sms-part-3gpp: decode Unicode SMS with non-BMP code points

Depsite 3GPP TS 23.038 specifies that Unicode SMS messages are encoded in
UCS-2, UTF-16 encoding is commonly used instead on many modern platforms to
allow encoding code points that fall outside the Basic Multilingual Plane
(BMP), such as Emoji. Most of the UCS-2 code points are identical to their
equivalent UTF-16 code points.  In UTF-16, non-BMP code points are encoded in a
pair of surrogate code points (i.e. a high surrogate in 0xD800..0xDBFF,
followed by a low surrogate in 0xDC00..0xDFFF). An isolated surrogate code
point has no general interpretation in UTF-16, but could be a valid (though
unmapped) code point in UCS-2.

This patch modifies the 3GPP SMS decoding to first try UTF-16BE and then fall
back to UCS-2BE on failure. If both fail, an empty string is returned
instead of a NULL pointer.

0 files changed, 0 insertions, 0 deletions