blob.hxx

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/* Binary Large Objects interface.
 *
 * Read or write large objects, stored in their own storage on the server.
 *
 * DO NOT INCLUDE THIS FILE DIRECTLY; include pqxx/largeobject instead.
 *
 * Copyright (c) 2000-2026, 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_BLOB_HXX
#define PQXX_BLOB_HXX
 
#if !defined(PQXX_HEADER_PRE)
#  error "Include libpqxx headers as <pqxx/header>, not <pqxx/header.hxx>."
#endif
 
#include <cstdint>
 
#include <ranges>
#include <span>
 
#include "pqxx/dbtransaction.hxx"
 
 
namespace pqxx
{
class PQXX_LIBEXPORT blob final
{
public:
 
  [[nodiscard]] static oid
  create(dbtransaction &, oid = 0, sl = sl::current());
 
  static void remove(dbtransaction &, oid, sl = sl::current());
 
  [[nodiscard]] static blob open_r(dbtransaction &, oid, sl = sl::current());
  // Open blob for writing.  Any attempt to read from it will fail.
  [[nodiscard]] static blob open_w(dbtransaction &, oid, sl = sl::current());
  // Open blob for reading and/or writing.
  [[nodiscard]] static blob open_rw(dbtransaction &, oid, sl = sl::current());
 
 
  blob() = default;
 
  blob(blob &&);
  blob &operator=(blob &&);
 
  blob(blob const &) = delete;
  blob &operator=(blob const &) = delete;
  ~blob();
 
 
  static constexpr std::size_t chunk_limit = 0x7fffffff;
 
 
  std::size_t read(bytes &buf, std::size_t size, sl = sl::current());
 
 
  template<std::size_t extent = std::dynamic_extent>
  writable_bytes_view
  read(std::span<std::byte, extent> buf, sl loc = sl::current())
  {
    return buf.first(raw_read(std::data(buf), std::size(buf), loc));
  }
 
 
  template<binary DATA>
  writable_bytes_view read(DATA &buf, sl loc = sl::current())
  {
    return {std::data(buf), raw_read(std::data(buf), std::size(buf), loc)};
  }
 
 
  template<binary DATA> void write(DATA const &data, sl loc = sl::current())
  {
    return raw_write(binary_cast(data), loc);
  }
 
 
  void resize(std::int64_t size, sl = sl::current());
 
  [[nodiscard]] std::int64_t tell(sl = sl::current()) const;
 
 
  std::int64_t seek_abs(std::int64_t offset = 0, sl = sl::current());
 
 
  std::int64_t seek_rel(std::int64_t offset = 0, sl = sl::current());
 
 
  std::int64_t seek_end(std::int64_t offset = 0, sl = sl::current());
 
 
  static oid
  from_buf(dbtransaction &tx, bytes_view data, oid id = 0, sl = sl::current());
 
 
  template<binary DATA>
  static oid from_buf(
    dbtransaction &tx, DATA const &data, oid id = 0, sl loc = sl::current())
  {
    return from_buf(tx, binary_cast(data), id, loc);
  }
 
 
  static void append_from_buf(
    dbtransaction &tx, bytes_view data, oid id, sl = sl::current());
 
 
  template<binary DATA>
  static void append_from_buf(
    dbtransaction &tx, DATA const &data, oid id, sl loc = sl::current())
  {
    append_from_buf(tx, binary_cast(data), id, loc);
  }
 
  [[nodiscard]] static oid
  from_file(dbtransaction &, zview path, sl = sl::current());
 
 
  static oid from_file(dbtransaction &, zview path, oid, sl = sl::current());
 
 
  static void to_buf(
    dbtransaction &, oid, bytes &, std::size_t max_size, sl = sl::current());
 
 
  static std::size_t append_to_buf(
    dbtransaction &tx, oid id, std::int64_t offset, bytes &buf,
    std::size_t append_max, sl = sl::current());
 
  static void to_file(dbtransaction &, oid, zview path, sl = sl::current());
 
 
  void close();
 
private:
  PQXX_PRIVATE blob(connection &cx, int fd) noexcept : m_conn{&cx}, m_fd{fd} {}
  static blob open_internal(dbtransaction &, oid, int, sl);
  PQXX_PRIVATE PQXX_PURE static pqxx::internal::pq::PGconn *
  raw_conn(pqxx::connection *) noexcept;
  PQXX_PRIVATE PQXX_PURE static pqxx::internal::pq::PGconn *
  raw_conn(pqxx::dbtransaction const &) noexcept;
  PQXX_PRIVATE static std::string errmsg(connection const *);
  PQXX_PRIVATE static std::string errmsg(dbtransaction const &tx)
  {
    return errmsg(&tx.conn());
  }
  PQXX_PRIVATE [[nodiscard]] std::string errmsg() const
  {
    return errmsg(m_conn);
  }
  PQXX_PRIVATE std::int64_t seek(std::int64_t offset, int whence, sl);
  std::size_t raw_read(std::byte buf[], std::size_t size, sl);
  void raw_write(bytes_view, sl);
 
  connection *m_conn = nullptr;
  int m_fd = -1;
};
} // namespace pqxx
#endif