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import base64
import magic
import hashlib
def gen_file_metadata(blob):
"""
Takes a file blob (bytestream) and returns hashes and other metadata.
Returns a dict: size_bytes, md5hex, sha1hex, sha256hex, mimetype
"""
assert blob
mimetype = magic.Magic(mime=True).from_buffer(blob)
hashes = [
hashlib.sha1(),
hashlib.sha256(),
hashlib.md5(),
]
for h in hashes:
h.update(blob)
return dict(
size_bytes=len(blob),
sha1hex=hashes[0].hexdigest(),
sha256hex=hashes[1].hexdigest(),
md5hex=hashes[2].hexdigest(),
mimetype=mimetype,
)
def b32_hex(s):
"""
Converts a base32-encoded SHA-1 checksum into hex-encoded
base32 checksums are used by, eg, heritrix and in wayback CDX files
"""
s = s.strip().split()[0].lower()
if s.startswith("sha1:"):
s = s[5:]
if len(s) != 32:
if len(s) == 40:
return s
raise ValueError("not a base-32 encoded SHA-1 hash: {}".format(s))
return base64.b16encode(base64.b32decode(s.upper())).lower().decode('utf-8')
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