1#!/bin/sh -
2#
3# $NetBSD: gzexe,v 1.3 2004/05/01 08:22:41 wiz Exp $
4# $OpenBSD: gzexe,v 1.3 2003/08/05 18:22:17 deraadt Exp $
5#
6#-
7#  Copyright (c) 2003 Otto Moerbeek <otto@drijf.net>
8#
9#  Permission to use, copy, modify, and distribute this software for any
10#  purpose with or without fee is hereby granted, provided that the above
11#  copyright notice and this permission notice appear in all copies.
12#
13#  THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
14#  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
15#  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
16#  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
17#  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
18#  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
19#  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
20#
21
22# The number of lines plus one in the on-the-fly decompression script
23lines=19
24
25# A simple string to recognize already compressed files
26magic="# compressed by gzexe"
27
28# Write the decompression script to stdout
29header () {
30	# first section needs variable expansion, second not
31	cat <<- EOF
32		#!/bin/sh -
33		$magic
34		lines=$lines
35	EOF
36	cat <<- 'EOF'
37		prog=`/usr/bin/basename "$0"`
38		tmp=`/usr/bin/mktemp -d /tmp/gzexeXXXXXXXXXX` || {
39			/bin/echo "$prog: cannot create tmp dir"; exit 1
40		}
41		trap '/bin/rm -rf "$tmp"' 0
42		if /usr/bin/tail +$lines "$0" |
43		    /usr/bin/gzip -dc > "$tmp/$prog" 2> /dev/null; then
44			/bin/chmod u+x "$tmp/$prog"
45			"$tmp/$prog" ${1+"$@"}
46			ret=$?
47		else
48			/bin/echo "$prog: cannot decompress $0"
49			ret=1
50		fi
51		exit $ret
52	EOF
53}
54
55# Test if a file is compressed by checking the magic line
56compressed () {
57	test "X`sed -n 2p "$1" 2> /dev/null`" = "X$magic"
58}
59
60# Decompress a file
61decompress () {
62	tmp=`mktemp /tmp/gzexeXXXXXXXXXX` || {
63		echo "$prog: cannot create tmp file"
64		return 1
65	}
66	if ! cp "$1" "$tmp"; then
67		echo "$prog: cannot copy $1 to $tmp"
68		rm -f "$tmp"
69		return 1
70	fi
71	if ! tail +$lines "$tmp" | gzip -vdc > "$1"; then
72		echo "$prog: cannot decompress $1"
73		cp "$tmp" "$1"
74		rm -f "$tmp"
75		return 1
76	fi
77}
78
79# Perform some sanity checks on the file
80check () {
81	if test ! -e "$1"; then
82		echo "$prog: cannot compress non-existing file $1"
83		return 1
84	fi
85
86	if test ! -f "$1"; then
87		echo "$prog: cannot compress non-regular file $1"
88		return 1
89	fi
90
91	case `basename "$1"` in
92		sh | mktemp | rm | echo | tail | gzip | chmod)
93			echo "$prog: cannot compress $1, I depend on it"
94			return 1
95	esac
96
97	if test ! -x "$1"; then
98		echo "$prog: cannot compress $1, it is not executable"
99		return 1
100	fi
101
102	if test -u "$1" -o -g "$1"; then
103		echo "$prog: cannot compress $1, it has an s bit set"
104		return 1
105	fi
106}
107
108# Compress a file
109compress () {
110	tmp=`mktemp /tmp/gzexeXXXXXXXXXX` || {
111		echo "$prog: cannot create tmp file"
112		return 1
113	}
114	if ! cp "$1" "$tmp"; then
115		echo "$prog: cannot copy $1 to $tmp"
116		rm -f "$tmp"
117		return 1
118	fi
119	if ! cp "$1" "$1"~; then
120		echo "$prog: cannot create backup copy $1~"
121		rm -f "$1"~ "$tmp"
122		return 1
123	fi
124
125	# Use cp to overwrite the existing file preserving mode and owner
126	# if possible. If the file is not writable, this will produce an
127	# error.
128
129	if header "$1" > "$tmp" && gzip -vc "$1" >> "$tmp"; then
130		if ! cp "$tmp" "$1"; then
131			echo "$prog: cannot copy $tmp to $1"
132			rm -f "$tmp"
133			return 1
134		fi
135	else
136		echo "$prog: cannot compress $1"
137		rm -f "$1"~ "$tmp"
138		return 1
139	fi
140}
141
142# Is the -d flag specified?
143dflag=
144
145# Return value
146rc=0
147
148if test "X$1" = X-d; then
149	dflag=1
150	shift
151fi
152
153prog=`basename "$0"`
154USAGE="usage: $prog [-d] file ..."
155if test $# -eq 0; then
156	echo $USAGE
157	exit 1
158fi
159
160while test $# -ne 0; do
161	if test $dflag; then
162		if ! compressed "$1"; then
163			echo "$prog: $1 is not compressed"
164			rc=1;
165		elif ! decompress "$1"; then
166			rc=$?
167		fi
168	else
169		if compressed "$1"; then
170			echo "$prog: $1 is already compressed"
171			rc=1;
172		elif ! check "$1" || ! compress "$1"; then
173			rc=$?
174		fi
175	fi
176	shift
177done
178exit $rc
179