xref: /openbsd/sys/msdosfs/msdosfs_conv.c (revision 3cab2bb3)
1 /*	$OpenBSD: msdosfs_conv.c,v 1.20 2019/09/04 14:40:22 cheloha Exp $	*/
2 /*	$NetBSD: msdosfs_conv.c,v 1.24 1997/10/17 11:23:54 ws Exp $	*/
3 
4 /*-
5  * Copyright (C) 1995, 1997 Wolfgang Solfrank.
6  * Copyright (C) 1995, 1997 TooLs GmbH.
7  * All rights reserved.
8  * Original code by Paul Popelka (paulp@uts.amdahl.com) (see below).
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  * 3. All advertising materials mentioning features or use of this software
19  *    must display the following acknowledgement:
20  *	This product includes software developed by TooLs GmbH.
21  * 4. The name of TooLs GmbH may not be used to endorse or promote products
22  *    derived from this software without specific prior written permission.
23  *
24  * THIS SOFTWARE IS PROVIDED BY TOOLS GMBH ``AS IS'' AND ANY EXPRESS OR
25  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
26  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
27  * IN NO EVENT SHALL TOOLS GMBH BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
28  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
29  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
30  * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
31  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
32  * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
33  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
34  */
35 /*
36  * Written by Paul Popelka (paulp@uts.amdahl.com)
37  *
38  * You can do anything you want with this software, just don't say you wrote
39  * it, and don't remove this notice.
40  *
41  * This software is provided "as is".
42  *
43  * The author supplies this software to be publicly redistributed on the
44  * understanding that the author is not responsible for the correct
45  * functioning of this software in any circumstances and is not liable for
46  * any damages caused by this software.
47  *
48  * October 1992
49  */
50 
51 /*
52  * System include files.
53  */
54 #include <sys/param.h>
55 #include <sys/systm.h>
56 #include <sys/time.h>
57 #include <sys/kernel.h>		/* defines tz */
58 #include <sys/dirent.h>
59 #include <sys/vnode.h>
60 #include <sys/lock.h>
61 
62 /*
63  * MSDOSFS include files.
64  */
65 #include <msdosfs/direntry.h>
66 #include <msdosfs/denode.h>
67 
68 /*
69  * Days in each month in a regular year.
70  */
71 const u_short regyear[] = {
72 	31, 28, 31, 30, 31, 30,
73 	31, 31, 30, 31, 30, 31
74 };
75 
76 /*
77  * Days in each month in a leap year.
78  */
79 const u_short leapyear[] = {
80 	31, 29, 31, 30, 31, 30,
81 	31, 31, 30, 31, 30, 31
82 };
83 
84 /*
85  * Variables used to remember parts of the last time conversion.  Maybe we
86  * can avoid a full conversion.
87  */
88 time_t lasttime;
89 uint32_t lastday;
90 u_short lastddate;
91 u_short lastdtime;
92 
93 /*
94  * Convert the unix version of time to dos's idea of time to be used in
95  * file timestamps. The passed in unix time is assumed to be in GMT.
96  */
97 void
98 unix2dostime(struct timespec *tsp, u_int16_t *ddp, u_int16_t *dtp, u_int8_t *dhp)
99 {
100 	time_t t;
101 	uint32_t days;
102 	uint32_t inc;
103 	uint32_t year;
104 	uint32_t month;
105 	const u_short *months;
106 
107 	/*
108 	 * If the time from the last conversion is the same as now, then
109 	 * skip the computations and use the saved result.
110 	 */
111 	t = tsp->tv_sec;
112 	t &= ~1;
113 	/*
114 	 * Before 1/1/1980 there is only a timeless void. After 12/31/2107
115 	 * there is only Cthulhu.
116 	 */
117 #define DOSEPOCH 315532800LL
118 #define DOSENDTIME 4354775999LL
119 	if (t < DOSEPOCH || t > DOSENDTIME)
120 		t = DOSEPOCH;
121 
122 	if (lasttime != t) {
123 		lasttime = t;
124 		lastdtime = (((t / 2) % 30) << DT_2SECONDS_SHIFT)
125 		    + (((t / 60) % 60) << DT_MINUTES_SHIFT)
126 		    + (((t / 3600) % 24) << DT_HOURS_SHIFT);
127 
128 		/*
129 		 * If the number of days since 1970 is the same as the last
130 		 * time we did the computation then skip all this leap year
131 		 * and month stuff.
