msdosfs_conv.c revision 12144 
1/*	$Id: msdosfs_conv.c,v 1.6 1995/10/29 15:31:46 phk Exp $ */
2/*	$NetBSD: msdosfs_conv.c,v 1.6.2.1 1994/08/30 02:27:57 cgd Exp $	*/
3
4/*
5 * Written by Paul Popelka (paulp@uts.amdahl.com)
6 *
7 * You can do anything you want with this software, just don't say you wrote
8 * it, and don't remove this notice.
9 *
10 * This software is provided "as is".
11 *
12 * The author supplies this software to be publicly redistributed on the
13 * understanding that the author is not responsible for the correct
14 * functioning of this software in any circumstances and is not liable for
15 * any damages caused by this software.
16 *
17 * October 1992
18 */
19
20/*
21 * System include files.
22 */
23#include <sys/param.h>
24#include <sys/time.h>
25#include <sys/kernel.h>		/* defines tz */
26#include <sys/systm.h>		/* defines tz */
27#include <machine/clock.h>
28
29/*
30 * MSDOSFS include files.
31 */
32#include <msdosfs/direntry.h>
33
34/*
35 * Total number of days that have passed for each month in a regular year.
36 */
37static u_short regyear[] = {
38	31, 59, 90, 120, 151, 181,
39	212, 243, 273, 304, 334, 365
40};
41
42/*
43 * Total number of days that have passed for each month in a leap year.
44 */
45static u_short leapyear[] = {
46	31, 60, 91, 121, 152, 182,
47	213, 244, 274, 305, 335, 366
48};
49
50/*
51 * Variables used to remember parts of the last time conversion.  Maybe we
52 * can avoid a full conversion.
53 */
54u_long lasttime;
55u_long lastday;
56u_short lastddate;
57u_short lastdtime;
58
59/*
60 * Convert the unix version of time to dos's idea of time to be used in
61 * file timestamps. The passed in unix time is assumed to be in GMT.
62 */
63void
64unix2dostime(tsp, ddp, dtp)
65	struct timespec *tsp;
66	u_short *ddp;
67	u_short *dtp;
68{
69	u_long t;
70	u_long days;
71	u_long inc;
72	u_long year;
73	u_long month;
74	u_short *months;
75
76	/*
77	 * If the time from the last conversion is the same as now, then
78	 * skip the computations and use the saved result.
79	 */
80	t = tsp->ts_sec - (tz.tz_minuteswest * 60) - adjkerntz;
81	     /* +- daylight savings time correction */ ;
82	if (lasttime != t) {
83		lasttime = t;
84		lastdtime = (((t % 60) >> 1) << DT_2SECONDS_SHIFT)
85		    + (((t / 60) % 60) << DT_MINUTES_SHIFT)
86		    + (((t / 3600) % 24) << DT_HOURS_SHIFT);
87
88		/*
89		 * If the number of days since 1970 is the same as the last
90		 * time we did the computation then skip all this leap year
91		 * and month stuff.
92		 */
93		days = t / (24 * 60 * 60);
94		if (days != lastday) {
95			lastday = days;
96			for (year = 1970;; year++) {
97				inc = year & 0x03 ? 365 : 366;
98				if (days < inc)
99					break;
100				days -= inc;
101			}
102			months = year & 0x03 ? regyear : leapyear;
103			for (month = 0; days > months[month]; month++)
104				;
105			if (month > 0)
106				days -= months[month - 1];
107			lastddate = ((days + 1) << DD_DAY_SHIFT)
108			    + ((month + 1) << DD_MONTH_SHIFT);
109			/*
110			 * Remember dos's idea of time is relative to 1980.
111			 * unix's is relative to 1970.  If somehow we get a
112			 * time before 1980 then don't give totally crazy
113			 * results.
