OS lb-6

semester-4/ОС/lb-6/src/.clangd

@@ -0,0 +1,17 @@
+CompileFlags:
+  Add: [-Wall, -Wextra, -std=c++23, -DBUILD_SHARED]
+  CompilationDatabase: build/
+
+Diagnostics:
+  UnusedIncludes: Strict
+
+InlayHints:
+  Enabled: Yes
+  ParameterNames: Yes
+  DeducedTypes: Yes
+
+Index:
+  Background: Build
+
+Hover:
+  ShowAKA: Yes

semester-4/ОС/lb-6/src/Makefile

@@ -0,0 +1,15 @@
+CXX      := clang++
+CXXFLAGS := -std=c++23 -Iinclude -Wall -Wextra
+LDFLAGS  := -lcrypto
+
+TARGET   := build/app
+SRC      := main.cpp
+
+.PHONY: all clean
+
+all:
+	@mkdir -p $(dir $(TARGET))
+	@$(CXX) $(CXXFLAGS) $(SRC) -o $(TARGET) $(LDFLAGS)
+
+clean:
+	rm -rf build

semester-4/ОС/lb-6/src/include/cache.hpp

@@ -0,0 +1,37 @@
+#pragma once
+
+#ifndef CACHE_LRU_HPP
+  #define CACHE_LRU_HPP
+
+  #include <cstdint>
+  #include <list>
+  #include <unordered_map>
+  #include <vector>
+
+namespace cache {
+
+class lru {
+public:
+  lru(int32_t line_count, int32_t associativity);
+  ~lru() = default;
+
+  bool access(uint64_t address);
+
+private:
+  struct block_entry {
+    uint64_t tag;
+  };
+
+  int32_t _lines;
+  int32_t _assoc;
+
+  std::vector<std::list<block_entry>> _cache_lines;
+  std::vector<std::unordered_map<uint64_t, std::list<block_entry>::iterator>>
+      _lookup;
+};
+
+} // namespace cache
+
+  #include "../src/cache.cpp"
+
+#endif

semester-4/ОС/lb-6/src/include/locked_buffer.hpp

@@ -0,0 +1,84 @@
+#pragma once
+
+#ifndef SEC_LOCKED_BUFFER_HPP
+  #define SEC_LOCKED_BUFFER_HPP
+
+  #include <cstdlib>
+  #include <cstring>
+  #include <stdexcept>
+  #include <sys/mman.h>
+  #include <unistd.h>
+
+namespace sec {
+
+template <typename T, std::size_t N> class locked_buffer {
+public:
+  locked_buffer() {
+    this->size_ = N * sizeof(T);
+    this->ptr_ = static_cast<T *>(std::malloc(this->size_));
+    if (!this->ptr_)
+      throw std::bad_alloc();
+    if (mlock(this->ptr_, this->size_) != 0) {
+      std::free(this->ptr_);
+      throw std::runtime_error("mlock failed");
+    }
+  }
+
+  ~locked_buffer() noexcept {
+    cleanse();
+    if (this->ptr_) {
+      munlock(this->ptr_, this->size_);
+      std::free(this->ptr_);
+    }
+  }
+
+  locked_buffer(const locked_buffer &) = delete;
+  locked_buffer &operator=(const locked_buffer &) = delete;
+
+  locked_buffer(locked_buffer &&other) noexcept
+      : ptr_(other.ptr_), size_(other.size_) {
+    other.ptr_ = nullptr;
+    other.size_ = 0;
+  }
+
+  locked_buffer &operator=(locked_buffer &&other) noexcept {
+    if (this != &other) {
+      cleanse();
+      if (this->ptr_) {
+        munlock(this->ptr_, this->size_);
+        std::free(this->ptr_);
+      }
+      this->ptr_ = other.ptr_;
+      this->size_ = other.size_;
+      other.ptr_ = nullptr;
+      other.size_ = 0;
+    }
+    return *this;
+  }
+
+  T *data() noexcept { return this->ptr_; }
+  const T *data() const noexcept { return this->ptr_; }
+  std::size_t size() const noexcept { return N; }
+
+  T &operator[](std::size_t i) { return this->ptr_[i]; }
+  const T &operator[](std::size_t i) const { return this->ptr_[i]; }
+
+  T *begin() noexcept { return this->ptr_; }
+  T *end() noexcept { return this->ptr_ + N; }
+  const T *begin() const noexcept { return this->ptr_; }
+  const T *end() const noexcept { return this->ptr_ + N; }
+
+private:
+  void cleanse() noexcept {
+    if (this->ptr_) {
+      std::memset(this->ptr_, 0, this->size_);
+    }
+  }
+
+  T *ptr_{nullptr};
+  std::size_t size_{0};
+};
+
+} // namespace sec
+
+#endif

