xref: /src/sys/fs/msdosfs/msdosfs_conv.c

/*	$NetBSD: msdosfs_conv.c,v 1.6 2009/03/14 15:36:21 dsl Exp $	*/

/*-
 * Copyright (C) 1995, 1997 Wolfgang Solfrank.
 * Copyright (C) 1995, 1997 TooLs GmbH.
 * All rights reserved.
 * Original code by Paul Popelka (paulp (at) uts.amdahl.com) (see below).
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by TooLs GmbH.
 * 4. The name of TooLs GmbH may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY TOOLS GMBH ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL TOOLS GMBH BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
/*
 * Written by Paul Popelka (paulp (at) uts.amdahl.com)
 *
 * You can do anything you want with this software, just don't say you wrote
 * it, and don't remove this notice.
 *
 * This software is provided "as is".
 *
 * The author supplies this software to be publicly redistributed on the
 * understanding that the author is not responsible for the correct
 * functioning of this software in any circumstances and is not liable for
 * any damages caused by this software.
 *
 * October 1992
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: msdosfs_conv.c,v 1.6 2009/03/14 15:36:21 dsl Exp $");

/*
 * System include files.
 */
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/time.h>
#include <sys/kernel.h>
#include <sys/dirent.h>
#include <sys/vnode.h>

/*
 * MSDOSFS include files.
 */
#include <fs/msdosfs/direntry.h>
#include <fs/msdosfs/denode.h>

/*
 * Days in each month in a regular year.
 */
u_short const regyear[] = {
	31, 28, 31, 30, 31, 30,
	31, 31, 30, 31, 30, 31
};

/*
 * Days in each month in a leap year.
 */
u_short const leapyear[] = {
	31, 29, 31, 30, 31, 30,
	31, 31, 30, 31, 30, 31
};

/*
 * Variables used to remember parts of the last time conversion.  Maybe we
 * can avoid a full conversion.
 */
u_long lasttime;
u_long lastday;
u_short lastddate;
u_short lastdtime;

/*
 * Convert the unix version of time to dos's idea of time to be used in
 * file timestamps. The passed in unix time is assumed to be in GMT.
 */
void
unix2dostime(const struct timespec *tsp, int gmtoff, u_int16_t *ddp, u_int16_t *dtp, u_int8_t *dhp)
{
	u_long t;
	u_long days;
	u_long inc;
	u_long year;
	u_long month;
	const u_short *months;

	/*
	 * If the time from the last conversion is the same as now, then
	 * skip the computations and use the saved result.
	 */
	t = tsp->tv_sec + gmtoff; /* time zone correction */
	t &= ~1;
	if (lasttime != t) {
		lasttime = t;
		lastdtime = (((t / 2) % 30) << DT_2SECONDS_SHIFT)
		    + (((t / 60) % 60) << DT_MINUTES_SHIFT)
		    + (((t / 3600) % 24) << DT_HOURS_SHIFT);

		/*
		 * If the number of days since 1970 is the same as the last
		 * time we did the computation then skip all this leap year
		 * and month stuff.
		 */
		days = t / (24 * 60 * 60);
		if (days != lastday) {
			lastday = days;
			for (year = 1970;; year++) {
				inc = year & 0x03 ? 365 : 366;
				if (days < inc)
					break;
				days -= inc;
			}
			months = year & 0x03 ? regyear : leapyear;
			for (month = 0; month < 12; month++) {
				if (days < months[month])
					break;
				days -= months[month];
			}
			lastddate = ((days + 1) << DD_DAY_SHIFT)
			    + ((month + 1) << DD_MONTH_SHIFT);
			/*
			 * Remember dos's idea of time is relative to 1980.
			 * unix's is relative to 1970.  If somehow we get a
			 * time before 1980 then don't give totally crazy
			 * results.
			 */
			if (year > 1980)
				lastddate += (year - 1980) << DD_YEAR_SHIFT;
		}
	}
	if (dtp)
		*dtp = lastdtime;
	if (dhp)
		*dhp = (tsp->tv_sec & 1) * 100 + tsp->tv_nsec / 10000000;

	*ddp = lastddate;
}

/*
 * The number of seconds between Jan 1, 1970 and Jan 1, 1980. In that
 * interval there were 8 regular years and 2 leap years.
 */
#define	SECONDSTO1980	(((8 * 365) + (2 * 366)) * (24 * 60 * 60))

u_short lastdosdate;
u_long lastseconds;

