Every real Guitar Pro 6 (.gpx) file failed to import with
"GPX BCFS sector pointer out of range (malformed file)".
A real .gpx's BCFZ-declared decompressed size isn't 0x1000-aligned, so
its last (small) container file lands in a partial trailing sector.
_parse_bcfs raised whenever a sector read would run past the buffer
end, rejecting the whole container before score.gpif could be extracted
-- so no GP6 file could be charted in the song editor. (GP7/GP8 .gp
files take the ZIP path, not BCFS, which is why this wasn't caught
earlier.)
Clamp the final sector read to the buffer end (the per-file size field
trims the padding anyway), matching canonical GPX readers (alphaTab /
PyGuitarPro). A sector whose start is past the end still raises, so the
malformed-file guard is preserved.
Verified against two real GP6 files -- both now unpack to valid GPIF
with all tracks. Adds the previously-missing positive BCFS round-trip
coverage: partial-final-sector, multi-file, sector-aligned baseline,
and the preserved out-of-range guard.
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Co-authored-by: byrongamatos <xasiklas@gmail.com>
