iankelling.org Git - lnf/blob - lnf

   1 #!/bin/bash
   2 # Copyright (C) 2014-2016 Ian Kelling
   3 # This program is under GPL v. 3 or later, see <http://www.gnu.org/licenses/>
   4
   5 _lnf_existing_link() {
   6   local target dest_file dest_dir
   7   target="$1"
   8   dest_file="$2"
   9   dest_dir="$3"
  10   if [[ -L $dest_file ]]; then
  11     if [[ $(readlink $dest_file) == "$target" ]]; then
  12       # Leave the link in place, but make sure it's
  13       # owner & group is as if we created it.
  14       # links all get 777 perms, so
  15       # we already know that is right.
  16
  17       # test for setgid.
  18       if [[ $(stat -L -c%a "$dest_dir") == 2??? ]]; then
  19         grp=$(stat -L -c%g "$dest_dir") || return $?
  20       else
  21         grp=$(id -g) || return $?
  22       fi
  23       if [[ $EUID == 0 && $(stat -c%u "$dest_file") != 0 ]]; then
  24         chown -h 0:$grp "$dest_file" || return $?
  25       elif [[ $(stat -c%g "$dest_file") != "$grp" ]]; then
  26         chgrp -h $grp "$dest_file" || return $?
  27       fi
  28       do_exit=true
  29       return 0
  30     fi
  31     to_remove+=("$dest_file")
  32   elif [[ -e $dest_file ]]; then
  33     to_remove+=("$dest_file")
  34   fi
  35   to_link+=("$target")
  36 }
  37 lnf() {
  38   local help="Usage:
  39        lnf [OPTIONS] -T TARGET LINK_NAME     (1st form)
  40        lnf [OPTIONS] TARGET                  (2nd form)
  41        lnf [OPTIONS] TARGET... DIRECTORY     (3rd form)
  42 Create symlinks forcefully
  43
  44 If the link already exists, make it's ownership be the same as if it was
  45 newly created (only chown if we are root).  Removes existing files using
  46 trash-put or rm -rf if it is not available, or if trash-put fails due to a
  47 limitation such as a cross-filesystem link. Create directory of link if
  48 needed. Slightly more restrictive arguments than ln.
  49
  50 In the 1st form, create a link to TARGET with the name LINK_NAME.  In the 2nd
  51 form, create a link to TARGET in the current directory.  In the 3rd form, create
  52 links to each TARGET in DIRECTORY.
  53
  54 -n|--dry-run     Do verbose dry run.
  55 -v|--verbose     Print commands which modify the filesystem.
  56 -h|--help        Print help and exit.
  57 "
  58
  59
  60   local temp nodir
  61   local verbose=false
  62   local dry_run=false
  63   local do_exit=false
  64   temp=$(getopt -l help,dry-run,verbose hnTv "$@") || usage 1
  65   eval set -- "$temp"
  66   while true; do
  67     case $1 in
  68       -n|--dry-run) dry_run=true; verbose=true; shift ;;
  69       -T) nodir=-T; shift ;;
  70       -v|--verbose) verbose=true; shift ;;
  71       -h|--help) echo "$help"; return 0 ;;
  72       --) shift; break ;;
  73       *) echo "$0: Internal error! unexpected args: $*" ; exit 1 ;;
  74     esac
  75   done
  76
  77   if (( $# == 0 )); then
  78     echo "$help"
  79     return 1
  80   fi
  81
  82   if [[ $nodir ]]; then
  83     if (( $# != 2 )); then
  84       echo "lnf: error: expected 2 arguments with -T flag. Got $#"
  85       return 1
  86     fi
  87   fi
  88
  89   local reset_extglob=false
  90   ! shopt extglob >/dev/null && reset_extglob=true
  91   shopt -s extglob
  92
  93
  94   local -a to_remove to_link
  95   local x ret prefix dest_dir grp target
  96   local mkdir=false
  97
  98   if [[ $nodir ]]; then
  99     dest_file="$2"
 100     dest_dir="$(dirname "$dest_file")"
 101     _lnf_existing_link "$1" "$dest_file" "$dest_dir" || return $?
 102     if $do_exit; then return 0; fi
 103     if [[ ! -d $dest_dir ]]; then
 104       mkdir=true
 105       if [[ -e $dest_dir || -L $dest_dir ]]; then
 106         to_remove+=("$dest_dir")
 107       fi
 108     fi
 109     to_link+=("$dest_file")
 110   elif (( $# >= 2 )); then
 111     dest_dir="${!#}"
 112     if [[ -d $dest_dir ]]; then
 113       prefix="$dest_dir" # last arg
 114       for target in "${@:1:$(( $# - 1 ))}"; do # all but last arg
 115         # Remove 1 or more trailing slashes, using.
 116         dest_file="${target%%+(/)}"
 117         # remove any leading directory components, add prefix
 118         dest_file="$prefix/${target##*/}"
 119         _lnf_existing_link "$target" "$dest_file" "$dest_dir"
 120       done
 121     else
 122       to_link+=("${@:1:$(( $# - 1 ))}")
 123       mkdir=true
 124     fi
 125     if (( ${#to_link[@]} == 0 )); then
 126       return 0
 127     fi
 128     to_link+=("$dest_dir")
 129   elif  [[ $# -eq 1 ]]; then
 130     dest_file="${1##*/}"
 131     _lnf_existing_link "$1" "$dest_file" . || return $?
 132     if $do_exit; then return 0; fi
 133   fi
 134   if (( ${#to_remove[@]} >= 1 )); then
 135     if type -P trash-put >/dev/null; then
 136       if $verbose; then
 137         echo "lnf: trash-put -- ${to_remove[*]}"
 138       fi
 139       if ! $dry_run; then
 140         trash-put -- "${to_remove[@]}" || ret=$?
 141       fi
 142       # trash-put will fail to trash a link that goes across filesystems (72),
 143       # and for empty files (74)
 144       # so revert to rm -rf in that case
 145       if [[ $ret == 72 ]]; then
 146         echo "lnf: using rm -rf to overcome cross filesystem trash-put limitation"
 147         rm -rf -- "${to_remove[@]}" || return $?
 148       elif [[ $ret == 74 ]]; then
 149         echo "lnf: using rm -rf to overcome empty file & hardlink trash-put limitation"
 150         rm -rf -- "${to_remove[@]}"
 151       elif [[ $ret && $ret != 0 ]]; then
 152         return $x
 153       fi
 154     else
 155       if $verbose; then
 156         echo "lnf: rm -rf -- ${to_remove[*]}"
 157       fi
 158       if ! $dry_run; then
 159         rm -rf -- "${to_remove[@]}"
 160       fi
 161     fi
 162   fi
 163
 164   $reset_extglob && shopt -u extglob
 165
 166   if $mkdir; then
 167     if $verbose; then
 168       echo "lnf: mkdir -p $dest_dir"
 169     fi
 170
 171     if ! $dry_run && ! mkdir -p "$dest_dir"; then
 172       echo "lnf error: failed to make directory $dest_dir"
 173       return 1
 174     fi
 175   fi
 176
 177   if $verbose; then
 178     echo "lnf: ln -s $nodir -- ${to_link[*]}"
 179   fi
 180   if ! $dry_run; then
 181     ln -s $nodir -- "${to_link[@]}"
 182   fi
 183 }
 184 lnf "$@"