132 		 */
133 		days = t / (24 * 60 * 60);
134 		if (days != lastday) {
135 			lastday = days;
136 			for (year = 1970;; year++) {
137 				inc = year & 0x03 ? 365 : 366;
138 				if (days < inc)
139 					break;
140 				days -= inc;
141 			}
142 			months = year & 0x03 ? regyear : leapyear;
143 			for (month = 0; month < 12; month++) {
144 				if (days < months[month])
145 					break;
146 				days -= months[month];
147 			}
148 			lastddate = ((days + 1) << DD_DAY_SHIFT)
149 			    + ((month + 1) << DD_MONTH_SHIFT);
150 			/*
151 			 * Remember dos's idea of time is relative to 1980.
152 			 * unix's is relative to 1970.  If somehow we get a
153 			 * time before 1980 then don't give totally crazy
154 			 * results.
155 			 */
156 			if (year > 1980)
157 				lastddate += (year - 1980) << DD_YEAR_SHIFT;
158 		}
159 	}
160 
161 	if (dtp != NULL)
162 		*dtp = lastdtime;
163 	if (dhp != NULL)
164 	        *dhp = (tsp->tv_sec & 1) * 100 + tsp->tv_nsec / 10000000;
165 
166 	*ddp = lastddate;
167 }
168 
169 /*
170  * The number of seconds between Jan 1, 1970 and Jan 1, 1980. In that
171  * interval there were 8 regular years and 2 leap years.
172  */
173 #define	SECONDSTO1980	(((8 * 365) + (2 * 366)) * (24 * 60 * 60))
174 
175 u_short lastdosdate;
176 uint32_t lastseconds;
177 
178 /*
179  * Convert from dos' idea of time to unix'. This will probably only be
180  * called from the stat(), and fstat() system calls and so probably need
181  * not be too efficient.
182  */
183 void
184 dos2unixtime(u_int dd, u_int dt, u_int dh, struct timespec *tsp)
185 {
186 	uint32_t seconds;
187 	uint32_t m, month;
188 	uint32_t y, year;
189 	uint32_t days;
190 	const u_short *months;
191 
192 	if (dd == 0) {
193 		/*
194 		 * Uninitialized field, return the epoch.
195 		 */
196 		tsp->tv_sec = 0;
197 		tsp->tv_nsec = 0;
198 		return;
199 	}
200 	seconds = ((dt & DT_2SECONDS_MASK) >> DT_2SECONDS_SHIFT) * 2
201 	    + ((dt & DT_MINUTES_MASK) >> DT_MINUTES_SHIFT) * 60
202 	    + ((dt & DT_HOURS_MASK) >> DT_HOURS_SHIFT) * 3600
203 	    + dh / 100;
204 	/*
205 	 * If the year, month, and day from the last conversion are the
206 	 * same then use the saved value.
207 	 */
208 	if (lastdosdate != dd) {
209 		lastdosdate = dd;
210 		days = 0;
211 		year = (dd & DD_YEAR_MASK) >> DD_YEAR_SHIFT;
212 		for (y = 0; y < year; y++)
213 			days += y & 0x03 ? 365 : 366;
214 		months = year & 0x03 ? regyear : leapyear;
215 		/*
216 		 * Prevent going from 0 to 0xffffffff in the following
217 		 * loop.
