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| author | Alan Stern <stern@rowland.harvard.edu> | 2009-04-30 10:08:18 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2009-06-15 21:44:43 -0700 |
| commit | 74675a58507e769beee7d949dbed788af3c4139d (patch) | |
| tree | d4ae3cc06dbfadecf1eaf6ed0aef249fc87b07e6 /include/linux | |
| parent | a853a3d4eb2edb066248a39f0634f6f5858816a0 (diff) | |
NLS: update handling of Unicode
This patch (as1239) updates the kernel's treatment of Unicode. The
character-set conversion routines are well behind the current state of
the Unicode specification: They don't recognize the existence of code
points beyond plane 0 or of surrogate pairs in the UTF-16 encoding.
The old wchar_t 16-bit type is retained because it's still used in
lots of places. This shouldn't cause any new problems; if a
conversion now results in an invalid 16-bit code then before it must
have yielded an undefined code.
Difficult-to-read names like "utf_mbstowcs" are replaced with more
transparent names like "utf8s_to_utf16s" and the ordering of the
parameters is rationalized (buffer lengths come immediate after the
pointers they refer to, and the inputs precede the outputs).
Fortunately the low-level conversion routines are used in only a few
places; the interfaces to the higher-level uni2char and char2uni
methods have been left unchanged.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Acked-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/nls.h | 35 |
1 files changed, 29 insertions, 6 deletions
diff --git a/include/linux/nls.h b/include/linux/nls.h index 52b1a76c1b4..d47beef08df 100644 --- a/include/linux/nls.h +++ b/include/linux/nls.h @@ -3,8 +3,23 @@ #include <linux/init.h> -/* unicode character */ -typedef __u16 wchar_t; +/* Unicode has changed over the years. Unicode code points no longer + * fit into 16 bits; as of Unicode 5 valid code points range from 0 + * to 0x10ffff (17 planes, where each plane holds 65536 code points). + * + * The original decision to represent Unicode characters as 16-bit + * wchar_t values is now outdated. But plane 0 still includes the + * most commonly used characters, so we will retain it. The newer + * 32-bit unicode_t type can be used when it is necessary to + * represent the full Unicode character set. + */ + +/* Plane-0 Unicode character */ +typedef u16 wchar_t; +#define MAX_WCHAR_T 0xffff + +/* Arbitrary Unicode character */ +typedef u32 unicode_t; struct nls_table { const char *charset; @@ -21,6 +36,13 @@ struct nls_table { /* this value hold the maximum octet of charset */ #define NLS_MAX_CHARSET_SIZE 6 /* for UTF-8 */ +/* Byte order for UTF-16 strings */ +enum utf16_endian { + UTF16_HOST_ENDIAN, + UTF16_LITTLE_ENDIAN, + UTF16_BIG_ENDIAN +}; + /* nls.c */ extern int register_nls(struct nls_table *); extern int unregister_nls(struct nls_table *); @@ -28,10 +50,11 @@ extern struct nls_table *load_nls(char *); extern void unload_nls(struct nls_table *); extern struct nls_table *load_nls_default(void); -extern int utf8_mbtowc(wchar_t *, const __u8 *, int); -extern int utf8_mbstowcs(wchar_t *, const __u8 *, int); -extern int utf8_wctomb(__u8 *, wchar_t, int); -extern int utf8_wcstombs(__u8 *, const wchar_t *, int); +extern int utf8_to_utf32(const u8 *s, int len, unicode_t *pu); +extern int utf32_to_utf8(unicode_t u, u8 *s, int maxlen); +extern int utf8s_to_utf16s(const u8 *s, int len, wchar_t *pwcs); +extern int utf16s_to_utf8s(const wchar_t *pwcs, int len, + enum utf16_endian endian, u8 *s, int maxlen); static inline unsigned char nls_tolower(struct nls_table *t, unsigned char c) { |