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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>
This commit is contained in:
Ernesto A. Fernández 2018-08-21 21:59:19 -07:00 committed by Linus Torvalds
parent 31651c6071
commit afd6c9e1f5
1 changed files with 56 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

62
fs/hfsplus/unicode.c
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@ -272,8 +272,8 @@ static inline int asc2unichar(struct super_block *sb, const char *astr, int len,
return size;
}
/* Decomposes a single unicode character. */
static inline u16 *decompose_unichar(wchar_t uc, int *size)
/* Decomposes a non-Hangul unicode character. */
static u16 *hfsplus_decompose_nonhangul(wchar_t uc, int *size)
{
int off;
@ -296,6 +296,51 @@ static inline u16 *decompose_unichar(wchar_t uc, int *size)
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)
@ -303,13 +348,14 @@ int hfsplus_asc2uni(struct super_block *sb,
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);
dstr = decompose_unichar(c, &dsize, dhangul);
else
dstr = NULL;
if (dstr) {
@ -344,6 +390,7 @@ int hfsplus_hash_dentry(const struct dentry *dentry, struct qstr *str)
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);
@ -357,7 +404,7 @@ int hfsplus_hash_dentry(const struct dentry *dentry, struct qstr *str)
len -= size;
if (decompose)
dstr = decompose_unichar(c, &dsize);
dstr = decompose_unichar(c, &dsize, dhangul);
else
dstr = NULL;
if (dstr) {
@ -396,6 +443,7 @@ int hfsplus_compare_dentry(const struct dentry *dentry,
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);
@ -413,7 +461,8 @@ int hfsplus_compare_dentry(const struct dentry *dentry,
len1 -= size;
if (decompose)
dstr1 = decompose_unichar(c, &dsize1);
dstr1 = decompose_unichar(c, &dsize1,
dhangul_1);
if (!decompose || !dstr1) {
c1 = c;
dstr1 = &c1;
@ -427,7 +476,8 @@ int hfsplus_compare_dentry(const struct dentry *dentry,
len2 -= size;
if (decompose)
dstr2 = decompose_unichar(c, &dsize2);
dstr2 = decompose_unichar(c, &dsize2,
dhangul_2);
if (!decompose || !dstr2) {
c2 = c;
dstr2 = &c2;