218 		 */
219 		month = (dd & DD_MONTH_MASK) >> DD_MONTH_SHIFT;
220 		if (month == 0) {
221 			printf("dos2unixtime(): month value out of range (%u)\n",
222 			    month);
223 			month = 1;
224 		}
225 		for (m = 0; m < month - 1; m++)
226 			days += months[m];
227 		days += ((dd & DD_DAY_MASK) >> DD_DAY_SHIFT) - 1;
228 		lastseconds = (days * 24 * 60 * 60) + SECONDSTO1980;
229 	}
230 	tsp->tv_sec = seconds + lastseconds;
231 	tsp->tv_nsec = (dh % 100) * 10000000;
232 }
233 
234 static const u_char
235 unix2dos[256] = {
236 	0,    0,    0,    0,    0,    0,    0,    0,	/* 00-07 */
237 	0,    0,    0,    0,    0,    0,    0,    0,	/* 08-0f */
238 	0,    0,    0,    0,    0,    0,    0,    0,	/* 10-17 */
239 	0,    0,    0,    0,    0,    0,    0,    0,	/* 18-1f */
240 	0,    0x21, 0,    0x23, 0x24, 0x25, 0x26, 0x27,	/* 20-27 */
241 	0x28, 0x29, 0,    0,    0,    0x2d, 0,    0,	/* 28-2f */
242 	0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37,	/* 30-37 */
243 	0x38, 0x39, 0,    0,    0,    0,    0,    0,	/* 38-3f */
244 	0x40, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47,	/* 40-47 */
245 	0x48, 0x49, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f,	/* 48-4f */
246 	0x50, 0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57,	/* 50-57 */
247 	0x58, 0x59, 0x5a, 0,    0,    0,    0x5e, 0x5f,	/* 58-5f */
248 	0x60, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47,	/* 60-67 */
249 	0x48, 0x49, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f,	/* 68-6f */
250 	0x50, 0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57,	/* 70-77 */
251 	0x58, 0x59, 0x5a, 0x7b, 0,    0x7d, 0x7e, 0,	/* 78-7f */
252 	0,    0,    0,    0,    0,    0,    0,    0,	/* 80-87 */
253 	0,    0,    0,    0,    0,    0,    0,    0,	/* 88-8f */
254 	0,    0,    0,    0,    0,    0,    0,    0,	/* 90-97 */
255 	0,    0,    0,    0,    0,    0,    0,    0,	/* 98-9f */
256 	0,    0xad, 0xbd, 0x9c, 0xcf, 0xbe, 0xdd, 0xf5,	/* a0-a7 */
257 	0xf9, 0xb8, 0xa6, 0xae, 0xaa, 0xf0, 0xa9, 0xee,	/* a8-af */
258 	0xf8, 0xf1, 0xfd, 0xfc, 0xef, 0xe6, 0xf4, 0xfa,	/* b0-b7 */
259 	0xf7, 0xfb, 0xa7, 0xaf, 0xac, 0xab, 0xf3, 0xa8,	/* b8-bf */
260 	0xb7, 0xb5, 0xb6, 0xc7, 0x8e, 0x8f, 0x92, 0x80,	/* c0-c7 */
261 	0xd4, 0x90, 0xd2, 0xd3, 0xde, 0xd6, 0xd7, 0xd8,	/* c8-cf */
262 	0xd1, 0xa5, 0xe3, 0xe0, 0xe2, 0xe5, 0x99, 0x9e,	/* d0-d7 */
263 	0x9d, 0xeb, 0xe9, 0xea, 0x9a, 0xed, 0xe8, 0xe1,	/* d8-df */
264 	0xb7, 0xb5, 0xb6, 0xc7, 0x8e, 0x8f, 0x92, 0x80,	/* e0-e7 */
265 	0xd4, 0x90, 0xd2, 0xd3, 0xde, 0xd6, 0xd7, 0xd8,	/* e8-ef */
266 	0xd1, 0xa5, 0xe3, 0xe0, 0xe2, 0xe5, 0x99, 0xf6,	/* f0-f7 */
267 	0x9d, 0xeb, 0xe9, 0xea, 0x9a, 0xed, 0xe8, 0x98,	/* f8-ff */
268 };
269 
270 static const u_char
271 dos2unix[256] = {
272 	0x3f, 0x3f, 0x3f, 0x3f, 0x3f, 0x3f, 0x3f, 0x3f,	/* 00-07 */
273 	0x3f, 0x3f, 0x3f, 0x3f, 0x3f, 0x3f, 0x3f, 0x3f,	/* 08-0f */
274 	0x3f, 0x3f, 0x3f, 0x3f, 0x3f, 0x3f, 0x3f, 0x3f,	/* 10-17 */
275 	0x3f, 0x3f, 0x3f, 0x3f, 0x3f, 0x3f, 0x3f, 0x3f,	/* 18-1f */
276 	0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27,	/* 20-27 */
277 	0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f,	/* 28-2f */
278 	0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37,	/* 30-37 */
279 	0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f,	/* 38-3f */
