udf: Add support for encoding UTF-16 characters

Add support to store characters outside of Base Multilingual Plane of
UTF-16 in CS0 encoding of UDF.

Signed-off-by: Jan Kara <jack@suse.cz>

diff --git a/fs/udf/unicode.c b/fs/udf/unicode.c
index 329be78..616ffee 100644 (file)
--- a/fs/udf/unicode.c
+++ b/fs/udf/unicode.c
@@ -28,9 +28,13 @@
 
 #include "udf_sb.h"
 
+#define PLANE_SIZE 0x10000
 #define UNICODE_MAX 0x10ffff
 #define SURROGATE_MASK 0xfffff800
 #define SURROGATE_PAIR 0x0000d800
+#define SURROGATE_LOW  0x00000400
+#define SURROGATE_CHAR_BITS 10
+#define SURROGATE_CHAR_MASK ((1 << SURROGATE_CHAR_BITS) - 1)
 
 static int udf_uni2char_utf8(wchar_t uni,
                             unsigned char *out,
@@ -51,26 +55,6 @@ static int udf_uni2char_utf8(wchar_t uni,
        return u_len;
 }
 
-static int udf_char2uni_utf8(const unsigned char *in,
-                            int boundlen,
-                            wchar_t *uni)
-{
-       int u_len;
-       unicode_t c;
-
-       u_len = utf8_to_utf32(in, boundlen, &c);
-       if (u_len < 0) {
-               *uni = '?';
-               return -EINVAL;
-       }
-
-       if (c > MAX_WCHAR_T)
-               *uni = '?';
-       else
-               *uni = c;
-       return u_len;
-}
-
 #define ILLEGAL_CHAR_MARK      '_'
 #define EXT_MARK               '.'
 #define CRC_MARK               '#'
@@ -261,19 +245,17 @@ static int udf_name_to_CS0(struct super_block *sb,
 {
        int i, len;
        unsigned int max_val;
-       wchar_t uni_char;
        int u_len, u_ch;
+       unicode_t uni_char;
        int (*conv_f)(const unsigned char *, int, wchar_t *);
 
        if (ocu_max_len <= 0)
                return 0;
 
-       if (UDF_QUERY_FLAG(sb, UDF_FLAG_UTF8)) {
-               conv_f = udf_char2uni_utf8;
-       } else if (UDF_QUERY_FLAG(sb, UDF_FLAG_NLS_MAP)) {
+       if (UDF_QUERY_FLAG(sb, UDF_FLAG_NLS_MAP))
                conv_f = UDF_SB(sb)->s_nls_map->char2uni;
-       } else
-               BUG();
+       else
+               conv_f = NULL;
 
        memset(ocu, 0, ocu_max_len);
        ocu[0] = 8;
@@ -282,30 +264,55 @@ static int udf_name_to_CS0(struct super_block *sb,
 
 try_again:
        u_len = 1;
-       for (i = 0; i < str_len; i++) {
+       for (i = 0; i < str_len; i += len) {
                /* Name didn't fit? */
                if (u_len + u_ch > ocu_max_len)
                        return 0;
-               len = conv_f(&str_i[i], str_len - i, &uni_char);
-               if (!len)
-                       continue;
+               if (conv_f) {
+                       wchar_t wchar;
+
+                       len = conv_f(&str_i[i], str_len - i, &wchar);
+                       if (len > 0)
+                               uni_char = wchar;
+               } else {
+                       len = utf8_to_utf32(&str_i[i], str_len - i,
+                                           &uni_char);
+               }
                /* Invalid character, deal with it */
-               if (len < 0) {
+               if (len <= 0 || uni_char > UNICODE_MAX) {
                        len = 1;
                        uni_char = '?';
                }
 
                if (uni_char > max_val) {
-                       max_val = 0xffff;
-                       ocu[0] = 0x10;
-                       u_ch = 2;
-                       goto try_again;
+                       unicode_t c;
+
+                       if (max_val == 0xff) {
+                               max_val = 0xffff;
+                               ocu[0] = 0x10;
+                               u_ch = 2;
+                               goto try_again;
+                       }
+                       /*
+                        * Use UTF-16 encoding for chars outside we
+                        * cannot encode directly.
+                        */
+                       if (u_len + 2 * u_ch > ocu_max_len)
+                               return 0;
+
+                       uni_char -= PLANE_SIZE;
+                       c = SURROGATE_PAIR |
+                           ((uni_char >> SURROGATE_CHAR_BITS) &
+                            SURROGATE_CHAR_MASK);
+                       ocu[u_len++] = (uint8_t)(c >> 8);
+                       ocu[u_len++] = (uint8_t)(c & 0xff);
+                       uni_char = SURROGATE_PAIR | SURROGATE_LOW |
+                                       (uni_char & SURROGATE_CHAR_MASK);
                }
 
                if (max_val == 0xffff)
                        ocu[u_len++] = (uint8_t)(uni_char >> 8);
                ocu[u_len++] = (uint8_t)(uni_char & 0xff);
-               i += len - 1;
        }
 
        return u_len;