python ctypes: get pointed type from a pointer variable

Question

I have a structure which contains primitive fields (int, uint8, ...) and also pointers. These pointers often point to an array of different structures type in order to keep a deeply nested structure. For example in C:

struct A
{
 int field1;
 int field2;
 struct B *fields3;
 unsigned int countofb;
}

struct B
{
  int anotherfield1;
  int anotherfield2;
}

In python with ctypes I create a wrapper of the structures A and B. iterating over _fields_ of structure A I reach the third field field3 and I get a ctype variable of type LP_struct_B .

The question is, is there a way, a function, a method of ctypes that convert a pointer to the pointed type ?

I need something like

a=A()
st=pointedtype(a.field3) # or also st = pointedtype2(LP_struct_B)
#desired output: st = struct_B

thanks

alexroat · Accepted Answer · 2017-12-18 10:40:13Z

2

Ok. I've empirically found the answer. Simply use the attribute _type_ of the variable or of the pointer type

a=A()
print a.fields3._type_ # struct_B
tipo=type(a.fields3) # tipo=LP_struct_B
print tipo._type_ # struct_B

answered Dec 18, 2017 at 10:40

alexroat

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