// SPDX-License-Identifier: GPL-2.0

  /*
   *  linux/fs/hfsplus/unicode.c
   *
   * Copyright (C) 2001
   * Brad Boyer (flar@allandria.com)
   * (C) 2003 Ardis Technologies <roman@ardistech.com>
   *
   * Handler routines for unicode strings
   */
  
  #include <linux/types.h>
  #include <linux/nls.h>
  #include "hfsplus_fs.h"
  #include "hfsplus_raw.h"
  
  /* Fold the case of a unicode char, given the 16 bit value */
  /* Returns folded char, or 0 if ignorable */
  static inline u16 case_fold(u16 c)
  {

  	u16 tmp;

  	tmp = hfsplus_case_fold_table[c >> 8];
  	if (tmp)
  		tmp = hfsplus_case_fold_table[tmp + (c & 0xff)];
  	else
  		tmp = c;
  	return tmp;

  }
  
  /* Compare unicode strings, return values like normal strcmp */

  int hfsplus_strcasecmp(const struct hfsplus_unistr *s1,
  		       const struct hfsplus_unistr *s2)

  {
  	u16 len1, len2, c1, c2;
  	const hfsplus_unichr *p1, *p2;
  
  	len1 = be16_to_cpu(s1->length);
  	len2 = be16_to_cpu(s2->length);
  	p1 = s1->unicode;
  	p2 = s2->unicode;
  
  	while (1) {
  		c1 = c2 = 0;
  
  		while (len1 && !c1) {
  			c1 = case_fold(be16_to_cpu(*p1));
  			p1++;
  			len1--;
  		}
  		while (len2 && !c2) {
  			c2 = case_fold(be16_to_cpu(*p2));
  			p2++;
  			len2--;
  		}
  
  		if (c1 != c2)
  			return (c1 < c2) ? -1 : 1;
  		if (!c1 && !c2)
  			return 0;
  	}
  }

  /* Compare names as a sequence of 16-bit unsigned integers */
  int hfsplus_strcmp(const struct hfsplus_unistr *s1,
  		   const struct hfsplus_unistr *s2)
  {
  	u16 len1, len2, c1, c2;
  	const hfsplus_unichr *p1, *p2;
  	int len;
  
  	len1 = be16_to_cpu(s1->length);
  	len2 = be16_to_cpu(s2->length);
  	p1 = s1->unicode;
  	p2 = s2->unicode;
  
  	for (len = min(len1, len2); len > 0; len--) {
  		c1 = be16_to_cpu(*p1);
  		c2 = be16_to_cpu(*p2);
  		if (c1 != c2)
  			return c1 < c2 ? -1 : 1;
  		p1++;
  		p2++;
  	}
  
  	return len1 < len2 ? -1 :
  	       len1 > len2 ? 1 : 0;
  }

  #define Hangul_SBase	0xac00
  #define Hangul_LBase	0x1100
  #define Hangul_VBase	0x1161
  #define Hangul_TBase	0x11a7
  #define Hangul_SCount	11172
  #define Hangul_LCount	19
  #define Hangul_VCount	21
  #define Hangul_TCount	28
  #define Hangul_NCount	(Hangul_VCount * Hangul_TCount)
  
  
  static u16 *hfsplus_compose_lookup(u16 *p, u16 cc)
  {
  	int i, s, e;
  
  	s = 1;
  	e = p[1];
  	if (!e || cc < p[s * 2] || cc > p[e * 2])
  		return NULL;
  	do {
  		i = (s + e) / 2;
  		if (cc > p[i * 2])
  			s = i + 1;
  		else if (cc < p[i * 2])
  			e = i - 1;
  		else
  			return hfsplus_compose_table + p[i * 2 + 1];
  	} while (s <= e);
  	return NULL;
  }

  int hfsplus_uni2asc(struct super_block *sb,
  		const struct hfsplus_unistr *ustr,
  		char *astr, int *len_p)

