/*
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 */

#include "watchman/bser.h"
#include <folly/ScopeGuard.h>
#include <folly/logging/xlog.h>
#include <folly/portability/GTest.h>
#include "watchman/thirdparty/jansson/jansson_private.h"

#ifdef _WIN32
#include <windows.h>
#else
// TODO: The portability header is not desired here: it injects
// symbols into the platform namespace and we don't want fake unix
// semantics on Windows. But I don't know how to shut up the linter.
#include <folly/portability/SysMman.h>
#endif

#define UTF8_PILE_OF_POO "\xf0\x9f\x92\xa9"

namespace {

// Construct a std::string from a literal that may have embedded NUL bytes.
// The -1 compensates for the NUL terminator that is included in sizeof()
template <size_t N>
std::string S(const char (&str)[N]) {
  return std::string{str, str + N - 1};
}

int dump_to_string(const char* buffer, size_t size, void* data) {
  auto str = (std::string*)data;
  str->append(buffer, size);
  return 0;
}

void hexdump(const char* start, const char* end) {
  int i;
  int maxbytes = 24;

  while (start < end) {
    ptrdiff_t limit = end - start;
    if (limit > maxbytes) {
      limit = maxbytes;
    }
    printf("# ");
    for (i = 0; i < limit; i++) {
      printf("%02x", (int)(uint8_t)start[i]);
    }
    while (i <= maxbytes) {
      printf("  ");
      i++;
    }
    printf("   ");
    for (i = 0; i < limit; i++) {
      printf("%c", isprint((uint8_t)start[i]) ? start[i] : '.');
    }
    printf("\n");
    start += limit;
  }
}

std::unique_ptr<std::string>
bdumps(uint32_t version, uint32_t capabilities, const json_ref& json) {
  std::string buffer;
  bser_ctx_t ctx{version, capabilities, dump_to_string};

  if (w_bser_dump(&ctx, json, &buffer) == 0) {
    return std::make_unique<std::string>(std::move(buffer));
  }

  return nullptr;
}

std::unique_ptr<std::string>
bdumps_pdu(uint32_t version, uint32_t capabilities, const json_ref& json) {
  std::string buffer;

  if (w_bser_write_pdu(version, capabilities, dump_to_string, json, &buffer) ==
      0) {
    return std::make_unique<std::string>(std::move(buffer));
  }

  return nullptr;
}

const char* json_inputs[] = {
    "null",
    "true",
    "false",
    "0",
    "-100",
    "\"hello\"",
    "{\"bar\": true, \"foo\": 42}",
    "[1, 2, 3]",
    "[null, true, false, 65536]",
    "[1.5, 2.0]",
    "[{\"lemon\": 2.5}, null, 16000, true, false]",
    "[1, 16000, 65536, 90000, 2147483648, 4294967295]",
};

struct {
  const char* json_text;
  const char* template_text;
} template_tests[] = {
    {"["
     "{\"age\": 20, \"name\": \"fred\"}, "
     "{\"age\": 30, \"name\": \"pete\"}, "
     "{\"age\": 25}"
     "]",
     "[\"name\", \"age\"]"},
    {"[{}, {}, {}, {}, {}]", "[]"},
};

struct {
  const char* json_text;
  std::string bserv1;
  std::string bserv2;
} serialization_tests[] = {
    {
        "[\"Tom\", \"Jerry\"]",
        S("\x00\x01\x03\x11\x00\x03\x02\x02\x03\x03\x54\x6f\x6d\x02\x03\x05\x4a"
          "\x65\x72\x72\x79"),
        S("\x00\x02\x00\x00\x00\x00\x03\x11\x00\x03\x02\x02\x03\x03\x54\x6f\x6d"
          "\x02\x03\x05\x4a\x65\x72\x72\x79"),
    },
    {
        "[1, 123, 12345, 1234567, 12345678912345678]",
        S("\x00\x01\x03\x18\x00\x03\x05\x03\x01\x03\x7b\x04\x39\x30\x05\x87\xd6"
          "\x12\x00\x06\x4e\xd6\x14\x5e\x54\xdc\x2b\x00"),
        S("\x00\x02\x00\x00\x00\x00\x03\x18\x00\x03\x05\x03\x01\x03\x7b\x04\x39"
          "\x30\x05\x87\xd6\x12\x00\x06\x4e\xd6\x14\x5e\x54\xdc\x2b\x00"),
    }};

