Currently iocharset=utf8 mount option is broken. To use UTF-8 as iocharset,
it is required to use utf8 mount option.

Fix iocharset=utf8 mount option to use be equivalent to the utf8 mount
option.

If UTF-8 as iocharset is used then s_nls_map is set to NULL. So simplify
code around, remove UDF_FLAG_NLS_MAP and UDF_FLAG_UTF8 flags as to
distinguish between UTF-8 and non-UTF-8 it is needed just to check if
s_nls_map set to NULL or not.

Link: https://lore.kernel.org/r/20210808162453.1653-4-pali@kernel.org
Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Jan Kara <jack@suse.cz>

Commit c26f6c615788 ("udf: Fix conversion of 'dstring' fields to UTF8")
started to be more strict when checking whether converted strings are
properly formatted. Sudip reports that there are DVDs where the volume
identification string is actually too long - UDF reports:

[  632.309320] UDF-fs: incorrect dstring lengths (32/32)

during mount and fails the mount. This is mostly harmless failure as we
don't need volume identification (and even less volume set
identification) for anything. So just truncate the volume identification
string if it is too long and replace it with 'Invalid' if we just cannot
convert it for other reasons. This keeps slightly incorrect media still
mountable.

CC: stable@vger.kernel.org
Fixes: c26f6c615788 ("udf: Fix conversion of 'dstring' fields to UTF8")
Reported-and-tested-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

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>

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>

Push superblock argument to udf_name_[to|from]_CS0() functions so that
we can decide about character conversion functions there.

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

iocharset= mount option specifies the character set used on *console*
(not on disk). So even dstrings from VRS need to be converted from CS0
to the specified charset and not always UTF-8. This is barely user
visible as those strings are shown only in UDF debug messages.

CC: Andrew Gabbasov <andrew_gabbasov@mentor.com>
Signed-off-by: Jan Kara <jack@suse.cz>

Instead of implementing our own functions converting to and from UTF-8,
use the ones provided by NLS.

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

OSTA UDF specification does not mention whether the CS0 charset in case
of two bytes per character encoding should be treated in UTF-16 or
UCS-2. The sample code in the standard does not treat UTF-16 surrogates
in any special way but on systems such as Windows which work in UTF-16
internally, filenames would be treated as being in UTF-16 effectively.
In Linux it is more difficult to handle characters outside of Base
Multilingual plane (beyond 0xffff) as NLS framework works with 2-byte
characters only. Just make sure we don't leak UTF-16 surrogates into the
resulting string when loading names from the filesystem for now.

CC: stable@vger.kernel.org # >= v4.6
Reported-by: Mingye Wang <arthur200126@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

Fix problems noted in compilion with -Wformat=2 -Wformat-signedness.
In particular, a mismatch between the signedness of a value and the
signedness of its format specifier can result in unsigned values being
printed as negative numbers, e.g.:

  Partition (0 type 1511) starts at physical 460, block length -1779968542

...which occurs when mounting a large (> 1 TiB) UDF partition.

Changes since V1:
* Fixed additional issues noted in udf_bitmap_free_blocks(),
  udf_get_fileident(), udf_show_options()

Signed-off-by: Steven J. Magnani <steve@digidescorp.com>
Signed-off-by: Jan Kara <jack@suse.cz>

Commit 9293fcfbc1812a22ad5ce1b542eb90c1bbe01be1
("udf: Remove struct ustr as non-needed intermediate storage"),
while getting rid of 'struct ustr', does not take any special care
of 'dstring' fields and effectively use fixed field length instead
of actual string length, encoded in the last byte of the field.

Also, commit 484a10f49387e4386bf2708532e75bf78ffea2cb
("udf: Merge linux specific translation into CS0 conversion function")
introduced checking of the length of the string being converted,
requiring proper alignment to number of bytes constituing each
character.

The UDF volume identifier is represented as a 32-bytes 'dstring',
and needs to be converted from CS0 to UTF8, while mounting UDF
filesystem. The changes in mentioned commits can in some cases
lead to incorrect handling of volume identifier:
- if the actual string in 'dstring' is of maximal length and
does not have zero bytes separating it from dstring encoded
length in last byte, that last byte may be included in conversion,
thus making incorrect resulting string;
- if the identifier is encoded with 2-bytes characters (compression
code is 16), the length of 31 bytes (32 bytes of field length minus
1 byte of compression code), taken as the string length, is reported
as an incorrect (unaligned) length, and the conversion fails, which
in its turn leads to volume mounting failure.

This patch introduces handling of 'dstring' encoded length field
in udf_CS0toUTF8 function, that is used in all and only cases
when 'dstring' fields are converted. Currently these cases are
processing of Volume Identifier and Volume Set Identifier fields.
The function is also renamed to udf_dstrCS0toUTF8 to distinctly
indicate that it handles 'dstring' input.

Signed-off-by: Andrew Gabbasov <andrew_gabbasov@mentor.com>
Signed-off-by: Jan Kara <jack@suse.cz>