Examples (Hex Rays) | Renaming a couple of variables that are parameters

Identify decompiled functions that use a pointer to a specific structure as one of its parameters

This example iterates through all decompiled functions while looking for a variable that is an argument and a pointer to a structure.

results = set()
for ea in db.functions.iterate(decompiled=True):
    f = hexrays.function(ea)
    for v in hexrays.variables.iterate(f, argument=True):
        ti = hexrays.variable.type(v)
        if not (ti.is_ptr() or struc.has(ti)): continue

        # Count the number of times that we need to dereference it before it isn't a pointer.
        count = 0
        while(ti.is_ptr()):
            ti = db.types.dereference(ti)
            count += 1

        # If the count was larger than 1, then check the structure name and add it to our results if it matches.
        if count > 1 and struc.by(ti).name == 'jsmisc32::global_1c5d0::arena':
            results.add(ea)
        continue
    continue

Rename any argument that points to a pointer to a specific structure

Now we'll use our results and iterate through the parameters again. Anything that points to a pointer to a structure will be displayed and then renamed while preserving the storage location offset in the suffix of the parameter name.

for ea in results:
    f = hexrays.function(ea)
    items = []
    for v in hexrays.variables.iterate(f, argument=True):
        ti = hexrays.variable.type(v)
        if not ti.is_ptr(): continue

        # count the number of times that it's referenced
        count = 0
        while(ti.is_ptr()):
            ti = db.types.dereference(ti)
            count += 1

        # if it matches, add it to our list of items
        if count > 1 and struc.by(ti).name == 'jsmisc32::global_1c5d0::arena':
            items.append(v)
        continue

    # iterate through the variables we collected, print them, then rename them.
    for v in items:
        print(hexrays.repr(v))

        # get their storage location and adjust them to subtract the size of the saved registers
        offset, size = hexrays.variable.storage(v) - (f.mba.frregs + f.mba.retsize)

        # now we can rename the variable using the offset we calculated.
        print(hexrays.variable.name(v, 'app','arena', offset))
    continue