/*
 * Convert from dos' idea of time to unix'. This will probably only be
 * called from the stat(), and fstat() system calls and so probably need
 * not be too efficient.
 */
void
dos2unixtime(u_int dd, u_int dt, u_int dh, int gmtoff, struct timespec *tsp)
{
	u_long seconds;
	u_long m, month;
	u_long y, year;
	u_long days;
	const u_short *months;

	if (dd == 0) {
		/*
		 * Uninitialized field, return the epoch.
		 */
		tsp->tv_sec = 0;
		tsp->tv_nsec = 0;
		return;
	}
	seconds = ((dt & DT_2SECONDS_MASK) >> DT_2SECONDS_SHIFT) * 2
	    + ((dt & DT_MINUTES_MASK) >> DT_MINUTES_SHIFT) * 60
	    + ((dt & DT_HOURS_MASK) >> DT_HOURS_SHIFT) * 3600
	    + dh / 100;
	/*
	 * If the year, month, and day from the last conversion are the
	 * same then use the saved value.
	 */
	if (lastdosdate != dd) {
		lastdosdate = dd;
		days = 0;
		year = (dd & DD_YEAR_MASK) >> DD_YEAR_SHIFT;
		for (y = 0; y < year; y++)
			days += y & 0x03 ? 365 : 366;
		months = year & 0x03 ? regyear : leapyear;
		/*
		 * Prevent going from 0 to 0xffffffff in the following
		 * loop.
		 */
		month = (dd & DD_MONTH_MASK) >> DD_MONTH_SHIFT;
		if (month == 0) {
			printf("dos2unixtime(): month value out of range (%ld)\n",
			    month);
			month = 1;
		}
		for (m = 0; m < month - 1; m++)
			days += months[m];
		days += ((dd & DD_DAY_MASK) >> DD_DAY_SHIFT) - 1;
		lastseconds = (days * 24 * 60 * 60) + SECONDSTO1980;
	}
	tsp->tv_sec = seconds + lastseconds;
	tsp->tv_sec -= gmtoff;	/* time zone correction */
	tsp->tv_nsec = (dh % 100) * 10000000;
}

static const u_char
unix2dos[256] = {
	0,    0,    0,    0,    0,    0,    0,    0,	/* 00-07 */
	0,    0,    0,    0,    0,    0,    0,    0,	/* 08-0f */
	0,    0,    0,    0,    0,    0,    0,    0,	/* 10-17 */
	0,    0,    0,    0,    0,    0,    0,    0,	/* 18-1f */
	0,    '!',  0,    '#',  '$',  '%',  '&',  '\'',	/* 20-27 */
	'(',  ')',  0,    '+',  0,    '-',  0,    0,	/* 28-2f */
	'0',  '1',  '2',  '3',  '4',  '5',  '6',  '7',	/* 30-37 */
	'8',  '9',  0,    0,    0,    0,    0,    0,	/* 38-3f */
	'@',  'A',  'B',  'C',  'D',  'E',  'F',  'G',	/* 40-47 */
	'H',  'I',  'J',  'K',  'L',  'M',  'N',  'O',	/* 48-4f */
	'P',  'Q',  'R',  'S',  'T',  'U',  'V',  'W',	/* 50-57 */
	'X',  'Y',  'Z',  0,    0,    0,    '^',  '_',	/* 58-5f */
	'`',  'A',  'B',  'C',  'D',  'E',  'F',  'G',	/* 60-67 */
	'H',  'I',  'J',  'K',  'L',  'M',  'N',  'O',	/* 68-6f */
	'P',  'Q',  'R',  'S',  'T',  'U',  'V',  'W',	/* 70-77 */
	'X',  'Y',  'Z',  '{',  0,    '}',  '~',  0,	/* 78-7f */
	0,    0,    0,    0,    0,    0,    0,    0,	/* 80-87 */
	0,    0,    0,    0,    0,    0,    0,    0,	/* 88-8f */
	0,    0,    0,    0,    0,    0,    0,    0,	/* 90-97 */
	0,    0,    0,    0,    0,    0,    0,    0,	/* 98-9f */
	0,    0xad, 0xbd, 0x9c, 0xcf, 0xbe, 0xdd, 0xf5,	/* a0-a7 */
	0xf9, 0xb8, 0xa6, 0xae, 0xaa, 0xf0, 0xa9, 0xee,	/* a8-af */
	0xf8, 0xf1, 0xfd, 0xfc, 0xef, 0xe6, 0xf4, 0xfa,	/* b0-b7 */
	0xf7, 0xfb, 0xa7, 0xaf, 0xac, 0xab, 0xf3, 0xa8,	/* b8-bf */
	0xb7, 0xb5, 0xb6, 0xc7, 0x8e, 0x8f, 0x92, 0x80,	/* c0-c7 */
	0xd4, 0x90, 0xd2, 0xd3, 0xde, 0xd6, 0xd7, 0xd8,	/* c8-cf */
	0xd1, 0xa5, 0xe3, 0xe0, 0xe2, 0xe5, 0x99, 0x9e,	/* d0-d7 */
	0x9d, 0xeb, 0xe9, 0xea, 0x9a, 0xed, 0xe8, 0xe1,	/* d8-df */
	0xb7, 0xb5, 0xb6, 0xc7, 0x8e, 0x8f, 0x92, 0x80,	/* e0-e7 */
	0xd4, 0x90, 0xd2, 0xd3, 0xde, 0xd6, 0xd7, 0xd8,	/* e8-ef */
	0xd1, 0xa5, 0xe3, 0xe0, 0xe2, 0xe5, 0x99, 0xf6,	/* f0-f7 */
	0x9d, 0xeb, 0xe9, 0xea, 0x9a, 0xed, 0xe8, 0x98,	/* f8-ff */
};