semester-4/ОС/lb-6/src/include/paging.hpp

@@ -0,0 +1,44 @@
+#pragma once
+
+#ifndef PAGE_REPLACEMENT_HPP
+  #define PAGE_REPLACEMENT_HPP
+
+  #include <cstdint>
+  #include <vector>
+
+namespace paging {
+
+class replacer {
+public:
+  explicit replacer(int32_t frame_count) : _frames(frame_count) {}
+  virtual ~replacer() = default;
+
+  virtual int32_t run(const std::vector<int32_t> &pages) = 0;
+
+protected:
+  int32_t _frames;
+};
+
+class optimal_replacer : public replacer {
+public:
+  using replacer::replacer;
+  int32_t run(const std::vector<int32_t> &pages) override;
+};
+
+class clock_replacer : public replacer {
+public:
+  using replacer::replacer;
+  int32_t run(const std::vector<int32_t> &pages) override;
+};
+
+class lru_replacer : public replacer {
+public:
+  using replacer::replacer;
+  int32_t run(const std::vector<int32_t> &pages) override;
+};
+
+} // namespace paging
+
+  #include "../src/paging.cpp"
+
+#endif

semester-4/ОС/lb-6/src/include/password.hpp

@@ -0,0 +1,68 @@
+#pragma once
+
+#ifndef PASSWORD_HPP
+  #define PASSWORD_HPP
+
+  #include <cstdint>
+  #include <string>
+  #include <string_view>
+
+  #include "locked_buffer.hpp"
+
+namespace sec {
+
+enum class strength_t : uint8_t {
+  very_weak = 0,
+  weak,
+  moderate,
+  strong,
+  very_strong
+};
+
+class password_hash;
+
+class password {
+public:
+  explicit password(std::string pass);
+
+  std::string_view view() const noexcept;
+
+  static sec::password from_console();
+  static sec::password from_string(const std::string &pass);
+
+  sec::password_hash to_hash() const;
+
+private:
+  sec::locked_buffer<char, 128> _buf;
+  std::size_t _len{};
+};
+
+class password_hash {
+public:
+  explicit password_hash(std::string hash);
+  const std::string &get() const noexcept;
+
+  bool verify(const sec::password &pwd) const;
+
+private:
+  std::string _hash;
+};
+
+class manager {
+public:
+  static bool has_lower(const sec::password &pwd);
+  static bool has_upper(const sec::password &pwd);
+  static bool has_digit(const sec::password &pwd);
+  static bool has_spec_symbol(const sec::password &pwd);
+
+  static std::string hash_password(const sec::password &pwd);
+  static sec::strength_t evaluate_strength(const sec::password &pwd);
+  static uint64_t time_to_crack(const sec::password &pwd);
+  static std::string format_duration(uint64_t seconds);
+};
+
+} // namespace sec
+
+  #include "../src/password.cpp"
+
+#endif

