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ajnavarroajnavarro
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Merge pull request #27 from ajnavarro/feature/temp-overlay
tmpfs: add temporal overlay filesystem
2 parents 99d8398 + c8ef2d3 commit cadb3c8

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‎tmpoverlayfs/tmpfs.go

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package tmpfs
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import (
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"errors"
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"io"
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"os"
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"path"
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"gopkg.in/src-d/go-billy.v2"
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"gopkg.in/src-d/go-billy.v2/subdirfs"
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)
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type tmpFs struct {
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fs billy.Filesystem
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tmp billy.Filesystem
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tempFiles map[string]bool
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}
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// New creates a new filesystem wrapping up 'fs' and using 'tmp' for temporary
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// files. Any file created with TempFile will be created in 'tmp'. It will be
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// moved to 'fs' if Rename is called on it.
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//
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// This is particularly useful to provide TempFile for filesystems that do not
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// support it or where there is a performance penalty in doing so.
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func New(fs billy.Filesystem, tmp billy.Filesystem) billy.Filesystem {
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return &tmpFs{
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fs: fs,
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tmp: tmp,
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tempFiles: map[string]bool{},
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}
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}
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func (t *tmpFs) Create(path string) (billy.File, error) {
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if t.isTmpFile(path) {
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return t.tmp.Create(path)
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}
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return t.fs.Create(path)
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}
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func (t *tmpFs) Open(path string) (billy.File, error) {
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if t.isTmpFile(path) {
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return t.tmp.Open(path)
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}
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return t.fs.Open(path)
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}
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func (t *tmpFs) OpenFile(p string, flag int, mode os.FileMode) (
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billy.File, error) {
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if t.isTmpFile(p) {
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return t.tmp.OpenFile(p, flag, mode)
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}
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return t.fs.OpenFile(p, flag, mode)
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}
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func (t *tmpFs) ReadDir(p string) ([]billy.FileInfo, error) {
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return t.fs.ReadDir(p)
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}
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func (t *tmpFs) Join(elem ...string) string {
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return t.fs.Join(elem...)
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}
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func (t *tmpFs) Dir(p string) billy.Filesystem {
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return subdirfs.New(t, p)
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}
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func (t *tmpFs) MkdirAll(filename string, perm os.FileMode) error {
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return t.fs.MkdirAll(filename, perm)
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}
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func (t *tmpFs) Base() string {
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return t.fs.Base()
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}
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func (t *tmpFs) TempFile(dir string, prefix string) (billy.File, error) {
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tmpFile, err := t.tmp.TempFile(dir, prefix)
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if err != nil {
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return nil, err
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}
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t.tempFiles[tmpFile.Filename()] = true
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return tmpFile, nil
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}
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func (t *tmpFs) Rename(from, to string) error {
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if t.isTmpFile(to) {
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return errors.New("cannot rename to temp file")
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}
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if t.isTmpFile(from) {
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err := copyPath(t.tmp, t.fs, from, to)
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if err != nil {
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return err
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}
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if err := t.tmp.Remove(from); err != nil {
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return err
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}
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t.removeTempReference(from)
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return nil
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}
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return t.fs.Rename(from, to)
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}
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func (t *tmpFs) Remove(path string) error {
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if t.isTmpFile(path) {
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if err := t.tmp.Remove(path); err != nil {
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return err
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}
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t.removeTempReference(path)
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return nil
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}
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return t.fs.Remove(path)
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}
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func (t *tmpFs) Stat(path string) (billy.FileInfo, error) {
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if t.isTmpFile(path) {
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return t.tmp.Stat(path)
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}
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return t.fs.Stat(path)
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}
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func (t *tmpFs) isTmpFile(p string) bool {
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p = path.Clean(p)
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_, ok := t.tempFiles[p]
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return ok
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}
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func (t *tmpFs) removeTempReference(p string) {
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p = path.Clean(p)
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delete(t.tempFiles, p)
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}
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// copyPath copies a file across filesystems.
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func copyPath(src billy.Filesystem, dst billy.Filesystem,
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srcPath string, dstPath string) error {
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dstFile, err := dst.Create(dstPath)
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if err != nil {
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return err
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}
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srcFile, err := src.Open(srcPath)
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if err != nil {
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return nil
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}
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_, err = io.Copy(dstFile, srcFile)
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if err != nil {
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return nil
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}
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err = dstFile.Close()
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if err != nil {
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_ = srcFile.Close()
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return err
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}
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return srcFile.Close()
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}

