github.com/keybase/client/go@v0.0.0-20240309051027-028f7c731f8b/kbfs/libfs/fs_test.go

// Copyright 2017 Keybase Inc. All rights reserved.
// Use of this source code is governed by a BSD
// license that can be found in the LICENSE file.

package libfs

import (
	"bytes"
	"context"
	"os"
	"path"
	"testing"
	"time"

	"github.com/keybase/client/go/kbfs/data"
	"github.com/keybase/client/go/kbfs/ioutil"
	"github.com/keybase/client/go/kbfs/kbfsmd"
	"github.com/keybase/client/go/kbfs/libcontext"
	"github.com/keybase/client/go/kbfs/libkbfs"
	"github.com/keybase/client/go/kbfs/test/clocktest"
	"github.com/keybase/client/go/kbfs/tlf"
	"github.com/keybase/client/go/kbfs/tlfhandle"
	"github.com/keybase/client/go/protocol/keybase1"
	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
	billy "gopkg.in/src-d/go-billy.v4"
)

func makeFSWithBranch(t *testing.T, branch data.BranchName, subdir string) (
	context.Context, *tlfhandle.Handle, *FS) {
	ctx := libcontext.BackgroundContextWithCancellationDelayer()
	config := libkbfs.MakeTestConfigOrBust(t, "user1", "user2")
	h, err := tlfhandle.ParseHandle(
		ctx, config.KBPKI(), config.MDOps(), nil, "user1", tlf.Private)
	require.NoError(t, err)
	fs, err := NewFS(
		ctx, config, h, branch, subdir, "", keybase1.MDPriorityNormal)
	require.NoError(t, err)
	return ctx, h, fs
}

func makeFS(t *testing.T, subdir string) (
	context.Context, *tlfhandle.Handle, *FS) {
	return makeFSWithBranch(t, data.MasterBranch, subdir)
}

func makeFSWithJournal(t *testing.T, subdir string) (
	context.Context, *tlfhandle.Handle, *FS, func()) {
	ctx := libcontext.BackgroundContextWithCancellationDelayer()
	config := libkbfs.MakeTestConfigOrBustLoggedInWithMode(
		t, 0, libkbfs.InitSingleOp, "user1")

	tempdir, err := os.MkdirTemp(os.TempDir(), "journal_server")
	require.NoError(t, err)
	defer func() {
		if err != nil {
			os.RemoveAll(tempdir)
		}
	}()
	err = config.EnableDiskLimiter(tempdir)
	require.NoError(t, err)
	err = config.EnableJournaling(
		ctx, tempdir, libkbfs.TLFJournalSingleOpBackgroundWorkEnabled)
	require.NoError(t, err)
	shutdown := func() {
		libkbfs.CheckConfigAndShutdown(ctx, t, config)
		err := ioutil.RemoveAll(tempdir)
		assert.NoError(t, err)
	}

	h, err := tlfhandle.ParseHandle(
		ctx, config.KBPKI(), config.MDOps(), nil, "user1", tlf.Private)
	require.NoError(t, err)
	fs, err := NewFS(
		ctx, config, h, data.MasterBranch, subdir, "",
		keybase1.MDPriorityNormal)
	require.NoError(t, err)

	return ctx, h, fs, shutdown
}

func testCreateFile(
	ctx context.Context, t *testing.T, fs *FS, file string,
	parent libkbfs.Node) {
	f, err := fs.Create(file)
	require.NoError(t, err)
	require.Equal(t, file, f.Name())

	children, err := fs.config.KBFSOps().GetDirChildren(ctx, parent)
	require.NoError(t, err)
	require.Contains(t, children, testPPS(path.Base(file)))

	// Write to the file.
	data := []byte{1}
	n, err := f.Write(data)
	require.NoError(t, err)
	require.Equal(t, 1, n)

	err = f.Close()
	require.NoError(t, err)

	// Re-open and read the file.
	f, err = fs.Open(file)
	require.NoError(t, err)
	gotData := make([]byte, len(data))
	n, err = f.Read(gotData)
	require.NoError(t, err)
	require.Equal(t, len(data), n)
	require.True(t, bytes.Equal(data, gotData))