280 	0x40, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47,	/* 40-47 */
281 	0x48, 0x49, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f,	/* 48-4f */
282 	0x50, 0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57,	/* 50-57 */
283 	0x58, 0x59, 0x5a, 0x5b, 0x5c, 0x5d, 0x5e, 0x5f,	/* 58-5f */
284 	0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67,	/* 60-67 */
285 	0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f,	/* 68-6f */
286 	0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77,	/* 70-77 */
287 	0x78, 0x79, 0x7a, 0x7b, 0x7c, 0x7d, 0x7e, 0x7f,	/* 78-7f */
288 	0xc7, 0xfc, 0xe9, 0xe2, 0xe4, 0xe0, 0xe5, 0xe7,	/* 80-87 */
289 	0xea, 0xeb, 0xe8, 0xef, 0xee, 0xec, 0xc4, 0xc5,	/* 88-8f */
290 	0xc9, 0xe6, 0xc6, 0xf4, 0xf6, 0xf2, 0xfb, 0xf9,	/* 90-97 */
291 	0xff, 0xd6, 0xdc, 0xf8, 0xa3, 0xd8, 0xd7, 0x3f,	/* 98-9f */
292 	0xe1, 0xed, 0xf3, 0xfa, 0xf1, 0xd1, 0xaa, 0xba,	/* a0-a7 */
293 	0xbf, 0xae, 0xac, 0xbd, 0xbc, 0xa1, 0xab, 0xbb,	/* a8-af */
294 	0x3f, 0x3f, 0x3f, 0x3f, 0x3f, 0xc1, 0xc2, 0xc0,	/* b0-b7 */
295 	0xa9, 0x3f, 0x3f, 0x3f, 0x3f, 0xa2, 0xa5, 0x3f,	/* b8-bf */
296 	0x3f, 0x3f, 0x3f, 0x3f, 0x3f, 0x3f, 0xe3, 0xc3,	/* c0-c7 */
297 	0x3f, 0x3f, 0x3f, 0x3f, 0x3f, 0x3f, 0x3f, 0xa4,	/* c8-cf */
298 	0xf0, 0xd0, 0xca, 0xcb, 0xc8, 0x3f, 0xcd, 0xce,	/* d0-d7 */
299 	0xcf, 0x3f, 0x3f, 0x3f, 0x3f, 0xa6, 0xcc, 0x3f,	/* d8-df */
300 	0xd3, 0xdf, 0xd4, 0xd2, 0xf5, 0xd5, 0xb5, 0xfe,	/* e0-e7 */
301 	0xde, 0xda, 0xdb, 0xd9, 0xfd, 0xdd, 0xaf, 0x3f,	/* e8-ef */
302 	0xad, 0xb1, 0x3f, 0xbe, 0xb6, 0xa7, 0xf7, 0xb8,	/* f0-f7 */
303 	0xb0, 0xa8, 0xb7, 0xb9, 0xb3, 0xb2, 0x3f, 0x3f,	/* f8-ff */
304 };
305 
306 static const u_char
307 u2l[256] = {
308 	0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, /* 00-07 */
309 	0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, /* 08-0f */
310 	0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, /* 10-17 */
311 	0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f, /* 18-1f */
312 	0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, /* 20-27 */
313 	0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f, /* 28-2f */
314 	0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, /* 30-37 */
315 	0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f, /* 38-3f */
316 	0x40, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, /* 40-47 */
317 	0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f, /* 48-4f */
318 	0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77, /* 50-57 */
319 	0x78, 0x79, 0x7a, 0x5b, 0x5c, 0x5d, 0x5e, 0x5f, /* 58-5f */
320 	0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, /* 60-67 */
321 	0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f, /* 68-6f */
322 	0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77, /* 70-77 */
323 	0x78, 0x79, 0x7a, 0x7b, 0x7c, 0x7d, 0x7e, 0x7f, /* 78-7f */
324 	0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87, /* 80-87 */
325 	0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f, /* 88-8f */
326 	0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, /* 90-97 */
327 	0x98, 0x99, 0x9a, 0x9b, 0x9c, 0x9d, 0x9e, 0x9f, /* 98-9f */
328 	0xa0, 0xa1, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7, /* a0-a7 */
329 	0xa8, 0xa9, 0xaa, 0xab, 0xac, 0xad, 0xae, 0xaf, /* a8-af */
