`fd_advise` behavior diverges from other runtimes with large offset + len
yagehu opened this issue · 1 comments
Describe the bug
fd_advise should not fail with inval even if given a very large offset and len combination.
I caused this in #4555 trying to rectify a behavior divergence with other runtimes. I over spec'd the test.
Steps to reproduce
Directly call fd_advise with a valid fd but very large (> INT64_MAX) offset and len.
Expected behavior
fd_advise should return 0.
Actual behavior
fd_advise returns inval (28).
Additional context
Mini PR incoming.
It's a little more complicated than I realized. Since most runtimes use posix_fadvise, and its behavior is such that a negative offset is OK while a negative len is not OK, the behavior divergence cannot be simply fixed by allowing all values. This seems to be a case of the permissiveness of WASI allows implementations to leak underlying details. IMO there's no obvious correct behavior here.