ircd::util: Move syscall() templates out of util; minor reorg includes.

ircd::sys: Add abstract sysfs tool and template from fs::dev.

include/ircd/ircd.h

@@ -56,11 +56,8 @@
 #include "time.h"
 #include "logger.h"
 #include "info.h"
-#include "nacl.h"
 #include "rand.h"
 #include "crh.h"
-#include "ed25519.h"
-#include "color.h"
 #include "lex_cast.h"
 #include "base.h"
 #include "stringops.h"
@@ -72,9 +69,12 @@
 #include "iov.h"
 #include "grammar.h"
 #include "parse.h"
+#include "color.h"
 #include "rfc1459.h"
 #include "json/json.h"
 #include "cbor/cbor.h"
+#include "nacl.h"
+#include "ed25519.h"
 #include "openssl.h"
 #include "pbc.h"
 #include "fmt.h"
@@ -83,6 +83,7 @@
 #include "conf.h"
 #include "magic.h"
 #include "stats.h"
+#include "sys.h"
 #include "prof/prof.h"
 #include "fs/fs.h"
 #include "ios.h"

include/ircd/sys.h

@@ -0,0 +1,168 @@
+// The Construct
+//
+// Copyright (C) The Construct Developers, Authors & Contributors
+// Copyright (C) 2016-2020 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_SYS_H
+
+namespace ircd::sys
+{
+	enum call :uint;
+
+	template<enum call = (enum call)0,
+	         class function,
+	         class... args>
+	long call(function&&, args&&...);
+
+	template<long number,
+	         enum call = (enum call)0,
+	         class... args>
+	long call(args&&... a);
+
+	// sysfs read to buffer
+	string_view get(const mutable_buffer &out, const string_view &path);
+
+	// sysfs read cast to type or defaults
+	template<class R = size_t,
+	         size_t bufmax = 32>
+	R get(const string_view &path, const R &def = 0);
+
+	extern log::log log;
+}
+
+/// System call template options; changes behaviors.
+enum ircd::sys::call
+:uint
+{
+	NOTHROW            = 0x01,
+	UNINTERRUPTIBLE    = 0x02,
+};
+
+/// Return a lex_cast'able (an integer) from a sysfs target.
+template<class T,
+         size_t bufmax>
+inline T
+ircd::sys::get(const string_view &path,
+               const T &def)
+{
+	char buf[bufmax];
+	const string_view val
+	{
+		get(buf, path)
+	};
+
+	return lex_castable<T>(val)?
+		lex_cast<T>(val):
+		def;
+}
+
+/// This template requires a system call number in the parameters. The
+/// arguments are only the actual arguments passed to the syscall because
+/// the number is given in the template.
+///
+template<long number,
+         enum ircd::sys::call opts,
+         class... args>
+inline long
+ircd::sys::call(args&&... a)
+{
+	return call<opts>(::syscall, number, std::forward<args>(a)...);
+}
+
+/// Posix system call template to check for returned error value and throw the
+/// approps errno in the proper std::system_error exception. Note the usage
+/// here, the libc wrapper function is the first argument i.e:
+/// syscall(::foo, bar, baz) not syscall(::foo(bar, baz));
+///
+/// when uninterruptible posix system call template; the syscall is
+/// restarted until it no longer returns with EINTR.
+///
+template<enum ircd::sys::call opts,
+         class function,
+         class... args>
+inline long
+ircd::sys::call(function&& f,
+                args&&... a)
+{
+	constexpr auto uninterruptible
+	{
+		opts & call::UNINTERRUPTIBLE
+	};
+
+	long ret; do
+	{
+		ret = f(std::forward<args>(a)...);
+	}
+	while(unlikely(uninterruptible && ret == -1 && errno == EINTR));
+
+	constexpr auto nothrow
+	{
+		opts & call::NOTHROW
+	};
+
+	if(unlikely(!nothrow && ret == -1L))
+		throw std::system_error
+		{
+			errno, std::system_category()
+		};
+
+	return ret;
+}
+
+///////////////////////////////////////////////////////////////////////////////
+//
+// Legacy convenience forwarder interface
+//
+namespace ircd {
+
+template<class function,
+         class... args>
+inline auto
+syscall(function&& f,
+        args&&... a)
+{
+	return sys::call(std::forward<function>(f), std::forward<args>(a)...);
+}
+
+template<long number,
+         class... args>
+inline auto
+syscall(args&&... a)
+{
+	return sys::call<number>(std::forward<args>(a)...);
+}
+
+template<class function,
+         class... args>
+inline auto
+syscall_nointr(function&& f,
+               args&&... a)
+{
+	constexpr enum sys::call opts
+	{
+		sys::call::UNINTERRUPTIBLE
+	};
+
+	return sys::call<opts>(std::forward<function>(f), std::forward<args>(a)...);
+}
+
+template<long number,
+         class... args>
+inline auto
+syscall_nointr(args&&... a)
+{
+	constexpr enum sys::call opts
+	{
+		sys::call::UNINTERRUPTIBLE
+	};
+
+	return sys::call<number, opts>(std::forward<args>(a)...);
+}
+
+} // namespace ircd

