fsevents @ 1055680

Which version of macOS are you using?

ProductName:    Mac OS X
ProductVersion: 10.15.7
BuildVersion:   19H1217

Please describe the issue that occurred.

FSEvents api supports two different ways of starting an event stream:

1. Uses a device id and function call FSEventStreamCreateRelativeToDevice which is expecting paths to be relative to the mount point of the device. This is called the per-disk event stream in the docs. The example/main.go uses this approach since it uses a non-zero device id. See the documentation here specifically about param pathsToWatchRelativeToDevice

pathsToWatchRelativeToDevice
A CFArray of CFStringRefs, each specifying a relative path to a directory on the device identified by the dev parameter. The paths should be relative to the root of the device. For example, if a volume "MyData" is mounted at "/Volumes/MyData" and you want to watch "/Volumes/MyData/Pictures/July", specify a path string of "Pictures/July". To watch the root of a volume pass a path of "" (the empty string).

2. The alternative is with function FSEventStreamCreate which is expecting absolute paths. This is the "per-host" event stream constructor. fsevents uses this approach if the Device in the EventStream struct is zero. While the docs are ambiguous, on my system, the "per-host" approach only works with absolute paths.

pathsToWatch
A CFArray of CFStringRefs, each specifying a path to a directory, signifying the root of a filesystem hierarchy to be watched for modifications.

However, wrap.go/createPaths() transforms all paths in an EventStream struct to absolute paths at

This prevents using the "per-disk" mode for all volumes except the root volume at /.

Are you able to reproduce the issue? Please provide steps to reproduce and a code sample if possible.

Yes.

1. Create a new Volume on OSX (I use APFS) mounted at /Volumes/fsevents-repo
2. Use the example/main.go program with path /Volumes/fsevents-repo (the only change)
3. go run ./example/main.go
4. touch /Volumes/fsevents-repo/testfile and observe there is no event reports.
5. Now, change wrap.go/createPaths to using

	for _, path := range paths {
		p := path
		cpath := C.CString(p)

and repeat the steps above.

PR coming shortly.