Fix the fix: Make EPERM from posix_fallocate work the same way as EINVAL

[ztane]

#3195 was supposed to fix error handling when posix_fallocate. However it does not fix all of them: AWS has disabled the Linux fallocate and fallocate64 system calls in Lambda and some other environments by making them return EPERM instead of the common EINVAL.

The fix would be to handle EPERM analogous to EINVAL in util/file.cpp, i.e. change the if from

if (status == EINVAL) {
    return false; // Retry with non-atomic version
}

to

if (status == EINVAL || status == EPERM) {
    return false; // Retry with non-atomic version
}

Expected results

Realm-core should try to use the same fallback it uses when fallocate and fallocate64 return EINVAL.

Actual Results

Error message posix_fallocate() failed: Operation not permitted

Steps & Code to Reproduce

See for example https://stackoverflow.com/q/57825072/918959

Core version

Core version: all since je/fix-fallocate-problem was merged.

[fealebenpae]

Hey @ztane, thanks for bringing this up and providing additional context. We’ll investigate the fix you propose and try to resolve the Lambda issue.