connection.hxx

/* Definition of the connection class.
 *
 * pqxx::connection encapsulates a connection to a database.
 *
 * DO NOT INCLUDE THIS FILE DIRECTLY; include pqxx/connection instead.
 *
 * Copyright (c) 2000-2022, Jeroen T. Vermeulen.
 *
 * See COPYING for copyright license.  If you did not receive a file called
 * COPYING with this source code, please notify the distributor of this
 * mistake, or contact the author.
 */
#ifndef PQXX_H_CONNECTION
#define PQXX_H_CONNECTION

#include <cstddef>
#include <ctime>
#include <functional>
#include <initializer_list>
#include <list>
#include <map>
#include <memory>
#include <string_view>
#include <tuple>

// Double-check in order to suppress an overzealous Visual C++ warning (#418).
#if defined(PQXX_HAVE_CONCEPTS) && __has_include(<ranges>)
#  include <ranges>
#endif

#include "pqxx/errorhandler.hxx"
#include "pqxx/except.hxx"
#include "pqxx/internal/concat.hxx"
#include "pqxx/params.hxx"
#include "pqxx/separated_list.hxx"
#include "pqxx/strconv.hxx"
#include "pqxx/types.hxx"
#include "pqxx/util.hxx"
#include "pqxx/zview.hxx"


namespace pqxx::internal
{
class sql_cursor;

#if defined(PQXX_HAVE_CONCEPTS)
template<typename T>
concept ZKey_ZValues = std::ranges::input_range<T> and requires(T t)
{
  {std::cbegin(t)};
  {
    std::get<0>(*std::cbegin(t))
    } -> ZString;
  {
    std::get<1>(*std::cbegin(t))
    } -> ZString;
} and std::tuple_size_v<typename std::ranges::iterator_t<T>::value_type>
== 2;
#endif // PQXX_HAVE_CONCEPTS
} // namespace pqxx::internal


namespace pqxx::internal::gate
{
class connection_dbtransaction;
class connection_errorhandler;
class connection_largeobject;
class connection_notification_receiver;
class connection_pipeline;
class connection_sql_cursor;
class connection_stream_from;
class connection_stream_to;
class connection_transaction;
class const_connection_largeobject;
} // namespace pqxx::internal::gate


namespace pqxx
{

using table_path = std::initializer_list<std::string_view>;


[[nodiscard,
  deprecated("Use connection::encrypt_password instead.")]] std::string
  PQXX_LIBEXPORT
  encrypt_password(char const user[], char const password[]);

[[nodiscard,
  deprecated("Use connection::encrypt_password instead.")]] inline std::string
encrypt_password(zview user, zview password)
{
#include "pqxx/internal/ignore-deprecated-pre.hxx"
  return encrypt_password(user.c_str(), password.c_str());
#include "pqxx/internal/ignore-deprecated-post.hxx"
}


enum class error_verbosity : int
{
  // These values must match those in libpq's PGVerbosity enum.
  terse = 0,
  normal = 1,
  verbose = 2
};



class PQXX_LIBEXPORT connection
{
public:
  connection() : connection{""} {}

  explicit connection(char const options[])
  {
    check_version();
    init(options);
  }

  explicit connection(zview options) : connection{options.c_str()}
  {
    // (Delegates to other constructor which calls check_version for us.)
  }


  connection(connection &&rhs);

#if defined(PQXX_HAVE_CONCEPTS)

  template<internal::ZKey_ZValues MAPPING>
  inline connection(MAPPING const &params);
#endif // PQXX_HAVE_CONCEPTS

  ~connection()
  {
    try
    {
      close();
    }
    catch (std::exception const &)
    {}
  }


  connection &operator=(connection &&rhs);

  connection(connection const &) = delete;
  connection &operator=(connection const &) = delete;


  [[nodiscard]] bool PQXX_PURE is_open() const noexcept;

  void process_notice(char const[]) noexcept;

  void process_notice(zview) noexcept;

  void trace(std::FILE *) noexcept;

  [[nodiscard]] char const *dbname() const;

  [[nodiscard]] char const *username() const;

  [[nodiscard]] char const *hostname() const;

  [[nodiscard]] char const *port() const;

  [[nodiscard]] int PQXX_PURE backendpid() const &noexcept;


  [[nodiscard]] int PQXX_PURE sock() const &noexcept;


  [[nodiscard]] int PQXX_PURE protocol_version() const noexcept;


