udf: Add support for decoding UTF-16 characters

Add support to decode characters outside of Base Multilingual Plane of
UTF-16 encoded in CS0 charset of UDF.

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

diff --git a/fs/udf/unicode.c b/fs/udf/unicode.c
index 616ffee..4523479 100644 (file)
--- a/fs/udf/unicode.c
+++ b/fs/udf/unicode.c
@@ -36,25 +36,6 @@
 #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,
-                            int boundlen)
-{
-       int u_len = 0;
-
-       if (boundlen <= 0)
-               return -ENAMETOOLONG;
-
-       u_len = utf32_to_utf8(uni, out, boundlen);
-       if (u_len < 0) {
-               if (uni > UNICODE_MAX ||
-                   (uni & SURROGATE_MASK) == SURROGATE_PAIR)
-                       return -EINVAL;
-               return -ENAMETOOLONG;
-       }
-       return u_len;
-}
-
 #define ILLEGAL_CHAR_MARK      '_'
 #define EXT_MARK               '.'
 #define CRC_MARK               '#'
@@ -62,6 +43,50 @@ static int udf_uni2char_utf8(wchar_t uni,
 /* Number of chars we need to store generated CRC to make filename unique */
 #define CRC_LEN                        5
 
+static unicode_t get_utf16_char(const uint8_t *str_i, int str_i_max_len,
+                               int str_i_idx, int u_ch, unicode_t *ret)
+{
+       unicode_t c;
+       int start_idx = str_i_idx;
+
+       /* Expand OSTA compressed Unicode to Unicode */
+       c = str_i[str_i_idx++];
+       if (u_ch > 1)
+               c = (c << 8) | str_i[str_i_idx++];
+       if ((c & SURROGATE_MASK) == SURROGATE_PAIR) {
+               unicode_t next;
+
+               /* Trailing surrogate char */
+               if (str_i_idx >= str_i_max_len) {
+                       c = UNICODE_MAX + 1;
+                       goto out;
+               }
+
+               /* Low surrogate must follow the high one... */
+               if (c & SURROGATE_LOW) {
+                       c = UNICODE_MAX + 1;
+                       goto out;
+               }
+
+               WARN_ON_ONCE(u_ch != 2);
+               next = str_i[str_i_idx++] << 8;
+               next |= str_i[str_i_idx++];
+               if ((next & SURROGATE_MASK) != SURROGATE_PAIR ||
+                   !(next & SURROGATE_LOW)) {
+                       c = UNICODE_MAX + 1;
+                       goto out;
+               }
+
+               c = PLANE_SIZE +
+                   ((c & SURROGATE_CHAR_MASK) << SURROGATE_CHAR_BITS) +
+                   (next & SURROGATE_CHAR_MASK);
+       }
+out:
+       *ret = c;
+       return str_i_idx - start_idx;
+}
+
+
 static int udf_name_conv_char(uint8_t *str_o, int str_o_max_len,
                              int *str_o_idx,
                              const uint8_t *str_i, int str_i_max_len,
@@ -70,27 +95,29 @@ static int udf_name_conv_char(uint8_t *str_o, int str_o_max_len,
                              int (*conv_f)(wchar_t, unsigned char *, int),
                              int translate)
 {
-       uint32_t c;
+       unicode_t c;
        int illChar = 0;
        int len, gotch = 0;
 
-       for (; (!gotch) && (*str_i_idx < str_i_max_len); *str_i_idx += u_ch) {
+       while (!gotch && *str_i_idx < str_i_max_len) {
                if (*str_o_idx >= str_o_max_len) {
                        *needsCRC = 1;
                        return gotch;
                }
 
-               /* Expand OSTA compressed Unicode to Unicode */
-               c = str_i[*str_i_idx];
-               if (u_ch > 1)
-                       c = (c << 8) | str_i[*str_i_idx + 1];
-
-               if (translate && (c == '/' || c == 0))
+               len = get_utf16_char(str_i, str_i_max_len, *str_i_idx, u_ch,
+                                    &c);
+               /* These chars cannot be converted. Replace them. */
+               if (c == 0 || c > UNICODE_MAX || (conv_f && c > MAX_WCHAR_T) ||
+                   (translate && c == '/')) {
                        illChar = 1;
-               else if (illChar)
+                       if (!translate)
+                               gotch = 1;
+               } else if (illChar)
                        break;
                else
                        gotch = 1;
+               *str_i_idx += len;
        }
        if (illChar) {
                *needsCRC = 1;
@@ -98,7 +125,15 @@ static int udf_name_conv_char(uint8_t *str_o, int str_o_max_len,
                gotch = 1;
        }
        if (gotch) {
-               len = conv_f(c, &str_o[*str_o_idx], str_o_max_len - *str_o_idx);
+               if (conv_f) {
+                       len = conv_f(c, &str_o[*str_o_idx],
+                                    str_o_max_len - *str_o_idx);
+               } else {
+                       len = utf32_to_utf8(c, &str_o[*str_o_idx],
+                                           str_o_max_len - *str_o_idx);
+                       if (len < 0)
+                               len = -ENAMETOOLONG;
+               }
                /* Valid character? */
                if (len >= 0)
                        *str_o_idx += len;
@@ -106,7 +141,7 @@ static int udf_name_conv_char(uint8_t *str_o, int str_o_max_len,
                        *needsCRC = 1;
                        gotch = 0;
                } else {
-                       str_o[(*str_o_idx)++] = '?';
+                       str_o[(*str_o_idx)++] = ILLEGAL_CHAR_MARK;
                        *needsCRC = 1;
                }
        }
@@ -142,12 +177,10 @@ static int udf_name_from_CS0(struct super_block *sb,
                return 0;
        }
 
-       if (UDF_QUERY_FLAG(sb, UDF_FLAG_UTF8)) {
-               conv_f = udf_uni2char_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->uni2char;
-       } else
-               BUG();
+       else
+               conv_f = NULL;
 
        cmp_id = ocu[0];
        if (cmp_id != 8 && cmp_id != 16) {