From 3b951cf9e5521db2c3bc7c2b76aaa3b801cd13e9 Mon Sep 17 00:00:00 2001
From: Michael Woolnough <130465766+mjkw31@users.noreply.github.com>
Date: Tue, 17 Dec 2024 12:53:58 +0000
Subject: [PATCH] Generate 'fake' directory entries for deleted directories.
 (#119)

* Output 'fake' entries for non-existent directories to maintain the tree for files in those dirs that may have been stat'd succesfully before the deletion
---
 stat/paths_test.go | 45 +++++++++++++++++++++++++++++++++++++++++++++
 stat/stat.go       | 37 +++++++++++++++++++++++++++++++++++++
 2 files changed, 82 insertions(+)

diff --git a/stat/paths_test.go b/stat/paths_test.go
index f635b993..20f9488c 100644
--- a/stat/paths_test.go
+++ b/stat/paths_test.go
@@ -26,6 +26,7 @@
 package stat
 
 import (
+	"fmt"
 	"io"
 	"io/fs"
 	"os"
@@ -208,6 +209,50 @@ func TestPaths(t *testing.T) {
 			So(string(output), ShouldContainSubstring, "\t1\t")
 			So(string(output), ShouldContainSubstring, "\tf\t")
 		})
+
+		Convey("can stat files and non-existent directories", func() {
+			dir := t.TempDir()
+
+			existingDir := filepath.Join(dir, "existingDir") + "/"
+			notExistingDir := filepath.Join(dir, "notExistingDir") + "/"
+			existingFile := filepath.Join(dir, "existingFile")
+
+			err := os.Mkdir(existingDir, 0755)
+			So(err, ShouldBeNil)
+
+			f, err := os.Create(existingFile)
+			So(err, ShouldBeNil)
+
+			_, err = f.Write([]byte{0})
+			So(err, ShouldBeNil)
+
+			err = f.Close()
+			So(err, ShouldBeNil)
+
+			r := strings.NewReader(strconv.Quote(existingDir) + "\n" +
+				strconv.Quote(notExistingDir) + "\n" +
+				strconv.Quote(filepath.Join(dir, "notExistingFile")) + "\n" +
+				strconv.Quote(existingFile) + "\n")
+
+			stats := make([]string, 0, 3)
+
+			err = p.AddOperation("file", func(absPath string, info fs.FileInfo) error {
+				stats = append(stats, fmt.Sprintf("%s\t%d", absPath, info.Size()))
+
+				return nil
+			})
+
+			So(err, ShouldBeNil)
+
+			err = p.Scan(r)
+			So(err, ShouldBeNil)
+
+			So(stats, ShouldResemble, []string{
+				existingDir + "\t4096",
+				notExistingDir + "\t0",
+				existingFile + "\t1",
+			})
+		})
 	})
 }
 
diff --git a/stat/stat.go b/stat/stat.go
index acf7fb67..40835119 100644
--- a/stat/stat.go
+++ b/stat/stat.go
@@ -26,8 +26,11 @@
 package stat
 
 import (
+	"errors"
 	"io/fs"
 	"os"
+	"path/filepath"
+	"strings"
 	"syscall"
 	"time"
 
@@ -132,9 +135,43 @@ func (s *StatterWithTimeout) Lstat(path string) (info fs.FileInfo, err error) {
 	}
 }
 
+type fakeDir struct {
+	name string
+	syscall.Stat_t
+}
+
+func (f *fakeDir) Name() string {
+	return f.name
+}
+
+func (fakeDir) Size() int64 {
+	return 0
+}
+
+func (fakeDir) ModTime() time.Time {
+	return time.Time{}
+}
+
+func (fakeDir) Mode() fs.FileMode {
+	return 0
+}
+
+func (fakeDir) IsDir() bool {
+	return true
+}
+
+func (f *fakeDir) Sys() any {
+	return &f.Stat_t
+}
+
 // doLstat does the actual Lstat call and sends results on the given channels.
 func (s *StatterWithTimeout) doLstat(path string, infoCh chan fs.FileInfo, errCh chan error) {
 	info, err := s.lstat(path)
+	if errors.Is(err, fs.ErrNotExist) && strings.HasSuffix(path, "/") {
+		err = nil
+		info = &fakeDir{name: filepath.Base(path)}
+	}
+
 	if err == nil {
 		stat, ok := info.Sys().(*syscall.Stat_t)
 		if ok {