Instruction:
How would you explain what the following Python 3 function does
def remove_cgc_attachments(self):

        cgc_package_list = None
        cgc_extended_application = None

        for data in self.data:
            if data.sort == 'cgc-package-list':
                cgc_package_list = data
            elif data.sort == 'cgc-extended-application':
                cgc_extended_application = data

        if not cgc_package_list or not cgc_extended_application:
            return False

        if cgc_package_list.skip or cgc_extended_application.skip:
            # they have already been removed
            # so we still return True to indicate that CGC attachments have been removed
            return True

        # there is a single function referencing them
        cgcpl_memory_data = self.cfg.memory_data.get(cgc_package_list.addr, None)
        cgcea_memory_data = self.cfg.memory_data.get(cgc_extended_application.addr, None)
        refs = self.cfg.model.references

        if cgcpl_memory_data is None or cgcea_memory_data is None:
            return False

        if len(refs.data_addr_to_ref[cgcpl_memory_data.addr]) != 1:
            return False
        if len(refs.data_addr_to_ref[cgcea_memory_data.addr]) != 1:
            return False

        # check if the irsb addresses are the same
        if next(iter(refs.data_addr_to_ref[cgcpl_memory_data.addr])).block_addr != \
                next(iter(refs.data_addr_to_ref[cgcea_memory_data.addr])).block_addr:
            return False

        insn_addr = next(iter(refs.data_addr_to_ref[cgcpl_memory_data.addr])).insn_addr
        # get the basic block
        cfg_node = self.cfg.get_any_node(insn_addr, anyaddr=True)
        if not cfg_node:
            return False

        func_addr = cfg_node.function_address

        # this function should be calling another function
        sub_func_addr = None
        if func_addr not in self.cfg.functions:
            return False
        function = self.cfg.functions[func_addr]
        # traverse the graph and make sure there is only one call edge
        calling_targets = [ ]
        for _, dst, data in function.transition_graph.edges(data=True):
            if 'type' in data and data['type'] == 'call':
                calling_targets.append(dst.addr)

        if len(calling_targets) != 1:
            return False

        sub_func_addr = calling_targets[0]

        # alright. We want to nop this function, as well as the subfunction
        proc = next((p for p in self.procedures if p.addr == func_addr), None)
        if proc is None:
            return False

        subproc = next((p for p in self.procedures if p.addr == sub_func_addr), None)
        if subproc is None:
            return False

        # if those two data entries have any label, we should properly modify them
        # at this point, we are fairly confident that none of those labels are direct data references to either package
        # list or extended application
        has_label = True
        lowest_address = min(cgc_package_list.addr, cgc_extended_application.addr)
        for obj in (cgc_package_list, cgc_extended_application):
            labels = obj.labels
            for addr, label in labels:
                if addr != lowest_address:
                    label.base_addr = lowest_address

        if has_label:
            # is there any memory data entry that ends right at the lowest address?
            data = next((d for d in self.data if d.addr is not None and d.addr + d.size == lowest_address), None)
            if data is None:
                # since there is no gap between memory data entries (we guarantee that), this can only be that no other
                # data resides in the same memory region that CGC attachments are in
                pass
            else:
                lbl = self.symbol_manager.addr_to_label[lowest_address][0]
                if lbl not in data.end_labels:
                    data.end_labels.append(lbl)

        # practically nop the function
        proc.asm_code = "\tret\n"
        subproc.asm_code = "\tret\n"

        # remove those two data entries
        cgc_package_list.skip = True
        cgc_extended_application.skip = True

        l.info('CGC attachments are removed.')

        return True

Response: Removes CGC attachments from the current state.


Instruction:
Create a Python 3 function to
remove unnecessary functions and data from the current object.

Response:
def remove_unnecessary_stuff(self):
        """
        Remove unnecessary functions and data

        :return: None
        """

        glibc_functions_blacklist = {
            '_start',
            '_init',
            '_fini',
            '__gmon_start__',
            '__do_global_dtors_aux',
            'frame_dummy',
            'atexit',
            'deregister_tm_clones',
            'register_tm_clones',
            '__x86.get_pc_thunk.bx',
            '__libc_csu_init',
            '__libc_csu_fini',
        }

        glibc_data_blacklist = {
            '__TMC_END__',
            '_GLOBAL_OFFSET_TABLE_',
            '__JCR_END__',
            '__dso_handle',
            '__init_array_start',
            '__init_array_end',

            #
            'stdout',
            'stderr',
            'stdin',
            'program_invocation_short_',
            'program_invocation_short_name',
            'program_invocation_name',
            '__progname_full',
            '_IO_stdin_used',
            'obstack_alloc_failed_hand',
            'optind',
            'optarg',
            '__progname',
            '_environ',
            'environ',
            '__environ',
        }

        glibc_references_blacklist = {
            'frame_dummy',
            '__do_global_dtors_aux',
        }

        self.procedures = [p for p in self.procedures if p.name not in glibc_functions_blacklist and not p.is_plt]

        self.data = [d for d in self.data if not any(lbl.name in glibc_data_blacklist for _, lbl in d.labels)]

        for d in self.data:
            if d.sort == 'pointer-array':
                for i in range(len(d.content)):
                    ptr = d.content[i]
                    if isinstance(ptr, Label) and ptr.name in glibc_references_blacklist:
                        d.content[i] = 0


Instruction:
How would you code a function in Python 3 to
initialize the binary. :return: None

Response:
def _initialize(self):
        """
        Initialize the binary.

        :return: None
        """

        # figure out section alignments
        for section in self.project.loader.main_object.sections:
            in_segment = False
            for segment in self.project.loader.main_object.segments:
                segment_addr = segment.vaddr
                if segment_addr <= section.vaddr < segment_addr + segment.memsize:
                    in_segment = True
                    break
            if not in_segment:
                continue

            # calculate alignments
            if section.vaddr % 0x20 == 0:
                alignment = 0x20
            elif section.vaddr % 0x10 == 0:
                alignment = 0x10
            elif section.vaddr % 0x8 == 0:
                alignment = 0x8
            elif section.vaddr % 0x4 == 0:
                alignment = 0x4
            else:
                alignment = 2

            self._section_alignments[section.name] = alignment

        l.debug('Generating CFG...')
        cfg = self.project.analyses.CFG(normalize=True, resolve_indirect_jumps=True, collect_data_references=True,
                                        extra_memory_regions=[(0x4347c000, 0x4347c000 + 0x1000)],
                                        data_type_guessing_handlers=[
                                            self._sequence_handler,
                                            self._cgc_extended_application_handler,
                                            self._unknown_data_size_handler,
                                        ],
                                        )

        self.cfg = cfg

        old_capstone_syntax = self.project.arch.capstone_x86_syntax
        if old_capstone_syntax is None:
            old_capstone_syntax = 'intel'

        if self.syntax == 'at&t':
            # switch capstone to AT&T style
            self.project.arch.capstone_x86_syntax = "at&t"
            # clear the block cache in lifter!
            self.project.factory.default_engine.clear_cache()

        # initialize symbol manager
        self.symbol_manager = SymbolManager(self, cfg)

        # collect address of all instructions
        l.debug('Collecting instruction addresses...')
        for cfg_node in self.cfg.nodes():
            self.all_insn_addrs |= set(cfg_node.instruction_addrs)

        # Functions

        l.debug('Creating functions...')
        for f in cfg.kb.functions.values():
            # Skip all SimProcedures
            if self.project.is_hooked(f.addr):
                continue
            elif self.project.simos.is_syscall_addr(f.addr):
                continue

            # Check which section the start address belongs to
            section = next(iter(sec.name for sec in self.project.loader.main_object.sections
                                if f.addr >= sec.vaddr and f.addr < sec.vaddr + sec.memsize
                                ),
                           ".text"
                           )

            if section in ('.got', '.plt', 'init', 'fini'):
                continue

            procedure = Procedure(self, f, section=section)
            self.procedures.append(procedure)

        self.procedures = sorted(self.procedures, key=lambda x: x.addr)

        # Data

        has_sections = len(self.project.loader.main_object.sections) > 0

        l.debug('Creating data entries...')
        for addr, memory_data in cfg._memory_data.items():

            if memory_data.sort in ('code reference', ):
                continue

            if memory_data.sort == 'string':
                # it might be the CGC package list
                new_sort, new_size = self._cgc_package_list_identifier(memory_data.address, memory_data.size)
                if new_sort is not None:
                    # oh we got it!
                    memory_data = memory_data.copy()
                    memory_data.sort = new_sort

            if has_sections:
                # Check which section the start address belongs to
                section = next(iter(sec for sec in self.project.loader.main_object.sections
                                    if sec.vaddr <= addr < sec.vaddr + sec.memsize
                                    ),
                               None
                               )

                if section is not None and section.name not in ('.note.gnu.build-id', ):  # ignore certain section names
                    data = Data(self, memory_data, section=section)
                    self.data.append(data)
                elif memory_data.sort == 'segment-boundary':
                    # it just points to the end of the segment or a section
                    section = next(iter(sec for sec in self.project.loader.main_object.sections
                                        if addr == sec.vaddr + sec.memsize),
                                   None
                                   )
                    if section is not None:
                        data = Data(self, memory_data, section=section)
                        self.data.append(data)

                else:
                    # data = Data(self, memory_data, section_name='.data')
                    # the data is not really within any existing section. weird. ignored it.
                    pass
            else:
                # the binary does not have any section
                # we use segment information instead
                # TODO: this logic needs reviewing
                segment = next(iter(seg for seg in self.project.loader.main_object.segments
                                    if seg.vaddr <= addr <= seg.vaddr + seg.memsize
                                    ),
                               None
                               )

                if segment is not None:
                    data = Data(self, memory_data, section_name='.data')
                    self.data.append(data)

