construct/include/ircd/fs/fd.h

// Matrix Construct
//
// Copyright (C) Matrix Construct Developers, Authors & Contributors
// Copyright (C) 2016-2018 Jason Volk <jason@zemos.net>
//
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice is present in all copies. The
// full license for this software is available in the LICENSE file.

#pragma once
#define HAVE_IRCD_FS_FD_H

namespace ircd::fs
{
	struct fd;

	size_t size(const fd &);
	string_view uuid(const fd &, const mutable_buffer &);
}

/// Object for maintaining state to an open file or directory. Instances can
/// be used with various functions around ircd::fs.
struct ircd::fs::fd
{
	struct opts;

	int fdno{-1};

  public:
	operator const int &() const
	{
		return fdno;
	}

	fd(const string_view &path, const opts &);
	fd(const string_view &path);
	fd() = default;
	fd(fd &&) noexcept;
	fd(const fd &) = delete;
	fd &operator=(fd &&) noexcept;
	fd &operator=(const fd &) = delete;
	~fd() noexcept(false);
};

struct ircd::fs::fd::opts
{
	/// open(2) flags. Usually generated from ios::open_mode ctor.
	ulong flags {0};

	/// open(2) mode_t mode used for file creation.
	ulong mask {0};

	/// Seek to end after open. This exists to convey the flag for open_mode.
	bool ate {false};

	/// (O_DIRECT) Direct IO bypassing the operating system caches.
	bool direct {false};

	/// (O_CLOEXEC) Close this descriptor on an exec().
	bool cloexec {true};

	/// Prevents file from being created if it doesn't exist. This clears
	/// any implied O_CREAT from the open_mode ctor and in flags too.
	bool nocreate {false};

	/// Construct options from an std::ios::open_mode bitmask.
	opts(const std::ios::open_mode &);
	opts() = default;
};