Parse a directory of torrent files and return the total size of all files within

torrent-sum.py

#!/usr/bin/env python

import os, glob
from io import BytesIO

class End(Exception): pass

def decode(stream):
    delim = stream.read(1)

    if delim == b'd':
        values = {}
        while True:
            try:
                key = decode(stream)
                val = decode(stream)
                values.update({key: val})
            except End:
                break
        return values

    elif delim == b'l':
        values = []
        while True:
            try:
                val = decode(stream)
                values.append(val)
            except End:
                break
        return values

    elif delim == b'i':
        t = ''
        while True:
            d = stream.read(1)
            if d == b'e':
                break
            t += d.decode()
        return int(t, 10)

    elif delim == b'e':
        raise End

    else: # byte string
        t = delim.decode()
        while True:
            d = stream.read(1)
            if d == b':':
                break
            t += d.decode()
        return stream.read(int(t, 10))

def human_readable(size, suffix='B'):
    fmt = '{:3.1f}{}{}'
    units = ['', 'Ki', 'Mi', 'Gi', 'Ti', 'Pi', 'Ei', 'Zi']
    for unit in units:
        if abs(size) < 1024.0:
            return fmt.format(size, unit, suffix)
        size /= 1024.0
    return fmt.format(size, 'Yi', suffix)

def main():
    import argparse
    parser = argparse.ArgumentParser()
    parser.add_argument('input')
    args = parser.parse_args()
    if os.path.isdir(args.input):
        torrents = glob.glob(args.input + '/*.torrent')
    else:
        torrents = [args.input]

    total_bytes = 0
    for torrent in torrents:
        with open(torrent, 'rb') as fp:
            stream = BytesIO(fp.read())
            parsed = decode(stream)
            info = parsed.get(b'info', {})
            if b'files' in info: # multi
                for fname in info[b'files']:
                    # print(fname[b'path'], fname[b'length'])
                    total_bytes += fname[b'length']
            elif b'length' in info: # single
                # print(info[b'name'], info[b'length'])
                total_bytes += info[b'length']
            else:
                print("could not find either 'files' or 'length' key in info dict")

    print(human_readable(total_bytes))

if __name__ == '__main__':
    main()