void check_roundtrip(
    uint32_t bser_version,
    uint32_t bser_capabilities,
    const char* input,
    const char* template_text) {
  XLOG(ERR) << "testing BSER version " << bser_version << ", capabilities "
            << bser_capabilities;
  std::optional<json_ref> templ;
  json_error_t jerr;

  auto expected = json_loads(input, JSON_DECODE_ANY, &jerr);
  ASSERT_TRUE(expected) << "loaded " << input << " " << jerr.text;
  if (template_text) {
    templ = json_loads(template_text, 0, &jerr);
    json_array_set_template_new(expected.value(), std::move(templ.value()));
  }

  auto dump_buf = bdumps(bser_version, bser_capabilities, expected.value());
  ASSERT_NE(dump_buf, nullptr) << "dumped something";
  const char* end = dump_buf->data() + dump_buf->size();
  hexdump(dump_buf->data(), end);

  auto decoded = bunser(dump_buf->data(), end);

  auto jdump = json_dumps(decoded, JSON_ENCODE_ANY | JSON_SORT_KEYS);
  EXPECT_TRUE(json_equal(expected.value(), decoded))
      << "round-tripped json_equal: " << jdump;
  EXPECT_EQ(jdump, input) << "round-tripped";
}

void check_serialization(
    uint32_t bser_version,
    uint32_t bser_capabilities,
    const char* json_in,
    const std::string& bser_out) {
  XLOG(ERR) << "testing BSER version " << bser_version << ", capabilities "
            << bser_capabilities;

  // Test JSON -> BSER serialization.
  json_error_t jerr;
  auto input = json_loads(json_in, 0, &jerr);
  auto bser_in = bdumps_pdu(bser_version, bser_capabilities, input.value());
  EXPECT_EQ(*bser_in, bser_out) << "raw bser comparison " << json_in;
}

// The strings are left as mixed escaped and unescaped bytes so that it's easy
// to see how it's constructed.
// The breaks in the middle of the string literals here are to prevent "\x05f"
// etc from being treated as a single character.
const std::string bser_typed_intro = S("\x00\x03\x03");
const std::string bser_typed_bytestring =
    S("\x02\x03\x05"
      "foo\xd0\xff");

const std::string bser_typed_utf8string_byte =
    S("\x02\x03\x07"
      "bar" UTF8_PILE_OF_POO);
const std::string bser_typed_utf8string_utf8 =
    S("\x0d\x03\x07"
      "bar" UTF8_PILE_OF_POO);

const std::string bser_typed_mixedstring_byte =
    S("\x02\x03\x0e"
      "baz\xb1\xc1\xe0\x90\x40" UTF8_PILE_OF_POO "\xf4\xff");
const std::string bser_typed_mixedstring_utf8 =
    S("\x0d\x03\x0e"
      "baz?????" UTF8_PILE_OF_POO "??");

