xref: /openbsd-src/sys/msdosfs/msdosfs_conv.c (revision 50b7afb2c2c0993b0894d4e34bf857cb13ed9c80)
1 /*	$OpenBSD: msdosfs_conv.c,v 1.17 2014/04/21 15:35:02 krw 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 
61 /*
62  * MSDOSFS include files.
63  */
64 #include <msdosfs/direntry.h>
65 #include <msdosfs/denode.h>
66 
67 /*
68  * Days in each month in a regular year.
69  */
70 const u_short regyear[] = {
71 	31, 28, 31, 30, 31, 30,
72 	31, 31, 30, 31, 30, 31
73 };
74 
75 /*
76  * Days in each month in a leap year.
77  */
78 const u_short leapyear[] = {
79 	31, 29, 31, 30, 31, 30,
80 	31, 31, 30, 31, 30, 31
81 };
82 
83 /*
84  * Variables used to remember parts of the last time conversion.  Maybe we
85  * can avoid a full conversion.
86  */
87 time_t lasttime;
88 uint32_t lastday;
89 u_short lastddate;
90 u_short lastdtime;
91 
92 /*
93  * Convert the unix version of time to dos's idea of time to be used in
94  * file timestamps. The passed in unix time is assumed to be in GMT.
95  */
96 void
97 unix2dostime(struct timespec *tsp, u_int16_t *ddp, u_int16_t *dtp, u_int8_t *dhp)
98 {
99 	time_t t;
100 	uint32_t days;
101 	uint32_t inc;
102 	uint32_t year;
103 	uint32_t month;
104 	const u_short *months;
105 
106 	/*
107 	 * If the time from the last conversion is the same as now, then
108 	 * skip the computations and use the saved result.
109 	 */
110 	t = tsp->tv_sec - (tz.tz_minuteswest * 60)
111 	     /* +- daylight saving time correction */ ;
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 + (tz.tz_minuteswest * 60)
231 	     /* -+ daylight saving time correction */ ;
232 	tsp->tv_nsec = (dh % 100) * 10000000;
233 }
234 
235 static const u_char
236 unix2dos[256] = {
237 	0,    0,    0,    0,    0,    0,    0,    0,	/* 00-07 */
238 	0,    0,    0,    0,    0,    0,    0,    0,	/* 08-0f */
239 	0,    0,    0,    0,    0,    0,    0,    0,	/* 10-17 */
240 	0,    0,    0,    0,    0,    0,    0,    0,	/* 18-1f */
241 	0,    0x21, 0,    0x23, 0x24, 0x25, 0x26, 0x27,	/* 20-27 */
242 	0x28, 0x29, 0,    0,    0,    0x2d, 0,    0,	/* 28-2f */
243 	0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37,	/* 30-37 */
244 	0x38, 0x39, 0,    0,    0,    0,    0,    0,	/* 38-3f */
245 	0x40, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47,	/* 40-47 */
246 	0x48, 0x49, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f,	/* 48-4f */
247 	0x50, 0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57,	/* 50-57 */
248 	0x58, 0x59, 0x5a, 0,    0,    0,    0x5e, 0x5f,	/* 58-5f */
249 	0x60, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47,	/* 60-67 */
250 	0x48, 0x49, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f,	/* 68-6f */
251 	0x50, 0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57,	/* 70-77 */
252 	0x58, 0x59, 0x5a, 0x7b, 0,    0x7d, 0x7e, 0,	/* 78-7f */
253 	0,    0,    0,    0,    0,    0,    0,    0,	/* 80-87 */
