angr-pyvex/make_ffi.py

import re
import os
import sys
import cffi
import subprocess
import platform

import logging

log = logging.getLogger("cffier")
log.setLevel(logging.DEBUG)


def find_good_scan(questionable):
    known_good = []

    end_line = len(questionable)

    while len(questionable):
        ffi = cffi.FFI()
        log.debug("scan - trying %d good and %d questionable", len(known_good), len(questionable))

        candidate = known_good + questionable[:end_line]
        failed_line = -1

        try:
            ffi.cdef("\n".join(candidate))

            known_good = candidate
            questionable = questionable[end_line:]
            end_line = len(questionable)
        except AssertionError:
            questionable = questionable[1:]
            end_line = len(questionable)
        except cffi.CDefError as e:
            if "<cdef source string>" in str(e):
                failed_line = int(str(e).split("\n")[-1].split(":")[1]) - 1
            elif str(e).count(":") >= 2:
                failed_line = int(str(e).split("\n")[1].split(":")[1])
                failed_line_description = str(e).split("\n")[0]
                idx1 = failed_line_description.index('"')
                idx2 = failed_line_description.rindex('"')
                failed_reason = failed_line_description[idx1 + 1 : idx2]

                for i in range(failed_line, -1, -1):
                    if failed_reason in candidate[i]:
                        failed_line = i
            elif "unrecognized construct" in str(e):
                failed_line = int(str(e).split()[1][:-1]) - 1
            elif "end of input" in str(e):
                end_line -= 1
            else:
                raise Exception("Unknown error")
        except cffi.FFIError as e:
            if str(e).count(":") >= 2:
                failed_line = int(str(e).split("\n")[0].split(":")[1]) - 1
            else:
                raise Exception("Unknown error")

        if failed_line != -1:
            end_line = failed_line - len(known_good)

        if end_line == 0:
            questionable = questionable[1:]
            end_line = len(questionable)
    return known_good


def doit(vex_path):
    cpplist = ["cl", "cpp"]
    cpp = os.getenv("CPP")
    if cpp:
        cpplist.insert(0, cpp)
    if platform.system() == "Darwin":
        cpplist.insert(0, "clang")

    errs = []
    for cpp in cpplist:
        cmd = [cpp, "-I" + vex_path, os.path.join("pyvex_c", "pyvex.h")]
        if cpp in ("cl", "clang", "gcc", "cc", "clang++", "g++"):
            cmd.append("-E")
        try:
            p = subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
            header, stderr = p.communicate()
            try:
                header = header.decode("utf-8")
                stderr = stderr.decode("utf-8")
            except UnicodeDecodeError:
                # They don't have to be unicode on Windows
                pass

            if not header.strip() or p.returncode != 0:
                errs.append((" ".join(cmd), p.returncode, stderr))
                continue
            else:
                break
        except OSError:
            errs.append((" ".join(cmd), -1, "does not exist"))
            continue
    else:
        log.warning("failed commands:\n" + "\n".join("{} ({}) -- {}".format(*e) for e in errs))
        raise Exception(
            "Couldn't process pyvex headers."
            + 'Please set CPP environmental variable to local path of "cpp".'
            + 'Note that "cpp" and "g++" are different.'
        )
    # header = vex_pp + pyvex_pp

    linesep = "\r\n" if "\r\n" in header else "\n"
    ffi_text = linesep.join(
        line
        for line in header.split(linesep)
        if "#" not in line and line.strip() != "" and "jmp_buf" not in line and not ("=" in line and ";" in line)
    )
    ffi_text = re.sub(r"\{\s*\} NoOp;", "{ int DONOTUSE; } NoOp;", ffi_text)
    ffi_text = re.sub(r"__attribute__\s*\(.*\)", "", ffi_text)
    ffi_text = re.sub(r"__declspec\s*\([^\)]*\)", "", ffi_text)
    ffi_text = ffi_text.replace("__const", "const")
    ffi_text = ffi_text.replace("__inline", "")
    ffi_text = ffi_text.replace("__w64", "")
    ffi_text = ffi_text.replace("__cdecl", "")
    ffi_text = ffi_text.replace("__int64", "long")
    ffi_lines = ffi_text.split(linesep)

    good = find_good_scan(ffi_lines)
    good += ["extern VexControl vex_control;"]

    with open("pyvex/vex_ffi.py", "w") as fp:
        fp.write('ffi_str = """' + "\n".join(good) + '"""\n')
        fp.write("guest_offsets = " + repr(get_guest_offsets(vex_path)) + "\n")


def get_guest_offsets(vex_path):
    fname = os.path.join(vex_path, "libvex_guest_offsets.h")
    out = {}
    with open(fname) as fp:
        for line in fp:
            if line.startswith("#define"):
                _, names, val = line.split()
                val = int(val, 0)
                assert names.startswith("OFFSET_")
                _, arch, reg = names.split("_", 2)
                out[(arch, reg.lower())] = val
    return out


if __name__ == "__main__":
    logging.basicConfig(level=logging.DEBUG)
    doit(sys.argv[1])