semester-4/ОС/lb-6/src/main.cpp

@@ -0,0 +1,73 @@
+#include <iostream>
+#include <print>
+#include <vector>
+
+#include "include/cache.hpp"
+#include "include/paging.hpp"
+#include "include/password.hpp"
+
+#include <openssl/sha.h>
+
+int main() {
+  std::vector<int> pages = {7, 0, 1, 2, 0, 3, 0, 4, 2, 3, 0, 3};
+  int frames = 3;
+
+  paging::optimal_replacer opt(frames);
+  paging::clock_replacer clk(frames);
+  paging::lru_replacer lru(frames);
+
+  std::println("Optimal faults: {}", opt.run(pages));
+  std::println("Clock   faults: {}", clk.run(pages));
+  std::println("LRU     faults: {}", lru.run(pages));
+
+  std::println("\nCache LRU Simulation:");
+  cache::lru cache(128, 4);
+  std::vector<uint64_t> addresses = {
+      0, 1024, 2048, 3072, 4096, 5120, 6144, 7168, 8192,
+  };
+  int32_t hits = 0, misses = 0;
+  for (auto addr : addresses) {
+    if (cache.access(addr)) {
+      ++hits;
+      std::println("Address 0x{:x}:\t HIT", addr);
+    } else {
+      ++misses;
+      std::println("Address 0x{:x}:\t MISS", addr);
+    }
+  }
+  std::println("Hits: {}, Misses: {}\n", hits, misses);
+
+  auto pwd = sec::password::from_console();
+  auto strength = sec::manager::evaluate_strength(pwd);
+  auto crack_time = sec::manager::time_to_crack(pwd);
+  auto crack_str = sec::manager::format_duration(crack_time);
+
+  std::print("Password strength: ");
+  switch (strength) {
+  case sec::strength_t::very_weak:
+    std::print("Very Weak");
+    break;
+  case sec::strength_t::weak:
+    std::print("Weak");
+    break;
+  case sec::strength_t::moderate:
+    std::print("Moderate");
+    break;
+  case sec::strength_t::strong:
+    std::print("Strong");
+    break;
+  case sec::strength_t::very_strong:
+    std::print("Very Strong");
+    break;
+  }
+  std::print("\nEstimated time to crack: {} secs\n({})\n", crack_time,
+             crack_str);
+
+  std::string input;
+  std::print("\nEnter password to verify: ");
+  std::getline(std::cin, input);
+  auto input_pwd = sec::password::from_string(input);
+  if (pwd.to_hash().verify(input_pwd)) {
+    std::print("Password verified successfully.\n");
+  }
+}

semester-4/ОС/lb-6/src/src/cache.cpp

@@ -0,0 +1,38 @@
+#pragma once
+
+#include "../include/cache.hpp"
+
+#include <cmath>
+
+namespace cache {
+
+cache::lru::lru(int32_t line_count, int32_t associativity)
+    : _lines(line_count), _assoc(associativity), _cache_lines(line_count),
+      _lookup(line_count) {}
+
+bool cache::lru::access(uint64_t address) {
+  uint64_t line = (address >> 6) % this->_lines;
+  uint64_t tag =
+      address >> (6 + static_cast<uint64_t>(std::log2(this->_lines)));
+
+  auto &line_list = this->_cache_lines[line];
+  auto &line_map = this->_lookup[line];
+
+  auto it = line_map.find(tag);
+  if (it != line_map.end()) {
+    line_list.splice(line_list.begin(), line_list, it->second);
+    line_map[tag] = line_list.begin();
+    return true;
+  }
+
+  if (static_cast<int32_t>(line_list.size()) >= this->_assoc) {
+    auto last = line_list.back();
+    line_map.erase(last.tag);
+    line_list.pop_back();
+  }
+  line_list.push_front({tag});
+  line_map[tag] = line_list.begin();
+  return false;
+}
+
+} // namespace cache

