feature/taildrop: do not use m.opts.Dir for Android (#16316)

In Android, we are prompting the user to select a Taildrop directory when they first receive a Taildrop: we block writes on Taildrop dir selection. This means that we cannot use Dir inside managerOptions, since the http request would not get the new Taildrop extension. This PR removes, in the Android case, the reliance on m.opts.Dir, and instead has FileOps hold the correct directory.

This expands FileOps to be the Taildrop interface for all file system operations.

Updates tailscale/corp#29211

Signed-off-by: kari-ts <kari@tailscale.com>

restore tstest

feature/taildrop/delete.go

@@ -6,9 +6,7 @@ package taildrop
 import (
 	"container/list"
 	"context"
-	"io/fs"
 	"os"
-	"path/filepath"
 	"strings"
 	"sync"
 	"time"
@@ -28,7 +26,6 @@ const deleteDelay = time.Hour
 type fileDeleter struct {
 	logf  logger.Logf
 	clock tstime.DefaultClock
-	dir   string
 	event func(string) // called for certain events; for testing only
 
 	mu     sync.Mutex
@@ -39,6 +36,7 @@ type fileDeleter struct {
 	group       syncs.WaitGroup
 	shutdownCtx context.Context
 	shutdown    context.CancelFunc
+	fs          FileOps // must be used for all filesystem operations
 }
 
 // deleteFile is a specific file to delete after deleteDelay.
@@ -50,15 +48,14 @@ type deleteFile struct {
 func (d *fileDeleter) Init(m *manager, eventHook func(string)) {
 	d.logf = m.opts.Logf
 	d.clock = m.opts.Clock
-	d.dir = m.opts.Dir
 	d.event = eventHook
+	d.fs = m.opts.fileOps
 
 	d.byName = make(map[string]*list.Element)
 	d.emptySignal = make(chan struct{})
 	d.shutdownCtx, d.shutdown = context.WithCancel(context.Background())
 
 	// From a cold-start, load the list of partial and deleted files.
-	//
 	// Only run this if we have ever received at least one file
 	// to avoid ever touching the taildrop directory on systems (e.g., MacOS)
 	// that pop up a security dialog window upon first access.
@@ -71,38 +68,45 @@ func (d *fileDeleter) Init(m *manager, eventHook func(string)) {
 	d.group.Go(func() {
 		d.event("start full-scan")
 		defer d.event("end full-scan")
-		rangeDir(d.dir, func(de fs.DirEntry) bool {
+
+		if d.fs == nil {
+			d.logf("deleter: nil FileOps")
+		}
+
+		files, err := d.fs.ListFiles()
+		if err != nil {
+			d.logf("deleter: ListDir error: %v", err)
+			return
+		}
+		for _, filename := range files {
 			switch {
 			case d.shutdownCtx.Err() != nil:
-				return false // terminate early
-			case !de.Type().IsRegular():
-				return true
-			case strings.HasSuffix(de.Name(), partialSuffix):
+				return // terminate early
+			case strings.HasSuffix(filename, partialSuffix):
 				// Only enqueue the file for deletion if there is no active put.
-				nameID := strings.TrimSuffix(de.Name(), partialSuffix)
+				nameID := strings.TrimSuffix(filename, partialSuffix)
 				if i := strings.LastIndexByte(nameID, '.'); i > 0 {
 					key := incomingFileKey{clientID(nameID[i+len("."):]), nameID[:i]}
 					m.incomingFiles.LoadFunc(key, func(_ *incomingFile, loaded bool) {
 						if !loaded {
-							d.Insert(de.Name())
+							d.Insert(filename)
 						}
 					})
 				} else {
-					d.Insert(de.Name())
+					d.Insert(filename)
 				}
-			case strings.HasSuffix(de.Name(), deletedSuffix):
+			case strings.HasSuffix(filename, deletedSuffix):
 				// Best-effort immediate deletion of deleted files.
-				name := strings.TrimSuffix(de.Name(), deletedSuffix)
-				if os.Remove(filepath.Join(d.dir, name)) == nil {
-					if os.Remove(filepath.Join(d.dir, de.Name())) == nil {
-						break
+				name := strings.TrimSuffix(filename, deletedSuffix)
+				if d.fs.Remove(name) == nil {
+					if d.fs.Remove(filename) == nil {
+						continue
 					}
 				}
-				// Otherwise, enqueue the file for later deletion.
-				d.Insert(de.Name())
+				// Otherwise enqueue for later deletion.
+				d.Insert(filename)
 			}
-			return true
-		})
+		}
 	})
 }
 
@@ -149,13 +153,13 @@ func (d *fileDeleter) waitAndDelete(wait time.Duration) {
 
 			// Delete the expired file.
 			if name, ok := strings.CutSuffix(file.name, deletedSuffix); ok {
-				if err := os.Remove(filepath.Join(d.dir, name)); err != nil && !os.IsNotExist(err) {
+				if err := d.fs.Remove(name); err != nil && !os.IsNotExist(err) {
 					d.logf("could not delete: %v", redactError(err))
 					failed = append(failed, elem)
 					continue
 				}
 			}
-			if err := os.Remove(filepath.Join(d.dir, file.name)); err != nil && !os.IsNotExist(err) {
+			if err := d.fs.Remove(file.name); err != nil && !os.IsNotExist(err) {
 				d.logf("could not delete: %v", redactError(err))
 				failed = append(failed, elem)
 				continue