static const u_char
dos2unix[256] = {
	 '?',  '?',  '?',  '?',  '?',  '?',  '?',  '?',	/* 00-07 */
	 '?',  '?',  '?',  '?',  '?',  '?',  '?',  '?',	/* 08-0f */
	 '?',  '?',  '?',  '?',  '?',  '?',  '?',  '?',	/* 10-17 */
	 '?',  '?',  '?',  '?',  '?',  '?',  '?',  '?',	/* 18-1f */
	 ' ',  '!',  '"',  '#',  '$',  '%',  '&', '\'',	/* 20-27 */
	 '(',  ')',  '*',  '+',  ',',  '-',  '.',  '/',	/* 28-2f */
	 '0',  '1',  '2',  '3',  '4',  '5',  '6',  '7',	/* 30-37 */
	 '8',  '9',  ':',  ';',  '<',  '=',  '>',  '?',	/* 38-3f */
	 '@',  'A',  'B',  'C',  'D',  'E',  'F',  'G',	/* 40-47 */
	 'H',  'I',  'J',  'K',  'L',  'M',  'N',  'O',	/* 48-4f */
	 'P',  'Q',  'R',  'S',  'T',  'U',  'V',  'W',	/* 50-57 */
	 'X',  'Y',  'Z',  '[', '\\',  ']',  '^',  '_',	/* 58-5f */
	 '`',  'a',  'b',  'c',  'd',  'e',  'f',  'g',	/* 60-67 */
	 'h',  'i',  'j',  'k',  'l',  'm',  'n',  'o',	/* 68-6f */
	 'p',  'q',  'r',  's',  't',  'u',  'v',  'w',	/* 70-77 */
	 'x',  'y',  'z',  '{',  '|',  '}',  '~', 0x7f,	/* 78-7f */
	0xc7, 0xfc, 0xe9, 0xe2, 0xe4, 0xe0, 0xe5, 0xe7,	/* 80-87 */
	0xea, 0xeb, 0xe8, 0xef, 0xee, 0xec, 0xc4, 0xc5,	/* 88-8f */
	0xc9, 0xe6, 0xc6, 0xf4, 0xf6, 0xf2, 0xfb, 0xf9,	/* 90-97 */
	0xff, 0xd6, 0xdc, 0xf8, 0xa3, 0xd8, 0xd7,  '?',	/* 98-9f */
	0xe1, 0xed, 0xf3, 0xfa, 0xf1, 0xd1, 0xaa, 0xba,	/* a0-a7 */
	0xbf, 0xae, 0xac, 0xbd, 0xbc, 0xa1, 0xab, 0xbb,	/* a8-af */
	 '?',  '?',  '?',  '?',  '?', 0xc1, 0xc2, 0xc0,	/* b0-b7 */
	0xa9,  '?',  '?',  '?',  '?', 0xa2, 0xa5,  '?',	/* b8-bf */
	 '?',  '?',  '?',  '?',  '?',  '?', 0xe3, 0xc3,	/* c0-c7 */
	 '?',  '?',  '?',  '?',  '?',  '?',  '?', 0xa4,	/* c8-cf */
	0xf0, 0xd0, 0xca, 0xcb, 0xc8,  '?', 0xcd, 0xce,	/* d0-d7 */
	0xcf,  '?',  '?',  '?',  '?', 0xa6, 0xcc,  '?',	/* d8-df */
	0xd3, 0xdf, 0xd4, 0xd2, 0xf5, 0xd5, 0xb5, 0xfe,	/* e0-e7 */
	0xde, 0xda, 0xdb, 0xd9, 0xfd, 0xdd, 0xaf, 0x3f,	/* e8-ef */
	0xad, 0xb1,  '?', 0xbe, 0xb6, 0xa7, 0xf7, 0xb8,	/* f0-f7 */
	0xb0, 0xa8, 0xb7, 0xb9, 0xb3, 0xb2,  '?',  '?',	/* f8-ff */
};

