msdosfs_conv.c revision 15053 
1/*	$Id: msdosfs_conv.c,v 1.7 1995/11/07 14:06:41 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)
81	    - wall_cmos_clock ? adjkerntz : 0;
82	    /* - daylight savings time correction */
83	if (lasttime != t) {
84		lasttime = t;
85		lastdtime = (((t % 60) >> 1) << DT_2SECONDS_SHIFT)
86		    + (((t / 60) % 60) << DT_MINUTES_SHIFT)
87		    + (((t / 3600) % 24) << DT_HOURS_SHIFT);
88
89		/*
90		 * If the number of days since 1970 is the same as the last
91		 * time we did the computation then skip all this leap year
92		 * and month stuff.
93		 */
94		days = t / (24 * 60 * 60);
95		if (days != lastday) {
96			lastday = days;
97			for (year = 1970;; year++) {
98				inc = year & 0x03 ? 365 : 366;
99				if (days < inc)
100					break;
101				days -= inc;
102			}
103			months = year & 0x03 ? regyear : leapyear;
104			for (month = 0; days > months[month]; month++)
105				;
106			if (month > 0)
107				days -= months[month - 1];
108			lastddate = ((days + 1) << DD_DAY_SHIFT)
109			    + ((month + 1) << DD_MONTH_SHIFT);
110			/*
111			 * Remember dos's idea of time is relative to 1980.
112			 * unix's is relative to 1970.  If somehow we get a
113			 * time before 1980 then don't give totally crazy
114			 * results.
115			 */
116			if (year > 1980)
117				lastddate += (year - 1980) << DD_YEAR_SHIFT;
118		}
119	}
120	*dtp = lastdtime;
121	*ddp = lastddate;
122}
123
124/*
125 * The number of seconds between Jan 1, 1970 and Jan 1, 1980. In that
126 * interval there were 8 regular years and 2 leap years.
127 */
128#define	SECONDSTO1980	(((8 * 365) + (2 * 366)) * (24 * 60 * 60))
129
130u_short lastdosdate;
131u_long lastseconds;
132
133/*
134 * Convert from dos' idea of time to unix'. This will probably only be
135 * called from the stat(), and fstat() system calls and so probably need
136 * not be too efficient.
137 */
138void
139dos2unixtime(dd, dt, tsp)
140	u_short dd;
141	u_short dt;
142	struct timespec *tsp;
143{
144	u_long seconds;
145	u_long month;
146	u_long year;
147	u_long days;
148	u_short *months;
149
150	seconds = (((dt & DT_2SECONDS_MASK) >> DT_2SECONDS_SHIFT) << 1)
151	    + ((dt & DT_MINUTES_MASK) >> DT_MINUTES_SHIFT) * 60
152	    + ((dt & DT_HOURS_MASK) >> DT_HOURS_SHIFT) * 3600;
153	/*
154	 * If the year, month, and day from the last conversion are the
155	 * same then use the saved value.
156	 */
157	if (lastdosdate != dd) {
158		lastdosdate = dd;
159		days = 0;
160		year = (dd & DD_YEAR_MASK) >> DD_YEAR_SHIFT;
161		days = year * 365;
162		days += year / 4 + 1;	/* add in leap days */
163		if ((year & 0x03) == 0)
164			days--;		/* if year is a leap year */
165		months = year & 0x03 ? regyear : leapyear;
166		month = (dd & DD_MONTH_MASK) >> DD_MONTH_SHIFT;
167		if (month < 1 || month > 12) {
168			printf(
169			    "dos2unixtime(): month value out of range (%ld)\n",
170			    month);
171			month = 1;
172		}
173		if (month > 1)
174			days += months[month - 2];
175		days += ((dd & DD_DAY_MASK) >> DD_DAY_SHIFT) - 1;
176		lastseconds = (days * 24 * 60 * 60) + SECONDSTO1980;
177	}
178	tsp->ts_sec = seconds + lastseconds + (tz.tz_minuteswest * 60)
179	     + wall_cmos_clock ? adjkerntz : 0;
180	     /* + daylight savings time correction */
181	tsp->ts_nsec = 0;
182}
183
184/*
185 * Cheezy macros to do case detection and conversion for the ascii
186 * character set.  DOESN'T work for ebcdic.
187 */
188#define	isupper(c)	(c >= 'A'  &&  c <= 'Z')
189#define	islower(c)	(c >= 'a'  &&  c <= 'z')
190#define	toupper(c)	(c & ~' ')
191#define	tolower(c)	(c | ' ')
192
193/*
194 * DOS filenames are made of 2 parts, the name part and the extension part.
195 * The name part is 8 characters long and the extension part is 3
196 * characters long.  They may contain trailing blanks if the name or
197 * extension are not long enough to fill their respective fields.
