[PATCH v2] io: Refactor close_range and closefrom

[PATCH v2] io: Refactor close_range and closefrom

[Adhemerval Zanella via Libc-alpha]

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.
---
Changes from v1:
  - Changed close_range() comment to specify close() errors are
    ignored.
  - Fixed close_range() default implementation.
  - __closefrom_fallback() for __ASSUME_CLOSE_RANGE.
---
 include/unistd.h                              | 10 ++++++
 io/Makefile                                   |  3 +-
 .../linux/closefrom.c => io/close_range.c     | 34 ++++++++++++-------
 io/closefrom.c                                | 16 +++++----
 .../unix/sysv/linux => io}/tst-close_range.c  |  8 +++++
 posix/unistd.h                                | 10 ++++++
 sysdeps/mach/hurd/Makefile                    |  2 +-
 sysdeps/mach/hurd/bits/unistd_ext.h           |  6 ----
 sysdeps/mach/hurd/closefrom.c                 | 29 ----------------
 sysdeps/mach/hurd/kernel-features.h           |  2 ++
 sysdeps/unix/sysv/linux/Makefile              |  1 -
 sysdeps/unix/sysv/linux/bits/unistd_ext.h     |  9 -----
 sysdeps/unix/sysv/linux/closefrom_fallback.c  |  4 +++
 sysdeps/unix/sysv/linux/kernel-features.h     |  8 +++++
 sysdeps/unix/sysv/linux/syscalls.list         |  2 +-
 15 files changed, 76 insertions(+), 68 deletions(-)
 rename sysdeps/unix/sysv/linux/closefrom.c => io/close_range.c (59%)
 rename {sysdeps/unix/sysv/linux => io}/tst-close_range.c (98%)
 delete mode 100644 sysdeps/mach/hurd/closefrom.c

diff --git a/include/unistd.h b/include/unistd.h
index 7849562c42..927d249380 100644
--- a/include/unistd.h
+++ b/include/unistd.h
@@ -3,6 +3,9 @@
 
 # ifndef _ISOMAC
 
+#  include <stdbool.h>
+#  include <kernel-features.h>
+
 libc_hidden_proto (_exit, __noreturn__)
 #  ifndef NO_RTLD_HIDDEN
 rtld_hidden_proto (_exit, __noreturn__)
@@ -158,7 +161,14 @@ extern int __brk (void *__addr) attribute_hidden;
 extern int __close (int __fd);
 libc_hidden_proto (__close)
 extern int __libc_close (int __fd);
+#if __ASSUME_CLOSE_RANGE
+static inline _Bool __closefrom_fallback (int __lowfd, _Bool dirfd_fallback)
+{
+  return false;
+}
+#else
 extern _Bool __closefrom_fallback (int __lowfd, _Bool) attribute_hidden;
+#endif
 extern ssize_t __read (int __fd, void *__buf, size_t __nbytes);
 libc_hidden_proto (__read)
 extern ssize_t __write (int __fd, const void *__buf, size_t __n);
diff --git a/io/Makefile b/io/Makefile
index ecf65aba60..83f6ffdb76 100644
--- a/io/Makefile
+++ b/io/Makefile
@@ -57,7 +57,7 @@ routines :=								\
 	utimensat futimens file_change_detection			\
 	fts64-time64							\
 	ftw64-time64							\
-	closefrom
+	closefrom close_range
 
 others		:= pwd
 test-srcs	:= ftwtest ftwtest-time64
@@ -79,6 +79,7 @@ tests		:= test-utime test-stat test-stat2 test-lfs tst-getcwd \
 		   tst-futimens \
 		   tst-utimensat \
 		   tst-closefrom \
+		   tst-close_range \
 		   tst-ftw-bz28126
 
 tests-time64 := \
diff --git a/sysdeps/unix/sysv/linux/closefrom.c b/io/close_range.c
similarity index 59%
rename from sysdeps/unix/sysv/linux/closefrom.c
rename to io/close_range.c
index 372896b775..26a615d8b9 100644
--- a/sysdeps/unix/sysv/linux/closefrom.c
+++ b/io/close_range.c
@@ -1,4 +1,4 @@
-/* Close a range of file descriptors.  Linux version.
+/* Close a range of file descriptors.
    Copyright (C) 2021 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
@@ -16,21 +16,29 @@
    License along with the GNU C Library; if not, see
    <https://www.gnu.org/licenses/>.  */
 