254 	0,    0,    0,    0,    0,    0,    0,    0,	/* 88-8f */
255 	0,    0,    0,    0,    0,    0,    0,    0,	/* 90-97 */
256 	0,    0,    0,    0,    0,    0,    0,    0,	/* 98-9f */
257 	0,    0xad, 0xbd, 0x9c, 0xcf, 0xbe, 0xdd, 0xf5,	/* a0-a7 */
258 	0xf9, 0xb8, 0xa6, 0xae, 0xaa, 0xf0, 0xa9, 0xee,	/* a8-af */
259 	0xf8, 0xf1, 0xfd, 0xfc, 0xef, 0xe6, 0xf4, 0xfa,	/* b0-b7 */
260 	0xf7, 0xfb, 0xa7, 0xaf, 0xac, 0xab, 0xf3, 0xa8,	/* b8-bf */
261 	0xb7, 0xb5, 0xb6, 0xc7, 0x8e, 0x8f, 0x92, 0x80,	/* c0-c7 */
262 	0xd4, 0x90, 0xd2, 0xd3, 0xde, 0xd6, 0xd7, 0xd8,	/* c8-cf */
263 	0xd1, 0xa5, 0xe3, 0xe0, 0xe2, 0xe5, 0x99, 0x9e,	/* d0-d7 */
264 	0x9d, 0xeb, 0xe9, 0xea, 0x9a, 0xed, 0xe8, 0xe1,	/* d8-df */
265 	0xb7, 0xb5, 0xb6, 0xc7, 0x8e, 0x8f, 0x92, 0x80,	/* e0-e7 */
266 	0xd4, 0x90, 0xd2, 0xd3, 0xde, 0xd6, 0xd7, 0xd8,	/* e8-ef */
267 	0xd1, 0xa5, 0xe3, 0xe0, 0xe2, 0xe5, 0x99, 0xf6,	/* f0-f7 */
268 	0x9d, 0xeb, 0xe9, 0xea, 0x9a, 0xed, 0xe8, 0x98,	/* f8-ff */
269 };
270 
271 static const u_char
272 dos2unix[256] = {
273 	0x3f, 0x3f, 0x3f, 0x3f, 0x3f, 0x3f, 0x3f, 0x3f,	/* 00-07 */
274 	0x3f, 0x3f, 0x3f, 0x3f, 0x3f, 0x3f, 0x3f, 0x3f,	/* 08-0f */
275 	0x3f, 0x3f, 0x3f, 0x3f, 0x3f, 0x3f, 0x3f, 0x3f,	/* 10-17 */
276 	0x3f, 0x3f, 0x3f, 0x3f, 0x3f, 0x3f, 0x3f, 0x3f,	/* 18-1f */
277 	0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27,	/* 20-27 */
278 	0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f,	/* 28-2f */
279 	0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37,	/* 30-37 */
280 	0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f,	/* 38-3f */
281 	0x40, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47,	/* 40-47 */
282 	0x48, 0x49, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f,	/* 48-4f */
283 	0x50, 0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57,	/* 50-57 */
284 	0x58, 0x59, 0x5a, 0x5b, 0x5c, 0x5d, 0x5e, 0x5f,	/* 58-5f */
285 	0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67,	/* 60-67 */
286 	0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f,	/* 68-6f */
287 	0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77,	/* 70-77 */
288 	0x78, 0x79, 0x7a, 0x7b, 0x7c, 0x7d, 0x7e, 0x7f,	/* 78-7f */
289 	0xc7, 0xfc, 0xe9, 0xe2, 0xe4, 0xe0, 0xe5, 0xe7,	/* 80-87 */
290 	0xea, 0xeb, 0xe8, 0xef, 0xee, 0xec, 0xc4, 0xc5,	/* 88-8f */
291 	0xc9, 0xe6, 0xc6, 0xf4, 0xf6, 0xf2, 0xfb, 0xf9,	/* 90-97 */
292 	0xff, 0xd6, 0xdc, 0xf8, 0xa3, 0xd8, 0xd7, 0x3f,	/* 98-9f */
293 	0xe1, 0xed, 0xf3, 0xfa, 0xf1, 0xd1, 0xaa, 0xba,	/* a0-a7 */
294 	0xbf, 0xae, 0xac, 0xbd, 0xbc, 0xa1, 0xab, 0xbb,	/* a8-af */
295 	0x3f, 0x3f, 0x3f, 0x3f, 0x3f, 0xc1, 0xc2, 0xc0,	/* b0-b7 */
296 	0xa9, 0x3f, 0x3f, 0x3f, 0x3f, 0xa2, 0xa5, 0x3f,	/* b8-bf */
297 	0x3f, 0x3f, 0x3f, 0x3f, 0x3f, 0x3f, 0xe3, 0xc3,	/* c0-c7 */
298 	0x3f, 0x3f, 0x3f, 0x3f, 0x3f, 0x3f, 0x3f, 0xa4,	/* c8-cf */