	// Shouldn't be able to write to a read-only file.
	_, err = f.Write(gotData)
	require.NotNil(t, err)

	err = f.Close()
	require.NoError(t, err)

	err = fs.SyncAll()
	require.NoError(t, err)
}

func TestCreateFileInRoot(t *testing.T) {
	ctx, h, fs := makeFS(t, "")
	defer libkbfs.CheckConfigAndShutdown(ctx, t, fs.config)

	rootNode, _, err := fs.config.KBFSOps().GetRootNode(
		ctx, h, data.MasterBranch)
	require.NoError(t, err)

	testCreateFile(ctx, t, fs, "foo", rootNode)
	testCreateFile(ctx, t, fs, "/bar", rootNode)
}

func testPPS(s string) data.PathPartString {
	return data.NewPathPartString(s, nil)
}

func TestCreateFileInSubdir(t *testing.T) {
	ctx, h, fs := makeFS(t, "")
	defer libkbfs.CheckConfigAndShutdown(ctx, t, fs.config)

	rootNode, _, err := fs.config.KBFSOps().GetRootNode(
		ctx, h, data.MasterBranch)
	require.NoError(t, err)
	aNode, _, err := fs.config.KBFSOps().CreateDir(ctx, rootNode, testPPS("a"))
	require.NoError(t, err)
	bNode, _, err := fs.config.KBFSOps().CreateDir(ctx, aNode, testPPS("b"))
	require.NoError(t, err)

	testCreateFile(ctx, t, fs, "a/b/foo", bNode)
}

func TestCreateFileInMissingSubdir(t *testing.T) {
	ctx, _, fs := makeFS(t, "")
	defer libkbfs.CheckConfigAndShutdown(ctx, t, fs.config)

	f, err := fs.Create("a/b/foo")
	require.NoError(t, err)
	require.Equal(t, "a/b/foo", f.Name())

	_, err = fs.Lstat("a")
	require.NoError(t, err)
	_, err = fs.Lstat("a/b")
	require.NoError(t, err)
}

func TestAppendFile(t *testing.T) {
	ctx, h, fs := makeFS(t, "")
	defer libkbfs.CheckConfigAndShutdown(ctx, t, fs.config)

	rootNode, _, err := fs.config.KBFSOps().GetRootNode(
		ctx, h, data.MasterBranch)
	require.NoError(t, err)

	testCreateFile(ctx, t, fs, "foo", rootNode)
	f, err := fs.OpenFile("foo", os.O_APPEND, 0600)
	require.NoError(t, err)

	// Append one byte to the file.
	data := []byte{2}
	n, err := f.Write(data)
	require.NoError(t, err)
	require.Equal(t, 1, n)

	err = f.Close()
	require.NoError(t, err)

	// Re-open and read the file.
	f, err = fs.Open("foo")
	require.NoError(t, err)
	gotData := make([]byte, 2)
	n, err = f.Read(gotData)
	require.NoError(t, err)
	require.Equal(t, len(gotData), n)

	err = f.Close()
	require.NoError(t, err)

	err = fs.SyncAll()
	require.NoError(t, err)
}

func TestRecreateAndExcl(t *testing.T) {
	ctx, h, fs := makeFS(t, "")
	defer libkbfs.CheckConfigAndShutdown(ctx, t, fs.config)

	rootNode, _, err := fs.config.KBFSOps().GetRootNode(
		ctx, h, data.MasterBranch)
	require.NoError(t, err)

	testCreateFile(ctx, t, fs, "foo", rootNode)

	// Re-create the same file.
	f, err := fs.Create("foo")
	require.NoError(t, err)
	err = f.Close()
	require.NoError(t, err)

	// Try to create it with EXCL, and fail.
	_, err = fs.OpenFile("foo", os.O_CREATE|os.O_EXCL, 0600)
	require.NotNil(t, err)

	// Creating a different file exclusively should work though.
	f, err = fs.OpenFile("foo2", os.O_CREATE|os.O_EXCL, 0600)
	require.NoError(t, err)
	err = f.Close()
	require.NoError(t, err)
	err = fs.SyncAll()
	require.NoError(t, err)
}

func TestStat(t *testing.T) {
	ctx, h, fs := makeFS(t, "")
	defer libkbfs.CheckConfigAndShutdown(ctx, t, fs.config)

	clock := &clocktest.TestClock{}
	clock.Set(time.Now())
	fs.config.SetClock(clock)

	rootNode, _, err := fs.config.KBFSOps().GetRootNode(
		ctx, h, data.MasterBranch)
	require.NoError(t, err)
	aNode, _, err := fs.config.KBFSOps().CreateDir(ctx, rootNode, testPPS("a"))
	require.NoError(t, err)
	testCreateFile(ctx, t, fs, "a/foo", aNode)