        # remove all data that belong to GCC-specific sections
        section_names_to_ignore = {'.init', '.fini', '.fini_array', '.jcr', '.dynamic', '.got', '.got.plt',
                                   '.eh_frame_hdr', '.eh_frame', '.rel.dyn', '.rel.plt', '.rela.dyn', '.rela.plt',
                                   '.dynstr', '.dynsym', '.interp', '.note.ABI-tag', '.note.gnu.build-id', '.gnu.hash',
                                   '.gnu.version', '.gnu.version_r'
                                   }

        # make sure there are always memory data entries pointing at the end of sections
        all_data_addrs = set(d.addr for d in self.data)
        all_procedure_addrs = set(f.addr for f in self.procedures)
        all_addrs = all_data_addrs | all_procedure_addrs

        if has_sections:
            for section in self.project.loader.main_object.sections:

                if section.name in section_names_to_ignore:
                    # skip all sections that are CGC specific
                    continue

                # make sure this section is inside a segment
                for segment in self.project.loader.main_object.segments:
                    segment_start = segment.vaddr
                    segment_end = segment_start + segment.memsize
                    if segment_start <= section.vaddr < segment_end:
                        break
                else:
                    # this section is not mapped into memory
                    continue

                section_boundary_addr = section.vaddr + section.memsize
                if section_boundary_addr not in all_addrs:
                    data = Data(self, addr=section_boundary_addr, size=0, sort='segment-boundary',
                                section_name=section.name
                                )
                    self.data.append(data)
                    # add the address to all_data_addrs so we don't end up adding another boundary in
                    all_data_addrs.add(section_boundary_addr)

        self.data = sorted(self.data, key=lambda x: x.addr)

        data_indices_to_remove = set()

        # Go through data entry list and refine them
        for i, data in enumerate(self.data):

            if i in data_indices_to_remove:
                continue

            # process the overlapping ones
            if i < len(self.data) - 1:
                if data.addr + data.size > self.data[i + 1].addr:
                    # they are overlapping :-(

                    # TODO: make sure new_size makes sense
                    new_size = self.data[i + 1].addr - data.addr

                    # there are cases that legit data is misclassified as pointers
                    # we are able to detect some of them here
                    if data.sort == 'pointer-array':
                        pointer_size = self.project.arch.bytes
                        if new_size % pointer_size != 0:
                            # the self.data[i+1] cannot be pointed to by a pointer
                            # remove that guy later
                            data_indices_to_remove.add(i + 1)
                            # mark the source as a non-pointer
                            # apparently the original Reassembleable Disassembler paper cannot get this case
                            source_addr = self.data[i + 1].memory_data.pointer_addr
                            if source_addr is not None:
                                # find the original data
                                original_data = next((d for d in self.data if d.addr <= source_addr < d.addr + d.size),
                                                     None
                                                     )
                                if original_data is not None:
                                    original_data.desymbolize()

                            continue

                    data.shrink(new_size)

            # process those ones whose type is unknown
            if data.sort == 'unknown' and data.size == 0:
                # increase its size until reaching the next item

                if i + 1 == len(self.data):
                    if data.section is None:
                        continue
                    data.size = data.section.vaddr + data.section.memsize - data.addr
                else:
                    data.size = self.data[i + 1].addr - data.addr

        for i in sorted(data_indices_to_remove, reverse=True):
            self.data = self.data[ : i] + self.data[i + 1 : ]

        # CGC-specific data filtering
        self.data = [ d for d in self.data if d.section_name not in section_names_to_ignore ]

        # restore capstone X86 syntax at the end
        if self.project.arch.capstone_x86_syntax != old_capstone_syntax:
            self.project.arch.capstone_x86_syntax = old_capstone_syntax
            self.project.factory.default_engine.clear_cache()

        l.debug('Initialized.')


Instruction:
Can you tell what is the following Python 3 function doing
def _sequence_handler(self, cfg, irsb, irsb_addr, stmt_idx, data_addr, max_size):  # pylint:disable=unused-argument

        if not self._is_sequence(cfg, data_addr, 5):
            # fail-fast
            return None, None

        sequence_max_size = min(256, max_size)

        for i in range(5, min(256, max_size)):
            if not self._is_sequence(cfg, data_addr, i):
                return 'sequence', i - 1

        return 'sequence', sequence_max_size

Response: This function handles the sequence processing.


Instruction:
Write a Python 3 function that can
return the identifier of the CGC package list associated with the CGC binary.

Response:
def _cgc_package_list_identifier(self, data_addr, data_size):
        """
        Identifies the CGC package list associated with the CGC binary.

        :param int data_addr: Address of the data in memory.
        :param int data_size: Maximum size possible.
        :return: A 2-tuple of data type and size.
        :rtype: tuple
        """

        if data_size < 100:
            return None, None

        data = self.fast_memory_load(data_addr, data_size, str)

        if data[:10] != 'The DECREE':
            return None, None

        if not all(i in string.printable for i in data):
            return None, None

        if not re.match(r"The DECREE packages used in the creation of this challenge binary were:", data):
            return None, None

        return 'cgc-package-list', data_size


Instruction:
Here you have a function in Python 3, explain what it does
def _cgc_extended_application_handler(self, cfg, irsb, irsb_addr, stmt_idx, data_addr, max_size):  # pylint:disable=unused-argument

        if max_size < 100:
            return None, None

        data = self.fast_memory_load(data_addr, 20, bytes)

        if data is not None and data[:4] != b'The ':
            return None, None

        # read everything in
        data = self.fast_memory_load(data_addr, max_size, str)

        m = re.match(r"The ([\d]+) byte CGC Extended Application follows.", data)
        if not m:
            return None, None
        pdf_size = int(m.group(1))

        if '%PDF' not in data:
            return None, None
        if '%%EOF' not in data:
            return None, None

        pdf_data = data[data.index('%PDF') : data.index('%%EOF') + 6]

        if len(pdf_data) != pdf_size:
            return None, None

        return 'cgc-extended-application', max_size

Response: Handles the CGC extended application processing.


Instruction:
Can you tell what is the following Python 3 function doing
def _unknown_data_size_handler(self, cfg, irsb, irsb_addr, stmt_idx, data_addr, max_size):  # pylint:disable=unused-argument

        sequence_offset = None

        for offset in range(1, max_size):
            if self._is_sequence(cfg, data_addr + offset, 5):
                # a potential sequence is found
                sequence_offset = offset
                break

        if sequence_offset is not None:
            if self.project.arch.bits == 32:
                max_size = min(max_size, sequence_offset)
            elif self.project.arch.bits == 64:
                max_size = min(max_size, sequence_offset + 5)  # high 5 bytes might be all zeros...

        ptr_size = cfg.project.arch.bytes

        size = None

        for offset in range(1, max_size - ptr_size + 1):
            ptr = self.fast_memory_load(data_addr + offset, ptr_size, int, endness=cfg.project.arch.memory_endness)
            if self._is_pointer(cfg, ptr):
                size = offset
                break

        if size is not None:
            return "unknown", size
        elif sequence_offset is not None:
            return "unknown", sequence_offset
        else:
            return None, None

Response: Internal method to handle unknown data size.


Instruction:
Implement a function in Python 3 to
test if there is any integer being used as a pointer

Response:
def _has_integer_used_as_pointers(self):
        """
        Test if there is any (suspicious) pointer decryption in the code.

        :return: True if there is any pointer decryption, False otherwise.
        :rtype: bool
        """

        # check all integer accesses and see if there is any integer being used as a pointer later, but it wasn't
        # classified as a pointer reference

        # we only care about unknown memory data that are 4 bytes long, and is directly referenced from an IRSB
        candidates = [ i for i in self.cfg.memory_data.values() if
                       i.sort in ('unknown', 'integer') and
                       i.size == self.project.arch.bytes and
                       i.irsb_addr is not None
                       ]

        if not candidates:
            return False

        for candidate in candidates:

            # if the candidate is in .bss, we don't care about it
            sec = self.cfg.project.loader.find_section_containing(candidate.address)
            if sec.name in ('.bss', '.got.plt'):
                continue

            # execute the single basic block and see how the value is used
            base_graph = networkx.DiGraph()
            candidate_node = self.cfg.get_any_node(candidate.irsb_addr)  # type: angr.analyses.cfg_node.CFGNode
            if candidate_node is None:
                continue
            base_graph.add_node(candidate_node)
            tmp_kb = KnowledgeBase(self.project)
            cfg = self.project.analyses.CFGEmulated(kb=tmp_kb,
                                                    starts=(candidate.irsb_addr,),
                                                    keep_state=True,
                                                    base_graph=base_graph
                                                    )
            candidate_irsb = cfg.get_any_irsb(candidate.irsb_addr)  # type: SimIRSB
            ddg = self.project.analyses.DDG(kb=tmp_kb, cfg=cfg)

            mem_var_node = None
            for node in ddg.simplified_data_graph.nodes():
                if isinstance(node.variable, SimMemoryVariable) and node.location.ins_addr == candidate.insn_addr:
                    # found it!
                    mem_var_node = node
                    break
            else:
                # mem_var_node is not found
                continue

            # get a sub graph
            subgraph = ddg.data_sub_graph(mem_var_node,
                                          simplified=False,
                                          killing_edges=False,
                                          excluding_types={'mem_addr'},
                                          )

            # is it used as a memory address anywhere?
            # TODO:

            # is it used as a jump target?
            next_tmp = None
            if isinstance(candidate_irsb.irsb.next, pyvex.IRExpr.RdTmp):
                next_tmp = candidate_irsb.irsb.next.tmp

            if next_tmp is not None:
                next_tmp_node = next((node for node in subgraph.nodes()
                                      if isinstance(node.variable, SimTemporaryVariable) and
                                         node.variable.tmp_id == next_tmp),
                                     None
                                     )
                if next_tmp_node is not None:
                    # ouch it's used as a jump target
                    return True

        return False


Instruction:
Can you tell what is the following Python 3 function doing
def fast_memory_load(self, addr, size, data_type, endness='Iend_LE'):

        if data_type is int:
            try:
                return self.project.loader.memory.unpack_word(addr, size=size, endness=endness)
            except KeyError:
                return None

        try:
            data = self.project.loader.memory.load(addr, size)
            if data_type is str:
                return "".join(chr(i) for i in data)
            return data
        except KeyError:
            return None

Response:
Load memory bytes from loader's memory backend.