static const u_char
u2l[256] = {
	0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, /* 00-07 */
	0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, /* 08-0f */
	0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, /* 10-17 */
	0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f, /* 18-1f */
	 ' ',  '!',  '"',  '#',  '$',  '%',  '&', '\'', /* 20-27 */
	 '(',  ')',  '*',  '+',  ',',  '-',  '.',  '/', /* 28-2f */
	 '0',  '1',  '2',  '3',  '4',  '5',  '6',  '7', /* 30-37 */
	 '8',  '9',  ':',  ';',  '<',  '=',  '>',  '?', /* 38-3f */
	 '@',  'a',  'b',  'c',  'd',  'e',  'f',  'g', /* 40-47 */
	 'h',  'i',  'j',  'k',  'l',  'm',  'n',  'o', /* 48-4f */
	 'p',  'q',  'r',  's',  't',  'u',  'v',  'w', /* 50-57 */
	 'x',  'y',  'z',  '[', '\\',  ']',  '^',  '_', /* 58-5f */
	 '`',  'a',  'b',  'c',  'd',  'e',  'f',  'g', /* 60-67 */
	 'h',  'i',  'j',  'k',  'l',  'm',  'n',  'o', /* 68-6f */
	 'p',  'q',  'r',  's',  't',  'u',  'v',  'w', /* 70-77 */
	 'x',  'y',  'z',  '{',  '|',  '}',  '~', 0x7f, /* 78-7f */
	0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87, /* 80-87 */
	0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f, /* 88-8f */
	0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, /* 90-97 */
	0x98, 0x99, 0x9a, 0x9b, 0x9c, 0x9d, 0x9e, 0x9f, /* 98-9f */
	0xa0, 0xa1, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7, /* a0-a7 */
	0xa8, 0xa9, 0xaa, 0xab, 0xac, 0xad, 0xae, 0xaf, /* a8-af */
	0xb0, 0xb1, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6, 0xb7, /* b0-b7 */
	0xb8, 0xb9, 0xba, 0xbb, 0xbc, 0xbd, 0xbe, 0xbf, /* b8-bf */
	0xe0, 0xe1, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7, /* c0-c7 */
	0xe8, 0xe9, 0xea, 0xeb, 0xec, 0xed, 0xee, 0xef, /* c8-cf */
	0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xd7, /* d0-d7 */
	0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe, 0xdf, /* d8-df */
	0xe0, 0xe1, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7, /* e0-e7 */
	0xe8, 0xe9, 0xea, 0xeb, 0xec, 0xed, 0xee, 0xef, /* e8-ef */
	0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, /* f0-f7 */
	0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe, 0xff, /* f8-ff */
};

/*
 * DOS filenames are made of 2 parts, the name part and the extension part.
 * The name part is 8 characters long and the extension part is 3
 * characters long.  They may contain trailing blanks if the name or
 * extension are not long enough to fill their respective fields.
 */

/*
 * Convert a DOS filename to a unix filename. And, return the number of
 * characters in the resulting unix filename excluding the terminating
 * null.
 */
int
dos2unixfn(dn, un, lower)
	u_char dn[11];
	u_char *un;
	int lower;
{
	int i, j;
	int thislong = 1;
	u_char c;

	/*
	 * If first char of the filename is SLOT_E5 (0x05), then the real
	 * first char of the filename should be 0xe5. But, they couldn't
	 * just have a 0xe5 mean 0xe5 because that is used to mean a freed
	 * directory slot. Another dos quirk.
	 */
	if (*dn == SLOT_E5)
		c = dos2unix[0xe5];
	else
		c = dos2unix[*dn];
	*un++ = lower ? u2l[c] : c;

