vpython: Add filesystem operation / test packages.

vpython/filesystem/remove_all.go

Index: vpython/filesystem/remove_all.go
diff --git a/vpython/filesystem/remove_all.go b/vpython/filesystem/remove_all.go
new file mode 100644
index 0000000000000000000000000000000000000000..e2cf31af0f5f16aa4f02c4f84cd7836196e1e4f6
--- /dev/null
+++ b/vpython/filesystem/remove_all.go
@@ -0,0 +1,92 @@
+// 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
+}