  {
  	const hfsplus_unichr *ip;

  	struct nls_table *nls = HFSPLUS_SB(sb)->nls;

  	u8 *op;
  	u16 cc, c0, c1;
  	u16 *ce1, *ce2;
  	int i, len, ustrlen, res, compose;
  
  	op = astr;
  	ip = ustr->unicode;
  	ustrlen = be16_to_cpu(ustr->length);
  	len = *len_p;
  	ce1 = NULL;

  	compose = !test_bit(HFSPLUS_SB_NODECOMPOSE, &HFSPLUS_SB(sb)->flags);

  
  	while (ustrlen > 0) {
  		c0 = be16_to_cpu(*ip++);
  		ustrlen--;
  		/* search for single decomposed char */
  		if (likely(compose))
  			ce1 = hfsplus_compose_lookup(hfsplus_compose_table, c0);

  		if (ce1)
  			cc = ce1[0];
  		else
  			cc = 0;
  		if (cc) {

  			/* start of a possibly decomposed Hangul char */
  			if (cc != 0xffff)
  				goto done;
  			if (!ustrlen)
  				goto same;
  			c1 = be16_to_cpu(*ip) - Hangul_VBase;
  			if (c1 < Hangul_VCount) {
  				/* compose the Hangul char */
  				cc = (c0 - Hangul_LBase) * Hangul_VCount;
  				cc = (cc + c1) * Hangul_TCount;
  				cc += Hangul_SBase;
  				ip++;
  				ustrlen--;
  				if (!ustrlen)
  					goto done;
  				c1 = be16_to_cpu(*ip) - Hangul_TBase;
  				if (c1 > 0 && c1 < Hangul_TCount) {
  					cc += c1;
  					ip++;
  					ustrlen--;
  				}
  				goto done;
  			}
  		}
  		while (1) {
  			/* main loop for common case of not composed chars */
  			if (!ustrlen)
  				goto same;
  			c1 = be16_to_cpu(*ip);
  			if (likely(compose))

  				ce1 = hfsplus_compose_lookup(
  					hfsplus_compose_table, c1);

  			if (ce1)
  				break;
  			switch (c0) {
  			case 0:
  				c0 = 0x2400;
  				break;
  			case '/':
  				c0 = ':';
  				break;
  			}
  			res = nls->uni2char(c0, op, len);
  			if (res < 0) {
  				if (res == -ENAMETOOLONG)
  					goto out;
  				*op = '?';
  				res = 1;
  			}
  			op += res;
  			len -= res;
  			c0 = c1;
  			ip++;
  			ustrlen--;
  		}
  		ce2 = hfsplus_compose_lookup(ce1, c0);
  		if (ce2) {
  			i = 1;
  			while (i < ustrlen) {

  				ce1 = hfsplus_compose_lookup(ce2,
  					be16_to_cpu(ip[i]));

  				if (!ce1)
  					break;
  				i++;
  				ce2 = ce1;
  			}

  			cc = ce2[0];
  			if (cc) {

  				ip += i;
  				ustrlen -= i;
  				goto done;
  			}
  		}

  same:

  		switch (c0) {
  		case 0:
  			cc = 0x2400;
  			break;
  		case '/':
  			cc = ':';
  			break;
  		default:
  			cc = c0;
  		}

  done:

  		res = nls->uni2char(cc, op, len);
  		if (res < 0) {
  			if (res == -ENAMETOOLONG)
  				goto out;
  			*op = '?';
  			res = 1;
  		}
  		op += res;
  		len -= res;
  	}
  	res = 0;
  out:
  	*len_p = (char *)op - astr;
  	return res;
  }

  /*
   * Convert one or more ASCII characters into a single unicode character.
   * Returns the number of ASCII characters corresponding to the unicode char.
   */
  static inline int asc2unichar(struct super_block *sb, const char *astr, int len,
  			      wchar_t *uc)

  {

  	int size = HFSPLUS_SB(sb)->nls->char2uni(astr, len, uc);

  	if (size <= 0) {
  		*uc = '?';
  		size = 1;
  	}
  	switch (*uc) {
  	case 0x2400:
  		*uc = 0;
  		break;
  	case ':':
  		*uc = '/';
  		break;
  	}
  	return size;
  }