114			 */
115			if (year > 1980)
116				lastddate += (year - 1980) << DD_YEAR_SHIFT;
117		}
118	}
119	*dtp = lastdtime;
120	*ddp = lastddate;
121}
122
123/*
124 * The number of seconds between Jan 1, 1970 and Jan 1, 1980. In that
125 * interval there were 8 regular years and 2 leap years.
126 */
127#define	SECONDSTO1980	(((8 * 365) + (2 * 366)) * (24 * 60 * 60))
128
129u_short lastdosdate;
130u_long lastseconds;
131
132/*
133 * Convert from dos' idea of time to unix'. This will probably only be
134 * called from the stat(), and fstat() system calls and so probably need
135 * not be too efficient.
136 */
137void
138dos2unixtime(dd, dt, tsp)
139	u_short dd;
140	u_short dt;
141	struct timespec *tsp;
142{
143	u_long seconds;
144	u_long month;
145	u_long year;
146	u_long days;
147	u_short *months;
148
149	seconds = (((dt & DT_2SECONDS_MASK) >> DT_2SECONDS_SHIFT) << 1)
150	    + ((dt & DT_MINUTES_MASK) >> DT_MINUTES_SHIFT) * 60
151	    + ((dt & DT_HOURS_MASK) >> DT_HOURS_SHIFT) * 3600;
152	/*
153	 * If the year, month, and day from the last conversion are the
154	 * same then use the saved value.
155	 */
156	if (lastdosdate != dd) {
157		lastdosdate = dd;
158		days = 0;
159		year = (dd & DD_YEAR_MASK) >> DD_YEAR_SHIFT;
160		days = year * 365;
161		days += year / 4 + 1;	/* add in leap days */
162		if ((year & 0x03) == 0)
163			days--;		/* if year is a leap year */
164		months = year & 0x03 ? regyear : leapyear;
165		month = (dd & DD_MONTH_MASK) >> DD_MONTH_SHIFT;
166		if (month < 1 || month > 12) {
167			printf(
168			    "dos2unixtime(): month value out of range (%ld)\n",
169			    month);
170			month = 1;
171		}
172		if (month > 1)
173			days += months[month - 2];
174		days += ((dd & DD_DAY_MASK) >> DD_DAY_SHIFT) - 1;
175		lastseconds = (days * 24 * 60 * 60) + SECONDSTO1980;
176	}
177	tsp->ts_sec = seconds + lastseconds + (tz.tz_minuteswest * 60)
178	     + adjkerntz 	/* -+ daylight savings time correction */ ;
179	tsp->ts_nsec = 0;
180}
181
182/*
183 * Cheezy macros to do case detection and conversion for the ascii
184 * character set.  DOESN'T work for ebcdic.
185 */
186#define	isupper(c)	(c >= 'A'  &&  c <= 'Z')
187#define	islower(c)	(c >= 'a'  &&  c <= 'z')
188#define	toupper(c)	(c & ~' ')
189#define	tolower(c)	(c | ' ')
190
191/*
192 * DOS filenames are made of 2 parts, the name part and the extension part.
193 * The name part is 8 characters long and the extension part is 3
194 * characters long.  They may contain trailing blanks if the name or
195 * extension are not long enough to fill their respective fields.
196 */
197
198/*
199 * Convert a DOS filename to a unix filename. And, return the number of
200 * characters in the resulting unix filename excluding the terminating
201 * null.
202 */
203int
204dos2unixfn(dn, un)
205	u_char dn[11];
206	u_char *un;
207{
208	int i;
209	int ni;
210	int ei;
211	int thislong = 0;
212	u_char c;
213	u_char *origun = un;
214
215	/*
216	 * Find the last character in the name portion of the dos filename.
217	 */
218	for (ni = 7; ni >= 0; ni--)
219		if (dn[ni] != ' ')
220			break;
221
222	/*
223	 * Find the last character in the extension portion of the
224	 * filename.