-#include <stdbool.h>
-#include <stdio.h>
-#include <sys/param.h>
+#include <errno.h>
+#include <not-cancel.h>
 #include <unistd.h>
 
-void
-__closefrom (int lowfd)
+/* Close the file descriptors from FIRST up to LAST, inclusive.  */
+int
+__close_range (unsigned int first, unsigned int last,
+	       int flags)
 {
-  int l = MAX (0, lowfd);
+  if (first > last || flags != 0)
+    {
+      __set_errno (EINVAL);
+      return -1;
+    }
 
-  int r = __close_range (l, ~0U, 0);
-  if (r == 0)
-    return;
+  int maxfd = __getdtablesize ();
+  if (maxfd == -1)
+    return -1;
 
-  if (!__closefrom_fallback (l, true))
-    __fortify_fail ("closefrom failed to close a file descriptor");
+  for (int i = first; i <= last && i < maxfd; i++)
+    __close_nocancel_nostatus (i);
+
+  return 0;
 }
-weak_alias (__closefrom, closefrom)
+libc_hidden_def (__close_range)
+weak_alias (__close_range, close_range)
diff --git a/io/closefrom.c b/io/closefrom.c
index 01660a7531..e9167687bc 100644
--- a/io/closefrom.c
+++ b/io/closefrom.c
@@ -16,19 +16,21 @@
    License along with the GNU C Library; if not, see
    <https://www.gnu.org/licenses/>.  */
 
+#include <stdbool.h>
 #include <stdio.h>
+#include <sys/param.h>
 #include <unistd.h>
-#include <not-cancel.h>
 
 void
 __closefrom (int lowfd)
 {
-  int maxfd = __getdtablesize ();
-  if (maxfd == -1)
-    __fortify_fail ("closefrom failed to get the file descriptor table size");
+  int l = MAX (0, lowfd);
 
-  for (int i = 0; i < maxfd; i++)
-    if (i >= lowfd)
-      __close_nocancel_nostatus (i);
+  int r = __close_range (l, ~0U, 0);
+  if (r == 0)
+    return ;
+
+  if (!__closefrom_fallback (l, true))
+    __fortify_fail ("closefrom failed to close a file descriptor");
 }
 weak_alias (__closefrom, closefrom)
diff --git a/sysdeps/unix/sysv/linux/tst-close_range.c b/io/tst-close_range.c
similarity index 98%
rename from sysdeps/unix/sysv/linux/tst-close_range.c
rename to io/tst-close_range.c
index f5069d1b8a..f05b4ff6ae 100644
--- a/sysdeps/unix/sysv/linux/tst-close_range.c
+++ b/io/tst-close_range.c
@@ -119,6 +119,7 @@ close_range_test (void)
   support_descriptors_free (descrs);
 }
 
+#ifdef __linux__
 _Noreturn static int
 close_range_test_fn (void *arg)
 {
@@ -155,8 +156,10 @@ close_range_test_subprocess (void)
   support_descriptors_check (descrs);
   support_descriptors_free (descrs);
 }
+#endif
 
 
+#ifdef CLOSE_RANGE_UNSHARE
 _Noreturn static int
 close_range_unshare_test_fn (void *arg)
 {
@@ -200,6 +203,7 @@ close_range_unshare_test (void)
   support_descriptors_check (descrs1);
   support_descriptors_free (descrs1);
 }
+#endif
 
 static bool
 is_in_array (int *arr, size_t len, int fd)
@@ -282,8 +286,12 @@ do_test (void)
 {
   close_range_test_max_upper_limit ();
   close_range_test ();
+#ifdef __linux__
   close_range_test_subprocess ();
+#endif
+#ifdef CLOSE_RANGE_UNSHARE
   close_range_unshare_test ();
+#endif
   close_range_cloexec_test ();
 
   return 0;
diff --git a/posix/unistd.h b/posix/unistd.h
index 7a61ff5e86..3c8a7ced6a 100644
--- a/posix/unistd.h
+++ b/posix/unistd.h
@@ -1199,6 +1199,16 @@ int getentropy (void *__buffer, size_t __length) __wur
     __attr_access ((__write_only__, 1, 2));
 #endif
 