// The tuples are (bser version, bser capabilities, expected BSER serialization)
std::vector<std::tuple<uint32_t, uint32_t, std::string>> typed_string_checks = {
    std::make_tuple(
        1,
        0,
        bser_typed_intro + bser_typed_bytestring + bser_typed_utf8string_byte +
            bser_typed_mixedstring_byte),
    std::make_tuple(
        2,
        0,
        bser_typed_intro + bser_typed_bytestring + bser_typed_utf8string_utf8 +
            bser_typed_mixedstring_utf8),
    std::make_tuple(
        2,
        BSER_CAP_DISABLE_UNICODE,
        bser_typed_intro + bser_typed_bytestring + bser_typed_utf8string_byte +
            bser_typed_mixedstring_byte),
    std::make_tuple(
        2,
        BSER_CAP_DISABLE_UNICODE_FOR_ERRORS,
        bser_typed_intro + bser_typed_bytestring + bser_typed_utf8string_utf8 +
            bser_typed_mixedstring_byte),

    std::make_tuple(
        2,
        BSER_CAP_DISABLE_UNICODE | BSER_CAP_DISABLE_UNICODE_FOR_ERRORS,
        bser_typed_intro + bser_typed_bytestring + bser_typed_utf8string_byte +
            bser_typed_mixedstring_byte)};

void check_bser_typed_strings() {
  auto bytestring = typed_string_to_json("foo\xd0\xff", W_STRING_BYTE);
  auto utf8string =
      typed_string_to_json("bar" UTF8_PILE_OF_POO, W_STRING_UNICODE);
  // This consists of
  // - ASCII (valid)
  // - bare continuation byte 0xB1 (invalid)
  // - overlong encoding of an ASCII byte 0xC1 (invalid)
  // - 3 byte sequence with valid start (0xE0 0x90) but an invalid byte (0x40)
  // - 4 byte sequence (valid)
  // - 4 byte sequence (0xF4) past the end of the string (invalid)
  auto mixedstring = typed_string_to_json(
      "baz\xb1\xc1\xe0\x90\x40" UTF8_PILE_OF_POO "\xf4\xff", W_STRING_MIXED);

  auto str_array = json_array({bytestring, utf8string, mixedstring});

  // check that this gets serialized correctly
  for (const auto& t : typed_string_checks) {
    uint32_t bser_version = std::get<0>(t);
    uint32_t bser_capabilities = std::get<1>(t);
    const std::string& bser_out = std::get<2>(t);
    XLOG(ERR) << "testing BSER version " << bser_version << ", capabilities "
              << bser_capabilities;

    auto bser_buf = bdumps(bser_version, bser_capabilities, str_array);
    EXPECT_EQ(*bser_buf, bser_out);
  }
}

TEST(Bser, bser_tests) {
  int num_templ = sizeof(template_tests) / sizeof(template_tests[0]);
  int num_serial = sizeof(serialization_tests) / sizeof(serialization_tests[0]);

  for (auto& json_input : json_inputs) {
    fmt::print("json_input = {}\n", json_input);
    check_roundtrip(1, 0, json_input, nullptr);
    check_roundtrip(2, 0, json_input, nullptr);
    check_roundtrip(2, BSER_CAP_DISABLE_UNICODE, json_input, nullptr);
    check_roundtrip(
        2, BSER_CAP_DISABLE_UNICODE_FOR_ERRORS, json_input, nullptr);
    check_roundtrip(
        2,
        BSER_CAP_DISABLE_UNICODE | BSER_CAP_DISABLE_UNICODE_FOR_ERRORS,
        json_input,
        nullptr);
  }

  for (int i = 0; i < num_templ; i++) {
    check_roundtrip(
        1, 0, template_tests[i].json_text, template_tests[i].template_text);
    check_roundtrip(
        2, 0, template_tests[i].json_text, template_tests[i].template_text);
    check_roundtrip(
        2,
        BSER_CAP_DISABLE_UNICODE,
        template_tests[i].json_text,
        template_tests[i].template_text);
    check_roundtrip(
        2,
        BSER_CAP_DISABLE_UNICODE_FOR_ERRORS,
        template_tests[i].json_text,
        template_tests[i].template_text);
    check_roundtrip(
        2,
        BSER_CAP_DISABLE_UNICODE | BSER_CAP_DISABLE_UNICODE_FOR_ERRORS,
        template_tests[i].json_text,
        template_tests[i].template_text);
  }

  for (int i = 0; i < num_serial; i++) {
    check_serialization(
        1, 0, serialization_tests[i].json_text, serialization_tests[i].bserv1);
    check_serialization(
        2, 0, serialization_tests[i].json_text, serialization_tests[i].bserv2);
  }

  check_bser_typed_strings();
}

TEST(Bser, bunser_int_returns_needed) {
  size_t needed;