  /* Decomposes a non-Hangul unicode character. */
  static u16 *hfsplus_decompose_nonhangul(wchar_t uc, int *size)

  {
  	int off;
  
  	off = hfsplus_decompose_table[(uc >> 12) & 0xf];
  	if (off == 0 || off == 0xffff)
  		return NULL;
  
  	off = hfsplus_decompose_table[off + ((uc >> 8) & 0xf)];
  	if (!off)
  		return NULL;
  
  	off = hfsplus_decompose_table[off + ((uc >> 4) & 0xf)];
  	if (!off)
  		return NULL;
  
  	off = hfsplus_decompose_table[off + (uc & 0xf)];
  	*size = off & 3;
  	if (*size == 0)
  		return NULL;
  	return hfsplus_decompose_table + (off / 4);
  }

  /*
   * Try to decompose a unicode character as Hangul. Return 0 if @uc is not
   * precomposed Hangul, otherwise return the length of the decomposition.
   *
   * This function was adapted from sample code from the Unicode Standard
   * Annex #15: Unicode Normalization Forms, version 3.2.0.
   *
   * Copyright (C) 1991-2018 Unicode, Inc.  All rights reserved.  Distributed
   * under the Terms of Use in http://www.unicode.org/copyright.html.
   */
  static int hfsplus_try_decompose_hangul(wchar_t uc, u16 *result)
  {
  	int index;
  	int l, v, t;
  
  	index = uc - Hangul_SBase;
  	if (index < 0 || index >= Hangul_SCount)
  		return 0;
  
  	l = Hangul_LBase + index / Hangul_NCount;
  	v = Hangul_VBase + (index % Hangul_NCount) / Hangul_TCount;
  	t = Hangul_TBase + index % Hangul_TCount;
  
  	result[0] = l;
  	result[1] = v;
  	if (t != Hangul_TBase) {
  		result[2] = t;
  		return 3;
  	}
  	return 2;
  }
  
  /* Decomposes a single unicode character. */
  static u16 *decompose_unichar(wchar_t uc, int *size, u16 *hangul_buffer)
  {
  	u16 *result;
  
  	/* Hangul is handled separately */
  	result = hangul_buffer;
  	*size = hfsplus_try_decompose_hangul(uc, result);
  	if (*size == 0)
  		result = hfsplus_decompose_nonhangul(uc, size);
  	return result;
  }

  int hfsplus_asc2uni(struct super_block *sb,
  		    struct hfsplus_unistr *ustr, int max_unistr_len,

  		    const char *astr, int len)
  {
  	int size, dsize, decompose;
  	u16 *dstr, outlen = 0;

  	wchar_t c;

  	u16 dhangul[3];

  	decompose = !test_bit(HFSPLUS_SB_NODECOMPOSE, &HFSPLUS_SB(sb)->flags);

  	while (outlen < max_unistr_len && len > 0) {

  		size = asc2unichar(sb, astr, len, &c);

  		if (decompose)

  			dstr = decompose_unichar(c, &dsize, dhangul);

  		else
  			dstr = NULL;
  		if (dstr) {

  			if (outlen + dsize > max_unistr_len)

  				break;
  			do {

  				ustr->unicode[outlen++] = cpu_to_be16(*dstr++);
  			} while (--dsize > 0);
  		} else
  			ustr->unicode[outlen++] = cpu_to_be16(c);
  
  		astr += size;
  		len -= size;

  	}
  	ustr->length = cpu_to_be16(outlen);
  	if (len > 0)
  		return -ENAMETOOLONG;
  	return 0;
  }

  
  /*
   * Hash a string to an integer as appropriate for the HFS+ filesystem.
   * Composed unicode characters are decomposed and case-folding is performed
   * if the appropriate bits are (un)set on the superblock.
   */

  int hfsplus_hash_dentry(const struct dentry *dentry, struct qstr *str)

