives: removing $link as no more alternatives exist for it"
 103                 rm $ad/$name
 104                 if [ -L $link ]; then
 105                         rm $link
 106                 fi
 107                 return 0
 108         fi
 109
 110         if [ ! -e $link -o -L $link ]; then
 111                 local link_dir=`dirname $link`
 112                 if [ ! -d $link_dir ]; then
 113                         mkdir -p $link_dir
 114                 fi
 115                 ln -sf $path $link
 116                 echo "update-alternatives: Linking $link to $path"
 117         else
 118                 echo "update-alternatives: Error: not linking $link to $path since $link exists and is not a link"
 119                 return 1
 120         fi
 121
 122         return 0
 123 }
 124
 125 do_install() {
 126         if [ $# -lt 4 ]; then
 127                 usage "--install needs <link> <name> <path> <priority>"
 128         fi
 129         local link="$1"
 130         local name="$2"
 131         local path="$3"
 132         local priority="$4"
 133
 134         path=`echo $path | sed 's|/\+|/|g'`
 135
 136         # This is a bad hack, but I haven't thought of a cleaner solution yet...
 137         [ -n "$OPKG_OFFLINE_ROOT" ] && path=`echo $path | sed "s|^$OPKG_OFFLINE_ROOT/*|/|"`
 138
 139         register_alt $name $link
 140         add_alt $name $path $priority
 141         find_best_alt $name
 142 }
 143
 144 do_remove() {
 145        if [ $# -lt 2 ]; then
 146                 usage "--remove needs <name> <path>"
 147         fi
 148         local name="$1"
 149         local path="$2"
 150
 151         path=`echo $path | sed 's|/\+|/|g'`
 152
 153         # This is a bad hack, but I haven't thought of a cleaner solution yet...
 154         [ -n "$OPKG_OFFLINE_ROOT" ] && path=`echo $path | sed "s|^$OPKG_OFFLINE_ROOT/*|/|"`
 155
 156         remove_alt $name $path
 157         find_best_alt $name
 158 }
 159
 160 ###
 161 # update-alternatives "main"
 162 ###
 163
 164 while [ $# -gt 0 ]; do
 165         arg="$1"
 166         shift
 167
 168         case $arg in
 169         --help)
 170                 usage "help:"
 171                 exit 0
 172                 ;;
 173         --install)
 174                 do_install $*
 175                 exit $?
 176                 ;;
 177         --remove)
 178                 do_remove $*
 179                 exit $?
 180                 ;;
 181         *)
 182                 usage "unknown argument \`$arg'"
 183                 ;;
 184         esac
 185 done
 186
 187 usage "at least one of --install or --remove must appear"
 188
 189 exit 0