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pythonstructuuidpack

How to pack a UUID into a struct in Python?


I have a UUID that I was thinking of packing into a struct using UUID.int, which turns it into a 128-bit integer. But none of the struct format characters are large enough to store it, how to go about doing this?

Sample code:

s = struct.Struct('L')
unique_id = uuid.uuid4()    
tuple = (unique_id.int)
packed = s.pack(*tuple)

The problem is, struct format 'L' is only 4 bytes...I need to store 16. Storing it as a 32-char string is a bit much.


Solution

  • It is a 128-bit integer, what would you expect it to be turned into? You can split it into several components — e.g. two 64-bit integers:

    max_int64 = 0xFFFFFFFFFFFFFFFF
    packed    = struct.pack('>QQ', (u.int >> 64) & max_int64, u.int & max_int64)
    # unpack
    a, b     = struct.unpack('>QQ', packed)
    unpacked = (a << 64) | b
    
    assert u.int == unpacked