+#ifdef __USE_GNU
+/* Close all file descriptors in the range FD up to MAX_FD.  The flag FLAGS
+   are define by the CLOSE_RANGE prefix.  This function behaves like close
+   on the range and gaps where the file descriptor is invalid or errors
+   encountered while closing file descriptors are ignored.   Returns 0 on
+   successor or -1 for failure (and sets errno accordingly).  */
+extern int close_range (unsigned int __fd, unsigned int __max_fd,
+			int __flags) __THROW;
+#endif
+
 /* Define some macros helping to catch buffer overflows.  */
 #if __USE_FORTIFY_LEVEL > 0 && defined __fortify_function
 # include <bits/unistd.h>
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
diff --git a/sysdeps/unix/sysv/linux/Makefile b/sysdeps/unix/sysv/linux/Makefile
index 76ad06361c..76042a6019 100644
--- a/sysdeps/unix/sysv/linux/Makefile
+++ b/sysdeps/unix/sysv/linux/Makefile
@@ -120,7 +120,6 @@ tests += tst-clone tst-clone2 tst-clone3 tst-fanotify tst-personality \
 	 tst-timerfd tst-ppoll \
 	 tst-clock_adjtime tst-adjtimex tst-ntp_adjtime tst-ntp_gettime \
 	 tst-ntp_gettimex tst-sigtimedwait tst-misalign-clone \
-  tst-close_range \
   tst-prctl \
   tst-scm_rights \
   # tests
diff --git a/sysdeps/unix/sysv/linux/bits/unistd_ext.h b/sysdeps/unix/sysv/linux/bits/unistd_ext.h
index ae9994403c..8f422e60da 100644
--- a/sysdeps/unix/sysv/linux/bits/unistd_ext.h
+++ b/sysdeps/unix/sysv/linux/bits/unistd_ext.h
@@ -47,13 +47,4 @@ extern __pid_t gettid (void) __THROW;
 # define CLOSE_RANGE_CLOEXEC (1U << 2)
 #endif
 
-/* Close all file descriptors in the range FD up to MAX_FD.  The flag FLAGS
-   are define by the CLOSE_RANGE prefix.  This function behaves like close
-   on the range, but in a fail-safe where it will either fail and not close
-   any file descriptor or close all of them.  Gaps where the file descriptor
-   is invalid are ignored.   Returns 0 on successor or -1 for failure (and
-   sets errno accordingly).  */
-extern int close_range (unsigned int __fd, unsigned int __max_fd,
-			int __flags) __THROW;
-
 #endif /* __USE_GNU  */
diff --git a/sysdeps/unix/sysv/linux/closefrom_fallback.c b/sysdeps/unix/sysv/linux/closefrom_fallback.c
index f215fd2c09..a377ebc544 100644
--- a/sysdeps/unix/sysv/linux/closefrom_fallback.c
+++ b/sysdeps/unix/sysv/linux/closefrom_fallback.c
@@ -21,6 +21,8 @@
 #include <not-cancel.h>
 #include <stdbool.h>
 
+#if !__ASSUME_CLOSE_RANGE
+
 /* Fallback code: iterates over /proc/self/fd, closing each file descriptor
    that fall on the criteria.  If DIRFD_FALLBACK is set, a failure on
    /proc/self/fd open will trigger a fallback that tries to close a file
@@ -97,3 +99,5 @@ err:
   __close_nocancel (dirfd);
   return ret;
 }
+
+#endif
diff --git a/sysdeps/unix/sysv/linux/kernel-features.h b/sysdeps/unix/sysv/linux/kernel-features.h
index ffb6af196b..a1108d434f 100644
--- a/sysdeps/unix/sysv/linux/kernel-features.h
+++ b/sysdeps/unix/sysv/linux/kernel-features.h
@@ -220,6 +220,14 @@
 # define __ASSUME_FACCESSAT2 0
 #endif
 