        :param int addr:    The address to begin memory loading.
        :param int size:    Size in bytes.
        :param data_type:   Type of the data.
        :param str endness: Endianness of this memory load.
        :return:            Data read out of the memory.
        :rtype:             int or bytes or str or None


Instruction:
Write a Python 3 function for
merging two abstract states.

Response:
def merge(self, other, successor=None):
        """
        Merge two abstract states.

        For any node A whose dominance frontier that the current node (at the current program location) belongs to, we
        create a phi variable V' for each variable V that is defined in A, and then replace all existence of V with V'
        in the merged abstract state.

        :param VariableRecoveryState other: The other abstract state to merge.
        :return:                            The merged abstract state.
        :rtype:                             VariableRecoveryState
        """

        replacements = {}
        if successor in self.dominance_frontiers:
            replacements = self._make_phi_variables(successor, self, other)

        merged_stack_region = self.stack_region.copy().replace(replacements).merge(other.stack_region,
                                                                                replacements=replacements)
        merged_register_region = self.register_region.copy().replace(replacements).merge(other.register_region,
                                                                                replacements=replacements)

        state = VariableRecoveryFastState(
            successor,
            self._analysis,
            self.arch,
            self.function,
            stack_region=merged_stack_region,
            register_region=merged_register_region,
            processor_state=self.processor_state.copy().merge(other.processor_state),
        )

        return state


Instruction:
Can you write a function in Python 3 where it
processes a block and update the state.

Response:
def _process_block(self, state, block):  # pylint:disable=no-self-use
        """
        Scan through all statements and perform the following tasks:
        - Find stack pointers and the VEX temporary variable storing stack pointers
        - Selectively calculate VEX statements
        - Track memory loading and mark stack and global variables accordingly

        :param angr.Block block:
        :return:
        """

        l.debug('Processing block %#x.', block.addr)

        processor = self._ail_engine if isinstance(block, ailment.Block) else self._vex_engine
        processor.process(state, block=block, fail_fast=self._fail_fast)

        # readjusting sp at the end for blocks that end in a call
        if block.addr in self._node_to_cc:
            cc = self._node_to_cc[block.addr]
            if cc is not None:
                state.processor_state.sp_adjustment += cc.sp_delta
                state.processor_state.sp_adjusted = True
                l.debug('Adjusting stack pointer at end of block %#x with offset %+#x.',
                        block.addr, state.processor_state.sp_adjustment)


Instruction:
Write a Python 3 script for
making a shallow copy of a graph and reverse the edges.

Response:
def shallow_reverse(g):
    """
    Make a shallow copy of a directional graph and reverse the edges. This is a workaround to solve the issue that one
    cannot easily make a shallow reversed copy of a graph in NetworkX 2, since networkx.reverse(copy=False) now returns
    a GraphView, and GraphViews are always read-only.

    :param networkx.DiGraph g:  The graph to reverse.
    :return:                    A new networkx.DiGraph that has all nodes and all edges of the original graph, with
                                edges reversed.
    """

    new_g = networkx.DiGraph()

    new_g.add_nodes_from(g.nodes())
    for src, dst, data in g.edges(data=True):
        new_g.add_edge(dst, src, **data)

    return new_g


Instruction:
Implement a Python 3 function for
doing a DFS traversal of the graph and return with the back edges.

Response:
def dfs_back_edges(graph, start_node):
    """
    Do a DFS traversal of the graph, and return with the back edges.

    Note: This is just a naive recursive implementation, feel free to replace it.
    I couldn't find anything in networkx to do this functionality. Although the
    name suggest it, but `dfs_labeled_edges` is doing something different.

    :param graph:       The graph to traverse.
    :param node:        The node where to start the traversal
    :returns:           An iterator of 'backward' edges
    """

    visited = set()
    finished = set()

    def _dfs_back_edges_core(node):
        visited.add(node)
        for child in iter(graph[node]):
            if child not in finished:
                if child in  visited:
                    yield node, child
                else:
                    for s,t in _dfs_back_edges_core(child):
                        yield s,t
        finished.add(node)

    for s,t in _dfs_back_edges_core(start_node):
        yield s,t


Instruction:
Write a Python 3 function for
computing a dominance frontier based on the given post - dominator tree.

Response:
def compute_dominance_frontier(graph, domtree):
    """
    Compute a dominance frontier based on the given post-dominator tree.

    This implementation is based on figure 2 of paper An Efficient Method of Computing Static Single Assignment
    Form by Ron Cytron, etc.

    :param graph:   The graph where we want to compute the dominance frontier.
    :param domtree: The dominator tree
    :returns:       A dict of dominance frontier
    """

    df = {}

    # Perform a post-order search on the dominator tree
    for x in networkx.dfs_postorder_nodes(domtree):

        if x not in graph:
            # Skip nodes that are not in the graph
            continue

        df[x] = set()

        # local set
        for y in graph.successors(x):
            if x not in domtree.predecessors(y):
                df[x].add(y)

        # up set
        if x is None:
            continue

        for z in domtree.successors(x):
            if z is x:
                continue
            if z not in df:
                continue
            for y in df[z]:
                if x not in list(domtree.predecessors(y)):
                    df[x].add(y)

    return df


Instruction:
How would you implement a function in Python 3 that
returns the successors of a node in the graph.

Response:
def _graph_successors(self, graph, node):
        """
        Return the successors of a node in the graph.
        This method can be overriden in case there are special requirements with the graph and the successors. For
        example, when we are dealing with a control flow graph, we may not want to get the FakeRet successors.

        :param graph: The graph.
        :param node:  The node of which we want to get the successors.
        :return:      An iterator of successors.
        :rtype:       iter
        """

        if self._graph_successors_func is not None:
            return self._graph_successors_func(graph, node)

        return graph.successors(node)


Instruction:
Can you tell what is the following Python 3 function doing
def _construct(self, graph, entry_node):

        # Step 1

        _prepared_graph, vertices, parent = self._prepare_graph(graph, entry_node)
        # vertices is a list of ContainerNode instances
        # parent is a dict storing the mapping from ContainerNode to ContainerNode
        # Each node in prepared_graph is a ContainerNode instance

        bucket = defaultdict(set)
        dom = [None] * (len(vertices))
        self._ancestor = [None] * (len(vertices) + 1)

        for i in range(len(vertices) - 1, 0, -1):
            w = vertices[i]

            # Step 2
            if w not in parent:
                # It's one of the start nodes
                continue

            predecessors = _prepared_graph.predecessors(w)
            for v in predecessors:
                u = self._pd_eval(v)
                if self._semi[u.index].index < self._semi[w.index].index:
                    self._semi[w.index] = self._semi[u.index]

            bucket[vertices[self._semi[w.index].index].index].add(w)

            self._pd_link(parent[w], w)

            # Step 3
            for v in bucket[parent[w].index]:
                u = self._pd_eval(v)
                if self._semi[u.index].index < self._semi[v.index].index:
                    dom[v.index] = u
                else:
                    dom[v.index] = parent[w]

            bucket[parent[w].index].clear()

        for i in range(1, len(vertices)):
            w = vertices[i]
            if w not in parent:
                continue
            if dom[w.index].index != vertices[self._semi[w.index].index].index:
                dom[w.index] = dom[dom[w.index].index]

        self.dom = networkx.DiGraph()  # The post-dom tree described in a directional graph
        for i in range(1, len(vertices)):
            if dom[i] is not None and vertices[i] is not None:
                self.dom.add_edge(dom[i].obj, vertices[i].obj)

        # Output
        self.prepared_graph = _prepared_graph

Response: This method is used to construct the internal structure of the internal structure of the internal structure.


Instruction:
Here you have a function in Python 3, explain what it does
def load_all_loggers(self):
        for name, logger in logging.Logger.manager.loggerDict.items():
            if any(name.startswith(x + '.') or name == x for x in self.IN_SCOPE):
                self._loggers[name] = logger

Response: A simple way to aggregate all loggers.


Instruction:
Create a Python 3 function to
perform execution with a state. :param state: The state with which to execute :param procedure: An instance of a SimProcedure to run :param ret_to: The address to return to when this procedure is finished :param inline: This is an inline execution. Do not bother copying the state. :param force_addr: Force execution to pretend that we're working at this concrete address :returns: A SimSuccessors object categorizing the execution's successor states

Response:
def process(self, state, procedure,
            ret_to=None,
            inline=None,
            force_addr=None,
            **kwargs):
        """
        Perform execution with a state.

        :param state:       The state with which to execute
        :param procedure:   An instance of a SimProcedure to run
        :param ret_to:      The address to return to when this procedure is finished
        :param inline:      This is an inline execution. Do not bother copying the state.
        :param force_addr:  Force execution to pretend that we're working at this concrete address
        :returns:           A SimSuccessors object categorizing the execution's successor states
        """
        return super(SimEngineProcedure, self).process(state, procedure,
                ret_to=ret_to,
                inline=inline,
                force_addr=force_addr)


Instruction:
Given the following Python 3 function, write the documentation
def get_default_value(self, state):
        if self._default_value_generator:
            return self._default_value_generator(state)
        else:
            return state.project.simos.get_default_value_by_type(self.element_type, state=state)

Response: Get the default value for the array elements.


Instruction:
Given the following Python 3 function, write the documentation
def add_function(self, func):
        for block in func.blocks:
            self.add_obj(block.addr, block)

Response: Add a function to the blanket.