	/*
	 * Copy the rest into the unix filename string, ignoring
	 * trailing blanks.
	 */

	for (j=7; (j >= 0) && (dn[j] == ' '); j--)
		;

	for (i = 1; i <= j; i++) {
		c = dos2unix[dn[i]];
		*un++ = lower ? u2l[c] : c;
		thislong++;
	}
	dn += 8;

	/*
	 * Now, if there is an extension then put in a period and copy in
	 * the extension.
	 */
	if (*dn != ' ') {
		*un++ = '.';
		thislong++;
		for (i = 0; i < 3 && *dn != ' '; i++) {
			c = dos2unix[*dn++];
			*un++ = lower ? u2l[c] : c;
			thislong++;
		}
	}
	*un++ = 0;

	return (thislong);
}

/*
 * Convert a unix filename to a DOS filename according to Win95 rules.
 * If applicable and gen is not 0, it is inserted into the converted
 * filename as a generation number.
 * Returns
 *	0 if name couldn't be converted
 *	1 if the converted name is the same as the original
 *	  (no long filename entry necessary for Win95)
 *	2 if conversion was successful
 *	3 if conversion was successful and generation number was inserted
 */
int
unix2dosfn(un, dn, unlen, gen)
	const u_char *un;
	u_char dn[12];
	int unlen;
	u_int gen;
{
	int i, j, l;
	int conv = 1;
	const u_char *cp, *dp, *dp1;
	u_char gentext[6], *wcp;
	int shortlen;

	/*
	 * Fill the dos filename string with blanks. These are DOS's pad
	 * characters.
	 */
	for (i = 0; i < 11; i++)
		dn[i] = ' ';
	dn[11] = 0;

	/*
	 * The filenames "." and ".." are handled specially, since they
	 * don't follow dos filename rules.
	 */
	if (un[0] == '.' && unlen == 1) {
		dn[0] = '.';
		return gen <= 1;
	}
	if (un[0] == '.' && un[1] == '.' && unlen == 2) {
		dn[0] = '.';
		dn[1] = '.';
		return gen <= 1;
	}

	/*
	 * Filenames with only blanks and dots are not allowed!
	 */
	for (cp = un, i = unlen; --i >= 0; cp++)
		if (*cp != ' ' && *cp != '.')
			break;
	if (i < 0)
		return 0;

	/*
	 * Now find the extension
	 * Note: dot as first char doesn't start extension
	 *	 and trailing dots and blanks are ignored
	 */
	dp = dp1 = 0;
	for (cp = un + 1, i = unlen - 1; --i >= 0;) {
		switch (*cp++) {
		case '.':
			if (!dp1)
				dp1 = cp;
			break;
		case ' ':
			break;
		default:
			if (dp1)
				dp = dp1;
			dp1 = 0;
			break;
		}
	}

	/*
	 * Now convert it
	 */
	if (dp) {
		if (dp1)
			l = dp1 - dp;
		else
			l = unlen - (dp - un);
		for (i = 0, j = 8; i < l && j < 11; i++, j++) {
			if (dp[i] != (dn[j] = unix2dos[dp[i]])
			    && conv != 3)
				conv = 2;
			if (!dn[j]) {
				conv = 3;
				dn[j--] = ' ';
			}
		}
		if (i < l)
			conv = 3;
		dp--;
	} else {
		for (dp = cp; *--dp == ' ' || *dp == '.';);
		dp++;
	}

	shortlen = (dp - un) <= 8;

	/*
	 * Now convert the rest of the name
	 */
	for (i = j = 0; un < dp && j < 8; i++, j++, un++) {
		if ((*un == ' ') && shortlen)
			dn[j] = ' ';
		else
			dn[j] = unix2dos[*un];
		if ((*un != dn[j])
		    && conv != 3)
			conv = 2;
		if (!dn[j]) {
			conv = 3;
			dn[j--] = ' ';
		}
	}
	if (un < dp)
		conv = 3;
	/*
	 * If we didn't have any chars in filename,
	 * generate a default
	 */
	if (!j)
		dn[0] = '_';

	/*
	 * The first character cannot be E5,
	 * because that means a deleted entry
	 */
	if (dn[0] == 0xe5)
		dn[0] = SLOT_E5;

