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>
diff --git a/fs/nls/nls_base.c b/fs/nls/nls_base.c
index 750abf2..477d37d 100644
--- a/fs/nls/nls_base.c
+++ b/fs/nls/nls_base.c
@@ -15,6 +15,7 @@
#include <linux/errno.h>
#include <linux/kmod.h>
#include <linux/spinlock.h>
+#include <asm/byteorder.h>
static struct nls_table default_table;
static struct nls_table *tables = &default_table;
@@ -43,10 +44,17 @@
{0, /* end of table */}
};
-int
-utf8_mbtowc(wchar_t *p, const __u8 *s, int n)
+#define UNICODE_MAX 0x0010ffff
+#define PLANE_SIZE 0x00010000
+
+#define SURROGATE_MASK 0xfffff800
+#define SURROGATE_PAIR 0x0000d800
+#define SURROGATE_LOW 0x00000400
+#define SURROGATE_BITS 0x000003ff
+
+int utf8_to_utf32(const u8 *s, int len, unicode_t *pu)
{
- long l;
+ unsigned long l;
int c0, c, nc;
const struct utf8_table *t;
@@ -57,12 +65,13 @@
nc++;
if ((c0 & t->cmask) == t->cval) {
l &= t->lmask;
- if (l < t->lval)
+ if (l < t->lval || l > UNICODE_MAX ||
+ (l & SURROGATE_MASK) == SURROGATE_PAIR)
return -1;
- *p = l;
+ *pu = (unicode_t) l;
return nc;
}
- if (n <= nc)
+ if (len <= nc)
return -1;
s++;
c = (*s ^ 0x80) & 0xFF;
@@ -72,76 +81,119 @@
}
return -1;
}
+EXPORT_SYMBOL(utf8_to_utf32);
-int
-utf8_mbstowcs(wchar_t *pwcs, const __u8 *s, int n)
+int utf32_to_utf8(unicode_t u, u8 *s, int maxlen)
{
- __u16 *op;
- const __u8 *ip;
- int size;
-
- op = pwcs;
- ip = s;
- while (*ip && n > 0) {
- if (*ip & 0x80) {
- size = utf8_mbtowc(op, ip, n);
- if (size == -1) {
- /* Ignore character and move on */
- ip++;
- n--;
- } else {
- op++;
- ip += size;
- n -= size;
- }
- } else {
- *op++ = *ip++;
- n--;
- }
- }
- return (op - pwcs);
-}
-
-int
-utf8_wctomb(__u8 *s, wchar_t wc, int maxlen)
-{
- long l;
+ unsigned long l;
int c, nc;
const struct utf8_table *t;
-
+
if (!s)
return 0;
-
- l = wc;
+
+ l = u;
+ if (l > UNICODE_MAX || (l & SURROGATE_MASK) == SURROGATE_PAIR)
+ return -1;
+
nc = 0;
for (t = utf8_table; t->cmask && maxlen; t++, maxlen--) {
nc++;
if (l <= t->lmask) {
c = t->shift;
- *s = t->cval | (l >> c);
+ *s = (u8) (t->cval | (l >> c));
while (c > 0) {
c -= 6;
s++;
- *s = 0x80 | ((l >> c) & 0x3F);
+ *s = (u8) (0x80 | ((l >> c) & 0x3F));
}
return nc;
}
}
return -1;
}
+EXPORT_SYMBOL(utf32_to_utf8);
-int
-utf8_wcstombs(__u8 *s, const wchar_t *pwcs, int maxlen)
+int utf8s_to_utf16s(const u8 *s, int len, wchar_t *pwcs)
{
- const __u16 *ip;
- __u8 *op;
+ u16 *op;
int size;
+ unicode_t u;
+
+ op = pwcs;
+ while (*s && len > 0) {
+ if (*s & 0x80) {
+ size = utf8_to_utf32(s, len, &u);
+ if (size < 0) {
+ /* Ignore character and move on */
+ size = 1;
+ } else if (u >= PLANE_SIZE) {
+ u -= PLANE_SIZE;
+ *op++ = (wchar_t) (SURROGATE_PAIR |
+ ((u >> 10) & SURROGATE_BITS));
+ *op++ = (wchar_t) (SURROGATE_PAIR |
+ SURROGATE_LOW |
+ (u & SURROGATE_BITS));
+ } else {
+ *op++ = (wchar_t) u;
+ }
+ s += size;
+ len -= size;
+ } else {
+ *op++ = *s++;
+ len--;
+ }
+ }
+ return op - pwcs;
+}
+EXPORT_SYMBOL(utf8s_to_utf16s);
+
+static inline unsigned long get_utf16(unsigned c, enum utf16_endian endian)
+{
+ switch (endian) {
+ default:
+ return c;
+ case UTF16_LITTLE_ENDIAN:
+ return __le16_to_cpu(c);
+ case UTF16_BIG_ENDIAN:
+ return __be16_to_cpu(c);
+ }
+}
+
+int utf16s_to_utf8s(const wchar_t *pwcs, int len, enum utf16_endian endian,
+ u8 *s, int maxlen)
+{
+ u8 *op;
+ int size;
+ unsigned long u, v;
op = s;
- ip = pwcs;
- while (*ip && maxlen > 0) {
- if (*ip > 0x7f) {
- size = utf8_wctomb(op, *ip, maxlen);
+ while (len > 0 && maxlen > 0) {
+ u = get_utf16(*pwcs, endian);
+ if (!u)
+ break;
+ pwcs++;
+ len--;
+ if (u > 0x7f) {
+ if ((u & SURROGATE_MASK) == SURROGATE_PAIR) {
+ if (u & SURROGATE_LOW) {
+ /* Ignore character and move on */
+ continue;
+ }
+ if (len <= 0)
+ break;
+ v = get_utf16(*pwcs, endian);
+ if ((v & SURROGATE_MASK) != SURROGATE_PAIR ||
+ !(v & SURROGATE_LOW)) {
+ /* Ignore character and move on */
+ continue;
+ }
+ u = PLANE_SIZE + ((u & SURROGATE_BITS) << 10)
+ + (v & SURROGATE_BITS);
+ pwcs++;
+ len--;
+ }
+ size = utf32_to_utf8(u, op, maxlen);
if (size == -1) {
/* Ignore character and move on */
} else {
@@ -149,13 +201,13 @@
maxlen -= size;
}
} else {
- *op++ = (__u8) *ip;
+ *op++ = (u8) u;
maxlen--;
}
- ip++;
}
- return (op - s);
+ return op - s;
}
+EXPORT_SYMBOL(utf16s_to_utf8s);
int register_nls(struct nls_table * nls)
{
@@ -467,9 +519,5 @@
EXPORT_SYMBOL(unload_nls);
EXPORT_SYMBOL(load_nls);
EXPORT_SYMBOL(load_nls_default);
-EXPORT_SYMBOL(utf8_mbtowc);
-EXPORT_SYMBOL(utf8_mbstowcs);
-EXPORT_SYMBOL(utf8_wctomb);
-EXPORT_SYMBOL(utf8_wcstombs);
MODULE_LICENSE("Dual BSD/GPL");