rename accessor to reduce confusion

as Free() makes me think of the statfs Free field which is
the space available to a privileged user. I am reporting the
space available to a non-privileged user, which is known as the field
Avail...

fstat/fstat.go

@@ -11,8 +11,8 @@ func (fs FilesystemStat) Used() uint64 {
 	return (fs.Blocks - fs.Bavail) * uint64(fs.Bsize)
 }
 
-// Free returns the number of bytes available to a non-privileged user.
-func (fs FilesystemStat) Free() uint64 {
+// Available returns the number of bytes available to a non-privileged user.
+func (fs FilesystemStat) Available() uint64 {
 	return fs.Bavail * uint64(fs.Bsize)
 }
 

fstat/fstat_test.go

@@ -7,22 +7,22 @@ import (
 )
 
 func TestFilesystemStat(t *testing.T) {
-	t.Run("FreeTotalUsed", func(t *testing.T) {
+	t.Run("AvailableTotalUsed", func(t *testing.T) {
 		fs := FilesystemStat(unix.Statfs_t{
 			Ffree:  200, // total free disk space
 			Bavail: 100, // free disk space accessible by a non-privileged user
 			Blocks: 400,
 			Bsize:  1024,
 		})
 
-		if want := uint64(100 * 1024); fs.Free() != want {
-			t.Errorf("FilesystemStat.Free() got %d, want %d", fs.Free(), want)
+		if want := uint64(100 * 1024); fs.Available() != want {
+			t.Errorf("FilesystemStat.Available() got %d, want %d", fs.Available(), want)
 		}
 		if want := uint64(400 * 1024); fs.Total() != want {
-			t.Errorf("FilesystemStat.Total() got %d, want %d", fs.Free(), want)
+			t.Errorf("FilesystemStat.Total() got %d, want %d", fs.Total(), want)
 		}
 		if want := uint64((400 - 100) * 1024); fs.Used() != want {
-			t.Errorf("FilesystemStat.Used() got %d, want %d", fs.Free(), want)
+			t.Errorf("FilesystemStat.Used() got %d, want %d", fs.Used(), want)
 		}
 	})
 	t.Run("HasReachedLimit", func(t *testing.T) {

usage/usage.go

@@ -96,7 +96,7 @@ func checkDiskUsage(basedir string, limit uint64) (Report, error) {
 		if fstat.HasReachedLimit(limit) {
 			r.Limits = append(r.Limits, Stats{
 				Path:  file.Name(),
-				Free:  fstat.Free(),
+				Free:  fstat.Available(),
 				Used:  fstat.Used(),
 				Total: fstat.Total(),
 			})