rc: add core/du to measure local disk usage

fs/operations/rc.go

@@ -12,7 +12,9 @@ import (
 	"time"
 
 	"github.com/rclone/rclone/fs"
+	"github.com/rclone/rclone/fs/config"
 	"github.com/rclone/rclone/fs/rc"
+	"github.com/rclone/rclone/lib/diskusage"
 )
 
 func init() {
@@ -620,3 +622,54 @@ func rcBackend(ctx context.Context, in rc.Params) (out rc.Params, err error) {
 	out["result"] = result
 	return out, nil
 }
+
+// This should really be in fs/rc/internal.go but can't go there due
+// to a circular dependency on config.
+func init() {
+	rc.Add(rc.Call{
+		Path:  "core/du",
+		Fn:    rcDu,
+		Title: "Returns disk usage of a locally attached disk.",
+		Help: `
+This returns the disk usage for the local directory passed in as dir.
+
+If the directory is not passed in, it defaults to the directory
+pointed to by --cache-dir.
+
+- dir - string (optional)
+
+Returns:
+
+` + "```" + `
+{
+	"dir": "/",
+	"info": {
+		"Available": 361769115648,
+		"Free": 361785892864,
+		"Total": 982141468672
+	}
+}
+` + "```" + `
+`,
+	})
+}
+
+// Terminates app
+func rcDu(ctx context.Context, in rc.Params) (out rc.Params, err error) {
+	dir, err := in.GetString("dir")
+	if rc.IsErrParamNotFound(err) {
+		dir = config.GetCacheDir()
+
+	} else if err != nil {
+		return nil, err
+	}
+	info, err := diskusage.New(dir)
+	if err != nil {
+		return nil, err
+	}
+	out = rc.Params{
+		"dir":  dir,
+		"info": info,
+	}
+	return out, nil
+}

fs/operations/rc_test.go

@@ -15,6 +15,7 @@ import (
 	"github.com/rclone/rclone/fs/operations"
 	"github.com/rclone/rclone/fs/rc"
 	"github.com/rclone/rclone/fstest"
+	"github.com/rclone/rclone/lib/diskusage"
 	"github.com/rclone/rclone/lib/rest"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
@@ -577,3 +578,20 @@ func TestRcCommand(t *testing.T) {
 	assert.Error(t, err)
 	assert.Contains(t, err.Error(), errTxt)
 }
+
+// operations/command: Runs a backend command
+func TestRcDu(t *testing.T) {
+	ctx := context.Background()
+	_, call := rcNewRun(t, "core/du")
+	in := rc.Params{}
+	out, err := call.Fn(ctx, in)
+	if err == diskusage.ErrUnsupported {
+		t.Skip(err)
+	}
+	assert.NotEqual(t, "", out["dir"])
+	info := out["info"].(diskusage.Info)
+	assert.True(t, info.Total != 0)
+	assert.True(t, info.Total > info.Free)
+	assert.True(t, info.Total > info.Available)
+	assert.True(t, info.Free >= info.Available)
+}