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pythoncstructctypesconstruct

python construct struct invalid DWORDLONG vallues

I am trying to parse a c struct in python using the construct library Here is my struct:

typedef struct _MACHINEID {
    UINT32        ui32Hash;
    DWORD        dwLength;
    DWORD        dwMemoryLoad;
    DWORDLONG    ullTotalPhys;
    DWORDLONG    ullAvailPhys;
    DWORDLONG    ullTotalPageFile;
    DWORDLONG    ullAvailPageFile;
    DWORDLONG    ullTotalVirtual;
    DWORDLONG    ullAvailVirtual;
    DWORDLONG    ullAvailExtendedVirtual;
} MACHINEID, * PMACHINEID;

from construct import Int32un, Int8sn, Int16un, Int64un, Int
from construct import Array, Struct
MACHINE_ID = Struct(
    'ui32Hash' / Int32un,
    'dwLength' / Int32un,
    'dwMemoryLoad' / Int32un,
    'ullTotalPhys' / Int64un,
    'ullAvailPhys' / Int64un,
    'ullTotalPageFile' / Int64un,
    'ullAvailPageFile' / Int64un,
    'ullTotalVirtual' / Int64un,
    'ullAvailVirtual' / Int64un,
    'ullAvailExtendedVirtual' / Int64un
)

But when i receive the struct in python as a bytes object The vallues of all DWORDLONG members are incorrect. Does anyone know whats causing this?

Solution

  • As "Some programmer dude" suggested it had to do with padding. Putting __pragma(pack(push, 1)) and __pragma(pack(pop)) around my struct to disable padding solves the issue.