idapython cfunc_t.treeitems always empty

Question

I am using the hexray api to get all the items of the AST tree (the ctree) obtained by decompiling a function.

Unfortunately, the treeitems vector is always empty. Specifically, the function paaaa in this code returns always '0' or 'E'.

from idautils import *
from idaapi import *
import idc
import ida_hexrays as hexray

def load_hex_ray():
    if not init_hexrays_plugin():
        idc.RunPlugin("hexx64", 0)
    if not init_hexrays_plugin():
        idc.RunPlugin("hexrays", 0)
    if not init_hexrays_plugin():
        idc.RunPlugin("hexarm", 0)

def paaaaa(address):
        try:
            cfun=hexray.decompile(address)
            #if I print cfun it shows correct decompiled code.
            cfun.refcnt=cfun.refcnt+1
            cfun.build_c_tree()
            return str((cfun.treeitems.size()))
        except:
            return 'E'

load_hex_ray()
#code that compute functions addresses and calls paaaaa

Any idea on what can be wrong? I am using an old version of IDA 7.0

Answer 1

I fixed the issue even if I do not fully understand why this solution work:

def paaaaa(address):
    try:
        cfun=hexray.decompile(address)
        print(cfun)
        return str((cfun.treeitems.size()))
    except:
        return 'E'

probably the print forces ida to correctly populate the ctree. I do not understand why the api cfun.build_c_tree() does not do the same.

However, for now, I am good with this workaround.