cmd/ncdu: highlight read errors instead of aborting - fixes #4014

When a directory cannot be walk-ed because of a permissions error
- or any error for that matter -, ncdu mode keeps track of the error
and highlights directories that could not be read.

Previously, the error would cause ncdu to abort.

Now, directories with unreadable sub-directories are displayed in yellow and
a message warns that the total may be underestimated.

Unreadable directories themselves are displayed in red along with the error message

cmd/ncdu/ncdu.go

@@ -281,7 +281,7 @@ func (u *UI) biggestEntry() (biggest int64) {
 		return
 	}
 	for i := range u.entries {
-		size, _, _, _ := u.d.AttrI(u.sortPerm[i])
+		size, _, _, _, _, _ := u.d.AttrI(u.sortPerm[i])
 		if size > biggest {
 			biggest = size
 		}
@@ -326,12 +326,18 @@ func (u *UI) Draw() error {
 			if y >= h-1 {
 				break
 			}
+			size, count, isDir, readable, entriesHaveErrors, err := u.d.AttrI(u.sortPerm[n])
 			fg := termbox.ColorWhite
+			if entriesHaveErrors {
+				fg = termbox.ColorYellow
+			}
+			if err != nil {
+				fg = termbox.ColorRed
+			}
 			bg := termbox.ColorBlack
 			if n == dirPos.entry {
 				fg, bg = bg, fg
 			}
-			size, count, isDir, readable := u.d.AttrI(u.sortPerm[n])
 			mark := ' '
 			if isDir {
 				mark = '/'
@@ -340,6 +346,12 @@ func (u *UI) Draw() error {
 			if !readable {
 				message = " [not read yet]"
 			}
+			if entriesHaveErrors {
+				message = " [some subdirectories could not be read, size may be underestimated]"
+			}
+			if err != nil {
+				message = fmt.Sprintf(" [%s]", err)
+			}
 			extras := ""
 			if u.showCounts {
 				if count > 0 {
@@ -512,8 +524,8 @@ type ncduSort struct {
 // Less is part of sort.Interface.
 func (ds *ncduSort) Less(i, j int) bool {
 	var iAvgSize, jAvgSize float64
-	isize, icount, _, _ := ds.d.AttrI(ds.sortPerm[i])
-	jsize, jcount, _, _ := ds.d.AttrI(ds.sortPerm[j])
+	isize, icount, _, _, _, _ := ds.d.AttrI(ds.sortPerm[i])
+	jsize, jcount, _, _, _, _ := ds.d.AttrI(ds.sortPerm[j])
 	iname, jname := ds.entries[ds.sortPerm[i]].Remote(), ds.entries[ds.sortPerm[j]].Remote()
 	if icount > 0 {
 		iAvgSize = float64(isize / icount)

cmd/ncdu/scan/scan.go

@@ -13,13 +13,15 @@ import (
 
 // Dir represents a directory found in the remote
 type Dir struct {
-	parent  *Dir
-	path    string
-	mu      sync.Mutex
-	count   int64
-	size    int64
-	entries fs.DirEntries
-	dirs    map[string]*Dir
+	parent            *Dir
+	path              string
+	mu                sync.Mutex
+	count             int64
+	size              int64
+	entries           fs.DirEntries
+	dirs              map[string]*Dir
+	readError         error
+	entriesHaveErrors bool
 }
 
 // Parent returns the directory above this one
@@ -35,12 +37,13 @@ func (d *Dir) Path() string {
 }
 
 // make a new directory
-func newDir(parent *Dir, dirPath string, entries fs.DirEntries) *Dir {
+func newDir(parent *Dir, dirPath string, entries fs.DirEntries, err error) *Dir {
 	d := &Dir{
-		parent:  parent,
-		path:    dirPath,
-		entries: entries,
-		dirs:    make(map[string]*Dir),
+		parent:    parent,
+		path:      dirPath,
+		entries:   entries,
+		dirs:      make(map[string]*Dir),
+		readError: err,
 	}
 	// Count size in this dir
 	for _, entry := range entries {
@@ -61,6 +64,9 @@ func newDir(parent *Dir, dirPath string, entries fs.DirEntries) *Dir {
 		parent.mu.Lock()
 		parent.count += d.count
 		parent.size += d.size
+		if d.readError != nil {
+			parent.entriesHaveErrors = true
+		}
 		parent.mu.Unlock()
 	}
 	return d
@@ -145,18 +151,19 @@ func (d *Dir) Attr() (size int64, count int64) {
 }
 
 // AttrI returns the size, count and flags for the i-th directory entry
-func (d *Dir) AttrI(i int) (size int64, count int64, isDir bool, readable bool) {
+func (d *Dir) AttrI(i int) (size int64, count int64, isDir bool, readable bool, entriesHaveErrors bool, err error) {
 	d.mu.Lock()
 	defer d.mu.Unlock()
 	subDir, isDir := d.getDir(i)
+
 	if !isDir {
-		return d.entries[i].Size(), 0, false, true
+		return d.entries[i].Size(), 0, false, true, d.entriesHaveErrors, d.readError
 	}
 	if subDir == nil {
-		return 0, 0, true, false
+		return 0, 0, true, false, false, nil
 	}
 	size, count = subDir.Attr()
-	return size, count, true, true
+	return size, count, true, true, subDir.entriesHaveErrors, subDir.readError
 }
 
 // Scan the Fs passed in, returning a root directory channel and an
@@ -169,9 +176,6 @@ func Scan(ctx context.Context, f fs.Fs) (chan *Dir, chan error, chan struct{}) {
 	go func() {
 		parents := map[string]*Dir{}
 		err := walk.Walk(ctx, f, "", false, ci.MaxDepth, func(dirPath string, entries fs.DirEntries, err error) error {
-			if err != nil {
-				return err // FIXME mark directory as errored instead of aborting
-			}
 			var parent *Dir
 			if dirPath != "" {
 				parentPath := path.Dir(dirPath)
@@ -184,7 +188,7 @@ func Scan(ctx context.Context, f fs.Fs) (chan *Dir, chan error, chan struct{}) {
 					errChan <- errors.Errorf("couldn't find parent for %q", dirPath)
 				}
 			}
-			d := newDir(parent, dirPath, entries)
+			d := newDir(parent, dirPath, entries, err)
 			parents[dirPath] = d
 			if dirPath == "" {
 				root <- d