225	 */
226	for (ei = 10; ei >= 8; ei--)
227		if (dn[ei] != ' ')
228			break;
229
230	/*
231	 * Copy the name portion into the unix filename string. NOTE: DOS
232	 * filenames are usually kept in upper case.  To make it more unixy
233	 * we convert all DOS filenames to lower case.  Some may like this,
234	 * some may not.
235	 */
236	for (i = 0; i <= ni; i++) {
237		c = dn[i];
238		*un++ = isupper(c) ? tolower(c) : c;
239		thislong++;
240	}
241
242	/*
243	 * Now, if there is an extension then put in a period and copy in
244	 * the extension.
245	 */
246	if (ei >= 8) {
247		*un++ = '.';
248		thislong++;
249		for (i = 8; i <= ei; i++) {
250			c = dn[i];
251			*un++ = isupper(c) ? tolower(c) : c;
252			thislong++;
253		}
254	}
255	*un++ = 0;
256
257	/*
258	 * If first char of the filename is SLOT_E5 (0x05), then the real
259	 * first char of the filename should be 0xe5. But, they couldn't
260	 * just have a 0xe5 mean 0xe5 because that is used to mean a freed
261	 * directory slot. Another dos quirk.
262	 */
263	if (*origun == SLOT_E5)
264		*origun = 0xe5;
265
266	return thislong;
267}
268
269/*
270 * Convert a unix filename to a DOS filename. This function does not ensure
271 * that valid characters for a dos filename are supplied.
272 */
273void
274unix2dosfn(un, dn, unlen)
275	u_char *un;
276	u_char dn[11];
277	int unlen;
278{
279	int i;
280	u_char c;
281
282	/*
283	 * Fill the dos filename string with blanks. These are DOS's pad
284	 * characters.
285	 */
286	for (i = 0; i <= 10; i++)
287		dn[i] = ' ';
288
289	/*
290	 * The filenames "." and ".." are handled specially, since they
291	 * don't follow dos filename rules.
292	 */
293	if (un[0] == '.' && unlen == 1) {
294		dn[0] = '.';
295		return;
296	}
297	if (un[0] == '.' && un[1] == '.' && unlen == 2) {
298		dn[0] = '.';
299		dn[1] = '.';
300		return;
301	}
302
303	/*
304	 * Copy the unix filename into the dos filename string upto the end
305	 * of string, a '.', or 8 characters. Whichever happens first stops
306	 * us. This forms the name portion of the dos filename. Fold to
307	 * upper case.
308	 */
309	for (i = 0; i <= 7 && unlen && (c = *un) && c != '.'; i++) {
310		dn[i] = islower(c) ? toupper(c) : c;
311		un++;
312		unlen--;
313	}
314
315	/*
316	 * If the first char of the filename is 0xe5, then translate it to
317	 * 0x05.  This is because 0xe5 is the marker for a deleted
318	 * directory slot.  I guess this means you can't have filenames
319	 * that start with 0x05.  I suppose we should check for this and
320	 * doing something about it.
321	 */
322	if (dn[0] == SLOT_DELETED)
323		dn[0] = SLOT_E5;
324
325	/*
326	 * Strip any further characters up to a '.' or the end of the
327	 * string.
328	 */
329	while (unlen && (c = *un)) {
330		un++;
331		unlen--;
332		/* Make sure we've skipped over the dot before stopping. */
333		if (c == '.')
334			break;
335	}
336
337	/*
338	 * Copy in the extension part of the name, if any. Force to upper
339	 * case. Note that the extension is allowed to contain '.'s.
340	 * Filenames in this form are probably inaccessable under dos.
341	 */
342	for (i = 8; i <= 10 && unlen && (c = *un); i++) {
343		dn[i] = islower(c) ? toupper(c) : c;
344		un++;
345		unlen--;
346	}
347}
348
349/*
350 * Get rid of these macros before someone discovers we are using such
351 * hideous things.
352 */
353#undef	isupper
354#undef	islower
355#undef	toupper
356#undef	tolower
357