	// Check the dir
	fi, err := fs.Stat("a")
	require.NoError(t, err)
	checkDir := func(fi os.FileInfo, isWriter bool) {
		require.Equal(t, "a", fi.Name())
		// Not sure exactly what the dir size should be.
		require.True(t, fi.Size() > 0)
		expectedMode := os.FileMode(0500) | os.ModeDir
		if isWriter {
			expectedMode |= 0200
		}
		require.Equal(t, expectedMode, fi.Mode())
		require.True(t, clock.Now().Equal(fi.ModTime()))
		require.True(t, fi.IsDir())
	}
	checkDir(fi, true)

	// Check the file
	fi, err = fs.Stat("a/foo")
	require.NoError(t, err)
	checkFile := func(fi os.FileInfo, isWriter bool) {
		require.Equal(t, "foo", fi.Name())
		require.Equal(t, int64(1), fi.Size())
		expectedMode := os.FileMode(0400)
		if isWriter {
			expectedMode |= 0200
		}
		require.Equal(t, expectedMode, fi.Mode())
		require.True(t, clock.Now().Equal(fi.ModTime()))
		require.False(t, fi.IsDir())
	}
	checkFile(fi, true)

	// Try a read-only file.
	config2 := libkbfs.ConfigAsUser(fs.config.(*libkbfs.ConfigLocal), "user2")
	defer libkbfs.CheckConfigAndShutdown(ctx, t, config2)
	config2.SetClock(clock)

	h2, err := tlfhandle.ParseHandle(
		ctx, config2.KBPKI(), config2.MDOps(), nil, "user2#user1", tlf.Private)
	require.NoError(t, err)
	fs2U2, err := NewFS(
		ctx, config2, h2, data.MasterBranch, "", "",
		keybase1.MDPriorityNormal)
	require.NoError(t, err)
	rootNode2, _, err := fs2U2.config.KBFSOps().GetRootNode(
		ctx, h2, data.MasterBranch)
	require.NoError(t, err)
	aNode2, _, err := fs2U2.config.KBFSOps().CreateDir(
		ctx, rootNode2, testPPS("a"))
	require.NoError(t, err)
	testCreateFile(ctx, t, fs2U2, "a/foo", aNode2)

	// Read as the reader.
	fs2U1, err := NewFS(
		ctx, fs.config, h2, data.MasterBranch, "", "",
		keybase1.MDPriorityNormal)
	require.NoError(t, err)

	fi, err = fs2U1.Stat("a")
	require.NoError(t, err)
	checkDir(fi, false)

	fi, err = fs2U1.Stat("a/foo")
	require.NoError(t, err)
	checkFile(fi, false)
}

func TestRename(t *testing.T) {
	ctx, h, fs := makeFS(t, "")
	defer libkbfs.CheckConfigAndShutdown(ctx, t, fs.config)

	rootNode, _, err := fs.config.KBFSOps().GetRootNode(
		ctx, h, data.MasterBranch)
	require.NoError(t, err)
	testCreateFile(ctx, t, fs, "foo", rootNode)
	err = fs.MkdirAll("a/b", os.FileMode(0600))
	require.NoError(t, err)

	f, err := fs.Open("foo")
	require.NoError(t, err)
	gotDataFoo := make([]byte, 1)
	_, err = f.Read(gotDataFoo)
	require.NoError(t, err)
	err = f.Close()
	require.NoError(t, err)

	err = fs.Rename("foo", "a/b/bar")
	require.NoError(t, err)

	f, err = fs.Open("a/b/bar")
	require.NoError(t, err)
	gotDataBar := make([]byte, 1)
	_, err = f.Read(gotDataBar)
	require.NoError(t, err)
	require.True(t, bytes.Equal(gotDataFoo, gotDataBar))
	err = f.Close()
	require.NoError(t, err)

