Raw MIME messages may contain non-ASCII characters. Attempting to
store them as TEXT by using String::from_utf8_lossy results in
non-ASCII characters being replaced with Unicode U+FFFD "REPLACEMENT
CHARACTER" which is later incorrectly decoded when attempting to parse
`mime_headers` content into HTML.
CString::yolo was still used in the ffi, this was an unsafe
transitional thing. To remove it there were two choices: 1. make
errors in creating CStrings hard errors or 2. try and be as lenient as
possible. Given the to_string_lossy() convention adopted in the ffi
this choose the lenient option and simply skips over embedded null
bytes, leaving the rest of the strings intact.
Thus now CString::new_lossy(). It's only used for .strdup() however
so no longer a public trait.
This also cleans up the public visibility of things in the strings.rs
file:
- Rename StrExt/OptStrExt traits to what they actually do: provide
.strdup() -> Strdup/OptStrdup.
- dc_strdup() should be an implementation detail, replace all usages
with Strdup.strdup() method.
- Only allow visibility inside the crate for all things.
- Reduce visibility to only the module for things not used in lib.rs.
We already have a .strdup() method on AsRef<str>, this adds this
method also to an option of this. In case the option is None a NULL
pointer is returned.
This is done by using a new trait, as the type system otherwise
considers such an implementation conflicting with the existing one.
