The missing `pip integrity` command

pip-integrity

#!/usr/bin/env python3
#
# The missing 'pip integrity' command.
# 
# This verifies the correctness of an unpacked pip package
# by examining the file hashes in the 'RECORD' file. 
# spec at https://peps.python.org/pep-0427/#the-dist-info-directory

import sys
import base64
import hashlib
from importlib.metadata import files

def integrity(package):

    valid = True

    for content in files(package):
        if content.hash:

            H = None
            try:
                H = hashlib.new(content.hash.mode)
                size = 0 
                with open(content.locate(), "rb") as fd:
                    while True:
                        B = fd.read(H.block_size)
                        size += len(B)
                        if not B: break
                        H.update(B)

                H = H.digest()
                # wheel stores hashes in unpadded base64, so convert to that
                H = base64.urlsafe_b64encode(H).decode().rstrip("=")
            except Exception:
                pass

            if H == content.hash.value:
                print(f"{content.locate()}: passed")
            else:
                print(f"{content.locate()}: failed")
                valid = False

    return valid


if __name__ == '__main__':
    
    valid = True
    for file in sys.argv[1:]:
        if not integrity(file):
            valid = False

    if not valid:
        raise SystemExit(1)