This extracts a utility `syscallfs.ReaderAtOffset()` to allow WASI and
gojs to re-use the same logic to implement `syscall.Pread`.
What's different than before is that if WASI passes multiple iovecs an
emulated `ReaderAt` will seek to the read position on each call to
`Read` vs once per loop. This was a design decision to keep the call
sites compatible between files that implement ReaderAt and those that
emulate them with Seeker (e.g. avoid the need for a read-scoped closer/
defer function). The main use case for emulation is `embed.file`, whose
seek function is cheap, so there's little performance impact to this.
Signed-off-by: Adrian Cole <adrian@tetrate.io>
This works around a known glitch in windows where directory entry stat
doesn't match its corresponding file stat (namely times don't). It
consolidates more test files, in the process, to ensure we are more
likely to trigger issues like this earlier.
Future work will finish the last couple places where we still use go's
fstest.MapFS internally, as well introduce stat tests at the syscallfs
abstraction: right now, most tests are still only defined in WASI.
Signed-off-by: Adrian Cole <adrian@tetrate.io>
@achille-roussel mentioned on chat that we have an accident waiting to
happen. This fixes it and backfills the missing test.
Signed-off-by: Adrian Cole <adrian@tetrate.io>
This consolidates test files and ensures our various implementations of
`syscallfs.FS` pass `fstest.TestFS`.
Signed-off-by: Adrian Cole <adrian@tetrate.io>
This masks interfaces returned by `fs.File` so that we don't
accidentally allow writes when opened for reading. This also adds
`syscall.NewReadFS` which can enforce read-only access in general, such
as would be ideal for tests that try to read files from the host root
filesystem (e.g. /etc/passwd).
Signed-off-by: Adrian Cole <adrian@tetrate.io>
As noted in slack, we are unlikley to long term use fs.FS internally.
This ensures we attempt to cast to syscallfs.FS for all I/O by panicing
on fs.Open.
Signed-off-by: Adrian Cole <adrian@tetrate.io>
This renames the internal writefs package to syscallfs as it is largely
dependent on syscall signatures. This also implements utimes in gojs.
WASI will be a follow-up change as it requires more infrastructure.
Notably, we also need non-TinyGo tests because TinyGo doesn't yet
support os.Chtimes or corresponding syscalls.
Signed-off-by: Adrian Cole <adrian@tetrate.io>
