IDA: Changing type of arguments to local type

Question

I have functions

foo_0(...,_ v0,...)
foo_1(...,_ v1,...)
...

And, for each (foo_x, _ v_x) pair, I would like to change the type of v_x in the declaration to ANIMAL *, where ANIMAL is a local type.

I recycled some code from this question, as follow:

from idaapi import *

tif = tinfo_t()
get_tinfo2(ea, tif)

funcdata = func_type_data_t()
tif.get_func_details(funcdata)

After this I was stuck, as funcdata[i].type is a tinfo_t object which I could not find a way to create/modify easily.

My last resort would be to use GuessType/GetType and modify the string before SetType, but this might be a tad complicated since some arguments are pointers to functions themselves.

Any suggestions would be most welcome!

Answer 1

This worked for me (checks might be needed on guess_tinfo and get_func_details)

tif = idaapi.tinfo_t()
ida_typeinf.guess_tinfo(ea,tif)                     
funcdata = idaapi.func_type_data_t()
tif.get_func_details(funcdata)
tif2 = idaapi.tinfo_t()
tif2.get_named_type(idaapi.get_idati(),"ANIMAL")       #tif2 = ANIMAL
tif3 = tinfo_t()
tif3.create_ptr(tif2)                                  #tif3 = ANIMAL *
funcdata[argnum].type = tif3                           #replace corresponding argument
function_tinfo = idaapi.tinfo_t()
function_tinfo.create_func(funcdata)
idaapi.apply_tinfo2(ea, function_tinfo, idaapi.TINFO_DEFINITE)