330 	0xb0, 0xb1, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6, 0xb7, /* b0-b7 */
331 	0xb8, 0xb9, 0xba, 0xbb, 0xbc, 0xbd, 0xbe, 0xbf, /* b8-bf */
332 	0xe0, 0xe1, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7, /* c0-c7 */
333 	0xe8, 0xe9, 0xea, 0xeb, 0xec, 0xed, 0xee, 0xef, /* c8-cf */
334 	0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xd7, /* d0-d7 */
335 	0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe, 0xdf, /* d8-df */
336 	0xe0, 0xe1, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7, /* e0-e7 */
337 	0xe8, 0xe9, 0xea, 0xeb, 0xec, 0xed, 0xee, 0xef, /* e8-ef */
338 	0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, /* f0-f7 */
339 	0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe, 0xff, /* f8-ff */
340 };
341 
342 /*
343  * DOS filenames are made of 2 parts, the name part and the extension part.
344  * The name part is 8 characters long and the extension part is 3
345  * characters long.  They may contain trailing blanks if the name or
346  * extension are not long enough to fill their respective fields.
347  */
348 
349 /*
350  * Convert a DOS filename to a unix filename. And, return the number of
351  * characters in the resulting unix filename excluding the terminating
352  * null.
353  */
354 int
355 dos2unixfn(u_char dn[11], u_char *un, int lower)
356 {
357 	int i;
358 	int thislong = 1;
359 	u_char c;
360 
361 	/*
362 	 * If first char of the filename is SLOT_E5 (0x05), then the real
363 	 * first char of the filename should be 0xe5. But, they couldn't
364 	 * just have a 0xe5 mean 0xe5 because that is used to mean a freed
365 	 * directory slot. Another dos quirk.
366 	 */
367 	if (*dn == SLOT_E5)
368 		c = dos2unix[0xe5];
369 	else
370 		c = dos2unix[*dn];
371 	*un++ = lower ? u2l[c] : c;
372 	dn++;
373 
374 	/*
375 	 * Copy the name portion into the unix filename string.
376 	 */
377 	for (i = 1; i < 8 && *dn != ' '; i++) {
378 		c = dos2unix[*dn++];
379 		*un++ = lower ? u2l[c] : c;
380 		thislong++;
381 	}
382 	dn += 8 - i;
383 
384 	/*
385 	 * Now, if there is an extension then put in a period and copy in
386 	 * the extension.
387 	 */
388 	if (*dn != ' ') {
389 		*un++ = '.';
390 		thislong++;
391 		for (i = 0; i < 3 && *dn != ' '; i++) {
392 			c = dos2unix[*dn++];
393 			*un++ = lower ? u2l[c] : c;
394 			thislong++;
395 		}
396 	}
397 	*un++ = 0;
398 
399 	return (thislong);
400 }
401 
402 /*
403  * Convert a unix filename to a DOS filename according to Win95 rules.
404  * If applicable and gen is not 0, it is inserted into the converted
405  * filename as a generation number.
406  * Returns
407  *	0 if name couldn't be converted
408  *	1 if the converted name is the same as the original
409  *	  (no long filename entry necessary for Win95)
410  *	2 if conversion was successful
411  *	3 if conversion was successful and generation number was inserted
412  */
413 int
414 unix2dosfn(u_char *un, u_char dn[11], int unlen, u_int gen)
415 {
416 	int i, j, l;
417 	int conv = 1;
418 	u_char *cp, *dp, *dp1;
419 	u_char gentext[6];
420 
421 	/*
422 	 * Fill the dos filename string with blanks. These are DOS's pad
423 	 * characters.
424 	 */
425 	for (i = 0; i < 11; i++)
426 		dn[i] = ' ';
427 
428 	/*
429 	 * The filenames "." and ".." are handled specially, since they
430 	 * don't follow dos filename rules.
