From af05e290cf2035e6edd68dbd9f079758d1818305 Mon Sep 17 00:00:00 2001
From: Nick Craig-Wood <nick@craig-wood.com>
Date: Mon, 14 Oct 2019 16:06:13 +0100
Subject: [PATCH] Fix --files-from without --no-traverse doing a recursive scan

In a28239f005aeb290 we made --files-from obey --no-traverse.  In the
process this caused --files-from without --no-traverse to do a
complete recursive scan unecessarily.

This was only noticeable in users of fs/march, so sync/copy/move/etc
not in ls/lsf/etc.

This fix makes sure that we use conventional directory listings in
fs/march unless `--files-from` and `--no-traverse` is set or
`--fast-list` is active.

Fixes #3619
---
 fs/march/march.go | 9 +++++++--
 fs/walk/walk.go   | 5 ++++-
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/fs/march/march.go b/fs/march/march.go
index 25642abca..4969a7e21 100644
--- a/fs/march/march.go
+++ b/fs/march/march.go
@@ -69,13 +69,18 @@ func (m *March) init() {
 // list a directory into entries, err
 type listDirFn func(dir string) (entries fs.DirEntries, err error)
 
-// makeListDir makes a listing function for the given fs and includeAll flags
+// makeListDir makes constructs a listing function for the given fs
+// and includeAll flags for marching through the file system.
 func (m *March) makeListDir(f fs.Fs, includeAll bool) listDirFn {
-	if (!fs.Config.UseListR || f.Features().ListR == nil) && !filter.Active.HaveFilesFrom() {
+	if !(fs.Config.UseListR && f.Features().ListR != nil) && // !--fast-list active and
+		!(fs.Config.NoTraverse && filter.Active.HaveFilesFrom()) { // !(--files-from and --no-traverse)
 		return func(dir string) (entries fs.DirEntries, err error) {
 			return list.DirSorted(m.Ctx, f, includeAll, dir)
 		}
 	}
+
+	// This returns a closure for use when --fast-list is active or for when
+	// --files-from and --no-traverse is set
 	var (
 		mu      sync.Mutex
 		started bool
diff --git a/fs/walk/walk.go b/fs/walk/walk.go
index a424e3a33..273c22456 100644
--- a/fs/walk/walk.go
+++ b/fs/walk/walk.go
@@ -553,12 +553,15 @@ func walkNDirTree(ctx context.Context, f fs.Fs, path string, includeAll bool, ma
 //
 // NB (f, path) to be replaced by fs.Dir at some point
 func NewDirTree(ctx context.Context, f fs.Fs, path string, includeAll bool, maxLevel int) (dirtree.DirTree, error) {
+	// if --no-traverse and --files-from build DirTree just from files
 	if fs.Config.NoTraverse && filter.Active.HaveFilesFrom() {
 		return walkRDirTree(ctx, f, path, includeAll, maxLevel, filter.Active.MakeListR(ctx, f.NewObject))
 	}
-	if ListR := f.Features().ListR; (maxLevel < 0 || maxLevel > 1) && ListR != nil {
+	// if have ListR; and recursing; and not using --files-from; then build a DirTree with ListR
+	if ListR := f.Features().ListR; (maxLevel < 0 || maxLevel > 1) && ListR != nil && !filter.Active.HaveFilesFrom() {
 		return walkRDirTree(ctx, f, path, includeAll, maxLevel, ListR)
 	}
+	// otherwise just use List
 	return walkNDirTree(ctx, f, path, includeAll, maxLevel, list.DirSorted)
 }