funcs.py 文件源码

def get_hash(infile, algorithm='md5', BLOCKSIZE=65536):
    """Generate file hash without reading in the entire file at once.

    Original code licensed under MIT.  Source:
    http://pythoncentral.io/hashing-files-with-python/

    Parameters
    ----------
    infile : str
        File of interest (including the path).
    algorithm : str (optional)
        Hash algorithm of choice. Defaults to 'md5'.
    BLOCKSIZE : int (optional)
        How much data in bytes to read in at once.

    Returns
    -------
    hash : str
        The hash of the file.

    Examples
    --------
    >>> import yt.funcs as funcs
    >>> funcs.get_hash('/path/to/test.png')
    'd38da04859093d430fa4084fd605de60'

    """
    import hashlib

    try:
        hasher = getattr(hashlib, algorithm)()
    except:
        raise NotImplementedError("'%s' not available!  Available algorithms: %s" %
                                  (algorithm, hashlib.algorithms))

    filesize   = os.path.getsize(infile)
    iterations = int(float(filesize)/float(BLOCKSIZE))

    pbar = get_pbar('Generating %s hash' % algorithm, iterations)

    iter = 0
    with open(infile,'rb') as f:
        buf = f.read(BLOCKSIZE)
        while len(buf) > 0:
            hasher.update(buf)
            buf = f.read(BLOCKSIZE)
            iter += 1
            pbar.update(iter)
        pbar.finish()

    return hasher.hexdigest()