tmpfile package added

[odeke-em]

Added a package for tmpfile usage and management. It exposes a few methods
of the underlying temp file like:

• Read
• Seek
• ReadAt
• Write
• Close
• Stat

But also the management of this package kicks in when you invoke
.Done() which runs exactly once and removes the file.

This package exposes two different flavours of usage:

• NewInIsolatedDir - Use this in packages for which you'd just to use a
  unique temp file in an isolated directory, Read from, Write to it and
  discard it at the end
  Sample usage

tmpf, err := tmpfile.NewInIsolatedDir()
if err != nil {
  return nil, err
}

defer tmpf.Done() // Cleanup after self.
if _, err = io.Copy(tmpf, cipherSource); err != nil {
  return nil, err
}

• New - Use this in situations where you'd like flexibility on suffix
  and location of directory/temp file.
  Sample usage

tmpf, err := tmpfile.New(&tmpfile.Context{
  Dir: "trims",
  Suffix: "mkv",
  CreateInIsolatedDir: true,
})
if err != nil {
  return nil, err
}

defer tmpf.Done() // Cleanup after self.
if _, err = io.Copy(tmpf, mediaRes.Body); err != nil {
  return nil, err
}

[sselph]

I think I'm having an issue from this. My system doesn't have TMPDIR. Maybe it could use os.TempDir? or ioutil.TempDir. It is placing files in the current working directory.

[odeke-em]

Ah I see. For some reason I though os.TempDir and ioutil.TempDir respect $TMPDIR. Thanks for letting me know.