#!/usr/bin/env python3

"""Fuzzes KECC.

For customization, one may restrict/loosen the replacement rule by adding/deleting the pair into
below `REPLACE_DICT`.

"""

import os
import subprocess
import argparse
import re
import random
from pathlib import Path

from install_smith import install_csmith

REPLACE_DICT = {
    "volatile ": "",
    "static ": "",
    "extern ": "",
    "__restrict": "",
    "long __undefined;": "",
    "return 0;": "return (unsigned char)(crc32_context);",
    r"__attribute__\s*\(\(.*\)\)": "",
    "_Float128": "double",
    "long double": "double",
    r"(\+[0-9^FL]*)L": r"\1",
    "union": "struct",
    r"enum[\w\s]*\{[^\}]*\};": "",
    r"typedef enum[\w\s]*\{[^;]*;[\s_A-Z]*;": "",
    r"const char \*const sys_errlist\[\];": "",  # ArraySize::Unknown 삭제
    r"[^\n]*printf[^;]*;": "",
    r"[^\n]*scanf[^;]*;": "",
    " restrict": "",
    "inline ": "",
    "_Nullable": "",
    r'"g_\w*", ': "",  # transparent_crc에서 프린트 목적으로 받은 StringLiteral 삭제
    r"char\* vname, ": "",  # transparent_crc에서 사용하지 않는 파라미터 삭제
    r"transparent_crc_bytes\s*\([^;]*\);": "",  # transparent_crc_bytes 삭제
    r"[^\n]*_IO_2_1_[^;]*;": "",  # extern을 지우면서 생긴 size를 알 수 없는 struct 삭제
    r"__asm\s*\([^\)]*\)": "",  # asm extension in mac
    r"__asm__\s*\([^\)]*\)": "",  # asm extension in linux
    "typedef __builtin_va_list __gnuc_va_list;": "",
    "typedef __gnuc_va_list va_list;": "",
    r"\(fabsf\(": "((",
    # todo: need to consider the case below in the future:
    # avoid compile-time constant expressed as complex expression such as `1 + 1`
    "char _unused2[^;]*;": "char _unused2[10];",
}
CSMITH_DIR = "csmith-2.3.0"
SKIP_TEST = 102


def generate(tests_dir, bin_path, seed, easy):
    """Feeding options to built Csmith to randomly generate test case.

    For generality, I disabled most of the features that are enabled by default.
    FYI, please take a look at `-h` flag. By adding or deleting one of `--blah-blah...`
    in `options` list below, csmith will be able to generate corresponding test case.
    A developer may customize the options to meet one's needs for testing.
    """
    global CSMITH_DIR
    options = [
        "--no-argc",
        "--no-arrays",
        "--no-jumps",
        "--no-pointers",
        "--no-structs",
        "--no-unions",
        "--float",
        "--strict-float",
        "--seed",
        str(seed),
    ]
    if easy:
        options += [
            "--max-block-depth",
            "2",
            "--max-block-size",
            "2",
            "--max-struct-fields",
            "3",
        ]
    args = [bin_path] + options

    try:
        proc = subprocess.Popen(args, cwd=tests_dir, stdout=subprocess.PIPE)
        (src, err) = proc.communicate()
        return src.decode()
    except subprocess.TimeoutExpired as e:
        proc.kill()
        raise e


def polish(src, inc_path):
    """Polishing test case to fit in kecc parser specification."""
    global REPLACE_DICT, CSMITH_DIR

    try:
        args = [
            "gcc",
            "-I",
            inc_path,
            "-E",
            "-P",
            "-",
        ]
        proc = subprocess.Popen(args, stdin=subprocess.PIPE, stdout=subprocess.PIPE)
        (src_preprocessed, err) = proc.communicate(src.encode())
        src_preprocessed = src_preprocessed.decode()
    except subprocess.TimeoutExpired as e:
        proc.kill()
        raise e

    src_replaced = src_preprocessed
    for _from, _to in REPLACE_DICT.items():
        src_replaced = re.sub(_from, _to, src_replaced)

