Split part of sys/eventfd.h into bits/eventfd.h

["Joseph S. Myers" <joseph at codesourcery dot com>]

This patch separates the architecture-dependent flags from
sys/eventfd.h into a separate bits/eventfd.h header.  (Presume that
patches for sys/epoll.h, sys/inotify.h, sys/signalfd.h and
sys/timerfd.h will follow once we've confirmed the desired approach
for this issue; I think it makes sense to patch it one header at a
time.)

This accords with the general use of <bits/*.h> headers in glibc and
reduces duplication: for the majority of the API in these headers that
is the same on all Linux architectures, only one header is needed.

A previous patch was sent by Guy Martin in
<http://sourceware.org/ml/libc-alpha/2010-08/msg00030.html> and
rejected; a revision
<http://sourceware.org/ml/libc-alpha/2010-08/msg00082.html> was also
posted but not accepted.  The approach in this patch differs from both
the previous patches in that it proposes a separate <bits/*.h> header
for each of the five <sys/*.h> headers listed.  Previous criticisms
are addressed thus:

* Namespace issues cited in
  <http://sourceware.org/ml/libc-alpha/2010-08/msg00033.html>: this
  does not use O_* names.

* "no requirement that all archs use the same value as O_CLOEXEC for
  the flags" in
  <http://sourceware.org/ml/libc-alpha/2010-08/msg00033.html> - by
  having a separate <bits/*.h> header for each <sys/*.h> header, no
  such assumption is involved.

* An objection in
  <http://sourceware.org/ml/libc-alpha/2010-08/msg00035.html> that all
  architectures should use the same values: not relevant since a
  kernel/userspace ABI is fixed once released; for such an objection
  to be useful it needs to be raised with kernel developers before a
  kernel is released with such a difference between architectures.

* An objection in
  <http://sourceware.org/ml/libc-alpha/2010-08/msg00038.html> that
  compiling would be made slower: I don't think the cost is
  significant, and if this were a significant issue it would apply to
  all other <bits/*.h> headers as well and would be better addressed
  by a scheme to inline them in other headers at install time.

Thus, I think the approach of this patch is the right way to address
the issues with maintenance of these five <sys/*.h> headers and
minimize the extent to which any per-architecture changes are needed
in future.

(General remark: I fixed comments referring to signalfd to refer to
eventfd instead.  Remark for SPARC maintainer: SPARC appears to be
missing EFD_SEMAPHORE, you may wish to add it to bits/eventfd.h after
this goes in.)

2012-02-10  Joseph Myers  <joseph@codesourcery.com>

	* sysdeps/unix/sysv/linux/bits/eventfd.h: New file.
	* sysdeps/unix/sysv/linux/sparc/bits/eventfd.h: Likewise.
	* sysdeps/unix/sysv/linux/sparc/sys/eventfd.h: Remove.
	* sysdeps/unix/sysv/linux/sys/eventfd.h: Get flags from
	<bits/eventfd.h>.
	(EFD_SEMAPHORE, EFD_CLOEXEC, EFD_NONBLOCK): Don't define here.
	* sysdeps/unix/sysv/linux/Makefile (sysdep_headers): Add
	bits/eventfd.h.

diff --git a/sysdeps/unix/sysv/linux/Makefile b/sysdeps/unix/sysv/linux/Makefile
index e684b16..7da5502 100644
--- a/sysdeps/unix/sysv/linux/Makefile
+++ b/sysdeps/unix/sysv/linux/Makefile
@@ -32,7 +32,7 @@ sysdep_headers += sys/mount.h sys/acct.h sys/sysctl.h \
 		  scsi/sg.h scsi/scsi.h scsi/scsi_ioctl.h sys/pci.h \
 		  sys/ultrasound.h sys/raw.h sys/personality.h sys/epoll.h \
 		  bits/a.out.h sys/inotify.h sys/signalfd.h sys/eventfd.h \
-		  sys/timerfd.h sys/fanotify.h
+		  sys/timerfd.h sys/fanotify.h bits/eventfd.h
 