Instruction:
Can you generate the documentation for the following Python 3 function
def dbg_repr(self):

        output = [ ]

        for obj in self.project.loader.all_objects:
            for section in obj.sections:
                if section.memsize == 0:
                    continue
                min_addr, max_addr = section.min_addr, section.max_addr
                output.append("### Object %s" % repr(section))
                output.append("### Range %#x-%#x" % (min_addr, max_addr))

                pos = min_addr
                while pos < max_addr:
                    try:
                        addr, thing = self.floor_item(pos)
                        output.append("%#x: %s" % (addr, repr(thing)))

                        if thing.size == 0: pos += 1
                        else: pos += thing.size
                    except KeyError:
                        pos += 1

                output.append("")

        return "\n".join(output)

Response: Returns a string representation of this CFBlanket.


Instruction:
Can you create a Python 3 function that
initializes CFBlanket from a CFG instance.

Response:
def _from_cfg(self, cfg):
        """
        Initialize CFBlanket from a CFG instance.

        :param cfg: A CFG instance.
        :return:    None
        """

        # Let's first add all functions first
        for func in cfg.kb.functions.values():
            self.add_function(func)

        self._mark_unknowns()


Instruction:
How would you explain what the following Python 3 function does
def _mark_unknowns(self):

        for obj in self.project.loader.all_objects:
            if isinstance(obj, cle.ELF):
                # sections?
                if obj.sections:
                    for section in obj.sections:
                        if not section.memsize or not section.vaddr:
                            continue
                        min_addr, max_addr = section.min_addr, section.max_addr
                        self._mark_unknowns_core(min_addr, max_addr + 1, obj=obj, section=section)
                elif obj.segments:
                    for segment in obj.segments:
                        if not segment.memsize:
                            continue
                        min_addr, max_addr = segment.min_addr, segment.max_addr
                        self._mark_unknowns_core(min_addr, max_addr + 1, obj=obj, segment=segment)
                else:
                    # is it empty?
                    _l.warning("Empty ELF object %s.", repr(obj))
            elif isinstance(obj, cle.PE):
                if obj.sections:
                    for section in obj.sections:
                        if not section.memsize:
                            continue
                        min_addr, max_addr = section.min_addr, section.max_addr
                        self._mark_unknowns_core(min_addr, max_addr + 1, obj=obj, section=section)
                else:
                    # is it empty?
                    _l.warning("Empty PE object %s.", repr(obj))
            else:
                min_addr, max_addr = obj.min_addr, obj.max_addr
                self._mark_unknowns_core(min_addr, max_addr + 1, obj=obj)

Response: Mark all unmapped regions.


Instruction:
Write a Python 3 script to
create a SimState object with the CGC state blanking all of the state information.

Response:
def state_blank(self, flag_page=None, **kwargs):
        """
        :param flag_page:   Flag page content, either a string or a list of BV8s
        """
        s = super(SimCGC, self).state_blank(**kwargs)  # pylint:disable=invalid-name

        # Special stack base for CGC binaries to work with Shellphish CRS
        s.regs.sp = 0xbaaaaffc

        # Map the special cgc memory
        if o.ABSTRACT_MEMORY not in s.options:
            s.memory.mem._preapproved_stack = IRange(0xbaaab000 - 1024 * 1024 * 8, 0xbaaab000)
            s.memory.map_region(0x4347c000, 4096, 1)

        # Create the CGC plugin
        s.get_plugin('cgc')

        # Set up the flag page
        if flag_page is None:
            flag_page = [s.solver.BVS("cgc-flag-byte-%d" % i, 8, key=('flag', i), eternal=True) for i in range(0x1000)]
        elif type(flag_page) is bytes:
            flag_page = [s.solver.BVV(c, 8) for c in flag_page]
        elif type(flag_page) is list:
            pass
        else:
            raise ValueError("Bad flag page: expected None, bytestring, or list, but got %s" % type(flag_page))

        s.cgc.flag_bytes = flag_page
        if s.mode != 'static':
            s.memory.store(0x4347c000, claripy.Concat(*s.cgc.flag_bytes), priv=True)

        # set up the address for concrete transmits
        s.unicorn.transmit_addr = self.syscall_from_number(2).addr

        s.libc.max_str_len = 1000000
        s.libc.max_strtol_len = 10
        s.libc.max_memcpy_size = 0x100000
        s.libc.max_buffer_size = 0x100000

        return s


Instruction:
Can you tell what is the following Python 3 function doing
def _stmt_inside_loop(self, stmt_idx):

        # TODO: This is slow. Fix the performance issue

        for node in self.loop.body_nodes:
            if node.addr.stmt_idx <= stmt_idx < node.addr.stmt_idx + node.size:
                return True
        return False

Response: Test whether a statement is inside the loop body or not.


Instruction:
Here you have a function in Python 3, explain what it does
def _is_bounded_iterator_based(self):

        # Condition 0
        check_0 = lambda cond: (isinstance(cond, Condition) and
                                cond.op == Condition.Equal and
                                cond.val1 == 0 and
                                isinstance(cond.val0, AnnotatedVariable) and
                                cond.val0.type == VariableTypes.HasNext
                                )

        check_0_results = [ (check_0(stmt[0]), stmt[0]) for stmt in self.loop_exit_stmts ]
        check_0_conds = [ cond for r, cond in check_0_results if r ]  # remove all False ones

        if not check_0_conds:
            return None

        the_iterator = check_0_conds[0].val0.variable

        # Condition 1
        check_1 = lambda local: (isinstance(local, AnnotatedVariable) and
                                 local.type == VariableTypes.Next and
                                 local.variable == the_iterator
                                 )

        if not any([ check_1(local) for local in self.locals.values() ]):
            return None

        return True

Response: Check if the iterator based check.


Instruction:
How would you implement a function in Python 3 that
kills existing definitions w. r. t atom with a dummy definition instance.

Response:
def kill_definitions(self, atom, code_loc, data=None, dummy=True):
        """
        Overwrite existing definitions w.r.t 'atom' with a dummy definition instance. A dummy definition will not be
        removed during simplification.

        :param Atom atom:
        :param CodeLocation code_loc:
        :param object data:
        :return: None
        """

        if data is None:
            data = DataSet(Undefined(atom.size), atom.size)

        self.kill_and_add_definition(atom, code_loc, data, dummy=dummy)


Instruction:
Can you create a Python 3 function that
creates an entry state.

Response:
def state_entry(self, args=None, **kwargs): # pylint: disable=arguments-differ
        """
        Create an entry state.

        :param args: List of SootArgument values (optional).
        """
        state = self.state_blank(**kwargs)
        # for the Java main method `public static main(String[] args)`,
        # we add symbolic cmdline arguments
        if not args and state.addr.method.name == 'main' and \
                        state.addr.method.params[0] == 'java.lang.String[]':
            cmd_line_args = SimSootExpr_NewArray.new_array(state, "java.lang.String", BVS('argc', 32))
            cmd_line_args.add_default_value_generator(self.generate_symbolic_cmd_line_arg)
            args = [SootArgument(cmd_line_args, "java.lang.String[]")]
            # for referencing the Java array, we need to know the array reference
            # => saves it in the globals dict
            state.globals['cmd_line_args'] = cmd_line_args
        # setup arguments
        SimEngineSoot.setup_arguments(state, args)
        return state


Instruction:
Can you write a function in Python 3 where it
generates a new symbolic cmd line argument string.

Response:
def generate_symbolic_cmd_line_arg(state, max_length=1000):
        """
        Generates a new symbolic cmd line argument string.
        :return: The string reference.
        """
        str_ref = SimSootValue_StringRef(state.memory.get_new_uuid())
        str_sym = StringS("cmd_line_arg", max_length)
        state.solver.add(str_sym != StringV(""))
        state.memory.store(str_ref, str_sym)
        return str_ref


Instruction:
Can you implement a function in Python 3 that
creates a native or java call state.

Response:
def state_call(self, addr, *args, **kwargs):
        """
        Create a native or a Java call state.

        :param addr:    Soot or native addr of the invoke target.
        :param args:   List of SootArgument values.
        """
        state = kwargs.pop('base_state', None)
        # check if we need to setup a native or a java callsite
        if isinstance(addr, SootAddressDescriptor):
            # JAVA CALLSITE
            # ret addr precedence: ret_addr kwarg > base_state.addr > terminator
            ret_addr = kwargs.pop('ret_addr', state.addr if state else SootAddressTerminator())
            cc = kwargs.pop('cc', SimCCSoot(self.arch))
            if state is None:
                state = self.state_blank(addr=addr, **kwargs)
            else:
                state = state.copy()
                state.regs.ip = addr
            cc.setup_callsite(state, ret_addr, args)
            return state

        else:
            # NATIVE CALLSITE
            # setup native argument values
            native_arg_values = []
            for arg in args:
                if arg.type in ArchSoot.primitive_types or \
                   arg.type == "JNIEnv":
                    # the value of primitive types and the JNIEnv pointer
                    # are just getting copied into the native memory
                    native_arg_value = arg.value
                    if self.arch.bits == 32 and arg.type == "long":
                        # On 32 bit architecture, long values (w/ 64 bit) are copied
                        # as two 32 bit integer
                        # TODO is this correct?
                        upper = native_arg_value.get_bytes(0, 4)
                        lower = native_arg_value.get_bytes(4, 4)
                        idx = args.index(arg)
                        args = args[:idx] \
                               + (SootArgument(upper, 'int'), SootArgument(lower, 'int')) \
                               + args[idx+1:]
                        native_arg_values += [upper, lower]
                        continue
                else:
                    # argument has a relative type
                    # => map Java reference to an opaque reference, which the native code
                    #    can use to access the Java object through the JNI interface
                    native_arg_value = state.jni_references.create_new_reference(obj=arg.value)
                native_arg_values += [native_arg_value]

            # setup native return type
            ret_type = kwargs.pop('ret_type')
            native_ret_type = self.get_native_type(ret_type)

            # setup function prototype, so the SimCC know how to init the callsite
            arg_types = [self.get_native_type(arg.type) for arg in args]
            prototype = SimTypeFunction(args=arg_types, returnty=native_ret_type)
            native_cc = self.get_native_cc(func_ty=prototype)

