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 "$@"