299 	0xf0, 0xd0, 0xca, 0xcb, 0xc8, 0x3f, 0xcd, 0xce,	/* d0-d7 */
300 	0xcf, 0x3f, 0x3f, 0x3f, 0x3f, 0xa6, 0xcc, 0x3f,	/* d8-df */
301 	0xd3, 0xdf, 0xd4, 0xd2, 0xf5, 0xd5, 0xb5, 0xfe,	/* e0-e7 */
302 	0xde, 0xda, 0xdb, 0xd9, 0xfd, 0xdd, 0xaf, 0x3f,	/* e8-ef */
303 	0xad, 0xb1, 0x3f, 0xbe, 0xb6, 0xa7, 0xf7, 0xb8,	/* f0-f7 */
304 	0xb0, 0xa8, 0xb7, 0xb9, 0xb3, 0xb2, 0x3f, 0x3f,	/* f8-ff */
305 };
306 
307 static const u_char
308 u2l[256] = {
309 	0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, /* 00-07 */
310 	0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, /* 08-0f */
311 	0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, /* 10-17 */
312 	0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f, /* 18-1f */
313 	0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, /* 20-27 */
314 	0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f, /* 28-2f */
315 	0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, /* 30-37 */
316 	0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f, /* 38-3f */
317 	0x40, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, /* 40-47 */
318 	0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f, /* 48-4f */
319 	0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77, /* 50-57 */
320 	0x78, 0x79, 0x7a, 0x5b, 0x5c, 0x5d, 0x5e, 0x5f, /* 58-5f */
321 	0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, /* 60-67 */
322 	0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f, /* 68-6f */
323 	0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77, /* 70-77 */
324 	0x78, 0x79, 0x7a, 0x7b, 0x7c, 0x7d, 0x7e, 0x7f, /* 78-7f */
325 	0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87, /* 80-87 */
326 	0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f, /* 88-8f */
327 	0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, /* 90-97 */
328 	0x98, 0x99, 0x9a, 0x9b, 0x9c, 0x9d, 0x9e, 0x9f, /* 98-9f */
329 	0xa0, 0xa1, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7, /* a0-a7 */
330 	0xa8, 0xa9, 0xaa, 0xab, 0xac, 0xad, 0xae, 0xaf, /* a8-af */
331 	0xb0, 0xb1, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6, 0xb7, /* b0-b7 */
332 	0xb8, 0xb9, 0xba, 0xbb, 0xbc, 0xbd, 0xbe, 0xbf, /* b8-bf */
333 	0xe0, 0xe1, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7, /* c0-c7 */
334 	0xe8, 0xe9, 0xea, 0xeb, 0xec, 0xed, 0xee, 0xef, /* c8-cf */
335 	0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xd7, /* d0-d7 */
336 	0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe, 0xdf, /* d8-df */
337 	0xe0, 0xe1, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7, /* e0-e7 */
338 	0xe8, 0xe9, 0xea, 0xeb, 0xec, 0xed, 0xee, 0xef, /* e8-ef */
339 	0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, /* f0-f7 */
340 	0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe, 0xff, /* f8-ff */
341 };
342 
343 /*
344  * DOS filenames are made of 2 parts, the name part and the extension part.
