Tree hash, Amazon style

[wvmarle]

Hash returned to the user at the end of an upload is the hash returned by Amazon for the complete file, if I understand the code correctly. No way to get the tree hash of the local file. So I hacked together a little script to calculate this. Standalone for now; not sure where to incorporate it and actually plan to stick to work on the glacier_lib as the intention is to move everything there asap. This script takes a file name on the command line, reads it 1MB chunk at a time, calculates the hash, and in the end calculates the tree hash.

#!/usr/bin/env python

from glaciercorecalls import tree_hash
from glaciercorecalls import chunk_hashes
from glaciercorecalls import bytes_to_hex
import sys
import math
import os.path

def main():

    # Calculate hash, Amazon style.
    filename = sys.argv[1]
    chunk = 1024*1024
    chunk_count = int(math.ceil(os.path.getsize(filename)/float(chunk)))

    f = file(filename, 'r')
    tree_hashes = [chunk_hashes(f.read(chunk))[0] for i in range(chunk_count)]
    print 'hash of %s: %s'% (filename, bytes_to_hex(tree_hash(tree_hashes)))

if __name__ == "__main__":
    sys.exit(main())

[wvmarle]

This one is now in the main branch; closing.