Mikhail Zabaluev authored Jan 14, 2018 and Philip Withnall committed Jan 19, 2018

The character encoding conversion utility functions g_locale_to_utf8()
and g_filename_to_utf8() had inconsistent behavior on producing strings
with inner NUL bytes: in the all-UTF-8 strdup path, the input string
validation prohibits embedded NULs, while g_convert(), using iconv(),
can produce UTF-8 output with NUL bytes inside the output buffer.
This, while valid UTF-8 per the Unicode standard, is not valid for
the nul-terminated (type utf8) return value format that the *_to_utf8()
functions are annotated with (as per discussion in bug 756128).

Check the output of g_convert() for embedded NUL bytes, and if any
are found, set the newly introduced error
G_CONVERT_ERROR_EMBEDDED_NUL.

Also document the error set by g_{locale,filename}_{from,to}_utf8()
when the input string contains nul bytes.

https://bugzilla.gnome.org/show_bug.cgi?id=792516