  [[nodiscard]] int PQXX_PURE server_version() const noexcept;


  [[nodiscard]] std::string get_client_encoding() const;


  void set_client_encoding(zview encoding) &
  {
    set_client_encoding(encoding.c_str());
  }


  void set_client_encoding(char const encoding[]) &;

  [[nodiscard]] int PQXX_PRIVATE encoding_id() const;



  void set_variable(std::string_view var, std::string_view value) &;


  std::string get_variable(std::string_view);



  int get_notifs();


  int await_notification();


  int await_notification(std::time_t seconds, long microseconds);

  [[nodiscard]] std::string
  encrypt_password(zview user, zview password, zview algorithm)
  {
    return encrypt_password(user.c_str(), password.c_str(), algorithm.c_str());
  }
  [[nodiscard]] std::string encrypt_password(
    char const user[], char const password[], char const *algorithm = nullptr);



  void prepare(zview name, zview definition) &
  {
    prepare(name.c_str(), definition.c_str());
  }

  void prepare(char const name[], char const definition[]) &;


  void prepare(char const definition[]) &;
  void prepare(zview definition) & { return prepare(definition.c_str()); }

  void unprepare(std::string_view name);



  [[nodiscard]] std::string adorn_name(std::string_view);



  [[deprecated("Use std::string_view or pqxx:zview.")]] std::string
  esc(char const text[], std::size_t maxlen) const
  {
    return esc(std::string_view{text, maxlen});
  }

  [[nodiscard]] std::string esc(char const text[]) const
  {
    return esc(std::string_view{text});
  }

#if defined(PQXX_HAVE_SPAN)

  [[nodiscard]] std::string_view
  esc(std::string_view text, std::span<char> buffer)
  {
    auto const size{std::size(text)}, space{std::size(buffer)};
    auto const needed{2 * size + 1};
    if (space < needed)
      throw range_error{internal::concat(
        "Not enough room to escape string of ", size, " byte(s): need ",
        needed, " bytes of buffer space, but buffer size is ", space, ".")};
    auto const data{buffer.data()};
    return {data, esc_to_buf(text, data)};
  }
#endif


  [[nodiscard]] std::string esc(std::string_view text) const;

#if defined(PQXX_HAVE_CONCEPTS)

  template<binary DATA> [[nodiscard]] std::string esc(DATA const &data) const
  {
    return esc_raw(data);
  }
#endif

#if defined(PQXX_HAVE_CONCEPTS) && defined(PQXX_HAVE_SPAN)

  template<binary DATA>
  [[nodiscard]] zview esc(DATA const &data, std::span<char> buffer) const
  {
    auto const size{std::size(data)}, space{std::size(buffer)};
    auto const needed{internal::size_esc_bin(std::size(data))};
    if (space < needed)
      throw range_error{internal::concat(
        "Not enough room to escape binary string of ", size, " byte(s): need ",
        needed, " bytes of buffer space, but buffer size is ", space, ".")};

    std::basic_string_view<std::byte> view{std::data(data), std::size(data)};
    auto const out{std::data(buffer)};
    // Actually, in the modern format, we know beforehand exactly how many
    // bytes we're going to fill.  Just leave out the trailing zero.
    internal::esc_bin(view, out);
    return zview{out, needed - 1};
  }
#endif

  [[deprecated("Use std::byte for binary data.")]] std::string
  esc_raw(unsigned char const bin[], std::size_t len) const;


  [[nodiscard]] std::string esc_raw(std::basic_string_view<std::byte>) const;

#if defined(PQXX_HAVE_SPAN)

  [[nodiscard]] std::string
  esc_raw(std::basic_string_view<std::byte>, std::span<char> buffer) const;
#endif

#if defined(PQXX_HAVE_CONCEPTS)

  template<binary DATA>
  [[nodiscard]] std::string esc_raw(DATA const &data) const
  {
    return esc_raw(
      std::basic_string_view<std::byte>{std::data(data), std::size(data)});
  }
#endif

#if defined(PQXX_HAVE_CONCEPTS) && defined(PQXX_HAVE_SPAN)
  template<binary DATA>
  [[nodiscard]] zview esc_raw(DATA const &data, std::span<char> buffer) const
  {
    return this->esc(binary_cast(data), buffer);
  }
#endif


  [[nodiscard, deprecated("Use unesc_bin() instead.")]] std::string
  unesc_raw(zview text) const
  {
#include "pqxx/internal/ignore-deprecated-pre.hxx"
    return unesc_raw(text.c_str());
#include "pqxx/internal/ignore-deprecated-post.hxx"
  }


  [[nodiscard, deprecated("Use unesc_bin() instead.")]] std::string
  unesc_raw(char const text[]) const;

  // TODO: Make "into buffer" variant to eliminate a string allocation.

