NewUsageValue exists to clip an oversized quota to the maximum value of an
int64, which is what dc95f36bc added it for when Box raised the Enterprise
space_amount to 1e+18 and started returning it as a float.
For the float64 instantiation the guard misses its own boundary.
float64(math.MaxInt64) is not 2**63-1, it rounds up to 2**63, so a quota of
exactly 2**63 fails the comparison and falls through to the int64 conversion,
which the spec leaves implementation dependent for an unrepresentable value.
On linux/amd64 it wraps:
Before: rclone about -> Total=-9223372036854775808
After: rclone about -> Total=9223372036854775807
A negative total is not just a wrong number. vfs.Statfs documents -1 as "not
known", vfs.fillInMissingSizes branches on total < 0, and serve sftp only
computes its usage percentage when total > 0, so the value is read back as a
missing quota.
The int64 and uint64 instantiations are unaffected, since for them
T(int64(math.MaxInt64)) is exact and clipping MaxInt64 to MaxInt64 is a no-op.
youdie006andNick Craig-Wood
52ac7e0e18