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authorAlan Stern <stern@rowland.harvard.edu>2009-04-30 10:08:18 -0400
committerGreg Kroah-Hartman <gregkh@suse.de>2009-06-15 21:44:43 -0700
commit74675a58507e769beee7d949dbed788af3c4139d (patch)
treed4ae3cc06dbfadecf1eaf6ed0aef249fc87b07e6 /include/linux/nls.h
parenta853a3d4eb2edb066248a39f0634f6f5858816a0 (diff)
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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/nls.h')
-rw-r--r--include/linux/nls.h35
1 files changed, 29 insertions, 6 deletions
diff --git a/include/linux/nls.h b/include/linux/nls.h
index 52b1a76..d47beef 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+ * wchar_t values is now outdated.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)
{
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