	_, err = fs.Open("foo")
	require.NotNil(t, err)

	err = fs.SyncAll()
	require.NoError(t, err)
}

func TestRemove(t *testing.T) {
	ctx, h, fs := makeFS(t, "")
	defer libkbfs.CheckConfigAndShutdown(ctx, t, fs.config)

	rootNode, _, err := fs.config.KBFSOps().GetRootNode(
		ctx, h, data.MasterBranch)
	require.NoError(t, err)
	testCreateFile(ctx, t, fs, "foo", rootNode)
	err = fs.MkdirAll("a/b", os.FileMode(0600))
	require.NoError(t, err)

	// Remove a file.
	err = fs.Remove("foo")
	require.NoError(t, err)
	_, err = fs.Open("foo")
	require.NotNil(t, err)

	// Removing "a" should fail because it's not empty.
	err = fs.Remove("a")
	require.NotNil(t, err)

	// Remove an empty dir and verify it's gone.
	err = fs.Remove("a/b")
	require.NoError(t, err)
	_, err = fs.Lstat("a/b")
	require.NotNil(t, err)

	err = fs.SyncAll()
	require.NoError(t, err)
}

func TestReadDir(t *testing.T) {
	ctx, h, fs := makeFS(t, "")
	defer libkbfs.CheckConfigAndShutdown(ctx, t, fs.config)

	rootNode, _, err := fs.config.KBFSOps().GetRootNode(
		ctx, h, data.MasterBranch)
	require.NoError(t, err)
	aNode, _, err := fs.config.KBFSOps().CreateDir(ctx, rootNode, testPPS("a"))
	require.NoError(t, err)
	testCreateFile(ctx, t, fs, "a/foo", aNode)
	testCreateFile(ctx, t, fs, "a/bar", aNode)
	expectedNames := map[string]bool{
		"foo": true,
		"bar": true,
	}

	fis, err := fs.ReadDir("a")
	require.NoError(t, err)
	require.Len(t, fis, len(expectedNames))
	for _, fi := range fis {
		require.True(t, expectedNames[fi.Name()])
		delete(expectedNames, fi.Name())
	}
	require.Len(t, expectedNames, 0)
}

func TestMkdirAll(t *testing.T) {
	ctx, _, fs := makeFS(t, "")
	defer libkbfs.CheckConfigAndShutdown(ctx, t, fs.config)

	err := fs.MkdirAll("a/b", os.FileMode(0600))
	require.NoError(t, err)

	err = fs.MkdirAll("a/b/c/d", os.FileMode(0600))
	require.NoError(t, err)

	f, err := fs.Create("a/b/c/d/foo")
	require.NoError(t, err)

	err = f.Close()
	require.NoError(t, err)
}

func TestSymlink(t *testing.T) {
	ctx, _, fs := makeFS(t, "")
	defer libkbfs.CheckConfigAndShutdown(ctx, t, fs.config)

	err := fs.MkdirAll("a/b/c", os.FileMode(0600))
	require.NoError(t, err)

	foo, err := fs.Create("a/b/c/foo")
	require.NoError(t, err)

	data := []byte{1, 2, 3, 4}
	n, err := foo.Write(data)
	require.Equal(t, len(data), n)
	require.NoError(t, err)
	err = foo.Close()
	require.NoError(t, err)

	t.Log("Basic file symlink in same dir")
	err = fs.Symlink("foo", "a/b/c/bar")
	require.NoError(t, err)

	_, err = fs.Open("a/b/c/bar")
	require.NoError(t, err)

	t.Log("Make sure Symlink creates parent directories as needed")
	err = fs.Symlink("../../foo", "a/b/c/d/e/bar")
	require.NoError(t, err)

	bar, err := fs.Open("a/b/c/d/e/bar")
	require.NoError(t, err)

	checkData := func(f billy.File) {
		gotData := make([]byte, len(data))
		n, err = f.Read(gotData)
		require.Equal(t, len(data), n)
		require.NoError(t, err)
		require.True(t, bytes.Equal(data, gotData))
	}
	checkData(bar)

	err = bar.Close()
	require.NoError(t, err)

	t.Log("File symlink across to a lower dir")
	err = fs.Symlink("b/c/foo", "a/bar")
	require.NoError(t, err)
	bar, err = fs.Open("a/bar")
	require.NoError(t, err)
	checkData(bar)
	err = bar.Close()
	require.NoError(t, err)

