// AtomicWriteFile updates the filename atomically and works otherwise
// like io/ioutil.WriteFile()
//
// Note that it won't follow symlinks and will replace existing symlinks
// with the real file
func AtomicWriteFile(filename string, data []byte, perm os.FileMode, flags AtomicWriteFlags) (err error) {
if flags&AtomicWriteFollow != 0 {
if fn, err := os.Readlink(filename); err == nil || (fn != "" && os.IsNotExist(err)) {
if filepath.IsAbs(fn) {
filename = fn
} else {
filename = filepath.Join(filepath.Dir(filename), fn)
}
}
}
tmp := filename + "." + strutil.MakeRandomString(12)
// XXX: if go switches to use aio_fsync, we need to open the dir for writing
dir, err := os.Open(filepath.Dir(filename))
if err != nil {
return err
}
defer dir.Close()
fd, err := os.OpenFile(tmp, os.O_WRONLY|os.O_CREATE|os.O_TRUNC|os.O_EXCL, perm)
if err != nil {
return err
}
defer func() {
e := fd.Close()
if err == nil {
err = e
}
if err != nil {
os.Remove(tmp)
}
}()
// according to the docs, Write returns a non-nil error when n !=
// len(b), so don't worry about short writes.
if _, err := fd.Write(data); err != nil {
return err
}
if err := fd.Sync(); err != nil {
return err
}
if err := os.Rename(tmp, filename); err != nil {
return err
}
return dir.Sync()
}
func (ts *AtomicWriteTestSuite) TestAtomicWriteFileNoOverwriteTmpExisting(c *C) {
tmpdir := c.MkDir()
// ensure we always get the same result
rand.Seed(1)
expectedRandomness := strutil.MakeRandomString(12)
// ensure we always get the same result
rand.Seed(1)
p := filepath.Join(tmpdir, "foo")
err := ioutil.WriteFile(p+"."+expectedRandomness, []byte(""), 0644)
c.Assert(err, IsNil)
err = AtomicWriteFile(p, []byte(""), 0600, 0)
c.Assert(err, ErrorMatches, "open .*: file exists")
}
// NewSubscriber returns a new subscriber containing the given websocket
// connection and type/resource filters set from the query string params in the
// supplied http request
func NewSubscriber(c websocketConnection, r *http.Request) *Subscriber {
s := &Subscriber{
uuid: strutil.MakeRandomString(16),
conn: c,
}
q := r.URL.Query()
if len(q["types"]) > 0 {
s.types = strings.Split(q["types"][0], ",")
}
if len(q["resource"]) > 0 {
s.resource = q["resource"][0]
}
return s
}
// genClassicScopeName generates an uniq name for the classic scope
func genClassicScopeName() string {
now := time.Now()
ti := fmt.Sprintf("%4d-%02d-%02d_%02d:%02d:%02d", now.Year(), now.Month(), now.Day(), now.Hour(), now.Minute(), now.Second())
return fmt.Sprintf("snappy-classic_%s_%s.scope", ti, strutil.MakeRandomString(5))
}
