So, in fact, Posix apps should strip the initial slash of an absolute pathname before concatenating it to file:///
https://tools.ietf.org/html/rfc8089Appendix B. Example URIs
The syntax in Section 2 is intended to support file URIs that take
the following forms:
Local files:
o A traditional file URI for a local file with an empty authority.
This is the most common format in use today. For example:
* "file:///path/to/file"
The test, as it is now, works for the native Windows port and fails for the Cygwin port. So to work on both, some special-casing will have to be done.
Note that file:/// is already used in several places in the sources.
> Posix says that the meaning of a path name starting with exactly two slashes is
> implementation-defined. On Cygwin, it's interpreted as a UNC path name,
> referring to a file on a network.
This is not about Posix pathnames, but RFC8089 URI schemes.