  // Work around a bug in googletest 1.11 (Ubuntu 22.04) on gcc 11.2.
  // https://github.com/google/googletest/issues/3384
  auto nullopt = std::optional<json_int_t>{};

  EXPECT_EQ(nullopt, bunser_int(nullptr, 0, &needed));
  EXPECT_EQ(1, needed);
  EXPECT_EQ(nullopt, bunser_int("\x03", 1, &needed));
  EXPECT_EQ(2, needed);
  EXPECT_EQ(nullopt, bunser_int("\x04", 1, &needed));
  EXPECT_EQ(3, needed);
  EXPECT_EQ(nullopt, bunser_int("\x05", 1, &needed));
  EXPECT_EQ(5, needed);
  EXPECT_EQ(nullopt, bunser_int("\x06", 1, &needed));
  EXPECT_EQ(9, needed);

  EXPECT_EQ(nullopt, bunser_int("\x00", 1, &needed));
  EXPECT_EQ(kDecodeIntFailed, needed);
}

// NOTE: The returned pointer may not be aligned.
using Alloc = std::unique_ptr<char[], std::function<void(void*)>>;

Alloc normal_malloc(size_t size) {
  void* p = malloc(size);
  if (!p) {
    throw std::bad_alloc{};
  }

  return {reinterpret_cast<char*>(p), &free};
}

#ifdef _WIN32

size_t get_page_size() {
  SYSTEM_INFO si{};
  GetSystemInfo(&si);
  return si.dwAllocationGranularity;
}

std::tuple<void*, size_t> allocate_pages(size_t size) {
  static size_t page_size = get_page_size();
  size_t actual_size = (size + (page_size - 1)) / page_size * page_size;

  // TODO: We should explicitly allocate guard pages at either side.
  void* p = VirtualAlloc(nullptr, actual_size, MEM_COMMIT, PAGE_READWRITE);
  if (!p) {
    throw std::bad_alloc{};
  }

  return {p, actual_size};
}

void deallocate_pages(void* p, size_t actual_size) {
  VirtualFree(p, actual_size, MEM_RELEASE);
}

#else

std::tuple<void*, size_t> allocate_pages(size_t size) {
  static size_t page_size = sysconf(_SC_PAGE_SIZE);
  size_t actual_size = (size + (page_size - 1)) / page_size * page_size;

  // TODO: We should explicitly allocate guard pages at either side.
  // But, so far, ASAN does a pretty good job of catching overflows.
  void* p = mmap(
      nullptr,
      actual_size,
      PROT_READ | PROT_WRITE,
      MAP_PRIVATE | MAP_ANONYMOUS,
      -1,
      0);
  if (p == MAP_FAILED) {
    perror("mmap failed");
    throw std::bad_alloc{};
  }
  return {p, actual_size};
}

void deallocate_pages(void* p, size_t actual_size) {
  munmap(p, actual_size);
}

#endif

Alloc page_head(size_t size) {
  auto [p, actual_size] = allocate_pages(size);
  return {
      reinterpret_cast<char*>(p), [p = p, actual_size = actual_size](void*) {
        deallocate_pages(p, actual_size);
      }};
}

Alloc page_tail(size_t size) {
  auto [p, actual_size] = allocate_pages(size);
  return {
      reinterpret_cast<char*>(p) + (actual_size - size),
      [p = p, actual_size = actual_size](void*) {
        deallocate_pages(p, actual_size);
      }};
}

using AllocFn = Alloc (*)(size_t);