            # setup native invoke state
            return self.native_simos.state_call(addr, *native_arg_values,
                                                base_state=state,
                                                ret_addr=self.native_return_hook_addr,
                                                cc=native_cc, **kwargs)


Instruction:
Here you have a function in Python 3, explain what it does
def get_default_value_by_type(type_, state=None):
        if type_ in ['byte', 'char', 'short', 'int', 'boolean']:
            return BVS('default_value_{}'.format(type_), 32)
        elif type_ == "long":
            return BVS('default_value_{}'.format(type_), 64)
        elif type_ == 'float':
            return FPS('default_value_{}'.format(type_), FSORT_FLOAT)
        elif type_ == 'double':
            return FPS('default_value_{}'.format(type_), FSORT_DOUBLE)
        elif state is not None:
            if type_ == 'java.lang.String':
                return SimSootValue_StringRef.new_string(state, StringS('default_value_{}'.format(type_), 1000))
            if type_.endswith('[][]'):
                raise NotImplementedError
                # multiarray = SimSootExpr_NewMultiArray.new_array(self.state, element_type, size)
                # multiarray.add_default_value_generator(lambda s: SimSootExpr_NewMultiArray._generate_inner_array(s, element_type, sizes))
                # return  multiarray
            elif type_.endswith('[]'):
                array = SimSootExpr_NewArray.new_array(state, type_[:-2], BVV(2, 32))
                return array
            else:
                return SimSootValue_ThisRef.new_object(state, type_, symbolic=True, init_object=False)
        else:
            # not a primitive type
            # => treat it as a reference
            return SootNullConstant()

Response: This method returns the default value for a given type.


Instruction:
Write a Python 3 function for
casting the value of primtive types to the specified type.

Response:
def cast_primitive(state, value, to_type):
        """
        Cast the value of primtive types.

        :param value:       Bitvector storing the primitive value.
        :param to_type:     Name of the targeted type.
        :return:            Resized value.
        """
        if to_type in ['float', 'double']:
            if value.symbolic:
                # TODO extend support for floating point types
                l.warning('No support for symbolic floating-point arguments.'
                          'Value gets concretized.')
            value = float(state.solver.eval(value))
            sort = FSORT_FLOAT if to_type == 'float' else FSORT_DOUBLE
            return FPV(value, sort)

        elif to_type == 'int' and isinstance(value, FP):
            # TODO fix fpToIEEEBV in claripty
            l.warning('Converting FP to BV might provide incorrect results.')
            return fpToIEEEBV(value)[63:32]

        elif to_type == 'long' and isinstance(value, FP):
            # TODO fix fpToIEEEBV in claripty
            l.warning('Converting FP to BV might provide incorrect results.')
            return fpToIEEEBV(value)

        else:
            # lookup the type size and extract value
            value_size = ArchSoot.sizeof[to_type]
            value_extracted = value.reversed.get_bytes(index=0, size=value_size//8).reversed

            # determine size of Soot bitvector and resize bitvector
            # Note: smaller types than int's are stored in a 32-bit BV
            value_soot_size = value_size if value_size >= 32 else 32
            if to_type in ['char', 'boolean']:
                # unsigned extend
                return value_extracted.zero_extend(value_soot_size-value_extracted.size())
            # signed extend
            return value_extracted.sign_extend(value_soot_size-value_extracted.size())


Instruction:
Explain what the following Python 3 code does
def init_static_field(state, field_class_name, field_name, field_type):
        field_ref = SimSootValue_StaticFieldRef.get_ref(state, field_class_name,
                                                        field_name, field_type)
        field_val = SimSootValue_ThisRef.new_object(state, field_type)
        state.memory.store(field_ref, field_val)

Response: Initialize the static field with an allocated but not initialized object of the given type.


Instruction:
How would you code a function in Python 3 to
get the address of the implementation from a native declared Java function.

Response:
def get_addr_of_native_method(self, soot_method):
        """
        Get address of the implementation from a native declared Java function.

        :param soot_method: Method descriptor of a native declared function.
        :return: CLE address of the given method.
        """
        for name, symbol in self.native_symbols.items():
            if soot_method.matches_with_native_name(native_method=name):
                l.debug("Found native symbol '%s' @ %x matching Soot method '%s'",
                        name, symbol.rebased_addr, soot_method)
                return symbol.rebased_addr

        native_symbols = "\n".join(self.native_symbols.keys())
        l.warning("No native method found that matches the Soot method '%s'. "
                  "Skipping statement.", soot_method.name)
        l.debug("Available symbols (prefix + encoded class path + encoded method "
                "name):\n%s", native_symbols)
        return None


Instruction:
Can you create a Python 3 function that
maps the Java type to a SimTypeReg representation of its native .

Response:
def get_native_type(self, java_type):
        """
        Maps the Java type to a SimTypeReg representation of its native
        counterpart. This type can be used to indicate the (well-defined) size
        of native JNI types.

        :return: A SymTypeReg with the JNI size of the given type.
        """
        if java_type in ArchSoot.sizeof.keys():
            jni_type_size = ArchSoot.sizeof[java_type]
        else:
            # if it's not a primitive type, we treat it as a reference
            jni_type_size = self.native_simos.arch.bits
        return SimTypeReg(size=jni_type_size)


Instruction:
Implement a Python 3 function for
returning the SimCC object for the native simos. .

Response:
def get_native_cc(self, func_ty=None):
        """
        :return: SimCC object for the native simos.
        """
        native_cc_cls = DEFAULT_CC[self.native_simos.arch.name]
        return native_cc_cls(self.native_simos.arch, func_ty=func_ty)


Instruction:
Write a Python 3 function that can
fill the class with constrained symbolic values.

Response:
def fill_symbolic(self):
        """
        Fill the class with constrained symbolic values.
        """
        self.wYear = self.state.solver.BVS('cur_year', 16, key=('api', 'GetLocalTime', 'cur_year'))
        self.wMonth = self.state.solver.BVS('cur_month', 16, key=('api', 'GetLocalTime', 'cur_month'))
        self.wDayOfWeek = self.state.solver.BVS('cur_dayofweek', 16, key=('api', 'GetLocalTime', 'cur_dayofweek'))
        self.wDay = self.state.solver.BVS('cur_day', 16, key=('api', 'GetLocalTime', 'cur_day'))
        self.wHour = self.state.solver.BVS('cur_hour', 16, key=('api', 'GetLocalTime', 'cur_hour'))
        self.wMinute = self.state.solver.BVS('cur_minute', 16, key=('api', 'GetLocalTime', 'cur_minute'))
        self.wSecond = self.state.solver.BVS('cur_second', 16, key=('api', 'GetLocalTime', 'cur_second'))
        self.wMilliseconds = self.state.solver.BVS('cur_millisecond', 16, key=('api', 'GetLocalTime', 'cur_millisecond'))

        self.state.add_constraints(self.wYear >= 1601)
        self.state.add_constraints(self.wYear <= 30827)
        self.state.add_constraints(self.wMonth >= 1)
        self.state.add_constraints(self.wMonth <= 12)
        self.state.add_constraints(self.wDayOfWeek <= 6)
        self.state.add_constraints(self.wDay >= 1)
        self.state.add_constraints(self.wDay <= 31)
        self.state.add_constraints(self.wHour <= 23)
        self.state.add_constraints(self.wMinute <= 59)
        self.state.add_constraints(self.wSecond <= 59)
        self.state.add_constraints(self.wMilliseconds <= 999)


Instruction:
Can you write a function in Python 3 where it
fills the class with the appropriate values extracted from the given timestamp.

Response:
def fill_from_timestamp(self, ts):
        """
        Fill the class with the appropriate values extracted from the given timestamp.

        :param ts:  A POSIX timestamp.
        """
        dt = datetime.datetime.fromtimestamp(ts)
        self.wYear = dt.year
        self.wMonth = dt.month
        self.wDayOfWeek = dt.isoweekday() % 7 # :/
        self.wDay = dt.day
        self.wHour = dt.hour
        self.wMinute = dt.minute
        self.wSecond = dt.second
        self.wMilliseconds = dt.microsecond // 1000


Instruction:
Can you tell what is the following Python 3 function doing
def from_digraph(self, digraph):

        for n1 in digraph.nodes():
            addr1, stmt_idx1 = n1
            self.add_statements_to_whitelist(addr1, (stmt_idx1,))

            successors = digraph[n1]
            for n2 in successors:
                addr2, stmt_idx2 = n2

                if addr1 != addr2:
                    # There is a control flow transition from block `addr1` to block `addr2`
                    self.add_exit_to_whitelist(addr1, addr2)

                self.add_statements_to_whitelist(addr2, (stmt_idx2,))

Response: Initialize this AnnotatedCFG object from a networkx. DiGraph.


Instruction:
Can you tell what is the following Python 3 function doing
def get_whitelisted_statements(self, addr):
        if addr in self._run_statement_whitelist:
            if self._run_statement_whitelist[addr] is True:
                return None # This is the default value used to say
                            # we execute all statements in this basic block. A
                            # little weird...

            else:
                return self._run_statement_whitelist[addr]

        else:
            return []

Response: Returns a list of statements that are whitelisted for the given address.


Instruction:
Given the following Python 3 function, write the documentation
def dbg_print_irsb(self, irsb_addr, project=None):

        if project is None:
            project = self._project

        if project is None:
            raise Exception("Dict addr_to_run is empty. " + \
                            "Give me a project, and I'll recreate the IRSBs for you.")
        else:
            vex_block = project.factory.block(irsb_addr).vex

        statements = vex_block.statements
        whitelist = self.get_whitelisted_statements(irsb_addr)
        for i in range(0, len(statements)):
            if whitelist is True or i in whitelist:
                line = "+"
            else:
                line = "-"
            line += "[% 3d] " % i
            # We cannot get data returned by pp(). WTF?
            print(line, end='')
            statements[i].pp()

Response: Pretty - print an IRSB with whitelist information.


Instruction:
Write a Python 3 function for
returning True if the path should be kept False otherwise.

