Last byte is truncated for file with specific size and specific number of threads

[panpawel88]

Hello,

I use pySmartDL 1.3.2 on Ubuntu 18.04. I noticed that the last byte of a downloaded file is truncated, when a file size is 1906023034 and a number of threads is 20.

Reproduction steps:

1. Generate a file with size 1906023034. I used 'fallocate' command:
   $ fallocate -l 1906023034 test_file
2. Put a test file on HTTP server. I used nginx, but any server which supports multiple connections and range-based requests shall be fine.
3. Download a file. Here is my program:

import logging
import tempfile

from pySmartDL import SmartDL

if __name__ == '__main__':
    logging.basicConfig(level=logging.DEBUG)
    urls = [
        'http://localhost:8000/test_file']
    tempdir = tempfile.mkdtemp()
    obj = SmartDL(urls=urls,
                  dest=tempdir,
                  threads=20,
                  logger=logging.getLogger(__name__))
    obj.timeout = 30
    obj.start(blocking=True)

4. Verify file size after download:
   $ du -b test_file
   1906023033 test_file

I also noticed that if you use 100 threads, then the file size is correct.

[ghost]

Same error with a file size of 261969919 and 32 threads, I got a file with size 261969918.
Same error with 4, 8, 16, 32 or 64 threads, ... (always with the same file), but works fine with 128 and 256 threads... !
Works fine with 30, (not 32!), 31, 33, 34, 35, 36, 37, 38, 39 or 40 threads with the same file.

With a file size of 351272960, seems to work with all thread configurations...

Can you look into this please ? Seems to be a very critical bug... thank you! (I can donate if needed, i realy need this lib^^ )

(I use pySmartDL 1.3.2 on Windows 10)

[iTaybb]

I'll look into it.

[ghost]

Thank you 🙏
(If you have a bitcoin wallet give me your address in pvt I will make you a donation when the fix will be released, if you want)

[iTaybb]

Thanks for the hard work.