// In local testing, I observed ASAN occasionally missing an overflow. To
// provide an additional chance of catching them, allocate the test data at the
// head and at the tail of a page.
constexpr AllocFn allAllocators[] = {
    page_tail,
    page_head,
    normal_malloc,
};

// Work around the fact that std::string_view{"\0"} has size() of 0.
template <size_t N>
std::string_view literal(const char (&p)[N]) {
  static_assert(N > 0);
  return std::string_view{p, N - 1};
}

TEST(Bser, fuzz_examples) {
  std::string_view corpus[] = {
      literal("\x08"),
      literal("\x00"),
      literal("\x00\x00"),
      literal("\x02"),
      literal("\x0b"),
      literal("\x01\x04\x2f\x01"),
      literal("\x07\xb3\xb3\x40\x3a\xb3\xb3\xb3"),
      literal("\x0b\x00\x04\x02\x00\x04\x02\x41\x08\x05\x02\xff\x01\x00"),
      literal("\x0b\x00\x03\x01\x04\x03\x00\x03\x01\x04\x03\x00"),
      literal("\x04\x00\xd2\x06\xd2\x04\xff\xff\xff\xff\x04\x00"
              "\xd2\x06\xd2\x04\xff\xff\xff\xff\xff\xff\xff"),
      literal("\x0b\x00\x03\xee\x06\x00\x00\x00\x00\x00\x00\x00\x01\x00"),
      literal("\x00\x06\x7f\xff\xff\xff\xff\xff\xff\xff"),
      literal("\x00\x06\xff\xff\xff\xff\xff\xff\xff\xff"),
      literal("\x02\x03\xf4"),
      literal("\x07\x00\xff\xff\x0a\x00\xff\xff\xff"),
      literal("\x02\x06\xff\xff\xff\xff\xff\xff\xff\xff"),
      literal("\x00\x05\xc6\x05\x05\x05\x05\x05\x05\x05\x05\x05\xee\x04\x05\x05"
              "\x05\x05\x05\x01\x05\x04\xf6\x05\x05\x05\x05\x05\x05\x05\x05\x05"
              "\x05\x05\x05\x05\x05\x05\x0b\x00\x03\x00\x05\x05\x05\x05\x05\x05"
              "\x05\x05\x05\x19\x05\x05\x05\x05\x01\x05\x05\x05\x05\x05\x05\x05"
              "\x05\x05\x05\x05\x05\x05\x05\x05\x05\x05\x05\x05\xe6\x05\x05\x05"
              "\x05\x05\x05\x01\x05\x04\xf6\x05\x05\x05\x05\x05\x05\x05\x05\x05"
              "\x05\x05\x05\x05\x05\x05\x0b\x00\x03\x00\x05\x05\x05\x05\x05\x05"
              "\x05\x05\x05\x19\x05\x05\x05\x05\x01\x05\x05\x05\x05\x05\x05\x05"
              "\x05\x05\x05\x05\x05\x05\x05\x05\x05\x05\x05\x05\xe6\x05\x05\x05"
              "\x05\x05\x05\x05\x05\x05\x21\x05\x05\x05\x05\x05\x05\x05\x21\x05"
              "\x05\x05\x05\x05"),
  };
  for (std::string_view input : corpus) {
    for (auto allocator : allAllocators) {
      CHECK_NE(0, input.size());

      // Make a non-null-terminated, heap-allocated input. This helps ASAN catch
      // any overflows.
      auto data = allocator(input.size());
      memcpy(data.get(), input.data(), input.size());

      try {
        bunser(data.get(), data.get() + input.size());
      } catch (const BserParseError&) {
      }
    }
  }
}

TEST(Bser, detect_array_stack_overflow) {
  const std::string_view rec{"\x00\x03\x01", 3};
  const size_t N = 1000;
  std::string str;
  str.reserve(N * rec.size());
  for (size_t i = 0; i < N; ++i) {
    str += rec;
  }
  EXPECT_THROW((bunser(str.data(), str.data() + str.size())), BserParseTooDeep);
}

} // namespace
