Adversarial review of the previous commit found four defects, three of them
mine and one of them fatal to the Local Library on Windows.
fs::canonicalize RETURNS extended-length syntax on Windows and
qbz-library/src/scan.rs stores that string for every scanned file, so the
helper saw \?\C:\Music\cover.jpg, read it as a UNC path whose server was
"?", and emitted file://%3F/C:/Music/... - every local cover, gone. Both
verbatim spellings are now undone, \?\UNC\ included.
local_path dropped the // that a UNC authority stands for, so the round trip
returned nas/music/x, a path that names nothing. It now returns
//nas/music/x, which is also what QUrl::toLocalFile gives back.
file_url pushed a third slash for any path that did not start with one, so a
relative artwork_path changed from file://covers/x to file:///covers/x on
Linux. Neither resolves - a relative path is not a valid file:// URL - but
Linux behaviour does not move in a Windows port. The extra slash is now
emitted only for a drive path.
is_local_abs_path now requires a separator after the colon, so C:cover.jpg
is drive-RELATIVE and no longer claimed as absolute on either platform.
The two residual ambiguities - a Unix path whose first component is a single
letter plus a colon - are documented at the top of the module rather than
papered over: no string algorithm separates them, and deciding by host would
put the failure back on the machine that ships.
Four regression tests added, one per defect.
cc
vicrodh
0ba1b05be9