‎tmpoverlayfs/tmpfs_specific_test.go

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package tmpfs
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import (
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"io"
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"io/ioutil"
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stdos "os"
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"path/filepath"
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"gopkg.in/src-d/go-billy.v2"
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"gopkg.in/src-d/go-billy.v2/osfs"
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. "gopkg.in/check.v1"
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)
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type SpecificFilesystemSuite struct {
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src billy.Filesystem
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tmp billy.Filesystem
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srcPath string
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tmpPath string
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}
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var _ = Suite(&SpecificFilesystemSuite{})
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func (s *SpecificFilesystemSuite) SetUpTest(c *C) {
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s.srcPath = c.MkDir()
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s.tmpPath = c.MkDir()
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s.src = osfs.New(s.srcPath)
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s.tmp = osfs.New(s.tmpPath)
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}
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func (s *SpecificFilesystemSuite) TestTempFileInTmpFs(c *C) {
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tmpFs := New(s.src, s.tmp)
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c.Assert(tmpFs, NotNil)
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f, err := tmpFs.TempFile("test-dir", "test-prefix")
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c.Assert(err, IsNil)
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c.Assert(f, NotNil)
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filename := f.Filename()
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c.Assert(f.Close(), IsNil)
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_, err = stdos.Stat(filepath.Join(s.srcPath, filename))
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c.Assert(stdos.IsNotExist(err), Equals, true)
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_, err = stdos.Stat(filepath.Join(s.tmpPath, filename))
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c.Assert(err, IsNil)
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}
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func (s *SpecificFilesystemSuite) TestNonTempFileInSrcFs(c *C) {
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tmpFs := New(s.src, s.tmp)
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c.Assert(tmpFs, NotNil)
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f, err := tmpFs.Create("foo")
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c.Assert(err, IsNil)
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c.Assert(f, NotNil)
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c.Assert(f.Close(), IsNil)
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_, err = stdos.Stat(filepath.Join(s.srcPath, "foo"))
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c.Assert(err, IsNil)
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_, err = stdos.Stat(filepath.Join(s.tmpPath, "foo"))
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c.Assert(stdos.IsNotExist(err), Equals, true)
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}
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func (s *SpecificFilesystemSuite) TestTempFileCanBeReopened(c *C) {
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tmpFs := New(s.src, s.tmp)
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c.Assert(tmpFs, NotNil)
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f, err := tmpFs.TempFile("test-dir", "test-prefix")
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c.Assert(err, IsNil)
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c.Assert(f, NotNil)
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n, err := f.Write([]byte("foo"))
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c.Assert(err, IsNil)
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c.Assert(n, Equals, 3)
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filename := f.Filename()
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c.Assert(f.Close(), IsNil)
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f, err = tmpFs.Open(filename)
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c.Assert(err, IsNil)
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c.Assert(f.Filename(), Equals, filename)
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content, err := ioutil.ReadAll(f)
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c.Assert(err, IsNil)
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c.Assert(string(content), Equals, "foo")
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c.Assert(f.Close(), IsNil)
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}
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func (s *SpecificFilesystemSuite) TestTempFileCanBeReopenedByOpenFile(c *C) {
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tmpFs := New(s.src, s.tmp)
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c.Assert(tmpFs, NotNil)
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f, err := tmpFs.TempFile("test-dir", "test-prefix")
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c.Assert(err, IsNil)
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c.Assert(f, NotNil)
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n, err := f.Write([]byte("foo"))
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c.Assert(err, IsNil)
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c.Assert(n, Equals, 3)
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filename := f.Filename()
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c.Assert(f.Close(), IsNil)
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f, err = tmpFs.OpenFile(filename, stdos.O_RDONLY, 0)
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c.Assert(err, IsNil)
