python write string directly to tarfile

Question

Is there a way to write a string directly to a tarfile? From http://docs.python.org/library/tarfile.html it looks like only files already written to the file system can be a

Answer 1

The solution in Python 3 uses io.BytesIO. Be sure to set TarInfo.size to the length of the bytes, not the length of the string.

Given a single string, the simplest solution is to call .encode() on it to obtain bytes. In this day and age you probably want UTF-8, but if the recipient is expecting a specific encoding, such as ASCII (i.e. no multi-byte characters), then use that instead.

import io
import tarfile

data = 'hello\n'.encode('utf8')
info = tarfile.TarInfo(name='foo.txt')
info.size = len(data)

with tarfile.TarFile('test.tar', 'w') as tar:
    tar.addfile(info, io.BytesIO(data))

If you really need a writable string buffer, similar to the accepted answer by @Stefano Borini for Python 2, then the solution is to use io.TextIOWrapper over an underlying io.BytesIO buffer.

import io
import tarfile

textIO = io.TextIOWrapper(io.BytesIO(), encoding='utf8')
textIO.write('hello\n')
bytesIO = textIO.detach()
info = tarfile.TarInfo(name='foo.txt')
info.size = bytesIO.tell()

with tarfile.TarFile('test.tar', 'w') as tar:
    bytesIO.seek(0)
    tar.addfile(info, bytesIO)