+/* The close_range system call was introduced across all architectures
+   in Linux 5.8.  */
+#if __LINUX_KERNEL_VERSION >= 0x050900
+# define __ASSUME_CLOSE_RANGE 1
+#else
+# define __ASSUME_CLOSE_RANGE 0
+#endif
+
 /* The FUTEX_LOCK_PI2 operation was introduced across all architectures in Linux
    5.14.  */
 #if __LINUX_KERNEL_VERSION >= 0x050e00
diff --git a/sysdeps/unix/sysv/linux/syscalls.list b/sysdeps/unix/sysv/linux/syscalls.list
index 29899eb264..c38dbb34a1 100644
--- a/sysdeps/unix/sysv/linux/syscalls.list
+++ b/sysdeps/unix/sysv/linux/syscalls.list
@@ -99,4 +99,4 @@ pkey_alloc	EXTRA	pkey_alloc	i:ii	pkey_alloc
 pkey_free	EXTRA	pkey_free	i:i	pkey_free
 gettid          EXTRA   gettid          Ei:     __gettid	gettid
 tgkill          EXTRA   tgkill          i:iii   __tgkill	tgkill
-close_range     EXTRA   close_range     i:iii   __close_range   close_range
+close_range     -       close_range     i:iii   __close_range   close_range
-- 
2.32.0

Re: [PATCH v2] io: Refactor close_range and closefrom

[Adhemerval Zanella via Libc-alpha]

If no one oposes it I will commit this shortly.

