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construct/include/ircd/mods/mapi.h

112 lines
3.4 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_MAPI_H
#define IRCD_MODULE_EXPORT_SECTION "ircd"
#define IRCD_MODULE_EXPORT \
__attribute__((section(IRCD_MODULE_EXPORT_SECTION)))
/// Module API: Interface for module developers.
namespace ircd::mapi
{
struct header;
struct metablock;
using magic_t = uint16_t;
using version_t = uint16_t;
using meta_data = std::map<string_view, string_view, std::less<>>;
using init_func = std::function<void ()>;
using fini_func = std::function<void ()>;
/// Used to communicate whether a module unload actually took place. dlclose() is allowed to return
/// success but the actual static destruction of the module's contents doesn't lie. (mods.cc)
extern bool static_destruction;
/// The name of the header variable in the module must match this string
const char *const header_symbol_name
{
"IRCD_MODULE"
};
/// Symbols in this section are automatically demangle-mapped on load.
const char *const import_section_name
{
IRCD_MODULE_EXPORT_SECTION
};
}
/// The magic number at the front of the header
constexpr const ircd::mapi::magic_t
IRCD_MAPI_MAGIC
{
0x4D41
};
/// The version number of this module's header.
constexpr const ircd::mapi::version_t
IRCD_MAPI_VERSION
{
4
};
/// Module Header
///
/// A static instance of this class must be included in an IRCd module with
/// the unmangled name of IRCD_MODULE (thus there can be only one). It must
/// be externally visible. If this is not present or not visible, ircd::mods
/// will not consider the file to be an IRCd module and it will be ignored.
///
struct ircd::mapi::header
{
const magic_t magic {IRCD_MAPI_MAGIC}; // The magic must match
const version_t version {IRCD_MAPI_VERSION}; // Version indicator
const int32_t _reserved_ {0}; // MBZ
const int64_t timestamp {RB_DATECODE}; // Module's compile epoch
std::unique_ptr<metablock> meta; // Non-standard-layout header data
mods::mod *self {nullptr}; // Point to mod instance once loaded
// get and set metadata
const string_view &operator[](const string_view &s) const;
string_view &operator[](const string_view &s);
// become self
operator const mods::mod &() const;
operator mods::mod &();
header(const string_view & = "<no description>",
init_func = {},
fini_func = {});
header(header &&) = delete;
header(const header &) = delete;
~header() noexcept;
};
struct ircd::mapi::metablock
{
init_func init; // Executed after dlopen()
fini_func fini; // Executed before dlclose()
meta_data meta; // Various key-value metadata
};
static_assert
(
std::is_standard_layout<ircd::mapi::header>(),
"The MAPI header must be standard layout so the magic and version numbers"
" can be parsed from the shared object file by external applications."
);
static_assert
(
sizeof(ircd::mapi::header) == 2 + 2 + 4 + 8 + 8 + 8,
"The MAPI header size has changed on this platform."
);