include/ircd/util/util.h

@@ -39,7 +39,6 @@ namespace ircd
 #include "reentrance.h"
 #include "enum.h"
 #include "custom_ptr.h"
-#include "syscall.h"
 #include "env.h"
 #include "va_rtti.h"
 #include "unique_iterator.h"

ircd/Makefile.am

@@ -169,6 +169,7 @@ endif
 if IOU
 libircd_la_SOURCES += fs_iou.cc
 endif
+libircd_la_SOURCES += sys.cc
 libircd_la_SOURCES += mods.cc
 if LINUX
 libircd_la_SOURCES += mods_ldso.cc

ircd/fs_dev.cc

@@ -60,51 +60,16 @@ ircd::string_view
 ircd::fs::dev::sysfs(const mutable_buffer &out,
                      const ulong &id,
                      const string_view &relpath)
-try
 {
+	thread_local char path_buf[1024];
 	const string_view path{fmt::sprintf
 	{
-		path_scratch, "%s/%s/%s",
+		path_buf, "dev/block/%s/%s",
-		blk::BASE_PATH,
 		sysfs_id(name_scratch, id),
 		relpath
 	}};
 
-	fs::fd::opts fdopts;
+	return sys::get(out, path);
-	fdopts.errlog = false;
-	const fs::fd fd
-	{
-		path, fdopts
-	};
-
-	fs::read_opts ropts;
-	ropts.aio = false;
-	string_view ret
-	{
-		fs::read(fd, out, ropts)
-	};
-
-	ret = rstrip(ret, '\n');
-	ret = rstrip(ret, ' ');
-	return ret;
-}
-catch(const ctx::interrupted &)
-{
-	throw;
-}
-catch(const std::exception &e)
-{
-	#if 0
-	log::derror
-	{
-		log, "sysfs query dev_id:%lu `%s' :%s",
-		id,
-		relpath,
-		e.what(),
-	};
-	#endif
-
-	return {};
 }
 
 ircd::string_view

ircd/sys.cc

@@ -0,0 +1,60 @@
+// The Construct
+//
+// Copyright (C) The Construct Developers, Authors & Contributors
+// Copyright (C) 2016-2020 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.
+
+decltype(ircd::sys::log)
+ircd::sys::log
+{
+	"sys"
+};
+
+ircd::string_view
+ircd::sys::get(const mutable_buffer &out,
+               const string_view &relpath)
+try
+{
+	thread_local char buf[1024];
+	string_view path(relpath);
+	path = lstrip(relpath, "/sys/"_sv); // tolerate any errant /sys/ prefix
+	path = strlcpy(buf, "/sys/"_sv);
+	path = strlcat(buf, relpath);
+
+	fs::fd::opts fdopts;
+	fdopts.errlog = false;
+	const fs::fd fd
+	{
+		path, fdopts
+	};
+
+	string_view ret
+	{
+		data(out), sys::call(::read, fd, data(out), size(out))
+	};
+
+	ret = rstrip(ret, '\n');
+	ret = rstrip(ret, ' ');
+	return ret;
+}
+catch(const ctx::interrupted &)
+{
+	throw;
+}
+catch(const std::exception &e)
+{
+	#if 0
+	log::derror
+	{
+		log, "sysfs query `%s' :%s",
+		relpath,
+		e.what(),
+	};
+	#endif
+
+	return {};
+}