summaryrefslogtreecommitdiff
path: root/bin/hstow
blob: 1c640425021ba9860d750e10cb895d14cae77cb7 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
#!/bin/sh

# hstow -- POSIX sh minimal reimplementation of GNU Stow for dotfiles
#
# Copyright (C) 2022  Sean Whitton <spwhitton@spwhitton.name>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or (at
# your option) any later version.
#
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
# General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

# The point of this script is to obtain minimally functional dotfiles
# handling in one's home directory on even machines that lack a Perl
# interpreter.  As such, many of GNU Stow's more advanced features are
# not reimplemented.  Git depends on Perl, for now, but my two methods
# for deploying my dotfiles to remote machines -- my INSINUATE-DOTFILES
# Consfigurator property and 'insinuate-dotfiles' shell script -- do not
# depend on having Git on the remote side.  See also 'bstraph' script.
#
# We completely skip filenames containing control characters, including
# newline and tab, as POSIX find(1) lacks -print0, and it's unlikely
# you'd need to stow any such files.
# Technique from <https://dwheeler.com/essays/filenames-in-shell.html>.

set -efu
IFS="$(printf '\n\t')"
export LC_ALL=C
tab="$(printf '\t')"
cchars="$(printf '*[\001-\037\177]*')"

if ! command -v readlink >/dev/null; then
    readlink () {
	# Safe parse of ls(1) output given its POSIX specification.
	ls -ld "$1" | tr -s ' ' \
	    | cut -d' ' -f9- | cut -c$((4 + $(echo "$1" | wc -m)))-
    }
fi

read_globs_file () {
    if [ -e "$DIR/$1" ]; then
	while read -r line; do
	    printf "|./%s" "$line"
	done <"$DIR/$1" | cut -c2-
    fi
}

dir_contents () {
    ( cd "$1"; find . ! -name . ! -name "$cchars" )
}

fail () {
    echo >&2 "hstow: $*"
    exit 127
}

usage () {
    fail "usage: hstow stow|unstow|restow|adopt DIRECTORY"
}

stow () {
    cd "$DIR"
    [ -d "$HOME/.STOW" ] || mkdir "$HOME/.STOW"
    [ -f "$HOME/.STOW/.stow" ] || touch "$HOME/.STOW/.stow"
    [ -h "$HOME/.STOW/$NAME" ] \
	|| ( cd "$HOME/.STOW"; ln -s "$DIR" "$NAME" )
    conflicts=
    ignores="$(read_globs_file .hstow-local-ignore)"

    # Files that (i) always/often have their symlinks replaced with
    # regular files when applications access them; and (ii) we don't
    # ever want to edit the copy under $DIR directly, but only via the
    # link/copy under $HOME.
    $always_adopt || adoptions="$(read_globs_file .hstow-always-adopt)"

    for file in $(find . ! -name . ! -type d ! -name "$cchars" \
		       ! -name .gitignore \
		       ! -name .hstow-local-ignore \
		       ! -name .hstow-always-adopt \
		      | grep -v '^\./\.git/'); do
	file_dir="$(dirname $file)"
	if [ -n "$ignores" ]; then
	    eval case "'$file'"     in "${ignores})" continue ";;" esac
	    eval case "'$file_dir'" in "${ignores})" continue ";;" esac
	fi

	rel="$(echo $file|sed -E 's#/dot[-.]([^/]+)#/.\1#g; s#^\./##')"
	dotdotslashes="$(echo $rel|sed -E 's#[^/]*$##; s#[^/]+#..#g')"
	target="${dotdotslashes}.STOW/$NAME/$rel"
	link="$HOME/$rel"
	link_target=
	[ -h "$link" ] && link_target="$(readlink $link)"

	[ "$target" = "$link_target" ] && continue

	if [ ! -h "$link" -a ! -h "$file" -a -f "$link" ]; then
	    if $always_adopt \
		    || ( [ -n "$adoptions" ] \
			     && eval case "'$file'" in \
				     "${adoptions})" exit 0 ";;" \
				     "*)"            exit 1 ";;" \
				     esac ); then
		mv -f "$link" "$file"
		ln -s "$target" "$link"
	    else
		conflicts="$conflicts${tab}$file"
	    fi
	elif [ -h "$link" ]; then
	    # With at least GNU ln(1), passing -f, but not also -T, does
	    # not replace an existing link in some cases.
	    # -T is not POSIX, so we remove any existing link first.
	    rm "$link"
	    ln -s "$target" "$link"
	else
	    mkdir -p "$HOME/$file_dir"
	    ln -s "$target" "$link"
	fi
    done
    [ -z "$conflicts" ] && return
    echo >&2 "hstow: encountered conflicts:"
    for conflict in $conflicts; do echo >&2 "  $conflict"; done
    exit 127
}

unstow () {
    cd "$HOME"
    dir_pat="^\.$(echo $DIR | cut -c$(echo $HOME|wc -m|tr -d ' ')-)/"
    for file in $(find . -type l ! -name . ! -name "$cchars" \
		      | grep -v "$dir_pat"); do
	if readlink "$file" | grep -Eq '^(\.\./)*\.STOW/'"$NAME/"; then
	    rm "$file"
	    while true; do
		file="$(dirname $file)"
		[ "$file" = . ] && break
		if [ -z "$(dir_contents $file)" ]; then
		    rmdir "$file"
		else
		    break
		fi
	    done
	fi
    done
    [ -e "$HOME/.STOW/$NAME" ] && rm "$HOME/.STOW/$NAME"
    if [ -d "$HOME/.STOW" ] \
	   && [ "$(dir_contents $HOME/.STOW)" = "./.stow" ]; then
	rm "$HOME/.STOW/.stow"
	rmdir "$HOME/.STOW"
    fi
}

[ $# = 2 ] || usage
[ -d "$2" ] || fail "$2 is not an existing directory"
DIR="$(cd $2; pwd)"
[ "$(echo $DIR | cut -c-$(($(echo $HOME | wc -m) - 1)))" = "$HOME" ] \
    || fail "$DIR is not below $HOME"

NAME="$(echo $DIR | tr / _)"
always_adopt=false
case "$1" in
    'stow')   stow			;;
    'unstow') unstow			;;
    'restow') unstow; stow		;;
    'adopt')  always_adopt=true; stow	;;
    *)        usage                     ;;
esac