[WIP] Partial bot skeleton, non-functional though

vendor/github.com/cockroachdb/pebble/vfs/disk_usage_unix.go

@@ -0,0 +1,26 @@
+// Copyright 2020 The LevelDB-Go and Pebble Authors. All rights reserved. Use
+// of this source code is governed by a BSD-style license that can be found in
+// the LICENSE file.
+
+//go:build darwin || openbsd || dragonfly || freebsd
+// +build darwin openbsd dragonfly freebsd
+
+package vfs
+
+import "golang.org/x/sys/unix"
+
+func (defaultFS) GetDiskUsage(path string) (DiskUsage, error) {
+	stat := unix.Statfs_t{}
+	if err := unix.Statfs(path, &stat); err != nil {
+		return DiskUsage{}, err
+	}
+
+	freeBytes := uint64(stat.Bsize) * uint64(stat.Bfree)
+	availBytes := uint64(stat.Bsize) * uint64(stat.Bavail)
+	totalBytes := uint64(stat.Bsize) * uint64(stat.Blocks)
+	return DiskUsage{
+		AvailBytes: availBytes,
+		TotalBytes: totalBytes,
+		UsedBytes:  totalBytes - freeBytes,
+	}, nil
+}