semester-4/ОС/lb-6/src/src/paging.cpp

@@ -0,0 +1,115 @@
+#pragma once
+
+#include "../include/paging.hpp"
+
+#include <algorithm>
+#include <limits>
+#include <ranges>
+#include <unordered_map>
+
+namespace paging {
+
+int32_t paging::optimal_replacer::run(const std::vector<int32_t> &pages) {
+  int32_t faults = 0;
+  std::vector<int32_t> frames;
+  frames.reserve(static_cast<size_t>(this->_frames));
+  for (size_t i : std::views::iota(size_t(0), pages.size())) {
+    int32_t p = pages[i];
+    if (std::find(frames.begin(), frames.end(), p) != frames.end())
+      continue;
+    ++faults;
+    if (static_cast<int32_t>(frames.size()) < this->_frames) {
+      frames.push_back(p);
+    } else {
+      int32_t idx_to_replace = 0;
+      size_t farthest = 0;
+      for (int32_t j : std::views::iota(0, this->_frames)) {
+        size_t k = i + 1;
+        while (k < pages.size() && pages[k] != frames[j])
+          ++k;
+        size_t dist =
+            (k < pages.size() ? k : std::numeric_limits<size_t>::max());
+        if (dist > farthest) {
+          farthest = dist;
+          idx_to_replace = j;
+        }
+      }
+      frames[idx_to_replace] = p;
+    }
+  }
+  return faults;
+}
+
+int32_t paging::clock_replacer::run(const std::vector<int32_t> &pages) {
+  int32_t faults = 0;
+  struct entry {
+    int32_t page;
+    bool ref;
+  };
+  std::vector<entry> frames;
+  frames.reserve(static_cast<size_t>(this->_frames));
+  int32_t hand = 0;
+
+  for (int32_t p : pages) {
+    bool hit = false;
+    for (auto &e : frames) {
+      if (e.page == p) {
+        e.ref = true;
+        hit = true;
+        break;
+      }
+    }
+    if (hit)
+      continue;
+    ++faults;
+    if (static_cast<int32_t>(frames.size()) < this->_frames) {
+      frames.push_back({p, true});
+    } else {
+      while (true) {
+        if (!frames[hand].ref) {
+          frames[hand] = {p, true};
+          hand = (hand + 1) % this->_frames;
+          break;
+        }
+        frames[hand].ref = false;
+        hand = (hand + 1) % this->_frames;
+      }
+    }
+  }
+  return faults;
+}
+
+int32_t paging::lru_replacer::run(const std::vector<int32_t> &pages) {
+  int32_t faults = 0;
+  std::vector<int32_t> frames;
+  std::unordered_map<int32_t, int32_t> last_used;
+  frames.reserve(static_cast<size_t>(this->_frames));
+
+  for (int32_t i : std::views::iota(0, static_cast<int32_t>(pages.size()))) {
+    int32_t p = pages[i];
+    if (std::find(frames.begin(), frames.end(), p) != frames.end()) {
+      last_used[p] = i;
+      continue;
+    }
+    ++faults;
+    if (static_cast<int32_t>(frames.size()) < this->_frames) {
+      frames.push_back(p);
+    } else {
+      int32_t lru_page = frames[0];
+      int32_t min_idx = last_used[lru_page];
+      for (int32_t q : frames) {
+        if (last_used[q] < min_idx) {
+          min_idx = last_used[q];
+          lru_page = q;
+        }
+      }
+      auto it = std::find(frames.begin(), frames.end(), lru_page);
+      if (it != frames.end())
+        *it = p;
+    }
+    last_used[p] = i;
+  }
+  return faults;
+}
+
+} // namespace paging