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c.Assert(f.Filename(), Equals, filename)
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content, err := ioutil.ReadAll(f)
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c.Assert(err, IsNil)
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c.Assert(string(content), Equals, "foo")
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c.Assert(f.Close(), IsNil)
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}
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func (s *SpecificFilesystemSuite) TestStatTempFile(c *C) {
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tmpFs := New(s.src, s.tmp)
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c.Assert(tmpFs, NotNil)
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f, err := tmpFs.TempFile("test-dir", "test-prefix")
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c.Assert(err, IsNil)
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c.Assert(f, NotNil)
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tempFilename := f.Filename()
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c.Assert(f.Close(), IsNil)
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fi, err := tmpFs.Stat(tempFilename)
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c.Assert(err, IsNil)
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c.Assert(fi, NotNil)
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}
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func (s *SpecificFilesystemSuite) TestRenameFromTempFile(c *C) {
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tmpFs := New(s.src, s.tmp)
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c.Assert(tmpFs, NotNil)
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f, err := tmpFs.TempFile("test-dir", "test-prefix")
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c.Assert(err, IsNil)
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c.Assert(f, NotNil)
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tempFilename := f.Filename()
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c.Assert(f.Close(), IsNil)
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err = tmpFs.Rename(tempFilename, "foo")
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c.Assert(err, IsNil)
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_, err = s.src.Stat("foo")
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c.Assert(err, IsNil)
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_, err = s.tmp.Stat("foo")
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c.Assert(err, NotNil)
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_, err = s.tmp.Stat(tempFilename)
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c.Assert(err, NotNil)
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}
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func (s *SpecificFilesystemSuite) TestCannotRenameToTempFile(c *C) {
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tmpFs := New(s.src, s.tmp)
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c.Assert(tmpFs, NotNil)
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f, err := tmpFs.TempFile("test-dir", "test-prefix")
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c.Assert(err, IsNil)
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c.Assert(f, NotNil)
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tempFilename := f.Filename()
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c.Assert(f.Close(), IsNil)
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f, err = tmpFs.Create("foo")
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c.Assert(err, IsNil)
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c.Assert(f, NotNil)
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c.Assert(f.Close(), IsNil)
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err = tmpFs.Rename("foo", tempFilename)
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c.Assert(err, NotNil)
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}
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func (s *SpecificFilesystemSuite) TestRemoveTempFile(c *C) {
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tmpFs := New(s.src, s.tmp)
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c.Assert(tmpFs, NotNil)
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f, err := tmpFs.TempFile("test-dir", "test-prefix")
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c.Assert(err, IsNil)
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c.Assert(f, NotNil)
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tempFilename := f.Filename()
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c.Assert(f.Close(), IsNil)
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err = tmpFs.Remove(tempFilename)
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c.Assert(err, IsNil)
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_, err = s.tmp.Stat(tempFilename)
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c.Assert(err, NotNil)
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}
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func (s *SpecificFilesystemSuite) TestCreateTempFile(c *C) {
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tmpFs := New(s.src, s.tmp)
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c.Assert(tmpFs, NotNil)
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f, err := tmpFs.TempFile("test-dir", "test-prefix")
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c.Assert(err, IsNil)
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c.Assert(f, NotNil)
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n, err := f.Write([]byte("TEST"))
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tempFilename := f.Filename()
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c.Assert(f.Close(), IsNil)
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createdFile, err := tmpFs.Create(tempFilename)
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c.Assert(err, IsNil)
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c.Assert(createdFile, NotNil)
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bRead := make([]byte, 4)
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n, err = createdFile.Read(bRead)
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c.Assert(n, Equals, 0)
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c.Assert(err, Equals, io.EOF)
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}

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