  [[nodiscard]] std::basic_string<std::byte>
  unesc_bin(std::string_view text) const
  {
    std::basic_string<std::byte> buf;
    buf.resize(pqxx::internal::size_unesc_bin(std::size(text)));
    pqxx::internal::unesc_bin(text, buf.data());
    return buf;
  }

  [[deprecated("Use quote(std::basic_string_view<std::byte>).")]] std::string
  quote_raw(unsigned char const bin[], std::size_t len) const;

  std::string quote_raw(std::basic_string_view<std::byte>) const;

#if defined(PQXX_HAVE_CONCEPTS)

  template<binary DATA>
  [[nodiscard]] std::string quote_raw(DATA const &data) const
  {
    return quote_raw(
      std::basic_string_view<std::byte>{std::data(data), std::size(data)});
  }
#endif

  // TODO: Make "into buffer" variant to eliminate a string allocation.
  [[nodiscard]] std::string quote_name(std::string_view identifier) const;

  // TODO: Make "into buffer" variant to eliminate a string allocation.

  [[nodiscard]] std::string quote_table(std::string_view name) const;

  // TODO: Make "into buffer" variant to eliminate a string allocation.

  [[nodiscard]] std::string quote_table(table_path) const;

  // TODO: Make "into buffer" variant to eliminate a string allocation.

  template<PQXX_CHAR_STRINGS_ARG STRINGS>
  inline std::string quote_columns(STRINGS const &columns) const;

  // TODO: Make "into buffer" variant to eliminate a string allocation.

  template<typename T>
  [[nodiscard]] inline std::string quote(T const &t) const;

  [[deprecated("Use std::byte for binary data.")]] std::string
  quote(binarystring const &) const;

  // TODO: Make "into buffer" variant to eliminate a string allocation.
  [[nodiscard]] std::string
  quote(std::basic_string_view<std::byte> bytes) const;

  // TODO: Make "into buffer" variant to eliminate a string allocation.

  [[nodiscard]] std::string
  esc_like(std::string_view text, char escape_char = '\\') const;


  void cancel_query();

#if defined(_WIN32) || __has_include(<fcntl.h>)
  void set_blocking(bool block) &;
#endif // defined(_WIN32) || __has_include(<fcntl.h>)


  void set_verbosity(error_verbosity verbosity) &noexcept;


  [[nodiscard]] std::vector<errorhandler *> get_errorhandlers() const;


  [[nodiscard]] std::string connection_string() const;


  void close();

private:
  friend class connecting;
  enum connect_mode
  {
    connect_nonblocking
  };
  connection(connect_mode, zview connection_string);


  std::pair<bool, bool> poll_connect();

  // Initialise based on connection string.
  void init(char const options[]);
  // Initialise based on parameter names and values.
  void init(char const *params[], char const *values[]);
  void complete_init();

  result make_result(
    internal::pq::PGresult *pgr, std::shared_ptr<std::string> const &query,
    std::string_view desc = ""sv);

  void PQXX_PRIVATE set_up_state();

  int PQXX_PRIVATE PQXX_PURE status() const noexcept;


  std::size_t esc_to_buf(std::string_view text, char *buf) const;

  friend class internal::gate::const_connection_largeobject;
  char const *PQXX_PURE err_msg() const noexcept;

  void PQXX_PRIVATE process_notice_raw(char const msg[]) noexcept;

  result exec_prepared(std::string_view statement, internal::c_params const &);

  void check_movable() const;
  void check_overwritable() const;

  friend class internal::gate::connection_errorhandler;
  void PQXX_PRIVATE register_errorhandler(errorhandler *);
  void PQXX_PRIVATE unregister_errorhandler(errorhandler *) noexcept;

  friend class internal::gate::connection_transaction;
  result PQXX_PRIVATE exec(std::string_view, std::string_view = ""sv);
  result
    PQXX_PRIVATE exec(std::shared_ptr<std::string>, std::string_view = ""sv);
  void PQXX_PRIVATE register_transaction(transaction_base *);
  void PQXX_PRIVATE unregister_transaction(transaction_base *) noexcept;