431 	 */
432 	if (un[0] == '.' && unlen == 1) {
433 		dn[0] = '.';
434 		return gen <= 1;
435 	}
436 	if (un[0] == '.' && un[1] == '.' && unlen == 2) {
437 		dn[0] = '.';
438 		dn[1] = '.';
439 		return gen <= 1;
440 	}
441 
442 	/*
443 	 * Filenames with only blanks and dots are not allowed!
444 	 */
445 	for (cp = un, i = unlen; --i >= 0; cp++)
446 		if (*cp != ' ' && *cp != '.')
447 			break;
448 	if (i < 0)
449 		return 0;
450 
451 	/*
452 	 * Now find the extension
453 	 * Note: dot as first char doesn't start extension
454 	 *	 and trailing dots and blanks are ignored
455 	 */
456 	dp = dp1 = 0;
457 	for (cp = un + 1, i = unlen - 1; --i >= 0;) {
458 		switch (*cp++) {
459 		case '.':
460 			if (!dp1)
461 				dp1 = cp;
462 			break;
463 		case ' ':
464 			break;
465 		default:
466 			if (dp1)
467 				dp = dp1;
468 			dp1 = 0;
469 			break;
470 		}
471 	}
472 
473 	/*
474 	 * Now convert it
475 	 */
476 	if (dp) {
477 		if (dp1)
478 			l = dp1 - dp;
479 		else
480 			l = unlen - (dp - un);
481 		for (i = 0, j = 8; i < l && j < 11; i++, j++) {
482 			if (dp[i] != (dn[j] = unix2dos[dp[i]])
483 			    && conv != 3)
484 				conv = 2;
485 			if (!dn[j]) {
486 				conv = 3;
487 				dn[j--] = ' ';
488 			}
489 		}
490 		if (i < l)
491 			conv = 3;
492 		dp--;
493 	} else {
494 		for (dp = cp; *--dp == ' ' || *dp == '.';);
495 		dp++;
496 	}
497 
498 	/*
499 	 * Now convert the rest of the name
500 	 */
501 	for (i = j = 0; un < dp && j < 8; i++, j++, un++) {
502 		if (*un != (dn[j] = unix2dos[*un])
503 		    && conv != 3)
504 			conv = 2;
505 		if (!dn[j]) {
506 			conv = 3;
507 			dn[j--] = ' ';
508 		}
509 	}
510 	if (un < dp)
511 		conv = 3;
512 	/*
513 	 * If we didn't have any chars in filename,
514 	 * generate a default
515 	 */
516 	if (!j)
517 		dn[0] = '_';
518 
519 	/*
520 	 * The first character cannot be E5,
521 	 * because that means a deleted entry
522 	 */
523 	if (dn[0] == 0xe5)
524 		dn[0] = SLOT_E5;
525 
526 	/*
527 	 * If there wasn't any char dropped,
528 	 * there is no place for generation numbers
529 	 */
530 	if (conv != 3) {
531 		if (gen > 1)
532 			return 0;
533 		return conv;
534 	}
535 
536 	/*
537 	 * Now insert the generation number into the filename part
538 	 */
539 	for (cp = gentext + sizeof(gentext); cp > gentext && gen; gen /= 10)
540 		*--cp = gen % 10 + '0';
541 	if (gen)
542 		return 0;
543 	for (i = 8; dn[--i] == ' ';);
544 	if (gentext + sizeof(gentext) - cp + 1 > 8 - i)
545 		i = 8 - (gentext + sizeof(gentext) - cp + 1);
546 	dn[i++] = '~';
547 	while (cp < gentext + sizeof(gentext))
548 		dn[i++] = *cp++;
549 	return 3;
550 }
551 
552 /*
553  * Create a Win95 long name directory entry
554  * Note: assumes that the filename is valid,
555  *	 i.e. doesn't consist solely of blanks and dots
556  */
557 int
