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"Fix" sym_resolve in python bindings #273

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"Fix" sym_resolve in python bindings #273

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f413561
py3 compat
wsxarcher Jan 6, 2017
58b7eb9
correct usage of ctypes pointer
wsxarcher Jan 6, 2017
c95d3c1
clean test
wsxarcher Jan 6, 2017
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4 changes: 2 additions & 2 deletions bindings/python/sample.py
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Original file line number Diff line number Diff line change
Expand Up @@ -22,11 +22,11 @@ def test_ks(arch, mode, code, syntax=0):

# test symbol resolver
def test_sym_resolver():
def sym_resolver(symbol, value):
def sym_resolver(symbol, p_value):
# is this the missing symbol we want to handle?
if symbol == "_l1":
# put value of this symbol in @value
value = 0x1002
p_value.contents.value = 0x1002
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@aquynh aquynh Jan 6, 2017 •
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oh now i see that this interface does not look good. would be simpler for user to return the value, rather than set the content value like this.

the reason is that this resolver must return bool value to indicate if it sets the symbol. perhaps we should change the API a bit: this function either returns symbol value, or None when it does not care. so the function above will be changed to be:

    def sym_resolver(symbol):
        # is this the missing symbol we want to handle?
        if symbol == "_l1":
            # we handled this symbol, so return symbol value
            return 0x1002

        # we did not handle this symbol, so return None
        return None

what do you think?

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It looks simpler to the end user but the C API should be changed... And what about dealing with the symbols resolved 0 in the C? Another problem

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It can be a problem if the bindings must respect the C API, but of course it can differ.

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we need a wrapper for this.

btw, with this PR applied, suite/regress/x64_sym_resolver.py still does not pass yet, right?

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@wsxarcher wsxarcher Jan 6, 2017 •
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You can also use [] but maybe it's less explicit I think

def sym_resolver(symbol, value):
        # is this the missing symbol we want to handle?
        if symbol == "_l1":
            # we handled this symbol, so return symbol value
            value[0] = 0x1002
            return True

        # we did not handle this symbol, so return None
        return None

Yes, x64_sym_resolver.py still not pass.

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The fix does not work at all.
sample.py works because jump relative symbol are not resolved by sym_resolve, so it is not called in any way.

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(because in that case is calculated by the starting point + instruction length)

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i just fixed Python binding in the "test" branch, so sample.py works now. but your x86_call_ptr_sym.py still fails for some unknown reason ...

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Maybe call is resolved differently from jmp? What about suite/regress/x64_sym_resolver.py ?

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there is a bug in the core for that testcase. will see how to fix that.

# we handled this symbol, so return true
return True

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8 changes: 4 additions & 4 deletions suite/regress/x64_sym_resolver.py
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Original file line number Diff line number Diff line change
Expand Up @@ -11,13 +11,13 @@

class TestX86(regress.RegressTest):
def runTest(self):
def sym_resolver(symbol, value):
def sym_resolver(symbol, p_value):
# is this the missing symbol we want to handle?
if symbol == "ZwQueryInformationProcess":
if symbol == b"ZwQueryInformationProcess":
# put value of this symbol in @value
value = 0x7FF98A050840
p_value.contents.value = 0x7FF98A050840
# we handled this symbol, so return true
print 'sym_resolver called!'
print('sym_resolver called!')
return True

# we did not handle this symbol, so return false
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7 changes: 2 additions & 5 deletions suite/regress/x86_call_ptr_sym.py
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Expand Up @@ -10,19 +10,16 @@
from keystone import *
import regress

def sym_resolver(symbol, value):
def sym_resolver(symbol, p_value):
if symbol == b'GetPhoneBuildString':
value = 0x41b000
p_value.contents.value = 0x41b000
return True
return False

class TestX86Nasm(regress.RegressTest):
def runTest(self):
ks = Ks(KS_ARCH_X86, KS_MODE_32)
ks.syntax = KS_OPT_SYNTAX_NASM

dir(sym_resolver)

ks.sym_resolver = sym_resolver
encoding, count = ks.asm(b"call [GetPhoneBuildString]")
self.assertEqual(encoding, [ 0xff, 0x15, 0x00, 0xb0, 0x41, 0x00 ])
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