lib/model: Don't fail on temporary chmod (fixes #8355, ref #8235) (#8356)

lib/model/util.go

@@ -116,13 +116,15 @@ func inWritableDir(fn func(string) error, targetFs fs.Filesystem, path string, i
 	}
 
 	const permBits = fs.ModePerm | fs.ModeSetuid | fs.ModeSetgid | fs.ModeSticky
+	var parentErr error
 	if mode := info.Mode() & permBits; mode&0200 == 0 {
 		// A non-writeable directory (for this user; we assume that's the
 		// relevant part). Temporarily change the mode so we can delete the
 		// file or directory inside it.
-		if err := targetFs.Chmod(dir, mode|0700); err != nil {
-			return err
-		}
+		parentErr = targetFs.Chmod(dir, mode|0700)
+		if parentErr != nil {
+			l.Debugf("Failed to make parent directory writable: %v", parentErr)
+		} else {
 			// Chmod succeeded, we should change the permissions back on the way
 			// out. If we fail we log the error as we have irrevocably messed up
 			// at this point. :( (The operation we were called to wrap has
@@ -138,6 +140,11 @@ func inWritableDir(fn func(string) error, targetFs fs.Filesystem, path string, i
 				}
 			}()
 		}
+	}
 
-	return fn(path)
+	err = fn(path)
+	if fs.IsPermission(err) && parentErr != nil {
+		err = fmt.Errorf("error after failing to make parent directory writable: %w", err)
+	}
+	return err
 }