    return src_replaced


def make_reduce_criteria(tests_dir, fuzz_arg, fuzz_errmsg, analyze):
    """Make executable reduce-criteria.sh"""
    # Make shell script i.e. dependent to KECC path
    arg_dict = {
        "$PROJECT_DIR": str(Path(tests_dir).parent),
        "$FUZZ_ARG": fuzz_arg,
        "$KECC_BIN": str(
            os.path.abspath(os.path.join(tests_dir, "../target/release/kecc"))
        ),
        "$FUZZ_BIN": str(
            os.path.abspath(os.path.join(tests_dir, "../target/release/fuzz"))
        ),
        "$FUZZ_ERRMSG": "'{}'".format(fuzz_errmsg),
        "$CLANG_ANALYZE": str(analyze).lower(),
    }
    with open(os.path.join(tests_dir, "reduce-criteria-template.sh"), "r") as t:
        temp = t.read()
        for _from, _to in arg_dict.items():
            temp = temp.replace(_from, _to)
        with open(os.path.join(tests_dir, "reduce-criteria.sh"), "w") as f:
            f.write(temp)

    # chmod the script executable
    try:
        args = ["chmod", "u+x", "reduce-criteria.sh"]
        proc = subprocess.Popen(
            args, stdout=subprocess.PIPE, stderr=subprocess.STDOUT, cwd=tests_dir
        )
        proc.communicate()
        if proc.returncode != 0:
            raise Exception(
                "`{}` failed with exit code {}.".format(" ".join(args), proc.returncode)
            )
    except subprocess.TimeoutExpired as e:
        proc.kill()
        raise e


def make_fuzz_errmsg(tests_dir, fuzz_arg):
    """Make fuzz error message in reduce-criteria.sh."""
    fuzz_errmsg = "panicked"
    try:
        args = [
            "cargo",
            "run",
            "--features=build-bin",
            "--bin",
            "fuzz",
            "--",
            fuzz_arg,
            "test_polished.c",
        ]
        proc = subprocess.Popen(
            args, stdout=subprocess.PIPE, stderr=subprocess.STDOUT, cwd=tests_dir
        )
        (out, err) = proc.communicate()
        if proc.returncode != 0:
            if "assertion failed" in out.decode():
                fuzz_errmsg = "assertion failed"
        else:
            raise Exception(
                "Reducing failed because `{}` returned 0".format(" ".join(args))
            )
    except subprocess.TimeoutExpired as e:
        proc.kill()
        raise e

    return fuzz_errmsg


def creduce(tests_dir, fuzz_arg, analyze):
    """Reduce `tests/test_polished.c` to `tests/test_reduced.c`

    First, we copy test_polished.c to test_reduced.c.
    Then, when Creduce reduces test_reduced.c, it overwrites partially reduced program to itself.
    Original file is moved to test_reduced.c.orig which is then identical to test_polished.c.
    """
    fuzz_errmsg = make_fuzz_errmsg(tests_dir, fuzz_arg)
    make_reduce_criteria(tests_dir, fuzz_arg, fuzz_errmsg, analyze)

    try:
        args = ["cp", "test_polished.c", "test_reduced.c"]
        proc = subprocess.Popen(
            args, stdout=subprocess.PIPE, stderr=subprocess.STDOUT, cwd=tests_dir
        )
        proc.communicate()
        if proc.returncode != 0:
            raise Exception(
                "`{}` failed with exit code {}.".format(" ".join(args), proc.returncode)
            )
    except subprocess.TimeoutExpired as e:
        proc.kill()
        raise e

    try:
        # --tidy: Do not make a backup copy of each file to reduce as file.orig
        args = [
            "creduce",
            "--tidy",
            "--timing",
            "--timeout",
            "20",
            "./reduce-criteria.sh",
            "test_reduced.c",
        ]
        proc = subprocess.Popen(
            args, stdout=subprocess.PIPE, stderr=subprocess.STDOUT, cwd=tests_dir
        )
        (out, err) = proc.communicate()
        if proc.returncode != 0:
            print(out.decode())
            raise Exception(
                "Reducing test_reduced.c by `{}` failed with exit code {}.".format(
                    " ".join(args), proc.returncode
                )
            )
        print("Reduce finished.")
    except subprocess.TimeoutExpired as e:
        proc.kill()
        raise e