198 */
199
200/*
201 * Convert a DOS filename to a unix filename. And, return the number of
202 * characters in the resulting unix filename excluding the terminating
203 * null.
204 */
205int
206dos2unixfn(dn, un)
207	u_char dn[11];
208	u_char *un;
209{
210	int i;
211	int ni;
212	int ei;
213	int thislong = 0;
214	u_char c;
215	u_char *origun = un;
216
217	/*
218	 * Find the last character in the name portion of the dos filename.
219	 */
220	for (ni = 7; ni >= 0; ni--)
221		if (dn[ni] != ' ')
222			break;
223
224	/*
225	 * Find the last character in the extension portion of the
226	 * filename.
227	 */
228	for (ei = 10; ei >= 8; ei--)
229		if (dn[ei] != ' ')
230			break;
231
232	/*
233	 * Copy the name portion into the unix filename string. NOTE: DOS
234	 * filenames are usually kept in upper case.  To make it more unixy
235	 * we convert all DOS filenames to lower case.  Some may like this,
236	 * some may not.
237	 */
238	for (i = 0; i <= ni; i++) {
239		c = dn[i];
240		*un++ = isupper(c) ? tolower(c) : c;
241		thislong++;
242	}
243
244	/*
245	 * Now, if there is an extension then put in a period and copy in
246	 * the extension.
247	 */
248	if (ei >= 8) {
249		*un++ = '.';
250		thislong++;
251		for (i = 8; i <= ei; i++) {
252			c = dn[i];
253			*un++ = isupper(c) ? tolower(c) : c;
254			thislong++;
255		}
256	}
257	*un++ = 0;
258
259	/*
260	 * If first char of the filename is SLOT_E5 (0x05), then the real
261	 * first char of the filename should be 0xe5. But, they couldn't
262	 * just have a 0xe5 mean 0xe5 because that is used to mean a freed
263	 * directory slot. Another dos quirk.
264	 */
265	if (*origun == SLOT_E5)
266		*origun = 0xe5;
267
268	return thislong;
269}
270
271/*
272 * Convert a unix filename to a DOS filename. This function does not ensure
273 * that valid characters for a dos filename are supplied.
274 */
275void
276unix2dosfn(un, dn, unlen)
277	u_char *un;
278	u_char dn[11];
279	int unlen;
280{
281	int i;
282	u_char c;
283
284	/*
285	 * Fill the dos filename string with blanks. These are DOS's pad
286	 * characters.
287	 */
288	for (i = 0; i <= 10; i++)
289		dn[i] = ' ';
290
291	/*
292	 * The filenames "." and ".." are handled specially, since they
293	 * don't follow dos filename rules.
294	 */
295	if (un[0] == '.' && unlen == 1) {
296		dn[0] = '.';
297		return;
298	}
299	if (un[0] == '.' && un[1] == '.' && unlen == 2) {
300		dn[0] = '.';
301		dn[1] = '.';
302		return;
303	}
304
305	/*
306	 * Copy the unix filename into the dos filename string upto the end
307	 * of string, a '.', or 8 characters. Whichever happens first stops
308	 * us. This forms the name portion of the dos filename. Fold to
309	 * upper case.
310	 */
311	for (i = 0; i <= 7 && unlen && (c = *un) && c != '.'; i++) {
312		dn[i] = islower(c) ? toupper(c) : c;
313		un++;
314		unlen--;
315	}
316
317	/*
318	 * If the first char of the filename is 0xe5, then translate it to
319	 * 0x05.  This is because 0xe5 is the marker for a deleted
320	 * directory slot.  I guess this means you can't have filenames
321	 * that start with 0x05.  I suppose we should check for this and
322	 * doing something about it.
323	 */
324	if (dn[0] == SLOT_DELETED)
325		dn[0] = SLOT_E5;
326
327	/*
328	 * Strip any further characters up to a '.' or the end of the
329	 * string.
330	 */
331	while (unlen && (c = *un)) {
332		un++;
333		unlen--;
334		/* Make sure we've skipped over the dot before stopping. */
335		if (c == '.')
336			break;
337	}
338
339	/*
340	 * Copy in the extension part of the name, if any. Force to upper
341	 * case. Note that the extension is allowed to contain '.'s.
342	 * Filenames in this form are probably inaccessable under dos.
343	 */
344	for (i = 8; i <= 10 && unlen && (c = *un); i++) {
345		dn[i] = islower(c) ? toupper(c) : c;
346		un++;
347		unlen--;
348	}
349}
350
351/*
352 * Get rid of these macros before someone discovers we are using such
353 * hideous things.
354 */
355#undef	isupper
356#undef	islower
357#undef	toupper
358#undef	tolower
359