[BUG] race condition in ReadSingleEvent

[capnspacehook]

What went wrong:
I tried to use read from Watcher.Events while multiple directories were being watched. Testing with the race detector, I found a race condition. FsEvents returned from Wather.ReadSingleEvent are directly casted using an unsafe.Pointer. Watcher.eventBuffer is reused between Wather.ReadSingleEvent calls, so when unix.Read writes to w.eventBuffer, it may write to the same memory of a previously returned FsEvents.

Steps to reproduce, or a short snippet of code that reproduces the problem:

Build https://github.com/tywkeene/go-fsevents/blob/master/examples/loop/loop.go with the race detector and trigger many file events quickly.

System and build environment information

Please run and paste the output of the following commands:

go version:
go version go1.21.0 linux/amd64

go env | grep "CGO_ENABLED\|GOOS":
GOOS='linux'
CGO_ENABLED='1'

uname -r:
6.4.6-76060406-generic

Additional context:
I think Wather.ReadSingleEvent should be removed and Watcher.Watch should be refactored so all events from a single unix.Read use a unique buffer. I'll see how easy this is and open a PR if it's doable.