def fuzz(tests_dir, fuzz_arg, num_iter, easy):
    global SKIP_TEST

    csmith_bin, csmith_inc = install_csmith()
    fuzz_bin = os.path.abspath(os.path.join(tests_dir, "../target/release/fuzz"))
    try:
        if num_iter is None:
            print(
                "Fuzzing with infinitely many test cases.  Please press [ctrl+C] to break."
            )
        else:
            assert num_iter > 0
            print("Fuzzing with {} test cases.".format(num_iter))

        i = 0
        skip = 0
        while True:
            print("Test case #{} (skipped: {})".format(i, skip))
            src = generate(tests_dir, csmith_bin, random.randint(1, 987654321), easy)
            with open(os.path.join(tests_dir, "test.c"), "w") as dst:
                dst.write(src)

            src_polished = polish(src, csmith_inc)
            with open(os.path.join(tests_dir, "test_polished.c"), "w") as dst:
                dst.write(src_polished)

            try:
                args = [fuzz_bin, fuzz_arg, os.path.join(tests_dir, "test_polished.c")]
                proc = subprocess.Popen(
                    args,
                    stdout=subprocess.PIPE,
                    stderr=subprocess.STDOUT,
                    cwd=tests_dir,
                )
                proc.communicate(timeout=60)

                # KECC sets an exit code of 102 when the test skipped.
                if proc.returncode == SKIP_TEST:
                    skip += 1
                    continue
                elif proc.returncode != 0:
                    raise Exception(
                        "Test `{}` failed with exit code {}.".format(
                            " ".join(args), proc.returncode
                        )
                    )

                i += 1
                if num_iter is not None:
                    if i > num_iter:
                        break
            except subprocess.TimeoutExpired as e:
                proc.kill()
                skip += 1
    except KeyboardInterrupt:
        proc.terminate()
        print("\n[Ctrl+C] interrupted")


if __name__ == "__main__":
    parser = argparse.ArgumentParser(description="Fuzzing KECC.")
    parser.add_argument("-n", "--num", type=int, help="The number of tests")
    parser.add_argument(
        "-p", "--print", action="store_true", help="Fuzzing C AST printer"
    )
    parser.add_argument("-i", "--irgen", action="store_true", help="Fuzzing irgen")
    parser.add_argument(
        "-r", "--reduce", action="store_true", help="Reducing input file"
    )
    parser.add_argument(
        "--skip-build", action="store_true", help="Skipping cargo build"
    )
    parser.add_argument(
        "--easy", action="store_true", help="Generate more easy code by csmith option"
    )
    parser.add_argument(
        "--seed", type=int, help="Provide seed of fuzz generation", default=-1
    )
    parser.add_argument(
        "--clang-analyze",
        action="store_true",
        help="Use clang static analyzer for reducing. It prevents undefined behaviors coming from reduced program, but perhaps take a long time to do so",
    )
    args = parser.parse_args()

    if args.print and args.irgen:
        raise Exception(
            "Choose an option used for fuzzing: '--print' or '--irgen', NOT both"
        )

    if args.print:
        fuzz_arg = "-p"
    elif args.irgen:
        fuzz_arg = "-i"
    else:
        raise Exception("Specify fuzzing argument")

    if args.seed != -1:
        print("Set seed as", args.seed)
        random.seed(args.seed)
    else:
        print("Use default random seed")

    tests_dir = os.path.abspath(os.path.dirname(__file__))

    if not args.skip_build:
        print("Building KECC..")
        try:
            proc = subprocess.Popen(
                [
                    "cargo",
                    "build",
                    "--features=build-bin",
                    "--release",
                    "--bin",
                    "fuzz",
                    "--bin",
                    "kecc",
                ],
                cwd=tests_dir,
            )
            proc.communicate()
        except subprocess.TimeoutExpired as e:
            proc.kill()
            raise e
    else:
        print(
            "Skip building. Please run `cargo build --features=build-bin --release --bin fuzz --bin kecc` to manually build."
        )

    if args.reduce:
        creduce(tests_dir, fuzz_arg, args.clang_analyze)
    else:
        fuzz(tests_dir, fuzz_arg, args.num, args.easy)