semester-4/ОС/lb-6/src/src/password.cpp

@@ -0,0 +1,151 @@
+#pragma once
+
+#include "../include/password.hpp"
+
+#include <algorithm>
+#include <cmath>
+#include <iomanip>
+#include <iostream>
+#include <openssl/sha.h>
+#include <print>
+#include <ranges>
+#include <sstream>
+
+namespace sec {
+
+sec::password::password(std::string pass) {
+  if (pass.size() > _buf.size()) {
+    throw std::length_error("Password too long");
+  }
+  _len = pass.size();
+  std::copy(pass.data(), pass.data() + _len, _buf.begin());
+}
+
+std::string_view sec::password::view() const noexcept {
+  return std::string_view(_buf.data(), _len);
+}
+
+sec::password sec::password::from_console() {
+  std::string p1, p2;
+  while (true) {
+    std::print("Enter password: ");
+    std::getline(std::cin, p1);
+    std::print("Re-enter password: ");
+    std::getline(std::cin, p2);
+    if (p1 != p2) {
+      std::print("Passwords do not match. Try again.\n");
+      continue;
+    }
+    if (sec::manager::evaluate_strength(sec::password(p1)) ==
+        sec::strength_t::very_weak) {
+      std::print("Password is too weak. Try again.\n");
+      continue;
+    }
+    break;
+  }
+  return sec::password(p1);
+}
+
+sec::password sec::password::from_string(const std::string &pass) {
+  if (sec::manager::evaluate_strength(sec::password(pass)) ==
+      sec::strength_t::very_weak) {
+    std::print("Password is too weak. Try again.\n\n");
+    throw std::invalid_argument("Weak password");
+  }
+  return sec::password(pass);
+}
+
+sec::password_hash::password_hash(std::string hash) : _hash(std::move(hash)) {}
+
+const std::string &sec::password_hash::get() const noexcept { return _hash; }
+
+bool sec::password_hash::verify(const sec::password &pwd) const {
+  return sec::manager::hash_password(pwd) == _hash;
+}
+
+sec::password_hash sec::password::to_hash() const {
+  return sec::password_hash(sec::manager::hash_password(*this));
+}
+
+bool sec::manager::has_lower(const sec::password &pwd) {
+  auto sv = pwd.view();
+  return std::any_of(sv.begin(), sv.end(), ::islower);
+}
+
+bool sec::manager::has_upper(const sec::password &pwd) {
+  auto sv = pwd.view();
+  return std::any_of(sv.begin(), sv.end(), ::isupper);
+}
+
+bool sec::manager::has_digit(const sec::password &pwd) {
+  auto sv = pwd.view();
+  return std::any_of(sv.begin(), sv.end(), ::isdigit);
+}
+
+bool sec::manager::has_spec_symbol(const sec::password &pwd) {
+  auto sv = pwd.view();
+  return std::any_of(sv.begin(), sv.end(),
+                     [](unsigned char c) { return std::ispunct(c); });
+}
+
+sec::strength_t sec::manager::evaluate_strength(const sec::password &pwd) {
+  uint8_t score = 0;
+
+  if (has_lower(pwd))
+    ++score;
+  if (has_upper(pwd))
+    ++score;
+  if (has_digit(pwd))
+    ++score;
+  if (has_spec_symbol(pwd))
+    ++score;
+  if (pwd.view().size() >= 8)
+    ++score;
+
+  if (score != 0)
+    score--;
+
+  uint8_t max_val = static_cast<uint8_t>(sec::strength_t::very_strong);
+  uint8_t idx = std::min(score, max_val);
+
+  return static_cast<sec::strength_t>(idx);
+}
+
+uint64_t sec::manager::time_to_crack(const sec::password &pwd) {
+  auto sv = pwd.view();
+  if (sv.empty())
+    return 0;
+  int charset = (has_lower(pwd) ? 26 : 0) + (has_upper(pwd) ? 26 : 0) +
+                (has_digit(pwd) ? 10 : 0) + (has_spec_symbol(pwd) ? 33 : 0);
+  constexpr double RATE = 1e7;
+  double combos = std::pow(static_cast<double>(charset), sv.size());
+  return static_cast<uint64_t>(combos / 2.0 / RATE);
+}
+
+std::string sec::manager::format_duration(uint64_t seconds) {
+  const uint64_t u[] = {31536000, 2592000, 86400, 3600, 60, 1};
+  const char *lbl[] = {"years", "months", "days", "hours", "mins", "secs"};
+  std::string s;
+  for (int i : std::views::iota(0, 6)) {
+    uint64_t v = seconds / u[i];
+    if (v) {
+      s += std::to_string(v) + " " + lbl[i] + ((i == 5) ? "" : " ");
+      seconds %= u[i];
+    }
+  }
+  return s.empty() ? "0 secs" : s;
+}
+
+std::string sec::manager::hash_password(const sec::password &pwd) {
+  auto sv = pwd.view();
+  unsigned char hash[SHA256_DIGEST_LENGTH];
+  SHA256(reinterpret_cast<const unsigned char *>(sv.data()), sv.size(), hash);
+  std::ostringstream oss;
+  for (int32_t i : std::views::iota(0, SHA256_DIGEST_LENGTH)) {
+    oss << std::hex << std::setw(2) << std::setfill('0')
+        << static_cast<int32_t>(hash[i]);
+  }
+  return oss.str();
+}
+
+} // namespace sec