 install-others += $(inst_includedir)/bits/syscall.h
 
diff --git a/sysdeps/unix/sysv/linux/bits/eventfd.h b/sysdeps/unix/sysv/linux/bits/eventfd.h
new file mode 100644
index 0000000..4c0b562
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/bits/eventfd.h
@@ -0,0 +1,31 @@
+/* Copyright (C) 2007-2012 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#ifndef	_SYS_EVENTFD_H
+# error "Never use <bits/eventfd.h> directly; include <sys/eventfd.h> instead."
+#endif
+
+/* Flags for eventfd.  */
+enum
+  {
+    EFD_SEMAPHORE = 1,
+#define EFD_SEMAPHORE EFD_SEMAPHORE
+    EFD_CLOEXEC = 02000000,
+#define EFD_CLOEXEC EFD_CLOEXEC
+    EFD_NONBLOCK = 04000
+#define EFD_NONBLOCK EFD_NONBLOCK
+  };
diff --git a/sysdeps/unix/sysv/linux/sparc/bits/eventfd.h b/sysdeps/unix/sysv/linux/sparc/bits/eventfd.h
new file mode 100644
index 0000000..b4cf7d4
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/sparc/bits/eventfd.h
@@ -0,0 +1,29 @@
+/* Copyright (C) 2007-2012 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#ifndef	_SYS_EVENTFD_H
+# error "Never use <bits/eventfd.h> directly; include <sys/eventfd.h> instead."
+#endif
+
+/* Flags for eventfd.  */
+enum
+  {
+    EFD_CLOEXEC = 0x400000,
+#define EFD_CLOEXEC EFD_CLOEXEC
+    EFD_NONBLOCK = 0x4000
+#define EFD_NONBLOCK EFD_NONBLOCK
+  };
diff --git a/sysdeps/unix/sysv/linux/sparc/sys/eventfd.h b/sysdeps/unix/sysv/linux/sparc/sys/eventfd.h
deleted file mode 100644
index 7ea0270..0000000
--- a/sysdeps/unix/sysv/linux/sparc/sys/eventfd.h
+++ /dev/null
@@ -1,51 +0,0 @@
-/* Copyright (C) 2007, 2008, 2009 Free Software Foundation, Inc.
-   This file is part of the GNU C Library.
-
-   The GNU C Library is free software; you can redistribute it and/or
-   modify it under the terms of the GNU Lesser General Public
-   License as published by the Free Software Foundation; either
-   version 2.1 of the License, or (at your option) any later version.
-
-   The GNU C Library is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-   Lesser General Public License for more details.
-
-   You should have received a copy of the GNU Lesser General Public
-   License along with the GNU C Library; if not, see
-   <http://www.gnu.org/licenses/>.  */
-
-#ifndef	_SYS_EVENTFD_H
-#define	_SYS_EVENTFD_H	1
-
-#include <stdint.h>
-
-
-/* Type for event counter.  */
-typedef uint64_t eventfd_t;
-
-/* Flags for signalfd.  */
-enum
-  {
-    EFD_CLOEXEC = 0x400000,
-#define EFD_CLOEXEC EFD_CLOEXEC
-    EFD_NONBLOCK = 0x4000
-#define EFD_NONBLOCK EFD_NONBLOCK
-  };
-
-
-__BEGIN_DECLS
-
-/* Return file descriptor for generic event channel.  Set initial
-   value to COUNT.  */
-extern int eventfd (int __count, int __flags) __THROW;
-
-/* Read event counter and possibly wait for events.  */
-extern int eventfd_read (int __fd, eventfd_t *__value);
-
-/* Increment event counter.  */
-extern int eventfd_write (int __fd, eventfd_t __value);
-
-__END_DECLS
-
-#endif /* sys/eventfd.h */
diff --git a/sysdeps/unix/sysv/linux/sys/eventfd.h b/sysdeps/unix/sysv/linux/sys/eventfd.h
index cca4316..1602c7e 100644
--- a/sysdeps/unix/sysv/linux/sys/eventfd.h
+++ b/sysdeps/unix/sysv/linux/sys/eventfd.h
@@ -1,4 +1,4 @@
-/* Copyright (C) 2007, 2008, 2009 Free Software Foundation, Inc.
+/* Copyright (C) 2007-2012 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
    The GNU C Library is free software; you can redistribute it and/or
@@ -20,21 +20,12 @@
 
 #include <stdint.h>
 
+/* Get the platform-dependent flags.  */
+#include <bits/eventfd.h>
 
 /* Type for event counter.  */
 typedef uint64_t eventfd_t;
 
-/* Flags for signalfd.  */
-enum
-  {
-    EFD_SEMAPHORE = 1,
-#define EFD_SEMAPHORE EFD_SEMAPHORE
-    EFD_CLOEXEC = 02000000,
-#define EFD_CLOEXEC EFD_CLOEXEC
-    EFD_NONBLOCK = 04000
-#define EFD_NONBLOCK EFD_NONBLOCK
-  };
-
 
 __BEGIN_DECLS
 

-- 
Joseph S. Myers
joseph@codesourcery.com