345  * The name part is 8 characters long and the extension part is 3
346  * characters long.  They may contain trailing blanks if the name or
347  * extension are not long enough to fill their respective fields.
348  */
349 
350 /*
351  * Convert a DOS filename to a unix filename. And, return the number of
352  * characters in the resulting unix filename excluding the terminating
353  * null.
354  */
355 int
356 dos2unixfn(u_char dn[11], u_char *un, int lower)
357 {
358 	int i;
359 	int thislong = 1;
360 	u_char c;
361 
362 	/*
363 	 * If first char of the filename is SLOT_E5 (0x05), then the real
364 	 * first char of the filename should be 0xe5. But, they couldn't
365 	 * just have a 0xe5 mean 0xe5 because that is used to mean a freed
366 	 * directory slot. Another dos quirk.
367 	 */
368 	if (*dn == SLOT_E5)
369 		c = dos2unix[0xe5];
370 	else
371 		c = dos2unix[*dn];
372 	*un++ = lower ? u2l[c] : c;
373 	dn++;
374 
375 	/*
376 	 * Copy the name portion into the unix filename string.
377 	 */
378 	for (i = 1; i < 8 && *dn != ' '; i++) {
379 		c = dos2unix[*dn++];
380 		*un++ = lower ? u2l[c] : c;
381 		thislong++;
382 	}
383 	dn += 8 - i;
384 
385 	/*
386 	 * Now, if there is an extension then put in a period and copy in
387 	 * the extension.
388 	 */
389 	if (*dn != ' ') {
390 		*un++ = '.';
391 		thislong++;
392 		for (i = 0; i < 3 && *dn != ' '; i++) {
393 			c = dos2unix[*dn++];
394 			*un++ = lower ? u2l[c] : c;
395 			thislong++;
396 		}
397 	}
398 	*un++ = 0;
399 
400 	return (thislong);
401 }
402 
403 /*
404  * Convert a unix filename to a DOS filename according to Win95 rules.
405  * If applicable and gen is not 0, it is inserted into the converted
406  * filename as a generation number.
407  * Returns
408  *	0 if name couldn't be converted
409  *	1 if the converted name is the same as the original
410  *	  (no long filename entry necessary for Win95)
411  *	2 if conversion was successful
412  *	3 if conversion was successful and generation number was inserted
413  */
414 int
415 unix2dosfn(u_char *un, u_char dn[11], int unlen, u_int gen)
416 {
417 	int i, j, l;
418 	int conv = 1;
419 	u_char *cp, *dp, *dp1;
420 	u_char gentext[6];
421 
422 	/*
423 	 * Fill the dos filename string with blanks. These are DOS's pad
424 	 * characters.
425 	 */
426 	for (i = 0; i < 11; i++)
427 		dn[i] = ' ';
428 
429 	/*
430 	 * The filenames "." and ".." are handled specially, since they
431 	 * don't follow dos filename rules.
432 	 */
433 	if (un[0] == '.' && unlen == 1) {
434 		dn[0] = '.';
435 		return gen <= 1;
436 	}
437 	if (un[0] == '.' && un[1] == '.' && unlen == 2) {
438 		dn[0] = '.';
439 		dn[1] = '.';
440 		return gen <= 1;
441 	}
442 
443 	/*
444 	 * Filenames with only blanks and dots are not allowed!
445 	 */
446 	for (cp = un, i = unlen; --i >= 0; cp++)
447 		if (*cp != ' ' && *cp != '.')
