/*-
 * SPDX-License-Identifier: BSD-4-Clause
 *
 * Copyright (C) 1994, 1995, 1997 Wolfgang Solfrank.
 * Copyright (C) 1994, 1995, 1997 TooLs GmbH.
 * All rights reserved.
 * Original code by Paul Popelka (paulp@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@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/param.h>
#include <sys/endian.h>

#include <dirent.h>
#include <stdio.h>
#include <string.h>

#include <fs/msdosfs/bpb.h>
#include "msdos/direntry.h"
#include <fs/msdosfs/msdosfsmount.h>

#include "makefs.h"
#include "msdos.h"

static int char8ucs2str(const uint8_t *in, int n, uint16_t *out, int m);
static void ucs2pad(uint16_t *buf, int len, int size);
static int char8match(uint16_t *w1, uint16_t *w2, int n);

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 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 */
};

/*
 * Determine the number of slots necessary for Win95 names
 */
int
winSlotCnt(const u_char *un, size_t unlen)
{
        const u_char *cp;

        /*
         * Drop trailing blanks and dots
         */
        for (cp = un + unlen; unlen > 0; unlen--)
                if (*--cp != ' ' && *cp != '.')
                        break;

        return howmany(unlen, WIN_CHARS);
}

/*
 * Compare our filename to the one in the Win95 entry
 * Returns the checksum or -1 if no match
 */
int
winChkName(const u_char *un, size_t unlen, struct winentry *wep, int chksum)
{
        uint16_t wn[WIN_MAXLEN], *p;
        uint16_t buf[WIN_CHARS];
        int i, len;

        /*
         * 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;

        /*
         * Translate UNIX name to ucs-2
         */
        len = char8ucs2str(un, unlen, wn, WIN_MAXLEN);
        ucs2pad(wn, len, WIN_MAXLEN);

        if (i >= len + 1)
                return -1;
        if ((wep->weCnt & WIN_LAST) && (len - i > WIN_CHARS))
                return -1;

        /*
         * Fetch name segment from directory entry
         */
        p = &buf[0];
        memcpy(p, wep->wePart1, sizeof(wep->wePart1));
        p += sizeof(wep->wePart1) / sizeof(*p);
        memcpy(p, wep->wePart2, sizeof(wep->wePart2));
        p += sizeof(wep->wePart2) / sizeof(*p);
        memcpy(p, wep->wePart3, sizeof(wep->wePart3));

        /*
         * And compare name segment
         */
        if (!(char8match(&wn[i], buf, WIN_CHARS)))
                return -1;

        return chksum;
}

/*
 * Compute the checksum of a DOS filename for Win95 use
 */
uint8_t
winChksum(uint8_t *name)
{
        int i;
        uint8_t s;

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

/*
 * 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, size_t unlen, struct winentry *wep, int cnt,
    int chksum)
{
        uint16_t wn[WIN_MAXLEN], *p;
        int i, len;
        const u_char *cp;

        /*
         * Drop trailing blanks and dots
         */
        for (cp = un + unlen; unlen > 0; unlen--)
                if (*--cp != ' ' && *cp != '.')
                        break;

        /*
         * Offset of this entry
         */
        i = (cnt - 1) * WIN_CHARS;

        /*
         * Translate UNIX name to ucs-2
         */
        len = char8ucs2str(un, unlen, wn, WIN_MAXLEN);
        ucs2pad(wn, len, WIN_MAXLEN);

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

        /*
         * Store name segment into directory entry
         */
        p = &wn[i];
        memcpy(wep->wePart1, p, sizeof(wep->wePart1));
        p += sizeof(wep->wePart1) / sizeof(*p);
        memcpy(wep->wePart2, p, sizeof(wep->wePart2));
        p += sizeof(wep->wePart2) / sizeof(*p);
        memcpy(wep->wePart3, p, sizeof(wep->wePart3));

        if (len > i + WIN_CHARS)
                return 1;

        wep->weCnt |= WIN_LAST;
        return 0;
}

/*
 * 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(const u_char *un, u_char dn[12], size_t 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;
}

/*
 * Convert 8bit character string into UCS-2 string
 * return total number of output chacters
 */
static int
char8ucs2str(const uint8_t *in, int n, uint16_t *out, int m)
{
        uint16_t *p;

        p = out;
        while (n > 0 && in[0] != 0) {
                if (m < 1)
                        break;
                if (p)
                        p[0] = htole16(in[0]);
                p += 1;
                m -= 1;
                in += 1;
                n -= 1;
        }

        return p - out;
}

static void
ucs2pad(uint16_t *buf, int len, int size)
{

        if (len < size-1)
                buf[len++] = 0x0000;
        while (len < size)
                buf[len++] = 0xffff;
}

/*
 * Compare two 8bit char conversions case-insensitive
 *
 * uses the DOS case folding table
 */
static int
char8match(uint16_t *w1, uint16_t *w2, int n)
{
        uint16_t u1, u2;

        while (n > 0) {
                u1 = le16toh(*w1);
                u2 = le16toh(*w2);
                if (u1 == 0 || u2 == 0)
                        return u1 == u2;
                if (u1 > 255 || u2 > 255)
                        return 0;
                u1 = u2l[u1 & 0xff];
                u2 = u2l[u2 & 0xff];
                if (u1 != u2)
                        return 0;
                ++w1;
                ++w2;
                --n;
        }

        return 1;
}