On 08/11/2021 14:28, Adhemerval Zanella wrote:
> 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.
> ---
> Changes from v1:
>   - Changed close_range() comment to specify close() errors are
>     ignored.
>   - Fixed close_range() default implementation.
>   - __closefrom_fallback() for __ASSUME_CLOSE_RANGE.
> ---
>  include/unistd.h                              | 10 ++++++
>  io/Makefile                                   |  3 +-
>  .../linux/closefrom.c => io/close_range.c     | 34 ++++++++++++-------
>  io/closefrom.c                                | 16 +++++----
>  .../unix/sysv/linux => io}/tst-close_range.c  |  8 +++++
>  posix/unistd.h                                | 10 ++++++
>  sysdeps/mach/hurd/Makefile                    |  2 +-
>  sysdeps/mach/hurd/bits/unistd_ext.h           |  6 ----
>  sysdeps/mach/hurd/closefrom.c                 | 29 ----------------
>  sysdeps/mach/hurd/kernel-features.h           |  2 ++
>  sysdeps/unix/sysv/linux/Makefile              |  1 -
>  sysdeps/unix/sysv/linux/bits/unistd_ext.h     |  9 -----
>  sysdeps/unix/sysv/linux/closefrom_fallback.c  |  4 +++
>  sysdeps/unix/sysv/linux/kernel-features.h     |  8 +++++
>  sysdeps/unix/sysv/linux/syscalls.list         |  2 +-
>  15 files changed, 76 insertions(+), 68 deletions(-)
>  rename sysdeps/unix/sysv/linux/closefrom.c => io/close_range.c (59%)
>  rename {sysdeps/unix/sysv/linux => io}/tst-close_range.c (98%)
>  delete mode 100644 sysdeps/mach/hurd/closefrom.c
> 
> diff --git a/include/unistd.h b/include/unistd.h
> index 7849562c42..927d249380 100644
> --- a/include/unistd.h
> +++ b/include/unistd.h
> @@ -3,6 +3,9 @@
>  
>  # ifndef _ISOMAC
>  
> +#  include <stdbool.h>
> +#  include <kernel-features.h>
> +
>  libc_hidden_proto (_exit, __noreturn__)
>  #  ifndef NO_RTLD_HIDDEN
>  rtld_hidden_proto (_exit, __noreturn__)
> @@ -158,7 +161,14 @@ extern int __brk (void *__addr) attribute_hidden;
>  extern int __close (int __fd);
>  libc_hidden_proto (__close)
>  extern int __libc_close (int __fd);
> +#if __ASSUME_CLOSE_RANGE
> +static inline _Bool __closefrom_fallback (int __lowfd, _Bool dirfd_fallback)
> +{
> +  return false;
> +}
> +#else
>  extern _Bool __closefrom_fallback (int __lowfd, _Bool) attribute_hidden;
> +#endif
>  extern ssize_t __read (int __fd, void *__buf, size_t __nbytes);
>  libc_hidden_proto (__read)
>  extern ssize_t __write (int __fd, const void *__buf, size_t __n);
> diff --git a/io/Makefile b/io/Makefile
> index ecf65aba60..83f6ffdb76 100644
> --- a/io/Makefile
> +++ b/io/Makefile
> @@ -57,7 +57,7 @@ routines :=								\
>  	utimensat futimens file_change_detection			\
>  	fts64-time64							\
>  	ftw64-time64							\
> -	closefrom
> +	closefrom close_range
>  
>  others		:= pwd
>  test-srcs	:= ftwtest ftwtest-time64
> @@ -79,6 +79,7 @@ tests		:= test-utime test-stat test-stat2 test-lfs tst-getcwd \
>  		   tst-futimens \
>  		   tst-utimensat \
>  		   tst-closefrom \
> +		   tst-close_range \
>  		   tst-ftw-bz28126
>  
>  tests-time64 := \
> diff --git a/sysdeps/unix/sysv/linux/closefrom.c b/io/close_range.c
> similarity index 59%
> rename from sysdeps/unix/sysv/linux/closefrom.c
> rename to io/close_range.c
> index 372896b775..26a615d8b9 100644
> --- a/sysdeps/unix/sysv/linux/closefrom.c
> +++ b/io/close_range.c
> @@ -1,4 +1,4 @@
> -/* Close a range of file descriptors.  Linux version.
> +/* Close a range of file descriptors.
>     Copyright (C) 2021 Free Software Foundation, Inc.
>     This file is part of the GNU C Library.
>  
> @@ -16,21 +16,29 @@
>     License along with the GNU C Library; if not, see
>     <https://www.gnu.org/licenses/>.  */
>  
> -#include <stdbool.h>
> -#include <stdio.h>
> -#include <sys/param.h>
> +#include <errno.h>
> +#include <not-cancel.h>
