Annotation of embedaddon/dhcp/contrib/dhclient-tz-exithook.sh, revision 1.1.1.1
1.1 misho 1: #!/bin/bash
2: #
3: # dhclient-tz-exithook.sh
4: # Version 1.01 elear
5: #
6: # Copyright (c) 2007, Cisco Systems, Inc.
7: # All rights reserved.
8: #
9: # Redistribution and use in source and binary forms, with or without
10: # modification, are permitted provided that the following conditions
11: # are met:
12: #
13: # - Redistributions of source code must retain the above copyright
14: # notice, this list of conditions and the following disclaimer.
15: #
16: # - Redistributions in binary form must reproduce the above copyright
17: # notice, this list of conditions and the following disclaimer in
18: # the documentation and/or other materials provided with the
19: # distribution.
20: #
21: # - Neither the name of Cisco Systems, Inc. nor the names of its
22: # contributors may be used to endorse or promote products derived
23: # from this software without specific prior written permission.
24: #
25: # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
26: # "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
27: # LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
28: # FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
29: # COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
30: # INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31: # DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
32: # GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
33: # INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
34: # WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
35: # NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
36: # THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
37: #
38: # the following script is used to set the timezone based on the new
39: # dhcp timezone option defined currently in the IETF document
40: # draft-ietf-dhc-timezone-option-04.txt.
41:
42: # this code is intended for use with ISC's dhclient. it is to be called
43: # either as, or by, dhclient-exit-hooks
44: #
45: # As this is test code, in order for it to be called two changes
46: # must be made to /etc/dhclient.conf. First, dhclient.conf must be
47: # aware of the tzName option. The IANA has assigned tzName option
48: # code 101. You may need to add this to your configuration file.
49: #
50: # option tzName code 101 = text;
51: #
52: # Next, add tzName to the list of options in the "request" statement.
53: # For example:
54: #
55: # request subnet-mask, broadcast-address, time-offset, routers,
56: # domain-name, domain-name-servers, host-name, tzName;
57: #
58: #
59: # And of course make sure that your dhcp server is transmitting timezone
60: # information for option 101. For IOS this can be done as follows:
61: #
62: # option 101 ascii "Europe/Berlin"
63: #
64:
65: timefile=/etc/localtime
66: oldfile=$timefile.old
67: tmpfile=$timefile.$$
68:
69: # function to clean up just in case we are interrupted or something
70: # bad happens.
71: restore_file () {
72:
73: if [ ! -f $timefile ]; then
74: $DEBUG mv $tmpfile $timefile
75: fi
76: $DEBUG rm $tmpfile
77: exit
78: }
79:
80:
81: #set DEBUG to "echo" to see what would happen.
82: if [ x$DEBUG = x ]; then
83: DEBUG=
84: fi
85:
86: # if something has already gone wrong we're not doing a thing.
87: if [ x$exit_status != x0 ]; then
88: exit $exit_status
89: fi
90:
91:
92: # if we don't have a new timezone, then we have nothing to change, so
93: # goodbye.
94: if [ x$new_tzName = x ]; then
95: exit 0
96: fi
97:
98: # if the timezone doesn't exist, goodbye.
99: if [ ! -e $timefile ]; then
100: exit 0
101: fi
102:
103: # find zoneinfo. use the first one.
104: ftz=0
105: for a in /usr/share/zoneinfo /usr/lib/zoneinfo /var/share/zoneinfo /var/zoneinfo; do
106: if [ -d $a -a $ftz = 0 ]; then
107: zoneinfo=$a
108: ftz=1
109: fi
110: done
111:
112: # no zoneinfo found. goodbye.
113: if [ x$zoneinfo = x ]; then
114: exit 0
115: fi
116:
117: # timezone not found. goodbye.
118: if [ ! -f $zoneinfo/$new_tzName ]; then
119: exit 0
120: fi
121:
122: # if we're here we can actually do something useful.
123: # first, link a copy of the existing timefile.
124:
125: $DEBUG ln $timefile $tmpfile
126:
127: if [ $? != 0 ]; then
128: echo "unable to create temporary file"
129: exit -1
130: fi
131:
132: # in case of interrupt, cleanup.
133: trap restore_file SIGINT SIGSEGV SIGQUIT SIGTERM
134:
135: # we destroy old backup files in this process. if we cannot and the
136: # file exists then something went wrong.
137: if [ -e $oldfile ]; then
138: $DEBUG rm $oldfile
139: if [ $? != 0 ]; then
140: echo "$0: failed to remove $oldfile"
141: rm -f $tmpfile
142: exit -1
143: fi
144: fi
145:
146: # sensitive part happens here:
147: #
148: $DEBUG mv $timefile $oldfile
149:
150: if [ $? != 0 ]; then
151: echo "$0: failed to move old $timefile file out of the way"
152: rm $tmpfile
153: exit -1
154: fi
155:
156: $DEBUG ln $zoneinfo/$new_tzName $timefile
157:
158: # we don't complain just yet- a hard link could fail because
159: # we're on two different file systems. Go for a soft link.
160: #
161:
162: if [ $? != 0 ]; then
163: $DEBUG ln -s $zoneinfo/$new_tzName $timefile
164: fi
165:
166: if [ $? != 0 ]; then # failed to softlink. now we're getting nervous.
167: echo "$0: unable to establish new timezone. Attempting to revert."
168: $DEBUG ln $tmpfile $timefile
169: fi
170:
171:
172: if [ $? != 0 ]; then # we're absolutely hosed
173: echo "$0: unable to link or softlink timezone file, and unable to restore old file - giving up!"
174: exit -1
175: fi
176:
177: $DEBUG rm $tmpfile
178:
179: exit $?
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