  friend class internal::gate::connection_stream_from;
  std::pair<std::unique_ptr<char, std::function<void(char *)>>, std::size_t>
    PQXX_PRIVATE read_copy_line();

  friend class internal::gate::connection_stream_to;
  void PQXX_PRIVATE write_copy_line(std::string_view);
  void PQXX_PRIVATE end_copy_write();

  friend class internal::gate::connection_largeobject;
  internal::pq::PGconn *raw_connection() const { return m_conn; }

  friend class internal::gate::connection_notification_receiver;
  void add_receiver(notification_receiver *);
  void remove_receiver(notification_receiver *) noexcept;

  friend class internal::gate::connection_pipeline;
  void PQXX_PRIVATE start_exec(char const query[]);
  bool PQXX_PRIVATE consume_input() noexcept;
  bool PQXX_PRIVATE is_busy() const noexcept;
  internal::pq::PGresult *get_result();

  friend class internal::gate::connection_dbtransaction;
  friend class internal::gate::connection_sql_cursor;

  result exec_params(std::string_view query, internal::c_params const &args);

  internal::pq::PGconn *m_conn = nullptr;


  transaction_base const *m_trans = nullptr;

  std::list<errorhandler *> m_errorhandlers;

  using receiver_list =
    std::multimap<std::string, pqxx::notification_receiver *>;
  receiver_list m_receivers;

  int m_unique_id = 0;
};


using connection_base = connection;



class PQXX_LIBEXPORT connecting
{
public:
  connecting(zview connection_string = ""_zv);

  connecting(connecting const &) = delete;
  connecting(connecting &&) = default;
  connecting &operator=(connecting const &) = delete;
  connecting &operator=(connecting &&) = default;

  [[nodiscard]] int sock() const &noexcept { return m_conn.sock(); }

  [[nodiscard]] bool wait_to_read() const &noexcept { return m_reading; }

  [[nodiscard]] bool wait_to_write() const &noexcept { return m_writing; }

  void process() &;

  [[nodiscard]] bool done() const &noexcept
  {
    return not m_reading and not m_writing;
  }


  [[nodiscard]] connection produce() &&;

private:
  connection m_conn;
  bool m_reading{false};
  bool m_writing{true};
};


template<typename T> inline std::string connection::quote(T const &t) const
{
  if constexpr (nullness<T>::always_null)
  {
    return "NULL";
  }
  else
  {
    if (is_null(t))
      return "NULL";
    auto const text{to_string(t)};

    // Okay, there's an easy way to do this and there's a hard way.  The easy
    // way was "quote, esc(to_string(t)), quote".  I'm going with the hard way
    // because it's going to save some string manipulation that will probably
    // incur some unnecessary memory allocations and deallocations.
    std::string buf{'\''};
    buf.resize(2 + 2 * std::size(text) + 1);
    auto const content_bytes{esc_to_buf(text, buf.data() + 1)};
    auto const closing_quote{1 + content_bytes};
    buf[closing_quote] = '\'';
    auto const end{closing_quote + 1};
    buf.resize(end);
    return buf;
  }
}


template<PQXX_CHAR_STRINGS_ARG STRINGS>
inline std::string connection::quote_columns(STRINGS const &columns) const
{
  return separated_list(
    ","sv, std::cbegin(columns), std::cend(columns),
    [this](auto col) { return this->quote_name(*col); });
}


#if defined(PQXX_HAVE_CONCEPTS)
template<internal::ZKey_ZValues MAPPING>
inline connection::connection(MAPPING const &params)
{
  check_version();

  std::vector<char const *> keys, values;
  if constexpr (std::ranges::sized_range<MAPPING>)
  {
    auto const size{std::ranges::size(params) + 1};
    keys.reserve(size);
    values.reserve(size);
  }
  for (auto const &[key, value] : params)
  {
    keys.push_back(internal::as_c_string(key));
    values.push_back(internal::as_c_string(value));
  }
  keys.push_back(nullptr);
  values.push_back(nullptr);
  init(std::data(keys), std::data(values));
}
#endif // PQXX_HAVE_CONCEPTS
} // namespace pqxx


namespace pqxx::internal
{
PQXX_LIBEXPORT void wait_fd(
  int fd, bool for_read, bool for_write, unsigned seconds = 1,
  unsigned microseconds = 0);
} // namespace pqxx::internal
#endif