448 			break;
449 	if (i < 0)
450 		return 0;
451 
452 	/*
453 	 * Now find the extension
454 	 * Note: dot as first char doesn't start extension
455 	 *	 and trailing dots and blanks are ignored
456 	 */
457 	dp = dp1 = 0;
458 	for (cp = un + 1, i = unlen - 1; --i >= 0;) {
459 		switch (*cp++) {
460 		case '.':
461 			if (!dp1)
462 				dp1 = cp;
463 			break;
464 		case ' ':
465 			break;
466 		default:
467 			if (dp1)
468 				dp = dp1;
469 			dp1 = 0;
470 			break;
471 		}
472 	}
473 
474 	/*
475 	 * Now convert it
476 	 */
477 	if (dp) {
478 		if (dp1)
479 			l = dp1 - dp;
480 		else
481 			l = unlen - (dp - un);
482 		for (i = 0, j = 8; i < l && j < 11; i++, j++) {
483 			if (dp[i] != (dn[j] = unix2dos[dp[i]])
484 			    && conv != 3)
485 				conv = 2;
486 			if (!dn[j]) {
487 				conv = 3;
488 				dn[j--] = ' ';
489 			}
490 		}
491 		if (i < l)
492 			conv = 3;
493 		dp--;
494 	} else {
495 		for (dp = cp; *--dp == ' ' || *dp == '.';);
496 		dp++;
497 	}
498 
499 	/*
500 	 * Now convert the rest of the name
501 	 */
502 	for (i = j = 0; un < dp && j < 8; i++, j++, un++) {
503 		if (*un != (dn[j] = unix2dos[*un])
504 		    && conv != 3)
505 			conv = 2;
506 		if (!dn[j]) {
507 			conv = 3;
508 			dn[j--] = ' ';
509 		}
510 	}
511 	if (un < dp)
512 		conv = 3;
513 	/*
514 	 * If we didn't have any chars in filename,
515 	 * generate a default
516 	 */
517 	if (!j)
518 		dn[0] = '_';
519 
520 	/*
521 	 * The first character cannot be E5,
522 	 * because that means a deleted entry
523 	 */
524 	if (dn[0] == 0xe5)
525 		dn[0] = SLOT_E5;
526 
527 	/*
528 	 * If there wasn't any char dropped,
529 	 * there is no place for generation numbers
530 	 */
531 	if (conv != 3) {
532 		if (gen > 1)
533 			return 0;
534 		return conv;
535 	}
536 
537 	/*
538 	 * Now insert the generation number into the filename part
539 	 */
540 	for (cp = gentext + sizeof(gentext); cp > gentext && gen; gen /= 10)
541 		*--cp = gen % 10 + '0';
542 	if (gen)
543 		return 0;
544 	for (i = 8; dn[--i] == ' ';);
545 	if (gentext + sizeof(gentext) - cp + 1 > 8 - i)
546 		i = 8 - (gentext + sizeof(gentext) - cp + 1);
547 	dn[i++] = '~';
548 	while (cp < gentext + sizeof(gentext))
549 		dn[i++] = *cp++;
550 	return 3;
551 }
552 
553 /*
554  * Create a Win95 long name directory entry
555  * Note: assumes that the filename is valid,
556  *	 i.e. doesn't consist solely of blanks and dots
557  */
558 int
559 unix2winfn(u_char *un, int unlen, struct winentry *wep, int cnt, int chksum)
560 {
561 	u_int8_t *cp;
562 	int i;
563 
564 	/*
565 	 * Drop trailing blanks and dots
566 	 */
567 	for (cp = un + unlen; *--cp == ' ' || *cp == '.'; unlen--);
568 
569 	un += (cnt - 1) * WIN_CHARS;
570 	unlen -= (cnt - 1) * WIN_CHARS;
571 
572 	/*
573 	 * Initialize winentry to some useful default
574 	 */
575 	for (cp = (u_int8_t *)wep, i = sizeof(*wep); --i >= 0; *cp++ = 0xff);