Response:
def keep_path(self, path):
        """
        Given a path, returns True if the path should be kept, False if it should be cut.
        """
        if len(path.addr_trace) < 2:
            return True

        return self.should_take_exit(path.addr_trace[-2], path.addr_trace[-1])


Instruction:
Make a summary of the following Python 3 code
def successor_func(self, path):

        whitelist = self.get_whitelisted_statements(path.addr)
        last_stmt = self.get_last_statement_index(path.addr)

        # pass in those arguments
        successors = path.step(
            stmt_whitelist=whitelist,
            last_stmt=None
        )

        # further filter successors based on the annotated CFG
        taken_successors = [ ]
        for suc in successors:
            try:
                taken = self.should_take_exit(path.addr, suc.addr)
            except AngrExitError:
                l.debug("Got an unknown exit that AnnotatedCFG does not know about: %#x -> %#x", path.addr, suc.addr)
                continue

            if taken:
                taken_successors.append(suc)

        return taken_successors

Response: This is the callback routine that takes in a path and returns all feasible successors to path group. It returns a list of all feasible successors to path group.


Instruction:
Explain what the following Python 3 code does
def to_valueset(self, state):
        return state.solver.VS(state.arch.bits, self.region, self.region_base_addr, self.address)

Response: Convert the current object into a ValueSet.


Instruction:
Write a Python 3 function for
adding a mapping between an absolute address and a region ID.

Response:
def map(self, absolute_address, region_id, related_function_address=None):
        """
        Add a mapping between an absolute address and a region ID. If this is a stack region map, all stack regions
        beyond (lower than) this newly added regions will be discarded.

        :param absolute_address:            An absolute memory address.
        :param region_id:                   ID of the memory region.
        :param related_function_address:    A related function address, mostly used for stack regions.
        """

        if self.is_stack:
            # Sanity check
            if not region_id.startswith('stack_'):
                raise SimRegionMapError('Received a non-stack memory ID "%d" in a stack region map' % region_id)

            # Remove all stack regions that are lower than the one to add
            while True:
                try:
                    addr = next(self._address_to_region_id.irange(maximum=absolute_address, reverse=True))
                    descriptor = self._address_to_region_id[addr]
                    # Remove this mapping
                    del self._address_to_region_id[addr]
                    # Remove this region ID from the other mapping
                    del self._region_id_to_address[descriptor.region_id]
                except StopIteration:
                    break

        else:
            if absolute_address in self._address_to_region_id:
                descriptor = self._address_to_region_id[absolute_address]
                # Remove this mapping
                del self._address_to_region_id[absolute_address]
                del self._region_id_to_address[descriptor.region_id]

        # Add this new region mapping
        desc = RegionDescriptor(
            region_id,
            absolute_address,
            related_function_address=related_function_address
        )

        self._address_to_region_id[absolute_address] = desc
        self._region_id_to_address[region_id] = desc


Instruction:
Implement a Python 3 function for
removing a mapping based on its absolute address.

Response:
def unmap_by_address(self, absolute_address):
        """
        Removes a mapping based on its absolute address.

        :param absolute_address: An absolute address
        """

        desc = self._address_to_region_id[absolute_address]
        del self._address_to_region_id[absolute_address]
        del self._region_id_to_address[desc.region_id]


Instruction:
Can you generate a brief explanation for the following Python 3 code
def absolutize(self, region_id, relative_address):

        if region_id == 'global':
            # The global region always bases 0
            return relative_address

        if region_id not in self._region_id_to_address:
            raise SimRegionMapError('Non-existent region ID "%s"' % region_id)

        base_address = self._region_id_to_address[region_id].base_address
        return base_address + relative_address

Response: Converts a relative address in some memory region to an absolute address.


Instruction:
Create a Python 3 function to
convert an absolute address to the memory offset in a memory region. Note that if an address belongs to heap region is passed in to a stack region map, it will be converted to an offset included in the closest stack frame, and vice versa for passing a stack address to a heap region. Therefore you should only pass in address that belongs to the same category (stack or non-stack) of this region map. :param absolute_address: An absolute memory address :return: A tuple of the closest region ID, the relative offset, and the related function address.

Response:
def relativize(self, absolute_address, target_region_id=None):
        """
        Convert an absolute address to the memory offset in a memory region.

        Note that if an address belongs to heap region is passed in to a stack region map, it will be converted to an
        offset included in the closest stack frame, and vice versa for passing a stack address to a heap region.
        Therefore you should only pass in address that belongs to the same category (stack or non-stack) of this region
        map.

        :param absolute_address:    An absolute memory address
        :return:                    A tuple of the closest region ID, the relative offset, and the related function
                                    address.
        """

        if target_region_id is None:
            if self.is_stack:
                # Get the base address of the stack frame it belongs to
                base_address = next(self._address_to_region_id.irange(minimum=absolute_address, reverse=False))

            else:
                try:
                    base_address = next(self._address_to_region_id.irange(maximum=absolute_address, reverse=True))

                except StopIteration:
                    # Not found. It belongs to the global region then.
                    return 'global', absolute_address, None

            descriptor = self._address_to_region_id[base_address]

        else:
            if target_region_id == 'global':
                # Just return the absolute address
                return 'global', absolute_address, None

            if target_region_id not in self._region_id_to_address:
                raise SimRegionMapError('Trying to relativize to a non-existent region "%s"' % target_region_id)

            descriptor = self._region_id_to_address[target_region_id]
            base_address = descriptor.base_address

        return descriptor.region_id, absolute_address - base_address, descriptor.related_function_address


Instruction:
Can you create a Python 3 function that
returns the category of this memory instance.

Response:
def category(self):
        """
        Return the category of this SimMemory instance. It can be one of the three following categories: reg, mem,
        or file.
        """

        if self.id in ('reg', 'mem'):
            return self.id

        elif self._abstract_backer:
            return 'mem'

        elif self.id.startswith('file'):
            return 'file'

        else:
            raise SimMemoryError('Unknown SimMemory category for memory_id "%s"' % self.id)


Instruction:
Create a Python 3 function for
setting the state of the current instance of the class.

Response:
def set_state(self, state):
        """
        Call the set_state method in SimStatePlugin class, and then perform the delayed initialization.

        :param state: The SimState instance
        """
        SimStatePlugin.set_state(self, state)

        # Delayed initialization
        stack_region_map, generic_region_map = self._temp_stack_region_map, self._temp_generic_region_map

        if stack_region_map or generic_region_map:
            # Inherited from its parent
            self._stack_region_map = stack_region_map.copy()
            self._generic_region_map = generic_region_map.copy()

        else:
            if not self._abstract_backer and o.REGION_MAPPING in self.state.options:
                # Only the top-level SimMemory instance can have region maps.
                self._stack_region_map = RegionMap(True)
                self._generic_region_map = RegionMap(False)

            else:
                self._stack_region_map = None
                self._generic_region_map = None


Instruction:
Implement a function in Python 3 to
convert a string into an AST.

Response:
def _convert_to_ast(self, data_e, size_e=None):
        """
        Make an AST out of concrete @data_e
        """
        if type(data_e) is bytes:
            # Convert the string into a BVV, *regardless of endness*
            bits = len(data_e) * self.state.arch.byte_width
            data_e = self.state.solver.BVV(data_e, bits)
        elif type(data_e) is int:
            data_e = self.state.solver.BVV(data_e, size_e*self.state.arch.byte_width if size_e is not None
                                       else self.state.arch.bits)
        else:
            data_e = data_e.raw_to_bv()

        return data_e


Instruction:
How would you explain what the following Python 3 function does
def set_stack_address_mapping(self, absolute_address, region_id, related_function_address=None):
        if self._stack_region_map is None:
            raise SimMemoryError('Stack region map is not initialized.')
        self._stack_region_map.map(absolute_address, region_id, related_function_address=related_function_address)

Response: Create a new mapping between an absolute address and a specific region ID.


Instruction:
Can you tell what is the following Python 3 function doing
def unset_stack_address_mapping(self, absolute_address):
        if self._stack_region_map is None:
            raise SimMemoryError('Stack region map is not initialized.')
        self._stack_region_map.unmap_by_address(absolute_address)

Response: Removes a stack mapping.


Instruction:
Here you have a function in Python 3, explain what it does
def stack_id(self, function_address):
        region_id = 'stack_0x%x' % function_address

        # deduplication
        region_ids = self._stack_region_map.region_ids
        if region_id not in region_ids:
            return region_id
        else:
            for i in range(0, 2000):
                new_region_id = region_id + '_%d' % i
                if new_region_id not in region_ids:
                    return new_region_id
            raise SimMemoryError('Cannot allocate region ID for function %#08x - recursion too deep' % function_address)

Response: Return a memory region ID for a function.


Instruction:
Can you generate a brief explanation for the following Python 3 code
def store(self, addr, data, size=None, condition=None, add_constraints=None, endness=None, action=None,
              inspect=True, priv=None, disable_actions=False):
        """
        Stores content into memory.

        :param addr:        A claripy expression representing the address to store at.
        :param data:        The data to store (claripy expression or something convertable to a claripy expression).
        :param size:        A claripy expression representing the size of the data to store.

        The following parameters are optional.

        :param condition:       A claripy expression representing a condition if the store is conditional.
        :param add_constraints: Add constraints resulting from the merge (default: True).
        :param endness:         The endianness for the data.
        :param action:          A SimActionData to fill out with the final written value and constraints.
        :param bool inspect:    Whether this store should trigger SimInspect breakpoints or not.
        :param bool disable_actions: Whether this store should avoid creating SimActions or not. When set to False,
                                     state options are respected.
        """

        _inspect = inspect and self.state.supports_inspect

        if priv is not None: self.state.scratch.push_priv(priv)

        addr_e = _raw_ast(addr)
        data_e = _raw_ast(data)
        size_e = _raw_ast(size)
        condition_e = _raw_ast(condition)
        add_constraints = True if add_constraints is None else add_constraints

        if isinstance(addr, str):
            named_addr, named_size = self._resolve_location_name(addr, is_write=True)
            addr = named_addr
            addr_e = addr
            if size is None:
                size = named_size
                size_e = size

        if isinstance(data_e, str):
            data_e = data_e.encode()
            l.warning("Storing unicode string encoded as utf-8. Did you mean to use a bytestring?")

