path: root/miasm2/core/parse_asm.py

#-*- coding:utf-8 -*-
import re

from miasm2.expression.expression import ExprId, ExprInt, ExprOp, ExprLoc, \
    LocKey
import miasm2.core.asmblock as asmblock
from miasm2.core.cpu import instruction, base_expr
from miasm2.core.asm_ast import AstInt, AstId, AstOp

declarator = {'byte': 8,
              'word': 16,
              'dword': 32,
              'qword': 64,
              'long': 32,
              }

size2pck = {8: 'B',
            16: 'H',
            32: 'I',
            64: 'Q',
            }

EMPTY_RE = re.compile(r'\s*$')
COMMENT_RE = re.compile(r'\s*;\S*')
LOCAL_LABEL_RE = re.compile(r'\s*(\.L\S+)\s*:')
DIRECTIVE_START_RE = re.compile(r'\s*\.')
DIRECTIVE_RE = re.compile(r'\s*\.(\S+)')
LABEL_RE = re.compile(r'\s*(\S+)\s*:')
FORGET_LABEL_RE = re.compile(r'\s*\.LF[BE]\d\s*:')


class Directive(object):

    """Stand for Directive"""

    pass

class DirectiveAlign(Directive):

    """Stand for alignment representation"""

    def __init__(self, alignment=1):
        self.alignment = alignment

    def __str__(self):
        return "Alignment %s" % self.alignment


class DirectiveSplit(Directive):

    """Stand for alignment representation"""

    pass


class DirectiveDontSplit(Directive):

    """Stand for alignment representation"""

    pass


def guess_next_new_label(symbol_pool):
    """Generate a new label
    @symbol_pool: the AsmSymbolPool instance"""
    i = 0
    gen_name = "loc_%.8X"
    while True:
        name = gen_name % i
        label = symbol_pool.getby_name(name)
        if label is None:
            return symbol_pool.add_location(name)
        i += 1


STATE_NO_BLOC = 0
STATE_IN_BLOC = 1


def asm_ast_to_expr_with_size(arg, symbol_pool, size):
    if isinstance(arg, AstId):
        return ExprId(arg.name, size)
    if isinstance(arg, AstOp):
        args = [asm_ast_to_expr_with_size(tmp, symbol_pool, size) for tmp in arg.args]
        return ExprOp(arg.op, *args)
    if isinstance(arg, AstInt):
        return ExprInt(arg.value, size)
    return None

def parse_txt(mnemo, attrib, txt, symbol_pool=None):
    """Parse an assembly listing. Returns a couple (asmcfg, symbol_pool), where
    asmcfg is an AsmCfg instance and symbol_pool the associated AsmSymbolPool

    @mnemo: architecture used
    @attrib: architecture attribute
    @txt: assembly listing
    @symbol_pool: (optional) the AsmSymbolPool instance used to handle labels
    of the listing

    """

    if symbol_pool is None:
        symbol_pool = asmblock.AsmSymbolPool()

    C_NEXT = asmblock.AsmConstraint.c_next
    C_TO = asmblock.AsmConstraint.c_to

    lines = []
    # parse each line
    for line in txt.split('\n'):
        # empty
        if EMPTY_RE.match(line):
            continue
        # comment
        if COMMENT_RE.match(line):
            continue
        # labels to forget
        if FORGET_LABEL_RE.match(line):
            continue
        # label beginning with .L
        match_re = LABEL_RE.match(line)
        if match_re:
            label_name = match_re.group(1)
            label = symbol_pool.getby_name_create(label_name)
            lines.append(label)
            continue
        # directive
        if DIRECTIVE_START_RE.match(line):
            match_re = DIRECTIVE_RE.match(line)
            directive = match_re.group(1)
            if directive in ['text', 'data', 'bss']:
                continue
            if directive in ['string', 'ascii']:
                # XXX HACK
                line = line.replace(r'\n', '\n').replace(r'\r', '\r')
                raw = line[line.find(r'"') + 1:line.rfind(r'"')]
                raw = raw.decode('string_escape')
                if directive == 'string':
                    raw += "\x00"
                lines.append(asmblock.AsmRaw(raw))
                continue
            if directive == 'ustring':
                # XXX HACK
                line = line.replace(r'\n', '\n').replace(r'\r', '\r')
                raw = line[line.find(r'"') + 1:line.rfind(r'"')] + "\x00"
                raw = raw.decode('string_escape')
                raw = "".join([string + '\x00' for string in raw])
                lines.append(asmblock.AsmRaw(raw))
                continue
            if directive in declarator:
                data_raw = line[match_re.end():].split(' ', 1)[1]
                data_raw = data_raw.split(',')
                size = declarator[directive]
                expr_list = []

