//go:build linux

package webapp

import (
	"syscall"
)

// statDisk fills Total/Free/Used for a DiskSample via statfs(2).
// Linux-only because syscall.Statfs_t is platform-specific. Tests
// that exercise the metric paths stub statDisk at the function
// boundary so the build is hermetic.
func statDisk(mount string, d *DiskSample) error {
	var st syscall.Statfs_t
	if err := syscall.Statfs(mount, &st); err != nil {
		return err
	}
	bsize := uint64(st.Frsize)
	total := st.Blocks * bsize
	free := st.Bavail * bsize
	used := total - free
	d.Total = total
	d.Free = free
	d.Used = used
	if total > 0 {
		d.UsedPct = pct(used, total)
	}
	return nil
}