	t.Log("File symlink across to a higher dir")
	err = fs.MkdirAll("a/b/c/d/e/f", os.FileMode(0600))
	require.NoError(t, err)
	err = fs.Symlink("../../../foo", "a/b/c/d/e/f/bar")
	require.NoError(t, err)
	bar, err = fs.Open("a/b/c/d/e/f/bar")
	require.NoError(t, err)
	checkData(bar)
	err = bar.Close()
	require.NoError(t, err)

	t.Log("File across dir symlink")
	err = fs.Symlink("b", "a/b2")
	require.NoError(t, err)
	bar, err = fs.Open("a/b2/c/bar")
	require.NoError(t, err)
	checkData(bar)
	err = bar.Close()
	require.NoError(t, err)

	t.Log("Infinite symlink loop")
	err = fs.Symlink("x", "y")
	require.NoError(t, err)
	err = fs.Symlink("y", "x")
	require.NoError(t, err)
	_, err = fs.Open("x")
	require.NotNil(t, err)

	t.Log("Symlink that tries to break chroot")
	err = fs.Symlink("../../a", "a/breakout")
	require.NoError(t, err)
	_, err = fs.Open("a/breakout")
	require.NotNil(t, err)

	t.Log("Symlink to absolute path")
	err = fs.Symlink("/etc/passwd", "absolute")
	require.NoError(t, err)
	_, err = fs.Open("absolute")
	require.NotNil(t, err)

	t.Log("Readlink")
	link, err := fs.Readlink("a/bar")
	require.NoError(t, err)
	require.Equal(t, "b/c/foo", link)

	fi, err := fs.Lstat("a/bar")
	require.NoError(t, err)
	require.Equal(t, "bar", fi.Name())

	err = fs.SyncAll()
	require.NoError(t, err)
}

func TestChmod(t *testing.T) {
	ctx, _, fs := makeFS(t, "")
	defer libkbfs.CheckConfigAndShutdown(ctx, t, fs.config)

	foo, err := fs.Create("foo")
	require.NoError(t, err)
	err = foo.Close()
	require.NoError(t, err)

	fi, err := fs.Stat("foo")
	require.NoError(t, err)
	require.True(t, fi.Mode()&0100 == 0)

	err = fs.Chmod("foo", 0777)
	require.NoError(t, err)

	fi, err = fs.Stat("foo")
	require.NoError(t, err)
	require.True(t, fi.Mode()&0100 != 0)
}

func TestChtimes(t *testing.T) {
	ctx, _, fs := makeFS(t, "")
	defer libkbfs.CheckConfigAndShutdown(ctx, t, fs.config)

	clock := &clocktest.TestClock{}
	clock.Set(time.Now())
	fs.config.SetClock(clock)

	foo, err := fs.Create("foo")
	require.NoError(t, err)
	err = foo.Close()
	require.NoError(t, err)

	fi, err := fs.Stat("foo")
	require.NoError(t, err)
	require.True(t, clock.Now().Equal(fi.ModTime()))

	mtime := time.Date(2015, 1, 2, 3, 4, 5, 6, time.Local)
	err = fs.Chtimes("foo", time.Now(), mtime)
	require.NoError(t, err)

	fi, err = fs.Stat("foo")
	require.NoError(t, err)
	require.Equal(t, mtime, fi.ModTime())
}

func TestChroot(t *testing.T) {
	ctx, _, fs := makeFS(t, "")
	defer libkbfs.CheckConfigAndShutdown(ctx, t, fs.config)

	require.Equal(t, "/keybase/private/user1", fs.Root())

	err := fs.MkdirAll("a/b/c", os.FileMode(0600))
	require.NoError(t, err)

	foo, err := fs.Create("a/b/c/foo")
	require.NoError(t, err)

	data := []byte{1, 2, 3, 4}
	n, err := foo.Write(data)
	require.Equal(t, len(data), n)
	require.NoError(t, err)
	err = foo.Close()
	require.NoError(t, err)

	err = fs.SyncAll()
	require.NoError(t, err)

	t.Log("Make a new FS with a deeper root")
	fs2, err := fs.Chroot("a/b")
	require.NoError(t, err)

	require.Equal(t, "/keybase/private/user1/a/b", fs2.Root())

	f, err := fs2.Open("c/foo")
	require.NoError(t, err)
	gotData := make([]byte, len(data))
	_, err = f.Read(gotData)
	require.NoError(t, err)
	require.True(t, bytes.Equal(data, gotData))
	err = f.Close()
	require.NoError(t, err)

	t.Log("Attempt a breakout")
	_, err = fs.Chroot("../../../etc/passwd")
	require.NotNil(t, err)
}

func TestFileLocking(t *testing.T) {
	_, _, fs, shutdown := makeFSWithJournal(t, "")
	defer shutdown()

