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construct/include/ircd/fs/read.h

62 lines
2.5 KiB
C++

// 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_READ_H
namespace ircd::fs
{
struct read_opts extern const read_opts_default;
// Yields ircd::ctx for read into buffers; returns bytes read
size_t read(const fd &, const mutable_buffers &, const read_opts & = read_opts_default);
size_t read(const string_view &path, const mutable_buffers &, const read_opts & = read_opts_default);
// Yields ircd::ctx for read into buffer; returns view of read portion.
const_buffer read(const fd &, const mutable_buffer &, const read_opts & = read_opts_default);
const_buffer read(const string_view &path, const mutable_buffer &, const read_opts & = read_opts_default);
// Yields ircd::ctx for read into allocated string; returns that string
std::string read(const fd &, const read_opts & = read_opts_default);
std::string read(const string_view &path, const read_opts & = read_opts_default);
// Test whether bytes in the specified range are cached and should not block
bool fincore(const fd &, const size_t &, const read_opts & = read_opts_default);
// Prefetch data for subsequent read(); offset given in opts (WILLNEED).
size_t prefetch(const fd &, const size_t &, const read_opts & = read_opts_default);
// Evict data which won't be read anymore (DONTNEED).
size_t evict(const fd &, const size_t &, const read_opts & = read_opts_default);
}
/// Options for a read operation
struct ircd::fs::read_opts
:opts
{
/// Yields the ircd::ctx until the buffers are full or EOF. This performs
/// the unix incremental read loop internally. When this option is true,
/// any return value from a function in the read suite will not be a
/// partial value requiring another invocation of read.
bool all {true};
/// Whether to propagate an EINTR; otherwise we reinvoke the syscall. For a
/// read(2) family call this can only happen before any data was read;
/// an exception will be thrown. We default to true because we have faith
/// in the useful propagation of an exception for this event.
bool interruptible {true};
read_opts(const off_t & = 0);
};
inline
ircd::fs::read_opts::read_opts(const off_t &offset)
:opts{offset, op::READ}
{}