annotate libtommath/bn_mp_gcd.c @ 1306:34e6127ef02e

merge fixes from PuTTY import.c toint() from misc.c (revids are from hggit conversion) changeset: 4620:60a336a6c85c user: Simon Tatham <[email protected]> date: Thu Feb 25 20:26:33 2016 +0000 files: import.c description: Fix potential segfaults in reading OpenSSH's ASN.1 key format. The length coming back from ber_read_id_len might have overflowed, so treat it as potentially negative. Also, while I'm here, accumulate it inside ber_read_id_len as an unsigned, so as to avoid undefined behaviour on integer overflow, and toint() it before return. Thanks to Hanno Böck for spotting this, with the aid of AFL. (cherry picked from commit 5b7833cd474a24ec098654dcba8cb9509f3bf2c1) Conflicts: import.c (cherry-picker's note: resolving the conflict involved removing an entire section of the original commit which fixed ECDSA code not present on this branch) changeset: 4619:9c6c638d98d8 user: Simon Tatham <[email protected]> date: Sun Jul 14 10:45:54 2013 +0000 files: import.c ssh.c sshdss.c sshpubk.c sshrsa.c description: Tighten up a lot of casts from unsigned to int which are read by one of the GET_32BIT macros and then used as length fields. Missing bounds checks against zero have been added, and also I've introduced a helper function toint() which casts from unsigned to int in such a way as to avoid C undefined behaviour, since I'm not sure I trust compilers any more to do the obviously sensible thing. [originally from svn r9918] changeset: 4618:3957829f24d3 user: Simon Tatham <[email protected]> date: Mon Jul 08 22:36:04 2013 +0000 files: import.c sshdss.c sshrsa.c description: Add an assortment of extra safety checks. [originally from svn r9896] changeset: 4617:2cddee0bce12 user: Jacob Nevins <[email protected]> date: Wed Dec 07 00:24:45 2005 +0000 files: import.c description: Institutional failure to memset() things pointed at rather than pointers. Things should now be zeroed and memory not leaked. Spotted by Brant Thomsen. [originally from svn r6476] changeset: 4616:24ac78a9c71d user: Simon Tatham <[email protected]> date: Wed Feb 11 13:58:27 2004 +0000 files: import.c description: Jacob's last-minute testing found a couple of trivial bugs in import.c, and my attempts to reproduce them in cmdgen found another one there :-) [originally from svn r3847] changeset: 4615:088d39a73db0 user: Simon Tatham <[email protected]> date: Thu Jan 22 18:52:49 2004 +0000 files: import.c description: Placate some gcc warnings. [originally from svn r3761] changeset: 4614:e4288bad4d93 parent: 1758:108b8924593d user: Simon Tatham <[email protected]> date: Fri Oct 03 21:21:23 2003 +0000 files: import.c description: My ASN.1 decoder returned wrong IDs for anything above 0x1E! Good job it's never had to yet. Ahem. [originally from svn r3479]
author Matt Johnston <matt@ucc.asn.au>
date Tue, 12 Jul 2016 23:00:01 +0800
parents 5ff8218bcee9
children 60fc6476e044
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
rev   line source
284
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diff changeset
1 #include <tommath.h>
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diff changeset
2 #ifdef BN_MP_GCD_C
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diff changeset
3 /* LibTomMath, multiple-precision integer library -- Tom St Denis
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diff changeset
4 *
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diff changeset
5 * LibTomMath is a library that provides multiple-precision
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diff changeset
6 * integer arithmetic as well as number theoretic functionality.
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diff changeset
7 *
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diff changeset
8 * The library was designed directly after the MPI library by
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diff changeset
9 * Michael Fromberger but has been written from scratch with
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diff changeset
10 * additional optimizations in place.
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diff changeset
11 *
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diff changeset
12 * The library is free for all purposes without any express
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diff changeset
13 * guarantee it works.
