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linux/fs/hfsplus/unicode.c
Ernesto A. Fernández afd6c9e1f5 hfsplus: fix decomposition of Hangul characters 
Files created under macOS cannot be opened under linux if their names
contain Korean characters, and vice versa.

The Korean alphabet is special because its normalization is done without a
table.  The module deals with it correctly when composing, but forgets
about it for the decomposition.

Fix this using the Hangul decomposition function provided in the Unicode
Standard.  The code fits a bit awkwardly because it requires a buffer,
while all the other normalizations are returned as pointers to the
decomposition table.  This is actually also a bug because reordering may
still be needed, but for now leave it as it is.

The patch will cause trouble for Hangul filenames already created by the
module in the past.  This shouldn't really be concern because its main
purpose was always sharing with macOS.  If a user actually needs to access
such a file the nodecompose mount option should be enough.

Link: http://lkml.kernel.org/r/20180717220951.p6qqrgautc4pxvzu@eaf
Signed-off-by: Ernesto A. Fernández <ernesto.mnd.fernandez@gmail.com>
Reported-by: Ting-Chang Hou <tchou@synology.com>
Tested-by: Ting-Chang Hou <tchou@synology.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-08-22 10:52:50 -07:00

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// 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;
}
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