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>

1 files changed, 43 insertions, 36 deletions

diff --git a/fs/udf/unicode.c b/fs/udf/unicode.c
index 329be783f98a..616ffee441c5 100644
--- 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;