        # store everything as a BV
        data_e = self._convert_to_ast(data_e, size_e if isinstance(size_e, int) else None)

        # zero extend if size is greater than len(data_e)
        stored_size = size_e*self.state.arch.byte_width if isinstance(size_e, int) else self.state.arch.bits
        if size_e is not None and self.category == 'reg' and len(data_e) < stored_size:
            data_e = data_e.zero_extend(stored_size - len(data_e))

        if type(size_e) is int:
            size_e = self.state.solver.BVV(size_e, self.state.arch.bits)
        elif size_e is None:
            size_e = self.state.solver.BVV(data_e.size() // self.state.arch.byte_width, self.state.arch.bits)

        if len(data_e) % self.state.arch.byte_width != 0:
            raise SimMemoryError("Attempting to store non-byte data to memory")
        if not size_e.symbolic and (len(data_e) < size_e*self.state.arch.byte_width).is_true():
            raise SimMemoryError("Provided data is too short for this memory store")

        if _inspect:
            if self.category == 'reg':
                self.state._inspect(
                    'reg_write',
                    BP_BEFORE,
                    reg_write_offset=addr_e,
                    reg_write_length=size_e,
                    reg_write_expr=data_e,
                    reg_write_condition=condition_e,
                )
                addr_e = self.state._inspect_getattr('reg_write_offset', addr_e)
                size_e = self.state._inspect_getattr('reg_write_length', size_e)
                data_e = self.state._inspect_getattr('reg_write_expr', data_e)
                condition_e = self.state._inspect_getattr('reg_write_condition', condition_e)
            elif self.category == 'mem':
                self.state._inspect(
                    'mem_write',
                    BP_BEFORE,
                    mem_write_address=addr_e,
                    mem_write_length=size_e,
                    mem_write_expr=data_e,
                    mem_write_condition=condition_e,
                )
                addr_e = self.state._inspect_getattr('mem_write_address', addr_e)
                size_e = self.state._inspect_getattr('mem_write_length', size_e)
                data_e = self.state._inspect_getattr('mem_write_expr', data_e)
                condition_e = self.state._inspect_getattr('mem_write_condition', condition_e)

        # if the condition is false, bail
        if condition_e is not None and self.state.solver.is_false(condition_e):
            if priv is not None: self.state.scratch.pop_priv()
            return

        if (
            o.UNDER_CONSTRAINED_SYMEXEC in self.state.options and
            isinstance(addr_e, claripy.ast.Base) and
            addr_e.uninitialized
        ):
            self._constrain_underconstrained_index(addr_e)

        request = MemoryStoreRequest(addr_e, data=data_e, size=size_e, condition=condition_e, endness=endness)
        try:
            self._store(request) #will use state_plugins/symbolic_memory.py
        except SimSegfaultError as e:
            e.original_addr = addr_e
            raise

        if _inspect:
            if self.category == 'reg': self.state._inspect('reg_write', BP_AFTER)
            elif self.category == 'mem': self.state._inspect('mem_write', BP_AFTER)
            # tracer uses address_concretization_add_constraints
            add_constraints = self.state._inspect_getattr('address_concretization_add_constraints', add_constraints)

        if add_constraints and len(request.constraints) > 0:
            self.state.add_constraints(*request.constraints)

        if not disable_actions:
            if request.completed and o.AUTO_REFS in self.state.options and action is None and not self._abstract_backer:
                ref_size = size * self.state.arch.byte_width if size is not None else data_e.size()
                region_type = self.category
                if region_type == 'file':
                    # Special handling for files to keep compatibility
                    # We may use some refactoring later
                    region_type = self.id
                action = SimActionData(self.state, region_type, 'write', addr=addr_e, data=data_e, size=ref_size,
                                       condition=condition
                                       )
                self.state.history.add_action(action)

            if request.completed and action is not None:
                action.actual_addrs = request.actual_addresses
                action.actual_value = action._make_object(request.stored_values[0]) # TODO
                if len(request.constraints) > 0:
                    action.added_constraints = action._make_object(self.state.solver.And(*request.constraints))
                else:
                    action.added_constraints = action._make_object(self.state.solver.true)

        if priv is not None: self.state.scratch.pop_priv()

Response: Stores the content of the specified data at the specified address.


Instruction:
Can you write a function in Python 3 where it
stores the contents of a bitvector into memory.

Response:
def store_cases(self, addr, contents, conditions, fallback=None, add_constraints=None, endness=None, action=None):
        """
        Stores content into memory, conditional by case.

        :param addr:            A claripy expression representing the address to store at.
        :param contents:        A list of bitvectors, not necessarily of the same size. Use None to denote an empty
                                write.
        :param conditions:      A list of conditions. Must be equal in length to contents.

        The following parameters are optional.

        :param fallback:        A claripy expression representing what the write should resolve to if all conditions
                                evaluate to false (default: whatever was there before).
        :param add_constraints: Add constraints resulting from the merge (default: True)
        :param endness:         The endianness for contents as well as fallback.
        :param action:          A SimActionData to fill out with the final written value and constraints.
        :type action:           SimActionData
        """

        if fallback is None and all(c is None for c in contents):
            l.debug("Avoiding an empty write.")
            return

        addr_e = _raw_ast(addr)
        contents_e = _raw_ast(contents)
        conditions_e = _raw_ast(conditions)
        fallback_e = _raw_ast(fallback)

        max_bits = max(c.length for c in contents_e if isinstance(c, claripy.ast.Bits)) \
            if fallback is None else fallback.length

        # if fallback is not provided by user, load it from memory
        # remember to specify the endianness!
        fallback_e = self.load(addr, max_bits//self.state.arch.byte_width, add_constraints=add_constraints, endness=endness) \
            if fallback_e is None else fallback_e

        req = self._store_cases(addr_e, contents_e, conditions_e, fallback_e, endness=endness)
        add_constraints = self.state._inspect_getattr('address_concretization_add_constraints', add_constraints)
        if add_constraints:
            self.state.add_constraints(*req.constraints)

        if req.completed and o.AUTO_REFS in self.state.options and action is None:
            region_type = self.category
            if region_type == 'file':
                # Special handling for files to keep compatibility
                # We may use some refactoring later
                region_type = self.id
            action = SimActionData(self.state, region_type, 'write', addr=addr_e, data=req.stored_values[-1],
                                   size=max_bits, condition=self.state.solver.Or(*conditions), fallback=fallback
                                   )
            self.state.history.add_action(action)

        if req.completed and action is not None:
            action.actual_addrs = req.actual_addresses
            action.actual_value = action._make_object(req.stored_values[-1])
            action.added_constraints = action._make_object(self.state.solver.And(*req.constraints)
                                                           if len(req.constraints) > 0 else self.state.solver.true)


Instruction:
Explain what the following Python 3 code does
def load(self, addr, size=None, condition=None, fallback=None, add_constraints=None, action=None, endness=None,
             inspect=True, disable_actions=False, ret_on_segv=False):
        """
        Loads size bytes from dst.

        :param dst:             The address to load from.
        :param size:            The size (in bytes) of the load.
        :param condition:       A claripy expression representing a condition for a conditional load.
        :param fallback:        A fallback value if the condition ends up being False.
        :param add_constraints: Add constraints resulting from the merge (default: True).
        :param action:          A SimActionData to fill out with the constraints.
        :param endness:         The endness to load with.
        :param bool inspect:    Whether this store should trigger SimInspect breakpoints or not.
        :param bool disable_actions: Whether this store should avoid creating SimActions or not. When set to False,
                                     state options are respected.
        :param bool ret_on_segv: Whether returns the memory that is already loaded before a segmentation fault is triggered. The default is False.

        There are a few possible return values. If no condition or fallback are passed in,
        then the return is the bytes at the address, in the form of a claripy expression.
        For example:

            <A BVV(0x41, 32)>

        On the other hand, if a condition and fallback are provided, the value is conditional:

            <A If(condition, BVV(0x41, 32), fallback)>
        """

        _inspect = inspect and self.state.supports_inspect

        add_constraints = True if add_constraints is None else add_constraints

        addr_e = _raw_ast(addr)
        size_e = _raw_ast(size)
        condition_e = _raw_ast(condition)
        fallback_e = _raw_ast(fallback)

        if isinstance(addr, str):
            named_addr, named_size = self._resolve_location_name(addr)
            addr = named_addr
            addr_e = addr
            if size is None:
                size = named_size
                size_e = size

        if size is None:
            size = self.state.arch.bits // self.state.arch.byte_width
            size_e = size

        if _inspect:
            if self.category == 'reg':
                self.state._inspect('reg_read', BP_BEFORE, reg_read_offset=addr_e, reg_read_length=size_e,
                                    reg_read_condition=condition_e
                                    )
                addr_e = self.state._inspect_getattr("reg_read_offset", addr_e)
                size_e = self.state._inspect_getattr("reg_read_length", size_e)
                condition_e = self.state._inspect_getattr("reg_read_condition", condition_e)

            elif self.category == 'mem':
                self.state._inspect('mem_read', BP_BEFORE, mem_read_address=addr_e, mem_read_length=size_e,
                                    mem_read_condition=condition_e
                                    )
                addr_e = self.state._inspect_getattr("mem_read_address", addr_e)
                size_e = self.state._inspect_getattr("mem_read_length", size_e)
                condition_e = self.state._inspect_getattr("mem_read_condition", condition_e)

        if (
            o.UNDER_CONSTRAINED_SYMEXEC in self.state.options and
            isinstance(addr_e, claripy.ast.Base) and
            addr_e.uninitialized
        ):
            self._constrain_underconstrained_index(addr_e)

