utils/update-alternatives.in

   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@opkglibdir@/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         prio=`sed -ne "1!p" $ad/$name | sed -e "s/\(.*\) \(.*\)/\2 \1/g" | sort -nr | head -n 1 | sed 's/ [^ ]*$//'`
  99         if [ -z "$prio" ]; then
 100                 echo "update-alternatives: removing $link as no more alternatives exist for it"
 101                 rm $ad/$name
 102                 if [ -L $link ]; then
 103                         rm $link
 104                 fi
 105                 return 0
 106         fi
 107
 108         ## Find last line with highest priority.
 109         path=`grep "${prio}$" $ad/$name | tail -n 1 | sed 's/ [^ ]*$//'`
 110
 111         if [ ! -e $link -o -L $link ]; then
 112                 local link_dir=`dirname $link`
 113                 if [ ! -d $link_dir ]; then
 114                         mkdir -p $link_dir
 115                 fi
 116                 if [ -h $link -a -d $link ]; then
 117                         # If $link exists and the target is a directory,
 118                         # 'ln -sf $path $link' doesn't replace the link to
 119                         # that directory, it creates new link inside.
 120                         echo "update-alternatives: Removing $link".
 121                         rm -f $link
 122                 fi
 123                 ln -sf $path $link
 124                 echo "update-alternatives: Linking $link to $path"
 125         else
 126                 echo "update-alternatives: Error: not linking $link to $path since $link exists and is not a link"
 127                 return 1
 128         fi
 129
 130         return 0
 131 }
 132
 133 do_install() {
 134         if [ $# -lt 4 ]; then
 135                 usage "--install needs <link> <name> <path> <priority>"
 136         fi
 137         local link="$1"
 138         local name="$2"
 139         local path="$3"
 140         local priority="$4"
 141
 142         path=`echo $path | sed 's|/\+|/|g'`
 143
 144         # This is a bad hack, but I haven't thought of a cleaner solution yet...
 145         [ -n "$OPKG_OFFLINE_ROOT" ] && path=`echo $path | sed "s|^$OPKG_OFFLINE_ROOT/*|/|"`
 146
 147         register_alt $name $link
 148         add_alt $name $path $priority
 149         find_best_alt $name
 150 }
 151
 152 do_remove() {
 153        if [ $# -lt 2 ]; then
 154                 usage "--remove needs <name> <path>"
 155         fi
 156         local name="$1"
 157         local path="$2"
 158
 159         path=`echo $path | sed 's|/\+|/|g'`
 160
 161         # This is a bad hack, but I haven't thought of a cleaner solution yet...
 162         [ -n "$OPKG_OFFLINE_ROOT" ] && path=`echo $path | sed "s|^$OPKG_OFFLINE_ROOT/*|/|"`
 163
 164         remove_alt $name $path
 165         find_best_alt $name
 166 }
 167
 168 ###
 169 # update-alternatives "main"
 170 ###
 171
 172 while [ $# -gt 0 ]; do
 173         arg="$1"
 174         shift
 175
 176         case $arg in
 177         --help)
 178                 usage "help:"
 179                 exit 0
 180                 ;;
 181         --install)
 182                 do_install $*
 183                 exit $?
 184                 ;;
 185         --remove)
 186                 do_remove $*
 187                 exit $?
 188                 ;;
 189         *)
 190                 usage "unknown argument \`$arg'"
 191                 ;;
 192         esac
 193 done
 194
 195 usage "at least one of --install or --remove must appear"
 196
 197 exit 0