                # parser

                for element in data_raw:
                    element = element.strip()
                    element_parsed = base_expr.parseString(element)[0]
                    element_expr = asm_ast_to_expr_with_size(element_parsed, symbol_pool, size)
                    expr_list.append(element_expr)

                raw_data = asmblock.AsmRaw(expr_list)
                raw_data.element_size = size
                lines.append(raw_data)
                continue
            if directive == 'comm':
                # TODO
                continue
            if directive == 'split':  # custom command
                lines.append(DirectiveSplit())
                continue
            if directive == 'dontsplit':  # custom command
                lines.append(DirectiveDontSplit())
                continue
            if directive == "align":
                align_value = int(line[match_re.end():], 0)
                lines.append(DirectiveAlign(align_value))
                continue
            if directive in ['file', 'intel_syntax', 'globl', 'local',
                             'type', 'size', 'align', 'ident', 'section']:
                continue
            if directive[0:4] == 'cfi_':
                continue

            raise ValueError("unknown directive %s" % str(directive))

        # label
        match_re = LABEL_RE.match(line)
        if match_re:
            label_name = match_re.group(1)
            label = symbol_pool.getby_name_create(label_name)
            lines.append(label)
            continue

        # code
        if ';' in line:
            line = line[:line.find(';')]
        line = line.strip(' ').strip('\t')
        instr = mnemo.fromstring(line, symbol_pool, attrib)

        if instr.dstflow():
            instr.dstflow2label(symbol_pool)
        lines.append(instr)

    asmblock.log_asmblock.info("___pre asm oki___")
    # make asmcfg

    cur_block = None
    state = STATE_NO_BLOC
    i = 0
    asmcfg = asmblock.AsmCFG(symbol_pool)
    block_to_nlink = None
    delayslot = 0
    while i < len(lines):
        if delayslot:
            delayslot -= 1
            if delayslot == 0:
                state = STATE_NO_BLOC
        line = lines[i]
        # no current block
        if state == STATE_NO_BLOC:
            if isinstance(line, DirectiveDontSplit):
                block_to_nlink = cur_block
                i += 1
                continue
            elif isinstance(line, DirectiveSplit):
                block_to_nlink = None
                i += 1
                continue
            elif not isinstance(line, LocKey):
                # First line must be a label. If it's not the case, generate
                # it.
                loc = guess_next_new_label(symbol_pool)
                cur_block = asmblock.AsmBlock(loc, alignment=mnemo.alignment)
            else:
                cur_block = asmblock.AsmBlock(line, alignment=mnemo.alignment)
                i += 1
            # Generate the current bloc
            asmcfg.add_block(cur_block)
            state = STATE_IN_BLOC
            if block_to_nlink:
                block_to_nlink.addto(
                    asmblock.AsmConstraint(
                        cur_block.loc_key,
                        C_NEXT
                    )
                )
            block_to_nlink = None
            continue

        # in block
        elif state == STATE_IN_BLOC:
            if isinstance(line, DirectiveSplit):
                state = STATE_NO_BLOC
                block_to_nlink = None
            elif isinstance(line, DirectiveDontSplit):
                state = STATE_NO_BLOC
                block_to_nlink = cur_block
            elif isinstance(line, DirectiveAlign):
                cur_block.alignment = line.alignment
            elif isinstance(line, asmblock.AsmRaw):
                cur_block.addline(line)
                block_to_nlink = cur_block
            elif isinstance(line, LocKey):
                if block_to_nlink:
                    cur_block.addto(
                        asmblock.AsmConstraint(line, C_NEXT)
                    )
                    block_to_nlink = None
                state = STATE_NO_BLOC
                continue
            # instruction
            elif isinstance(line, instruction):
                cur_block.addline(line)
                block_to_nlink = cur_block
                if not line.breakflow():
                    i += 1
                    continue
                if delayslot:
                    raise RuntimeError("Cannot have breakflow in delayslot")
                if line.dstflow():
                    for dst in line.getdstflow(symbol_pool):
                        if not isinstance(dst, ExprId):
                            continue
                        if dst in mnemo.regs.all_regs_ids:
                            continue
                        cur_block.addto(asmblock.AsmConstraint(dst.name, C_TO))

                if not line.splitflow():
                    block_to_nlink = None

                delayslot = line.delayslot + 1
            else:
                raise RuntimeError("unknown class %s" % line.__class__)
        i += 1

    for block in asmcfg.blocks:
        # Fix multiple constraints
        block.fix_constraints()

        # Log block
        asmblock.log_asmblock.info(block)
    return asmcfg, symbol_pool