>  #include <unistd.h>
>  
> -void
> -__closefrom (int lowfd)
> +/* Close the file descriptors from FIRST up to LAST, inclusive.  */
> +int
> +__close_range (unsigned int first, unsigned int last,
> +	       int flags)
>  {
> -  int l = MAX (0, lowfd);
> +  if (first > last || flags != 0)
> +    {
> +      __set_errno (EINVAL);
> +      return -1;
> +    }
>  
> -  int r = __close_range (l, ~0U, 0);
> -  if (r == 0)
> -    return;
> +  int maxfd = __getdtablesize ();
> +  if (maxfd == -1)
> +    return -1;
>  
> -  if (!__closefrom_fallback (l, true))
> -    __fortify_fail ("closefrom failed to close a file descriptor");
> +  for (int i = first; i <= last && i < maxfd; i++)
> +    __close_nocancel_nostatus (i);
> +
> +  return 0;
>  }
> -weak_alias (__closefrom, closefrom)
> +libc_hidden_def (__close_range)
> +weak_alias (__close_range, close_range)
> diff --git a/io/closefrom.c b/io/closefrom.c
> index 01660a7531..e9167687bc 100644
> --- a/io/closefrom.c
> +++ b/io/closefrom.c
> @@ -16,19 +16,21 @@
>     License along with the GNU C Library; if not, see
>     <https://www.gnu.org/licenses/>.  */
>  
> +#include <stdbool.h>
>  #include <stdio.h>
> +#include <sys/param.h>
>  #include <unistd.h>
> -#include <not-cancel.h>
>  
>  void
>  __closefrom (int lowfd)
>  {
> -  int maxfd = __getdtablesize ();
> -  if (maxfd == -1)
> -    __fortify_fail ("closefrom failed to get the file descriptor table size");
> +  int l = MAX (0, lowfd);
>  
> -  for (int i = 0; i < maxfd; i++)
> -    if (i >= lowfd)
> -      __close_nocancel_nostatus (i);
> +  int r = __close_range (l, ~0U, 0);
> +  if (r == 0)
> +    return ;
> +
> +  if (!__closefrom_fallback (l, true))
> +    __fortify_fail ("closefrom failed to close a file descriptor");
>  }
>  weak_alias (__closefrom, closefrom)
> diff --git a/sysdeps/unix/sysv/linux/tst-close_range.c b/io/tst-close_range.c
> similarity index 98%
> rename from sysdeps/unix/sysv/linux/tst-close_range.c
> rename to io/tst-close_range.c
> index f5069d1b8a..f05b4ff6ae 100644
> --- a/sysdeps/unix/sysv/linux/tst-close_range.c
> +++ b/io/tst-close_range.c
> @@ -119,6 +119,7 @@ close_range_test (void)
>    support_descriptors_free (descrs);
>  }
>  
> +#ifdef __linux__
>  _Noreturn static int
>  close_range_test_fn (void *arg)
>  {
> @@ -155,8 +156,10 @@ close_range_test_subprocess (void)
>    support_descriptors_check (descrs);
>    support_descriptors_free (descrs);
>  }
> +#endif
>  
>  
> +#ifdef CLOSE_RANGE_UNSHARE
>  _Noreturn static int
>  close_range_unshare_test_fn (void *arg)
>  {
> @@ -200,6 +203,7 @@ close_range_unshare_test (void)
>    support_descriptors_check (descrs1);
>    support_descriptors_free (descrs1);
>  }
> +#endif
>  
>  static bool
>  is_in_array (int *arr, size_t len, int fd)
> @@ -282,8 +286,12 @@ do_test (void)
>  {
>    close_range_test_max_upper_limit ();
>    close_range_test ();
> +#ifdef __linux__
>    close_range_test_subprocess ();
> +#endif
> +#ifdef CLOSE_RANGE_UNSHARE
>    close_range_unshare_test ();
> +#endif
>    close_range_cloexec_test ();
>  
>    return 0;
> diff --git a/posix/unistd.h b/posix/unistd.h
> index 7a61ff5e86..3c8a7ced6a 100644
> --- a/posix/unistd.h
> +++ b/posix/unistd.h
> @@ -1199,6 +1199,16 @@ int getentropy (void *__buffer, size_t __length) __wur
>      __attr_access ((__write_only__, 1, 2));
>  #endif
>  
> +#ifdef __USE_GNU
> +/* Close all file descriptors in the range FD up to MAX_FD.  The flag FLAGS
> +   are define by the CLOSE_RANGE prefix.  This function behaves like close
> +   on the range and gaps where the file descriptor is invalid or errors
> +   encountered while closing file descriptors are ignored.   Returns 0 on
> +   successor or -1 for failure (and sets errno accordingly).  */