	/*
	 * If there wasn't any char dropped,
	 * there is no place for generation numbers
	 */
	if (conv != 3) {
		if (gen > 1)
			return 0;
		return conv;
	}

	/*
	 * Now insert the generation number into the filename part
	 */
	for (wcp = gentext + sizeof(gentext); wcp > gentext && gen; gen /= 10)
		*--wcp = gen % 10 + '0';
	if (gen)
		return 0;
	for (i = 8; dn[--i] == ' ';);
	i++;
	if (gentext + sizeof(gentext) - wcp + 1 > 8 - i)
		i = 8 - (gentext + sizeof(gentext) - wcp + 1);
	dn[i++] = '~';
	while (wcp < gentext + sizeof(gentext))
		dn[i++] = *wcp++;
	return 3;
}

/*
 * Create a Win95 long name directory entry
 * Note: assumes that the filename is valid,
 *	 i.e. doesn't consist solely of blanks and dots
 */
int
unix2winfn(const u_char *un, int unlen, struct winentry *wep, int cnt, int chksum)
{
	const u_int8_t *cp;
	u_int8_t *wcp;
	int i;

	/*
	 * Drop trailing blanks and dots
	 */
	for (cp = un + unlen; *--cp == ' ' || *cp == '.'; unlen--);

	un += (cnt - 1) * WIN_CHARS;
	unlen -= (cnt - 1) * WIN_CHARS;

	/*
	 * Initialize winentry to some useful default
	 */
	for (wcp = (u_int8_t *)wep, i = sizeof(*wep); --i >= 0; *wcp++ = 0xff);
	wep->weCnt = cnt;
	wep->weAttributes = ATTR_WIN95;
	wep->weReserved1 = 0;
	wep->weChksum = chksum;
	wep->weReserved2 = 0;

	/*
	 * Now convert the filename parts
	 */
	for (wcp = wep->wePart1, i = sizeof(wep->wePart1)/2; --i >= 0;) {
		if (--unlen < 0)
			goto done;
		*wcp++ = *un++;
		*wcp++ = 0;
	}
	for (wcp = wep->wePart2, i = sizeof(wep->wePart2)/2; --i >= 0;) {
		if (--unlen < 0)
			goto done;
		*wcp++ = *un++;
		*wcp++ = 0;
	}
	for (wcp = wep->wePart3, i = sizeof(wep->wePart3)/2; --i >= 0;) {
		if (--unlen < 0)
			goto done;
		*wcp++ = *un++;
		*wcp++ = 0;
	}
	if (!unlen)
		wep->weCnt |= WIN_LAST;
	return unlen;

done:
	*wcp++ = 0;
	*wcp++ = 0;
	wep->weCnt |= WIN_LAST;
	return 0;
}

/*
 * Compare our filename to the one in the Win95 entry
 * Returns the checksum or -1 if no match
 */
int
winChkName(const u_char *un, int unlen, struct winentry *wep, int chksum)
{
	u_int8_t *cp;
	int i;

	/*
	 * First compare checksums
	 */
	if (wep->weCnt&WIN_LAST)
		chksum = wep->weChksum;
	else if (chksum != wep->weChksum)
		chksum = -1;
	if (chksum == -1)
		return -1;

	/*
	 * Offset of this entry
	 */
	i = ((wep->weCnt&WIN_CNT) - 1) * WIN_CHARS;
	un += i;
	if ((unlen -= i) < 0)
		return -1;

	/*
	 * Ignore redundant winentries (those with only \0\0 on start in them).
	 * An appearance of such entry is a bug; unknown if in NetBSD msdosfs
	 * or MS Windows.
	 */
	if (unlen == 0) {
		if (wep->wePart1[0] == '\0' && wep->wePart1[1] == '\0')
			return chksum;
		else
			return -1;
	}

	if ((wep->weCnt&WIN_LAST) && unlen > WIN_CHARS)
		return -1;