  {
  	struct super_block *sb = dentry->d_sb;
  	const char *astr;
  	const u16 *dstr;

  	int casefold, decompose, size, len;

  	unsigned long hash;
  	wchar_t c;
  	u16 c2;

  	u16 dhangul[3];

  	casefold = test_bit(HFSPLUS_SB_CASEFOLD, &HFSPLUS_SB(sb)->flags);
  	decompose = !test_bit(HFSPLUS_SB_NODECOMPOSE, &HFSPLUS_SB(sb)->flags);

  	hash = init_name_hash(dentry);

  	astr = str->name;
  	len = str->len;
  	while (len > 0) {

  		int uninitialized_var(dsize);

  		size = asc2unichar(sb, astr, len, &c);
  		astr += size;
  		len -= size;

  		if (decompose)

  			dstr = decompose_unichar(c, &dsize, dhangul);

  		else
  			dstr = NULL;
  		if (dstr) {

  			do {
  				c2 = *dstr++;

  				if (casefold)
  					c2 = case_fold(c2);
  				if (!casefold || c2)

  					hash = partial_name_hash(c2, hash);
  			} while (--dsize > 0);
  		} else {
  			c2 = c;

  			if (casefold)
  				c2 = case_fold(c2);
  			if (!casefold || c2)

  				hash = partial_name_hash(c2, hash);
  		}
  	}
  	str->hash = end_name_hash(hash);
  
  	return 0;
  }
  
  /*
   * Compare strings with HFS+ filename ordering.
   * Composed unicode characters are decomposed and case-folding is performed
   * if the appropriate bits are (un)set on the superblock.
   */

  int hfsplus_compare_dentry(const struct dentry *dentry,

  		unsigned int len, const char *str, const struct qstr *name)

  {

  	struct super_block *sb = dentry->d_sb;

  	int casefold, decompose, size;
  	int dsize1, dsize2, len1, len2;
  	const u16 *dstr1, *dstr2;
  	const char *astr1, *astr2;
  	u16 c1, c2;
  	wchar_t c;

  	u16 dhangul_1[3], dhangul_2[3];

  	casefold = test_bit(HFSPLUS_SB_CASEFOLD, &HFSPLUS_SB(sb)->flags);
  	decompose = !test_bit(HFSPLUS_SB_NODECOMPOSE, &HFSPLUS_SB(sb)->flags);

  	astr1 = str;
  	len1 = len;
  	astr2 = name->name;
  	len2 = name->len;

  	dsize1 = dsize2 = 0;
  	dstr1 = dstr2 = NULL;
  
  	while (len1 > 0 && len2 > 0) {
  		if (!dsize1) {
  			size = asc2unichar(sb, astr1, len1, &c);
  			astr1 += size;
  			len1 -= size;

  			if (decompose)

  				dstr1 = decompose_unichar(c, &dsize1,
  							  dhangul_1);

  			if (!decompose || !dstr1) {

  				c1 = c;
  				dstr1 = &c1;
  				dsize1 = 1;
  			}
  		}
  
  		if (!dsize2) {
  			size = asc2unichar(sb, astr2, len2, &c);
  			astr2 += size;
  			len2 -= size;

  			if (decompose)

  				dstr2 = decompose_unichar(c, &dsize2,
  							  dhangul_2);

  			if (!decompose || !dstr2) {

  				c2 = c;
  				dstr2 = &c2;
  				dsize2 = 1;
  			}
  		}
  
  		c1 = *dstr1;
  		c2 = *dstr2;
  		if (casefold) {

  			c1 = case_fold(c1);
  			if (!c1) {

  				dstr1++;
  				dsize1--;
  				continue;
  			}

  			c2 = case_fold(c2);
  			if (!c2) {

  				dstr2++;
  				dsize2--;
  				continue;
  			}
  		}
  		if (c1 < c2)
  			return -1;
  		else if (c1 > c2)
  			return 1;
  
  		dstr1++;
  		dsize1--;
  		dstr2++;
  		dsize2--;
  	}
  
  	if (len1 < len2)
  		return -1;
  	if (len1 > len2)
  		return 1;
  	return 0;
  }