	// TODO: Write an integration tests where we also check to make sure lock
	// namespace isn't empty.
	f, err := fs.Create("a")
	require.NoError(t, err)

	err = f.Lock()
	require.NoError(t, err)

	err = f.Unlock()
	require.NoError(t, err)

	// The lock has been released, and we haven't made any changes.
	// This should be a no-op.
	err = f.Unlock()
	require.NoError(t, err)

	// Make some more change so next Unlock actually needs to write a MD.
	_, err = fs.Create("c")
	require.NoError(t, err)

	// Now we do have some stuff that needs to flush, but we don't
	// have the lock, so this should complete without flushing
	// anything.
	err = f.Unlock()
	require.NoError(t, err)

	// Make sure the journal didn't flush.
	err = fs.SyncAll()
	require.NoError(t, err)
	jManager, err := libkbfs.GetJournalManager(fs.config)
	require.NoError(t, err)
	status, err := jManager.JournalStatus(fs.root.GetFolderBranch().Tlf)
	require.NoError(t, err)
	require.NotEqual(t, kbfsmd.RevisionUninitialized, status.RevisionStart)

	// Now manually flush again so the journal is clean.
	err = jManager.FinishSingleOp(fs.ctx,
		fs.root.GetFolderBranch().Tlf, nil, keybase1.MDPriorityNormal)
	require.NoError(t, err)
}

func TestFileLockingExpiration(t *testing.T) {
	_, _, fs, shutdown := makeFSWithJournal(t, "")
	defer shutdown()

	clock := &clocktest.TestClock{}
	clock.Set(time.Now())
	fs.config.SetClock(clock)

	f, err := fs.Create("a")
	require.NoError(t, err)

	err = f.Lock()
	require.NoError(t, err)

	_, err = fs.Create("b")
	require.NoError(t, err)

	clock.Add(2 * time.Minute)

	// Close/Unlock should fail because the clock expired.
	err = f.Close()
	require.Error(t, err)

	// Shut down the MD server first to avoid state-checking, since
	// the journal is in a weird state.
	fs.config.MDServer().Shutdown()
}

func TestArchivedByRevision(t *testing.T) {
	ctx, h, fs := makeFS(t, "")
	defer libkbfs.CheckConfigAndShutdown(ctx, t, fs.config)

	rootNode, _, err := fs.config.KBFSOps().GetRootNode(
		ctx, h, data.MasterBranch)
	require.NoError(t, err)

	testCreateFile(ctx, t, fs, "foo", rootNode)
	fis, err := fs.ReadDir("")
	require.NoError(t, err)
	require.Len(t, fis, 1)

	_, _, fsArchived := makeFSWithBranch(
		t, data.MakeRevBranchName(kbfsmd.Revision(1)), "")
	defer libkbfs.CheckConfigAndShutdown(ctx, t, fsArchived.config)
	fis, err = fsArchived.ReadDir("")
	require.NoError(t, err)
	require.Len(t, fis, 0)
}

func TestEmptyFS(t *testing.T) {
	ctx := libcontext.BackgroundContextWithCancellationDelayer()
	config := libkbfs.MakeTestConfigOrBust(t, "user1", "user2")
	defer libkbfs.CheckConfigAndShutdown(ctx, t, config)

	h, err := tlfhandle.ParseHandle(
		ctx, config.KBPKI(), config.MDOps(), nil, "user1", tlf.Private)
	require.NoError(t, err)
	fs, err := NewFSIfExists(
		ctx, config, h, data.MasterBranch, "", "", keybase1.MDPriorityNormal)
	require.NoError(t, err)

	require.True(t, fs.IsEmpty())

	fis, err := fs.ReadDir("")
	require.NoError(t, err)
	require.Len(t, fis, 0)

	err = fs.MkdirAll("a", 0777)
	require.Error(t, err)
}