576 	wep->weCnt = cnt;
577 	wep->weAttributes = ATTR_WIN95;
578 	wep->weReserved1 = 0;
579 	wep->weChksum = chksum;
580 	wep->weReserved2 = 0;
581 
582 	/*
583 	 * Now convert the filename parts
584 	 */
585 	for (cp = wep->wePart1, i = sizeof(wep->wePart1)/2; --i >= 0;) {
586 		if (--unlen < 0)
587 			goto done;
588 		*cp++ = *un++;
589 		*cp++ = 0;
590 	}
591 	for (cp = wep->wePart2, i = sizeof(wep->wePart2)/2; --i >= 0;) {
592 		if (--unlen < 0)
593 			goto done;
594 		*cp++ = *un++;
595 		*cp++ = 0;
596 	}
597 	for (cp = wep->wePart3, i = sizeof(wep->wePart3)/2; --i >= 0;) {
598 		if (--unlen < 0)
599 			goto done;
600 		*cp++ = *un++;
601 		*cp++ = 0;
602 	}
603 	if (!unlen)
604 		wep->weCnt |= WIN_LAST;
605 	return unlen;
606 
607 done:
608 	*cp++ = 0;
609 	*cp++ = 0;
610 	wep->weCnt |= WIN_LAST;
611 	return 0;
612 }
613 
614 /*
615  * Compare our filename to the one in the Win95 entry
616  * Returns the checksum or -1 if no match
617  */
618 int
619 winChkName(u_char *un, int unlen, struct winentry *wep, int chksum)
620 {
621 	u_int8_t *cp;
622 	int i;
623 
624 	/*
625 	 * First compare checksums
626 	 */
627 	if (wep->weCnt&WIN_LAST)
628 		chksum = wep->weChksum;
629 	else if (chksum != wep->weChksum)
630 		chksum = -1;
631 	if (chksum == -1)
632 		return -1;
633 
634 	/*
635 	 * Offset of this entry
636 	 */
637 	i = ((wep->weCnt&WIN_CNT) - 1) * WIN_CHARS;
638 	if ((unlen -= i) <= 0)
639 		return -1;
640 	un += i;
641 
642 	if ((wep->weCnt&WIN_LAST) && unlen > WIN_CHARS)
643 		return -1;
644 
645 	/*
646 	 * Compare the name parts
647 	 */
648 	for (cp = wep->wePart1, i = sizeof(wep->wePart1)/2; --i >= 0;) {
649 		if (--unlen < 0) {
650 			if (!*cp++ && !*cp)
651 				return chksum;
652 			return -1;
653 		}
654 		if (u2l[*cp++] != u2l[*un++] || *cp++)
655 			return -1;
656 	}
657 	for (cp = wep->wePart2, i = sizeof(wep->wePart2)/2; --i >= 0;) {
658 		if (--unlen < 0) {
659 			if (!*cp++ && !*cp)
660 				return chksum;
661 			return -1;
662 		}
663 		if (u2l[*cp++] != u2l[*un++] || *cp++)
664 			return -1;
665 	}
666 	for (cp = wep->wePart3, i = sizeof(wep->wePart3)/2; --i >= 0;) {
667 		if (--unlen < 0) {
668 			if (!*cp++ && !*cp)
669 				return chksum;
670 			return -1;
671 		}
672 		if (u2l[*cp++] != u2l[*un++] || *cp++)
673 			return -1;
674 	}
675 	return chksum;
676 }
677 
678 /*
679  * Convert Win95 filename to dirbuf.
680  * Returns the checksum or -1 if impossible
681  */
682 int
683 win2unixfn(struct winentry *wep, struct dirent *dp, int chksum)
684 {
685 	u_int8_t *cp;
686 	u_int8_t *np, *ep = dp->d_name + WIN_MAXLEN;
687 	int i;
688 
689 	if ((wep->weCnt&WIN_CNT) > howmany(WIN_MAXLEN, WIN_CHARS)
690 	    || !(wep->weCnt&WIN_CNT))
691 		return -1;
692 
693 	/*
694 	 * First compare checksums
695 	 */
696 	if (wep->weCnt&WIN_LAST) {
697 		chksum = wep->weChksum;
698 		/*
699 		 * This works even though d_namlen is one byte!