558 unix2winfn(u_char *un, int unlen, struct winentry *wep, int cnt, int chksum)
559 {
560 	u_int8_t *cp;
561 	int i;
562 
563 	/*
564 	 * Drop trailing blanks and dots
565 	 */
566 	for (cp = un + unlen; *--cp == ' ' || *cp == '.'; unlen--);
567 
568 	un += (cnt - 1) * WIN_CHARS;
569 	unlen -= (cnt - 1) * WIN_CHARS;
570 
571 	/*
572 	 * Initialize winentry to some useful default
573 	 */
574 	for (cp = (u_int8_t *)wep, i = sizeof(*wep); --i >= 0; *cp++ = 0xff);
575 	wep->weCnt = cnt;
576 	wep->weAttributes = ATTR_WIN95;
577 	wep->weReserved1 = 0;
578 	wep->weChksum = chksum;
579 	wep->weReserved2 = 0;
580 
581 	/*
582 	 * Now convert the filename parts
583 	 */
584 	for (cp = wep->wePart1, i = sizeof(wep->wePart1)/2; --i >= 0;) {
585 		if (--unlen < 0)
586 			goto done;
587 		*cp++ = *un++;
588 		*cp++ = 0;
589 	}
590 	for (cp = wep->wePart2, i = sizeof(wep->wePart2)/2; --i >= 0;) {
591 		if (--unlen < 0)
592 			goto done;
593 		*cp++ = *un++;
594 		*cp++ = 0;
595 	}
596 	for (cp = wep->wePart3, i = sizeof(wep->wePart3)/2; --i >= 0;) {
597 		if (--unlen < 0)
598 			goto done;
599 		*cp++ = *un++;
600 		*cp++ = 0;
601 	}
602 	if (!unlen)
603 		wep->weCnt |= WIN_LAST;
604 	return unlen;
605 
606 done:
607 	*cp++ = 0;
608 	*cp++ = 0;
609 	wep->weCnt |= WIN_LAST;
610 	return 0;
611 }
612 
613 /*
614  * Compare our filename to the one in the Win95 entry
615  * Returns the checksum or -1 if no match
616  */
617 int
618 winChkName(u_char *un, int unlen, struct winentry *wep, int chksum)
619 {
620 	u_int8_t *cp;
621 	int i;
622 
623 	/*
624 	 * First compare checksums
625 	 */
626 	if (wep->weCnt&WIN_LAST)
627 		chksum = wep->weChksum;
628 	else if (chksum != wep->weChksum)
629 		chksum = -1;
630 	if (chksum == -1)
631 		return -1;
632 
633 	/*
634 	 * Offset of this entry
635 	 */
636 	i = ((wep->weCnt&WIN_CNT) - 1) * WIN_CHARS;
637 	if ((unlen -= i) <= 0)
638 		return -1;
639 	un += i;
640 
641 	if ((wep->weCnt&WIN_LAST) && unlen > WIN_CHARS)
642 		return -1;
643 
644 	/*
645 	 * Compare the name parts
646 	 */
647 	for (cp = wep->wePart1, i = sizeof(wep->wePart1)/2; --i >= 0;) {
648 		if (--unlen < 0) {
649 			if (!*cp++ && !*cp)
650 				return chksum;
651 			return -1;
652 		}
653 		if (u2l[*cp++] != u2l[*un++] || *cp++)
654 			return -1;
655 	}
656 	for (cp = wep->wePart2, i = sizeof(wep->wePart2)/2; --i >= 0;) {
657 		if (--unlen < 0) {
658 			if (!*cp++ && !*cp)
659 				return chksum;
660 			return -1;
661 		}
662 		if (u2l[*cp++] != u2l[*un++] || *cp++)
663 			return -1;
664 	}
665 	for (cp = wep->wePart3, i = sizeof(wep->wePart3)/2; --i >= 0;) {
666 		if (--unlen < 0) {
667 			if (!*cp++ && !*cp)
668 				return chksum;
669 			return -1;
670 		}
671 		if (u2l[*cp++] != u2l[*un++] || *cp++)
672 			return -1;
673 	}
674 	return chksum;
675 }
676 
677 /*
678  * Convert Win95 filename to dirbuf.
