pause_split.py

#!/usr/bin/python3

import os
import os.path
import time
import math
import subprocess
import sys

filename = None
try:
    filename_index = sys.argv.index("--filename")
    filename = sys.argv[filename_index + 1]
except ValueError as err:
    print("filename not found")
    sys.exit(1)
finally:
    if filename is None:
        filename = ""

try:
    splitsize_index = sys.argv.index("--bytes")
    splitsize = sys.argv[splitsize_index + 1]
except ValueError as err:
    splitsize = None
finally:
    if splitsize is None:
        #splitsize = 1000 * 1000 * 1000 * 4.71 - 1024
        splitsize = 1024 * 1024 * 5

chunksize = 1024 * 1024
letters_width = 2
letters = ["a", "b", "c", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n",
"o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z"]


def get_suffix(index):
    suffix_array = []
    while True:
        quotient = math.floor(index/26)
        letter_index = index % 26
        suffix_array.append(letters[letter_index])
        if quotient > 0:
            index = quotient
        else:
            break
    if letters_width - len(suffix_array) > 0:
        for i in range(0, letters_width - len(suffix_array)):
            suffix_array.append("a")
    suffix_str = ""
    for i in range(0, letters_width):
        suffix_str += suffix_array.pop()
    return suffix_str


_data_leftover = None

def read_stdin(size, chunksize):
    global _data_leftover
    bytes_read = 0
    while True:
        if bytes_read > size:
            break
        if _data_leftover is not None:
            data = _data_leftover
            _data_leftover = None
            data += sys.stdin.buffer.read(chunksize - len(data))
        else:
            data = sys.stdin.buffer.read(chunksize)
        bytes_read += len(data)
        if bytes_read > size:
            excedent = bytes_read - size
            excedent_index = len(data) - excedent
            _data_leftover = data[excedent_index:len(data) - 1]
            data = data[0:excedent_index - 1]
        if data:
            yield data
        else:
            break


def run():
    global _data_leftover
    i = 0
    directory = 'backup'
    os.makedirs(directory, exist_ok=True)
    while True:
        if not _data_leftover:
            _data_leftover = sys.stdin.buffer.read(1024)
            if not _data_leftover:
                break
        # Create a file
        suffix = get_suffix(i)
        split_filename = "{}/{}.{}".format(directory, filename, suffix)
        print("==> Creating {}...".format(split_filename))
        with open(split_filename, 'w+b') as w:
            for chunk in read_stdin(splitsize, 1024 * 1024):
                w.write(chunk)
            w.close()
        print("Done.")
        print("Creating sha256 file.")
        shasum = subprocess.getoutput("sha256sum {}".format(split_filename))
        with open("{}.sha256".format(split_filename), 'w') as w:
            w.write(shasum)
        print("Waiting {} to be deleted...".format(split_filename))
        while True:
            time.sleep(1)
            if not os.path.isfile(split_filename):
                break
        i += 1

run()