> +extern int close_range (unsigned int __fd, unsigned int __max_fd,
> +			int __flags) __THROW;
> +#endif
> +
>  /* Define some macros helping to catch buffer overflows.  */
>  #if __USE_FORTIFY_LEVEL > 0 && defined __fortify_function
>  # include <bits/unistd.h>
> 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
> diff --git a/sysdeps/unix/sysv/linux/Makefile b/sysdeps/unix/sysv/linux/Makefile
> index 76ad06361c..76042a6019 100644
> --- a/sysdeps/unix/sysv/linux/Makefile
> +++ b/sysdeps/unix/sysv/linux/Makefile
> @@ -120,7 +120,6 @@ tests += tst-clone tst-clone2 tst-clone3 tst-fanotify tst-personality \
>  	 tst-timerfd tst-ppoll \
>  	 tst-clock_adjtime tst-adjtimex tst-ntp_adjtime tst-ntp_gettime \
>  	 tst-ntp_gettimex tst-sigtimedwait tst-misalign-clone \
> -  tst-close_range \
>    tst-prctl \
>    tst-scm_rights \
>    # tests
> diff --git a/sysdeps/unix/sysv/linux/bits/unistd_ext.h b/sysdeps/unix/sysv/linux/bits/unistd_ext.h
> index ae9994403c..8f422e60da 100644
> --- a/sysdeps/unix/sysv/linux/bits/unistd_ext.h
> +++ b/sysdeps/unix/sysv/linux/bits/unistd_ext.h
> @@ -47,13 +47,4 @@ extern __pid_t gettid (void) __THROW;
>  # define CLOSE_RANGE_CLOEXEC (1U << 2)
>  #endif
>  
> -/* Close all file descriptors in the range FD up to MAX_FD.  The flag FLAGS
> -   are define by the CLOSE_RANGE prefix.  This function behaves like close
> -   on the range, but in a fail-safe where it will either fail and not close
> -   any file descriptor or close all of them.  Gaps where the file descriptor
> -   is invalid are ignored.   Returns 0 on successor or -1 for failure (and
> -   sets errno accordingly).  */
> -extern int close_range (unsigned int __fd, unsigned int __max_fd,
> -			int __flags) __THROW;
> -
>  #endif /* __USE_GNU  */
> diff --git a/sysdeps/unix/sysv/linux/closefrom_fallback.c b/sysdeps/unix/sysv/linux/closefrom_fallback.c
> index f215fd2c09..a377ebc544 100644
> --- a/sysdeps/unix/sysv/linux/closefrom_fallback.c
> +++ b/sysdeps/unix/sysv/linux/closefrom_fallback.c
> @@ -21,6 +21,8 @@
>  #include <not-cancel.h>
>  #include <stdbool.h>
>  
> +#if !__ASSUME_CLOSE_RANGE
> +
>  /* Fallback code: iterates over /proc/self/fd, closing each file descriptor
>     that fall on the criteria.  If DIRFD_FALLBACK is set, a failure on
>     /proc/self/fd open will trigger a fallback that tries to close a file
> @@ -97,3 +99,5 @@ err:
>    __close_nocancel (dirfd);
>    return ret;
>  }
> +
> +#endif
> diff --git a/sysdeps/unix/sysv/linux/kernel-features.h b/sysdeps/unix/sysv/linux/kernel-features.h
> index ffb6af196b..a1108d434f 100644
> --- a/sysdeps/unix/sysv/linux/kernel-features.h
> +++ b/sysdeps/unix/sysv/linux/kernel-features.h
> @@ -220,6 +220,14 @@
>  # define __ASSUME_FACCESSAT2 0
>  #endif
>  
> +/* The close_range system call was introduced across all architectures
> +   in Linux 5.8.  */
> +#if __LINUX_KERNEL_VERSION >= 0x050900
> +# define __ASSUME_CLOSE_RANGE 1
> +#else
> +# define __ASSUME_CLOSE_RANGE 0
> +#endif
> +
>  /* The FUTEX_LOCK_PI2 operation was introduced across all architectures in Linux
>     5.14.  */
>  #if __LINUX_KERNEL_VERSION >= 0x050e00
> diff --git a/sysdeps/unix/sysv/linux/syscalls.list b/sysdeps/unix/sysv/linux/syscalls.list
> index 29899eb264..c38dbb34a1 100644
> --- a/sysdeps/unix/sysv/linux/syscalls.list
> +++ b/sysdeps/unix/sysv/linux/syscalls.list
> @@ -99,4 +99,4 @@ pkey_alloc	EXTRA	pkey_alloc	i:ii	pkey_alloc
>  pkey_free	EXTRA	pkey_free	i:i	pkey_free
>  gettid          EXTRA   gettid          Ei:     __gettid	gettid
>  tgkill          EXTRA   tgkill          i:iii   __tgkill	tgkill
> -close_range     EXTRA   close_range     i:iii   __close_range   close_range
> +close_range     -       close_range     i:iii   __close_range   close_range
> 

