io: Refactor close_range and closefrom

Now that Hurd implementis both close_range and closefrom (f2c996597d),
we can make close_range() a base ABI, and make the default closefrom()
implementation on top of close_range().

The generic closefrom() implementation based on __getdtablesize() is
moved to generic close_range().  On Linux it will be overriden by
the auto-generation syscall while on Hurd it will be a system specific
implementation.

The closefrom() now calls close_range() and __closefrom_fallback().
Since on Hurd close_range() does not fail, __closefrom_fallback() is an
empty static inline function set by__ASSUME_CLOSE_RANGE.

The __ASSUME_CLOSE_RANGE also allows optimize Linux
__closefrom_fallback() implementation when --enable-kernel=5.9 or
higher is used.

Finally the Linux specific tst-close_range.c is moved to io and
enabled as default.  The Linuxism and CLOSE_RANGE_UNSHARE are
guarded so it can be built for Hurd (I have not actually test it).

Checked on x86_64-linux-gnu, i686-linux-gnu, and with a i686-gnu
build.

4 files changed, 3 insertions, 36 deletions

diff --git a/sysdeps/mach/hurd/Makefile b/sysdeps/mach/hurd/Makefile
index 9acbe80f26..17bb643c18 100644
--- a/sysdeps/mach/hurd/Makefile
+++ b/sysdeps/mach/hurd/Makefile
@@ -196,7 +196,7 @@ sysdep_routines += cthreads
 endif
 
 ifeq (io, $(subdir))
-sysdep_routines += f_setlk close_nocancel close_nocancel_nostatus close_range \
+sysdep_routines += f_setlk close_nocancel close_nocancel_nostatus \
 		   fcntl_nocancel open_nocancel openat_nocancel read_nocancel \
 		   pread64_nocancel write_nocancel pwrite64_nocancel \
 		   wait4_nocancel \
diff --git a/sysdeps/mach/hurd/bits/unistd_ext.h b/sysdeps/mach/hurd/bits/unistd_ext.h
index 288f504a3c..14f85539d5 100644
--- a/sysdeps/mach/hurd/bits/unistd_ext.h
+++ b/sysdeps/mach/hurd/bits/unistd_ext.h
@@ -25,10 +25,4 @@
 /* Set the FD_CLOEXEC bit instead of closing the file descriptor.  */
 #define CLOSE_RANGE_CLOEXEC (1U << 2)
 
-/* Close the file descriptors from FIRST up to LAST, inclusive.
-   If CLOSE_RANGE_CLOEXEC is set in FLAGS, set the FD_CLOEXEC flag
-   instead of closing.  */
-extern int close_range (unsigned int __first, unsigned int __last,
-			int __flags) __THROW;
-
 #endif /* __USE_GNU  */
diff --git a/sysdeps/mach/hurd/closefrom.c b/sysdeps/mach/hurd/closefrom.c
deleted file mode 100644
index 5d667cf6c4..0000000000
--- a/sysdeps/mach/hurd/closefrom.c
+++ /dev/null
@@ -1,29 +0,0 @@
-/* Close a range of file descriptors.  Hurd version.
-   Copyright (C) 2021 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
-   <https://www.gnu.org/licenses/>.  */
-
-#include <unistd.h>
-#include <sys/param.h>
-
-void
-__closefrom (int lowfd)
-{
-  int l = MAX (0, lowfd);
-
-  (void) __close_range (l, ~0U, 0);
-}
-weak_alias (__closefrom, closefrom)
diff --git a/sysdeps/mach/hurd/kernel-features.h b/sysdeps/mach/hurd/kernel-features.h
index 7d4eaee0a6..5fd37a6d7b 100644
--- a/sysdeps/mach/hurd/kernel-features.h
+++ b/sysdeps/mach/hurd/kernel-features.h
@@ -19,3 +19,5 @@
 /* This file can define __ASSUME_* macros checked by certain source files.
    Almost none of these are used outside of sysdeps/unix/sysv/linux code.
    But those referring to POSIX-level features like O_* flags can be.  */
+
+#define __ASSUME_CLOSE_RANGE 1