	/*
	 * Compare the name parts
	 */
	for (cp = wep->wePart1, i = sizeof(wep->wePart1)/2; --i >= 0;) {
		if (--unlen < 0) {
			if (!*cp++ && !*cp)
				return chksum;
			return -1;
		}
		if (u2l[*cp++] != u2l[*un++] || *cp++)
			return -1;
	}
	for (cp = wep->wePart2, i = sizeof(wep->wePart2)/2; --i >= 0;) {
		if (--unlen < 0) {
			if (!*cp++ && !*cp)
				return chksum;
			return -1;
		}
		if (u2l[*cp++] != u2l[*un++] || *cp++)
			return -1;
	}
	for (cp = wep->wePart3, i = sizeof(wep->wePart3)/2; --i >= 0;) {
		if (--unlen < 0) {
			if (!*cp++ && !*cp)
				return chksum;
			return -1;
		}
		if (u2l[*cp++] != u2l[*un++] || *cp++)
			return -1;
	}
	return chksum;
}

/*
 * Convert Win95 filename to dirbuf.
 * Returns the checksum or -1 if impossible
 */
int
win2unixfn(struct winentry *wep, struct dirent *dp, int chksum)
{
	u_int8_t *cp;
	u_int8_t *np, *ep = dp->d_name + WIN_MAXLEN;
	int i;

	if ((wep->weCnt&WIN_CNT) > howmany(WIN_MAXLEN, WIN_CHARS)
	    || !(wep->weCnt&WIN_CNT))
		return -1;

	/*
	 * First compare checksums
	 */
	if (wep->weCnt&WIN_LAST) {
		chksum = wep->weChksum;
		/*
		 * This works even though d_namlen is one byte!
		 */
		dp->d_namlen = (wep->weCnt&WIN_CNT) * WIN_CHARS;
	} else if (chksum != wep->weChksum)
		chksum = -1;
	if (chksum == -1)
		return -1;

	/*
	 * Offset of this entry
	 */
	i = ((wep->weCnt&WIN_CNT) - 1) * WIN_CHARS;
	np = (u_int8_t *)dp->d_name + i;

	/*
	 * Convert the name parts
	 */
	for (cp = wep->wePart1, i = sizeof(wep->wePart1)/2; --i >= 0;) {
		switch (*np++ = *cp++) {
		case 0:
			dp->d_namlen -= sizeof(wep->wePart2)/2
			    + sizeof(wep->wePart3)/2 + i + 1;
			return chksum;
		case '/':
			np[-1] = 0;
			return -1;
		}
		/*
		 * The size comparison should result in the compiler
		 * optimizing the whole if away
		 */
		if (WIN_MAXLEN % WIN_CHARS < sizeof(wep->wePart1) / 2
		    && np > ep) {
			np[-1] = 0;
			return -1;
		}
		if (*cp++)
			return -1;
	}
	for (cp = wep->wePart2, i = sizeof(wep->wePart2)/2; --i >= 0;) {
		switch (*np++ = *cp++) {
		case 0:
			dp->d_namlen -= sizeof(wep->wePart3)/2 + i + 1;
			return chksum;
		case '/':
			np[-1] = 0;
			return -1;
		}
		/*
		 * The size comparisons should be optimized away
		 */
		if (WIN_MAXLEN % WIN_CHARS >= sizeof(wep->wePart1) / 2
		    && WIN_MAXLEN % WIN_CHARS < (sizeof(wep->wePart1) + sizeof(wep->wePart2)) / 2
		    && np > ep) {
			np[-1] = 0;
			return -1;
		}
		if (*cp++)
			return -1;
	}
	for (cp = wep->wePart3, i = sizeof(wep->wePart3)/2; --i >= 0;) {
		switch (*np++ = *cp++) {
		case 0:
			dp->d_namlen -= i + 1;
			return chksum;
		case '/':
			np[-1] = 0;
			return -1;
		}
		/*
		 * See above
		 */
		if (WIN_MAXLEN % WIN_CHARS >= (sizeof(wep->wePart1) + sizeof(wep->wePart2)) / 2
		    && np > ep) {
			np[-1] = 0;
			return -1;
		}
		if (*cp++)
			return -1;
	}
	return chksum;
}

/*
 * Compute the checksum of a DOS filename for Win95 use
 */
u_int8_t
winChksum(u_int8_t *name)
{
	int i;
	u_int8_t s;

	for (s = 0, i = 11; --i >= 0; s += *name++)
		s = (s << 7)|(s >> 1);
	return s;
}

/*
 * Determine the number of slots necessary for Win95 names
 */
int
winSlotCnt(const u_char *un, int unlen)
{
	for (un += unlen; unlen > 0; unlen--)
		if (*--un != ' ' && *un != '.')
			break;
	if (unlen > WIN_MAXLEN)
		return 0;
	return howmany(unlen, WIN_CHARS);
}