tail

[Marco Sulla]

Something like this is OK?

import os

def tail(f):
    chunk_size = 100
    size = os.stat(f.fileno()).st_size

    positions = iter(range(size, -1, -chunk_size))
    next(positions)

    chunk_line_pos = -1
    pos = 0

    for pos in positions:
        f.seek(pos)
        chars = f.read(chunk_size)
        chunk_line_pos = chars.rfind(b"\n")

        if chunk_line_pos != -1:
            break

    if chunk_line_pos == -1:
        nbytes = pos
        pos = 0
        f.seek(pos)
        chars = f.read(nbytes)
        chunk_line_pos = chars.rfind(b"\n")

    if chunk_line_pos == -1:
        line_pos = pos
    else:
        line_pos = pos + chunk_line_pos + 1

    f.seek(line_pos)

    return f.readline()

This is simply for one line and for utf8.