        try:
            a,r,c = self._load(addr_e, size_e, condition=condition_e, fallback=fallback_e, inspect=_inspect,
                               events=not disable_actions, ret_on_segv=ret_on_segv)
        except SimSegfaultError as e:
            e.original_addr = addr_e
            raise
        if _inspect:
            # tracer uses address_concretization_add_constraints to overwrite the add_constraints value
            # TODO: Make this logic less arbitrary
            add_constraints = self.state._inspect_getattr('address_concretization_add_constraints', add_constraints)
        if add_constraints and c:
            self.state.add_constraints(*c)

        if (self.category == 'mem' and o.SIMPLIFY_MEMORY_READS in self.state.options) or \
           (self.category == 'reg' and o.SIMPLIFY_REGISTER_READS in self.state.options):  # pylint:disable=too-many-boolean-expressions
            l.debug("simplifying %s read...", self.category)
            r = self.state.simplify(r)

        if not self._abstract_backer and \
                o.UNINITIALIZED_ACCESS_AWARENESS in self.state.options and \
                self.state.uninitialized_access_handler is not None and \
                (r.op == 'Reverse' or r.op == 'BVV') and \
                getattr(r._model_vsa, 'uninitialized', False):
            normalized_addresses = self.normalize_address(addr)
            if len(normalized_addresses) > 0 and type(normalized_addresses[0]) is AddressWrapper:
                normalized_addresses = [ (aw.region, aw.address) for aw in normalized_addresses ]
            self.state.uninitialized_access_handler(self.category, normalized_addresses, size, r, self.state.scratch.bbl_addr, self.state.scratch.stmt_idx)

        # the endianess
        endness = self.endness if endness is None else endness
        if endness == "Iend_LE":
            r = r.reversed

        if _inspect:
            if self.category == 'mem':
                self.state._inspect('mem_read', BP_AFTER, mem_read_expr=r)
                r = self.state._inspect_getattr("mem_read_expr", r)

            elif self.category == 'reg':
                self.state._inspect('reg_read', BP_AFTER, reg_read_expr=r)
                r = self.state._inspect_getattr("reg_read_expr", r)

        if not disable_actions:
            if o.AST_DEPS in self.state.options and self.category == 'reg':
                r = SimActionObject(r, reg_deps=frozenset((addr,)))

            if o.AUTO_REFS in self.state.options and action is None:
                ref_size = size * self.state.arch.byte_width if size is not None else r.size()
                region_type = self.category
                if region_type == 'file':
                    # Special handling for files to keep compatibility
                    # We may use some refactoring later
                    region_type = self.id
                action = SimActionData(self.state, region_type, 'read', addr=addr, data=r, size=ref_size,
                                       condition=condition, fallback=fallback)
                self.state.history.add_action(action)

            if action is not None:
                action.actual_addrs = a
                action.added_constraints = action._make_object(self.state.solver.And(*c)
                                                               if len(c) > 0 else self.state.solver.true)

        return r

Response: Load a memory area from the specified address.


Instruction:
How would you explain what the following Python 3 function does
def find(self, addr, what, max_search=None, max_symbolic_bytes=None, default=None, step=1,
             disable_actions=False, inspect=True, chunk_size=None):
        """
        Returns the address of bytes equal to 'what', starting from 'start'. Note that,  if you don't specify a default
        value, this search could cause the state to go unsat if no possible matching byte exists.

        :param addr:               The start address.
        :param what:                What to search for;
        :param max_search:          Search at most this many bytes.
        :param max_symbolic_bytes:  Search through at most this many symbolic bytes.
        :param default:             The default value, if what you're looking for wasn't found.
        :param step:                The stride that the search should use while scanning memory
        :param disable_actions:     Whether to inhibit the creation of SimActions for memory access
        :param inspect:             Whether to trigger SimInspect breakpoints

        :returns:                   An expression representing the address of the matching byte.
        """
        addr = _raw_ast(addr)
        what = _raw_ast(what)
        default = _raw_ast(default)

        if isinstance(what, bytes):
            # Convert it to a BVV
            what = claripy.BVV(what, len(what) * self.state.arch.byte_width)

        r,c,m = self._find(addr, what, max_search=max_search, max_symbolic_bytes=max_symbolic_bytes, default=default,
                           step=step, disable_actions=disable_actions, inspect=inspect, chunk_size=chunk_size)
        if o.AST_DEPS in self.state.options and self.category == 'reg':
            r = SimActionObject(r, reg_deps=frozenset((addr,)))

        return r,c,m

Response: Searches for a given byte in memory and returns the address of the matching byte.


Instruction:
Can you create a Python 3 function that
copies the contents of src into dst within a memory.

Response:
def copy_contents(self, dst, src, size, condition=None, src_memory=None, dst_memory=None, inspect=True,
                      disable_actions=False):
        """
        Copies data within a memory.

        :param dst:         A claripy expression representing the address of the destination
        :param src:         A claripy expression representing the address of the source

        The following parameters are optional.

        :param src_memory:  Copy data from this SimMemory instead of self
        :param src_memory:  Copy data to this SimMemory instead of self
        :param size:        A claripy expression representing the size of the copy
        :param condition:   A claripy expression representing a condition, if the write should be conditional. If this
                            is determined to be false, the size of the copy will be 0.
        """
        dst = _raw_ast(dst)
        src = _raw_ast(src)
        size = _raw_ast(size)
        condition = _raw_ast(condition)

        return self._copy_contents(dst, src, size, condition=condition, src_memory=src_memory, dst_memory=dst_memory,
                                   inspect=inspect, disable_actions=disable_actions)


Instruction:
Create a Python 3 function to
return the VFGNode at the given address or None if no such node exists.

Response:
def _vfg_node(self, addr):
        """
        Gets vfg node at @addr
        Returns VFGNode or None
        """
        for n in self._vfg._nodes.values():
            if n.addr == addr:
                return n
        raise DataGraphError("No VFG node at 0x%x" % addr)


Instruction:
Make a summary of the following Python 3 code
def _branch(self, live_defs, node, path=""):

        irsb = self._irsb(node.state)
        path = path + " -> " + hex(irsb.addr)

        if isinstance(irsb, SimProcedure):
            self._simproc_map[irsb.addr] = repr(irsb)

        l.debug("--> Branch: running block 0x%x" % irsb.addr)
        block = self._make_block(irsb, live_defs)
        self._imarks.update(block._imarks)
        if block.stop == True:
            #l.debug(" ### Stopping at block 0x%x" % (irsb.addr))
            l.debug(" ### End of path %s" % path)
            return irsb.addr
        succ = self._vfg._graph.successors(node)

        defer = []
        for s in succ:
            # Consider fake returns last
            if self._vfg._graph.edge[node][s]['jumpkind'] == 'Ijk_FakeRet':
                defer.append(s)
                continue
            # We need to make a copy of the dict !
            self._branch(dict(block.live_defs), s, path)

            # We explore every other paths before taking fake rets.
            # Ideally, we want to take fake rets only when functions don't
            # return.
            for s in defer:
                self._branch(dict(block.live_defs), s, path)

Response: Recursive function that branches in every possible path in the VFG.


Instruction:
Can you implement a function in Python 3 that
gets a list of abstract locations that are within the range of addr and addr + size.

Response:
def get_abstract_locations(self, addr, size):
        """
        Get a list of abstract locations that is within the range of [addr, addr + size]

        This implementation is pretty slow. But since this method won't be called frequently, we can live with the bad
        implementation for now.

        :param addr:    Starting address of the memory region.
        :param size:    Size of the memory region, in bytes.
        :return:        A list of covered AbstractLocation objects, or an empty list if there is none.
        """

        ret = [ ]
        for aloc in self._alocs.values():
            for seg in aloc.segments:
                if seg.offset >= addr and seg.offset < addr + size:
                    ret.append(aloc)
                    break

        return ret


Instruction:
Can you tell what is the following Python 3 function doing
def dbg_print(self, indent=0):
        print("%sA-locs:" % (" " * indent))
        for aloc_id, aloc in self._alocs.items():
            print("%s<0x%x> %s" % (" " * (indent + 2), aloc_id, aloc))

        print("%sMemory:" % (" " * indent))
        self.memory.dbg_print(indent=indent + 2)

Response: Print out debugging information for this object.


Instruction:
How would you explain what the following Python 3 function does
def _region_base(self, region):

        if region == 'global':
            region_base_addr = 0
        elif region.startswith('stack_'):
            region_base_addr = self._stack_region_map.absolutize(region, 0)
        else:
            region_base_addr = self._generic_region_map.absolutize(region, 0)

        return region_base_addr

Response: Get the base address of a memory region.


Instruction:
Given the following Python 3 function, write the documentation
def create_region(self, key, state, is_stack, related_function_addr, endness, backer_dict=None):

        self._regions[key] = MemoryRegion(key,
                                          state=state,
                                          is_stack=is_stack,
                                          related_function_addr=related_function_addr,
                                          endness=endness,
                                          backer_dict=backer_dict,
                                          )

Response: Create a new MemoryRegion with the specified key and store it in self. _regions.


Instruction:
Can you write a function in Python 3 where it
overrides the SimStatePlugin. set_state method.

Response:
def set_state(self, state):
        """
        Overriding the SimStatePlugin.set_state() method

        :param state: A SimState object
        :return: None
        """

        # Sanity check
        if REGION_MAPPING not in state.options:
            # add REGION_MAPPING into state.options
            l.warning('Option "REGION_MAPPING" must be enabled when using SimAbstractMemory as the memory model. '
                      'The option is added to state options as a courtesy.'
                      )
            state.options.add(REGION_MAPPING)

        SimMemory.set_state(self, state)

        for _,v in self._regions.items():
            v.set_state(state)

        # Delayed initialization of backer argument from __init__
        if self._temp_backer is not None:
            for region, backer_dict in self._temp_backer.items():
                self._regions[region] = MemoryRegion(region, self.state,
                                                     init_memory=True,
                                                     backer_dict=backer_dict,
                                                     endness=self.endness
                                                     )
            self._temp_backer = None