679  * Returns the checksum or -1 if impossible
680  */
681 int
682 win2unixfn(struct winentry *wep, struct dirent *dp, int chksum)
683 {
684 	u_int8_t *cp;
685 	u_int8_t *np, *ep = dp->d_name + WIN_MAXLEN;
686 	int i;
687 
688 	if ((wep->weCnt&WIN_CNT) > howmany(WIN_MAXLEN, WIN_CHARS)
689 	    || !(wep->weCnt&WIN_CNT))
690 		return -1;
691 
692 	/*
693 	 * First compare checksums
694 	 */
695 	if (wep->weCnt&WIN_LAST) {
696 		chksum = wep->weChksum;
697 		/*
698 		 * This works even though d_namlen is one byte!
699 		 */
700 		dp->d_namlen = (wep->weCnt&WIN_CNT) * WIN_CHARS;
701 	} else if (chksum != wep->weChksum)
702 		chksum = -1;
703 	if (chksum == -1)
704 		return -1;
705 
706 	/*
707 	 * Offset of this entry
708 	 */
709 	i = ((wep->weCnt&WIN_CNT) - 1) * WIN_CHARS;
710 	np = (u_int8_t *)dp->d_name + i;
711 
712 	/*
713 	 * Convert the name parts
714 	 */
715 	for (cp = wep->wePart1, i = sizeof(wep->wePart1)/2; --i >= 0;) {
716 		switch (*np++ = *cp++) {
717 		case 0:
718 			dp->d_namlen -= sizeof(wep->wePart2)/2
719 			    + sizeof(wep->wePart3)/2 + i + 1;
720 			return chksum;
721 		case '/':
722 			np[-1] = 0;
723 			return -1;
724 		}
725 		/*
726 		 * The size comparison should result in the compiler
727 		 * optimizing the whole if away
728 		 */
729 		if (WIN_MAXLEN % WIN_CHARS < sizeof(wep->wePart1) / 2
730 		    && np > ep) {
731 			np[-1] = 0;
732 			return -1;
733 		}
734 		if (*cp++)
735 			return -1;
736 	}
737 	for (cp = wep->wePart2, i = sizeof(wep->wePart2)/2; --i >= 0;) {
738 		switch (*np++ = *cp++) {
739 		case 0:
740 			dp->d_namlen -= sizeof(wep->wePart3)/2 + i + 1;
741 			return chksum;
742 		case '/':
743 			np[-1] = 0;
744 			return -1;
745 		}
746 		/*
747 		 * The size comparisons should be optimized away
748 		 */
749 		if (WIN_MAXLEN % WIN_CHARS >= sizeof(wep->wePart1) / 2
750 		    && WIN_MAXLEN % WIN_CHARS < (sizeof(wep->wePart1) + sizeof(wep->wePart2)) / 2
751 		    && np > ep) {
752 			np[-1] = 0;
753 			return -1;
754 		}
755 		if (*cp++)
756 			return -1;
757 	}
758 	for (cp = wep->wePart3, i = sizeof(wep->wePart3)/2; --i >= 0;) {
759 		switch (*np++ = *cp++) {
760 		case 0:
761 			dp->d_namlen -= i + 1;
762 			return chksum;
763 		case '/':
764 			np[-1] = 0;
765 			return -1;
766 		}
767 		/*
768 		 * See above
769 		 */
770 		if (WIN_MAXLEN % WIN_CHARS >= (sizeof(wep->wePart1) + sizeof(wep->wePart2)) / 2
771 		    && np > ep) {
772 			np[-1] = 0;
773 			return -1;
774 		}
775 		if (*cp++)
776 			return -1;
777 	}
778 	return chksum;
779 }
780 
781 /*
782  * Compute the checksum of a DOS filename for Win95 use
783  */
784 u_int8_t
785 winChksum(u_int8_t *name)
786 {
787 	int i;
788 	u_int8_t s;
789 
790 	for (s = 0, i = 11; --i >= 0; s += *name++)
791 		s = (s << 7)|(s >> 1);
792 	return s;
793 }
794 
795 /*
796  * Determine the number of slots necessary for Win95 names
797  */
798 int
799 winSlotCnt(u_char *un, int unlen)
800 {
801 	for (un += unlen; unlen > 0; unlen--)
802 		if (*--un != ' ' && *un != '.')
803 			break;
804 	if (unlen > WIN_MAXLEN)
805 		return 0;
806 	return howmany(unlen, WIN_CHARS);
807 }
808