Python 2.7-compatible file-based/streaming base64 encode/decode (from https://stackoverflow.com/questions/22734401/base64-encode-decode-to-from-files-in-chunks-with-python-2-7)

file_encode_decode_base64.py

# from https://stackoverflow.com/questions/22734401/base64-encode-decode-to-from-files-in-chunks-with-python-2-7
#
# write_base64_file_from_file
# write_file_from_base64_file
#               - must run with python 2.7
#               - must process data in chunks to limit memory consumption
#               - base64 data must be JSON compatible, i.e.
#                 use base64 "modern" interface,
#                 not base64.encodestring() which contains linefeeds
#
import base64
import shutil


def write_base64_file_from_file(src_fname, b64_fname, chunk_size=8192):
    chunk_size -= chunk_size % 3  # align to multiples of 3
    with open(src_fname, 'rb') as fin, open(b64_fname, 'w') as fout:
        while True:
            bin_data = fin.read(chunk_size)
            if not bin_data:
                break
            #print 'bin %s data len: %d' % (type(bin_data), len(bin_data))
            b64_data = base64.b64encode(bin_data)
            #print 'b64 %s data len: %d' % (type(b64_data), len(b64_data))
            fout.write(b64_data)


def write_file_from_base64_file(b64_fname, dst_fname, chunk_size=8192):
    chunk_size -= chunk_size % 4  # align to multiples of 4
    with open(b64_fname, 'r') as fin, open(dst_fname, 'wb') as fout:
        while True:
            b64_data = fin.read(chunk_size)
            if not b64_data:
                break
            #print 'b64 %s data len: %d' % (type(b64_data), len(b64_data))
            bin_data = base64.b64decode(b64_data)
            #print 'bin %s data len: %d' % (type(bin_data), len(bin_data))
            fout.write(bin_data)