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+=("$target")
  36 }
  37 lnf() {
  38   local help="Usage:
  39        lnf [OPTIONS] -T TARGET LINK_NAME     (1st form)
  40        lnf [OPTIONS] TARGET                  (2nd form)
  41        lnf [OPTIONS] TARGET... DIRECTORY     (3rd form)
  42 Create symlinks forcefully
  43
  44 If the link already exists, make it's ownership be the same as if it was
  45 newly created (only chown if we are root).  Removes existing files using
  46 rm -rf. Create directory of link if needed. Slightly more restrictive
  47 arguments than ln.
  48
  49 In the 1st form, create a link to TARGET with the name LINK_NAME.  In the 2nd
  50 form, create a link to TARGET in the current directory.  In the 3rd form, create
  51 links to each TARGET in DIRECTORY.
  52
  53 -n|--dry-run     Do verbose dry run.
  54 -v|--verbose     Print commands which modify the filesystem.
  55 -h|--help        Print help and exit.
  56 "
  57
  58
  59   local temp nodir
  60   local verbose=false
  61   local dry_run=false
  62   local do_exit=false
  63   temp=$(getopt -l help,dry-run,verbose hnTv "$@") || usage 1
  64   eval set -- "$temp"
  65   while true; do
  66     case $1 in
  67       -n|--dry-run) dry_run=true; verbose=true; shift ;;
  68       -T) nodir=-T; shift ;;
  69       -v|--verbose) verbose=true; shift ;;
  70       -h|--help) echo "$help"; return 0 ;;
  71       --) shift; break ;;
  72       *) echo "$0: Internal error! unexpected args: $*" ; exit 1 ;;
  73     esac
  74   done
  75
  76   if (( $# == 0 )); then
  77     echo "$help"
  78     return 1
  79   fi
  80
  81   if [[ $nodir ]]; then
  82     if (( $# != 2 )); then
  83       echo "lnf: error: expected 2 arguments with -T flag. Got $#"
  84       return 1
  85     fi
  86   fi
  87
  88   local reset_extglob=false
  89   ! shopt extglob >/dev/null && reset_extglob=true
  90   shopt -s extglob
  91
  92
  93   local -a to_remove to_link
  94   local ret prefix dest_dir grp target
  95   local mkdir=false
  96
  97   if [[ $nodir ]]; then
  98     dest_file="$2"
  99     dest_dir="$(dirname "$dest_file")"
 100     _lnf_existing_link "$1" "$dest_file" "$dest_dir" || return $?
 101     if $do_exit; then return 0; fi
 102     if [[ ! -d $dest_dir ]]; then
 103       mkdir=true
 104       if [[ -e $dest_dir || -L $dest_dir ]]; then
 105         to_remove+=("$dest_dir")
 106       fi
 107     fi
 108     to_link+=("$dest_file")
 109   elif (( $# >= 2 )); then
 110     dest_dir="${!#}"
 111     if [[ -d $dest_dir ]]; then
 112       prefix="$dest_dir" # last arg
 113       for target in "${@:1:$(( $# - 1 ))}"; do # all but last arg
 114         # Remove 1 or more trailing slashes, using.
 115         dest_file="${target%%+(/)}"
 116         # remove any leading directory components, add prefix
 117         dest_file="$prefix/${target##*/}"
 118         _lnf_existing_link "$target" "$dest_file" "$dest_dir"
 119       done
 120     else
 121       to_link+=("${@:1:$(( $# - 1 ))}")
 122       mkdir=true
 123     fi
 124     if (( ${#to_link[@]} == 0 )); then
 125       return 0
 126     fi
 127     to_link+=("$dest_dir")
 128   elif  [[ $# -eq 1 ]]; then
 129     dest_file="${1##*/}"
 130     _lnf_existing_link "$1" "$dest_file" . || return $?
 131     if $do_exit; then return 0; fi
 132   fi
 133   if (( ${#to_remove[@]} >= 1 )); then
 134     if $verbose; then
 135       echo "lnf: rm -rf -- ${to_remove[*]}"
 136     fi
 137     if ! $dry_run; then
 138       rm -rf -- "${to_remove[@]}"
 139     fi
 140   fi
 141
 142   $reset_extglob && shopt -u extglob
 143
 144   if $mkdir; then
 145     if $verbose; then
 146       echo "lnf: mkdir -p $dest_dir"
 147     fi
 148
 149     if ! $dry_run && ! mkdir -p "$dest_dir"; then
 150       echo "lnf error: failed to make directory $dest_dir"
 151       return 1
 152     fi
 153   fi
 154
 155   if $verbose; then
 156     echo "lnf: ln -s $nodir -- ${to_link[*]}"
 157   fi
 158   if ! $dry_run; then
 159     ln -s $nodir -- "${to_link[@]}"
 160   fi
 161 }
 162 lnf "$@"