vpython: Add filesystem operation / test packages.

vpython/filesystem/remove_all.go

+// Copyright 2017 The LUCI Authors. All rights reserved.
+// Use of this source code is governed under the Apache License, Version 2.0
+// that can be found in the LICENSE file.
+
+package filesystem
+
+import (
+        "io"
+        "os"
+        "syscall"
+
+        "github.com/luci/luci-go/common/errors"
+)
+
+// removeAllImpl removes path and any children it contains.
+// It removes everything it can but returns the first error
+// it encounters. If the path does not exist, RemoveAll
+// returns nil (no error).
+//
+// removeAllImpl is a clone of Go's os.RemoveAll which is a wrapper around
+// os.RemoveAll which uses the supplied removeFunc for deletion. removeFunc is
+// given a path and an optional os.FileMode (will be nil if absent).
+//
+// This was copied from:
+// https://github.com/golang/go/blob/964639cc338db650ccadeafb7424bc8ebb2c0f6c/src/os/path.go
+func removeAllImpl(path string, removeFunc func(string, os.FileInfo) error) error {
+        // Simple case: if Remove works, we're done.
+        err := removeFunc(path, nil)
+        if err == nil || IsNotExist(err) {
+                return nil
+        }
+
+        // Otherwise, is this a directory we need to recurse into?
+        dir, serrWrapped := os.Lstat(path)
+        if serrWrapped != nil {
+                serr := errors.Unwrap(serrWrapped)
+                if serr, ok := serr.(*os.PathError); ok && (IsNotExist(serr.Err) || serr.Err == syscall.ENOTDIR) {
+                        return nil
+                }
+                return serr
+        }
+        if !dir.IsDir() {
+                // Not a directory; return the error from Remove.
+                return err
+        }
+
+        // Directory.
+        fd, err := os.Open(path)
+        if err != nil {
+                if IsNotExist(err) {
+                        // Race. It was deleted between the Lstat and Open.
+                        // Return nil per RemoveAll's docs.
+                        return nil
+                }
+                return err
+        }
+
+        // Remove contents & return first error.
+        err = nil
+        for {
+                names, err1 := fd.Readdirnames(100)
+                for _, name := range names {
+                        err1 := removeAllImpl(path+string(os.PathSeparator)+name, removeFunc)
+                        if err == nil {
+                                err = err1
+                        }
+                }
+                if err1 == io.EOF {
+                        break
+                }
+                // If Readdirnames returned an error, use it.
+                if err == nil {
+                        err = err1
+                }
+                if len(names) == 0 {
+                        break
+                }
+        }
+
+        // Close directory, because windows won't remove opened directory.
+        fd.Close()
+
+        // Remove directory.
+        err1 := removeFunc(path, dir)
+        if err1 == nil || IsNotExist(err1) {
+                return nil
+        }
+        if err == nil {
+                err = err1
+        }
+        return err
+}