mirror of
https://github.com/matrix-construct/construct
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169 lines
3.7 KiB
C
169 lines
3.7 KiB
C
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// The Construct
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//
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// Copyright (C) The Construct Developers, Authors & Contributors
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// Copyright (C) 2016-2020 Jason Volk <jason@zemos.net>
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//
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// Permission to use, copy, modify, and/or distribute this software for any
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// purpose with or without fee is hereby granted, provided that the above
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// copyright notice and this permission notice is present in all copies. The
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// full license for this software is available in the LICENSE file.
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#pragma once
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#define HAVE_IRCD_SYS_H
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namespace ircd::sys
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{
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enum call :uint;
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template<enum call = (enum call)0,
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class function,
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class... args>
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long call(function&&, args&&...);
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template<long number,
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enum call = (enum call)0,
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class... args>
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long call(args&&... a);
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// sysfs read to buffer
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string_view get(const mutable_buffer &out, const string_view &path);
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// sysfs read cast to type or defaults
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template<class R = size_t,
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size_t bufmax = 32>
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R get(const string_view &path, const R &def = 0);
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extern log::log log;
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}
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/// System call template options; changes behaviors.
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enum ircd::sys::call
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:uint
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{
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NOTHROW = 0x01,
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UNINTERRUPTIBLE = 0x02,
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};
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/// Return a lex_cast'able (an integer) from a sysfs target.
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template<class T,
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size_t bufmax>
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inline T
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ircd::sys::get(const string_view &path,
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const T &def)
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{
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char buf[bufmax];
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const string_view val
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{
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get(buf, path)
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};
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return lex_castable<T>(val)?
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lex_cast<T>(val):
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def;
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}
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/// This template requires a system call number in the parameters. The
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/// arguments are only the actual arguments passed to the syscall because
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/// the number is given in the template.
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///
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template<long number,
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enum ircd::sys::call opts,
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class... args>
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inline long
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ircd::sys::call(args&&... a)
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{
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return call<opts>(::syscall, number, std::forward<args>(a)...);
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}
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/// Posix system call template to check for returned error value and throw the
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/// approps errno in the proper std::system_error exception. Note the usage
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/// here, the libc wrapper function is the first argument i.e:
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/// syscall(::foo, bar, baz) not syscall(::foo(bar, baz));
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///
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/// when uninterruptible posix system call template; the syscall is
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/// restarted until it no longer returns with EINTR.
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///
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template<enum ircd::sys::call opts,
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class function,
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class... args>
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inline long
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ircd::sys::call(function&& f,
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args&&... a)
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{
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constexpr auto uninterruptible
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{
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opts & call::UNINTERRUPTIBLE
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};
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long ret; do
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{
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ret = f(std::forward<args>(a)...);
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}
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while(unlikely(uninterruptible && ret == -1 && errno == EINTR));
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constexpr auto nothrow
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{
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opts & call::NOTHROW
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};
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if(unlikely(!nothrow && ret == -1L))
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throw std::system_error
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{
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errno, std::system_category()
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};
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return ret;
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}
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///////////////////////////////////////////////////////////////////////////////
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//
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// Legacy convenience forwarder interface
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//
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namespace ircd {
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template<class function,
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class... args>
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inline auto
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syscall(function&& f,
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args&&... a)
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{
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return sys::call(std::forward<function>(f), std::forward<args>(a)...);
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}
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template<long number,
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class... args>
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inline auto
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syscall(args&&... a)
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{
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return sys::call<number>(std::forward<args>(a)...);
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}
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template<class function,
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class... args>
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inline auto
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syscall_nointr(function&& f,
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args&&... a)
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{
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constexpr enum sys::call opts
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{
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sys::call::UNINTERRUPTIBLE
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};
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return sys::call<opts>(std::forward<function>(f), std::forward<args>(a)...);
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}
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template<long number,
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class... args>
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inline auto
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syscall_nointr(args&&... a)
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{
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constexpr enum sys::call opts
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{
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sys::call::UNINTERRUPTIBLE
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};
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return sys::call<number, opts>(std::forward<args>(a)...);
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}
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} // namespace ircd
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