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diff changeset
14 *
389
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diff changeset
15 * Tom St Denis, [email protected], http://math.libtomcrypt.com
284
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16 */
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17
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diff changeset
18 /* Greatest Common Divisor using the binary method */
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diff changeset
19 int mp_gcd (mp_int * a, mp_int * b, mp_int * c)
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diff changeset
20 {
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diff changeset
21 mp_int u, v;
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diff changeset
22 int k, u_lsb, v_lsb, res;
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23
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
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diff changeset
24 /* either zero than gcd is the largest */
389
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parents: 284
diff changeset
25 if (mp_iszero (a) == MP_YES) {
284
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Matt Johnston <matt@ucc.asn.au>
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diff changeset
26 return mp_abs (b, c);
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27 }
389
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parents: 284
diff changeset
28 if (mp_iszero (b) == MP_YES) {
284
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Matt Johnston <matt@ucc.asn.au>
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diff changeset
29 return mp_abs (a, c);
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30 }
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31
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Matt Johnston <matt@ucc.asn.au>
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diff changeset
32 /* get copies of a and b we can modify */
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diff changeset
33 if ((res = mp_init_copy (&u, a)) != MP_OKAY) {
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Matt Johnston <matt@ucc.asn.au>
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diff changeset
34 return res;
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35 }
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36
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diff changeset
37 if ((res = mp_init_copy (&v, b)) != MP_OKAY) {
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diff changeset
38 goto LBL_U;
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39 }
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Matt Johnston <matt@ucc.asn.au>
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40
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
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diff changeset
41 /* must be positive for the remainder of the algorithm */
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diff changeset
42 u.sign = v.sign = MP_ZPOS;
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43
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
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diff changeset
44 /* B1. Find the common power of two for u and v */
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diff changeset
45 u_lsb = mp_cnt_lsb(&u);
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diff changeset
46 v_lsb = mp_cnt_lsb(&v);
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diff changeset
47 k = MIN(u_lsb, v_lsb);
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48
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Matt Johnston <matt@ucc.asn.au>
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diff changeset
49 if (k > 0) {
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diff changeset
50 /* divide the power of two out */
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diff changeset
51 if ((res = mp_div_2d(&u, k, &u, NULL)) != MP_OKAY) {
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parents:
diff changeset
52 goto LBL_V;
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Matt Johnston <matt@ucc.asn.au>
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diff changeset
53 }
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parents:
diff changeset
54
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
55 if ((res = mp_div_2d(&v, k, &v, NULL)) != MP_OKAY) {
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Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
56 goto LBL_V;
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parents:
diff changeset
57 }
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parents:
diff changeset
58 }
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parents:
diff changeset
59
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
60 /* divide any remaining factors of two out */
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parents:
diff changeset
61 if (u_lsb != k) {
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Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
62 if ((res = mp_div_2d(&u, u_lsb - k, &u, NULL)) != MP_OKAY) {
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Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
63 goto LBL_V;
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Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
64 }
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Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
65 }
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Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
66
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
67 if (v_lsb != k) {
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Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
68 if ((res = mp_div_2d(&v, v_lsb - k, &v, NULL)) != MP_OKAY) {
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
69 goto LBL_V;
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Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
70 }
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Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
71 }
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
72
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
73 while (mp_iszero(&v) == 0) {
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Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
74 /* make sure v is the largest */
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Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
75 if (mp_cmp_mag(&u, &v) == MP_GT) {
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Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
76 /* swap u and v to make sure v is >= u */
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Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
77 mp_exch(&u, &v);
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Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
78 }
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
79
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
80 /* subtract smallest from largest */
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
81 if ((res = s_mp_sub(&v, &u, &v)) != MP_OKAY) {
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
82 goto LBL_V;
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
83 }
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
84
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
85 /* Divide out all factors of two */
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
86 if ((res = mp_div_2d(&v, mp_cnt_lsb(&v), &v, NULL)) != MP_OKAY) {
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
87 goto LBL_V;
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
88 }
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
89 }
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
90
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
91 /* multiply by 2**k which we divided out at the beginning */
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
92 if ((res = mp_mul_2d (&u, k, c)) != MP_OKAY) {
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
93 goto LBL_V;
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
94 }
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
95 c->sign = MP_ZPOS;
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
96 res = MP_OKAY;
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
97 LBL_V:mp_clear (&u);
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
98 LBL_U:mp_clear (&v);
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
99 return res;
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
100 }
eed26cff980b propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583)
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
101 #endif
389
5ff8218bcee9 propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 2af95f00ebd5bb7a28b3817db1218442c935388e)
Matt Johnston <matt@ucc.asn.au>
parents: 284
diff changeset
102
5ff8218bcee9 propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 2af95f00ebd5bb7a28b3817db1218442c935388e)
Matt Johnston <matt@ucc.asn.au>
parents: 284
diff changeset
103 /* $Source: /cvs/libtom/libtommath/bn_mp_gcd.c,v $ */
5ff8218bcee9 propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 2af95f00ebd5bb7a28b3817db1218442c935388e)
Matt Johnston <matt@ucc.asn.au>
parents: 284
diff changeset
104 /* $Revision: 1.4 $ */
5ff8218bcee9 propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 2af95f00ebd5bb7a28b3817db1218442c935388e)
Matt Johnston <matt@ucc.asn.au>
parents: 284
diff changeset
105 /* $Date: 2006/03/31 14:18:44 $ */