detect_max_batch_sectors() is a Linux-sysfs probe with no platform
gate. It derived the device name with rsplit('/'), which never splits a
Windows \.\CdRom0 / \.\D: path, so the whole path became the device
name, no /sys node matched, is_optical fell to false, and the function
returned the 8192-sector block default (16 MiB/request) instead of the
60-sector optical default. That value then took the Some(b) arm in
Disc::copy and bypassed the 510-sector optical clamp that lives only in
the sysfs branch, leaving every Windows rip/verify running ~16x over the
optical cap (coarser bad-sector recovery, 16 MiB UDF reads).
Gate the sysfs probe behind a new sysfs_batch_probe_supported() helper
(Linux-only, requires a '/'-delimited path) and return the optical
default for any path the probe can't handle. Add regression tests for
the \.\ device-path forms.
Matthew Jackson
c9bf92cd6f