Tar Stream.

tarstream.py

from tarfile import TarInfo
from os import path
from io import BytesIO


class TarIO:
    """Stream Tar IO.

        >>> from tempfile import gettempdir
        >>> from tarfile import open as taropen
        >>> from io import BytesIO
        >>> tmpdir = gettempdir()
        >>> open("{}/{}".format(tmpdir, "test1.txt"), 'w').write("one"*1024)
        >>> open("{}/{}".format(tmpdir, "test2.txt"), 'w').write("two"*1024)
        >>> tio = TarIO([
        ...     "{}/{}".format(tmpdir, "test1.txt"),
        ...     "{}/{}".format(tmpdir, "test2.txt")
        ... ])
        >>> tardata = b""
        >>> tmpdata = tio.read(2048)
        >>> while tmpdata:
        ...     tardata += tmpdata
        ...     tmpdata = tio.read(2048)
        >>> tarobj = taropen(fileobj=BytesIO(tardata))
        >>> list(tarobj)[0].name
        'test1.txt'
        >>> list(tarobj)[1].name
        'test2.txt'
        >>> list(tarobj)[0].size
        3072
    """
    def __init__(self, locations):
        self.tarlist = []
        self.pos = 0
        for location in locations:
            tinfo = TarInfo(path.split(location)[-1])
            file = open(location, 'rb')
            file.seek(0, 2)
            fsize = file.tell()
            file.close()
            tinfo.mtime = path.getmtime(location)
            tinfo.size = fsize
            tailsize = ((512 + fsize) // 512 + 1) * 512 - (512 + fsize)
            self.tarlist.append((512, BytesIO(tinfo.tobuf())))
            self.tarlist.append((fsize, open(location, 'rb')))
            self.tarlist.append((tailsize, BytesIO(b"\00" * tailsize)))

    def seek(self, pos, whence=0):
        if whence == 0 or whence == None:
            self.pos = pos
        elif whence == 1:
            self.pos += pos
        elif whence == 2:
            self.pos = sum(map((lambda t: t[0]), self.tarlist)) - pos
        return self.pos

    def tell(self):
        return self.pos

    def read(self, size=None):
        _bytes = b""

        if size is None:
            for _, get_bytes in self.tarlist:
                _bytes += get_bytes.read()
        else:
            pos_count = 0
            for num, bio in self.tarlist:
                if size <= 0:
                    break
                pos_count += num
                if pos_count < self.pos:
                    continue
                bpos = self.pos - (pos_count - num)
                bio.seek(bpos)
                readsize = ((num - bpos) if size > (num - bpos) else size)
                _bytes += bio.read(readsize)
                self.pos += readsize
                size -= readsize

        return _bytes