700 		 */
701 		dp->d_namlen = (wep->weCnt&WIN_CNT) * WIN_CHARS;
702 	} else if (chksum != wep->weChksum)
703 		chksum = -1;
704 	if (chksum == -1)
705 		return -1;
706 
707 	/*
708 	 * Offset of this entry
709 	 */
710 	i = ((wep->weCnt&WIN_CNT) - 1) * WIN_CHARS;
711 	np = (u_int8_t *)dp->d_name + i;
712 
713 	/*
714 	 * Convert the name parts
715 	 */
716 	for (cp = wep->wePart1, i = sizeof(wep->wePart1)/2; --i >= 0;) {
717 		switch (*np++ = *cp++) {
718 		case 0:
719 			dp->d_namlen -= sizeof(wep->wePart2)/2
720 			    + sizeof(wep->wePart3)/2 + i + 1;
721 			return chksum;
722 		case '/':
723 			np[-1] = 0;
724 			return -1;
725 		}
726 		/*
727 		 * The size comparison should result in the compiler
728 		 * optimizing the whole if away
729 		 */
730 		if (WIN_MAXLEN % WIN_CHARS < sizeof(wep->wePart1) / 2
731 		    && np > ep) {
732 			np[-1] = 0;
733 			return -1;
734 		}
735 		if (*cp++)
736 			return -1;
737 	}
738 	for (cp = wep->wePart2, i = sizeof(wep->wePart2)/2; --i >= 0;) {
739 		switch (*np++ = *cp++) {
740 		case 0:
741 			dp->d_namlen -= sizeof(wep->wePart3)/2 + i + 1;
742 			return chksum;
743 		case '/':
744 			np[-1] = 0;
745 			return -1;
746 		}
747 		/*
748 		 * The size comparisons should be optimized away
749 		 */
750 		if (WIN_MAXLEN % WIN_CHARS >= sizeof(wep->wePart1) / 2
751 		    && WIN_MAXLEN % WIN_CHARS < (sizeof(wep->wePart1) + sizeof(wep->wePart2)) / 2
752 		    && np > ep) {
753 			np[-1] = 0;
754 			return -1;
755 		}
756 		if (*cp++)
757 			return -1;
758 	}
759 	for (cp = wep->wePart3, i = sizeof(wep->wePart3)/2; --i >= 0;) {
760 		switch (*np++ = *cp++) {
761 		case 0:
762 			dp->d_namlen -= i + 1;
763 			return chksum;
764 		case '/':
765 			np[-1] = 0;
766 			return -1;
767 		}
768 		/*
769 		 * See above
770 		 */
771 		if (WIN_MAXLEN % WIN_CHARS >= (sizeof(wep->wePart1) + sizeof(wep->wePart2)) / 2
772 		    && np > ep) {
773 			np[-1] = 0;
774 			return -1;
775 		}
776 		if (*cp++)
777 			return -1;
778 	}
779 	return chksum;
780 }
781 
782 /*
783  * Compute the checksum of a DOS filename for Win95 use
784  */
785 u_int8_t
786 winChksum(u_int8_t *name)
787 {
788 	int i;
789 	u_int8_t s;
790 
791 	for (s = 0, i = 11; --i >= 0; s += *name++)
792 		s = (s << 7)|(s >> 1);
793 	return s;
794 }
795 
796 /*
797  * Determine the number of slots necessary for Win95 names
798  */
799 int
800 winSlotCnt(u_char *un, int unlen)
801 {
802 	for (un += unlen; unlen > 0; unlen--)
803 		if (*--un != ' ' && *un != '.')
804 			break;
805 	if (unlen > WIN_MAXLEN)
806 		return 0;
807 	return howmany(unlen, WIN_CHARS);
808 }
809