Re: [PATCH v2] io: Refactor close_range and closefrom

[Florian Weimer via Libc-alpha]

* Adhemerval Zanella via Libc-alpha:

> diff --git a/include/unistd.h b/include/unistd.h
> index 7849562c42..927d249380 100644
> --- a/include/unistd.h
> +++ b/include/unistd.h
> @@ -3,6 +3,9 @@
>  
>  # ifndef _ISOMAC
>  
> +#  include <stdbool.h>
> +#  include <kernel-features.h>
> +
>  libc_hidden_proto (_exit, __noreturn__)
>  #  ifndef NO_RTLD_HIDDEN
>  rtld_hidden_proto (_exit, __noreturn__)
> @@ -158,7 +161,14 @@ extern int __brk (void *__addr) attribute_hidden;
>  extern int __close (int __fd);
>  libc_hidden_proto (__close)
>  extern int __libc_close (int __fd);
> +#if __ASSUME_CLOSE_RANGE
> +static inline _Bool __closefrom_fallback (int __lowfd, _Bool dirfd_fallback)
> +{
> +  return false;
> +}
> +#else
>  extern _Bool __closefrom_fallback (int __lowfd, _Bool) attribute_hidden;
> +#endif
>  extern ssize_t __read (int __fd, void *__buf, size_t __nbytes);
>  libc_hidden_proto (__read)
>  extern ssize_t __write (int __fd, const void *__buf, size_t __n);

#if indentation seems off.

I expect this will break the Hurd build because it does not define
__ASSUME_CLOSE_RANGE in its <kernel-features.h>.

Thanks,
Florian

Re: [PATCH v2] io: Refactor close_range and closefrom

[Adhemerval Zanella via Libc-alpha]

On 24/11/2021 06:52, Florian Weimer wrote:
> * Adhemerval Zanella via Libc-alpha:
> 
>> diff --git a/include/unistd.h b/include/unistd.h
>> index 7849562c42..927d249380 100644
>> --- a/include/unistd.h
>> +++ b/include/unistd.h
>> @@ -3,6 +3,9 @@
>>  
>>  # ifndef _ISOMAC
>>  
>> +#  include <stdbool.h>
>> +#  include <kernel-features.h>
>> +
>>  libc_hidden_proto (_exit, __noreturn__)
>>  #  ifndef NO_RTLD_HIDDEN
>>  rtld_hidden_proto (_exit, __noreturn__)
>> @@ -158,7 +161,14 @@ extern int __brk (void *__addr) attribute_hidden;
>>  extern int __close (int __fd);
>>  libc_hidden_proto (__close)
>>  extern int __libc_close (int __fd);
>> +#if __ASSUME_CLOSE_RANGE
>> +static inline _Bool __closefrom_fallback (int __lowfd, _Bool dirfd_fallback)
>> +{
>> +  return false;
>> +}
>> +#else
>>  extern _Bool __closefrom_fallback (int __lowfd, _Bool) attribute_hidden;
>> +#endif
>>  extern ssize_t __read (int __fd, void *__buf, size_t __nbytes);
>>  libc_hidden_proto (__read)
>>  extern ssize_t __write (int __fd, const void *__buf, size_t __n);
> 
> #if indentation seems off.

Ack.

> 
> I expect this will break the Hurd build because it does not define
> __ASSUME_CLOSE_RANGE in its <kernel-features.h>.



> 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

It does add it here (I also checked with a build for i688-gnu).

> 
> Thanks,
> Florian
> 

Re: [PATCH v2] io: Refactor close_range and closefrom

[Florian Weimer via Libc-alpha]

* Adhemerval Zanella:

>> 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
>
> It does add it here (I also checked with a build for i688-gnu).

Hmm, this doesn't match existing practice.  We haven't unified
implementations in light of such divergence, I think.  If the Hurd
developers don't object, it should be fine, though..

Thanks,
Florian

Re: [PATCH v2] io: Refactor close_range and closefrom

[Samuel Thibault via Libc-alpha]

Florian Weimer, le mer. 24 nov. 2021 13:03:19 +0100, a ecrit:
> * Adhemerval Zanella:
> 
> >> 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
> >
> > It does add it here (I also checked with a build for i688-gnu).
> 
> Hmm, this doesn't match existing practice.  We haven't unified
> implementations in light of such divergence, I think.  If the Hurd
> developers don't object, it should be fine, though..

I'm fine with it yes. This is not a "kernel-feature" since it's actually
implemented inside glibc itself, but from the point of view of the rest
of the world that's how people understand it, so better adhere to it :)

Samuel

Re: [PATCH v2] io: Refactor close_range and closefrom

[Adhemerval Zanella via Libc-alpha]

On 24/11/2021 09:03, Florian Weimer wrote:
> * Adhemerval Zanella:
> 
>>> 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
>>
>> It does add it here (I also checked with a build for i688-gnu).
> 
> Hmm, this doesn't match existing practice.  We haven't unified
> implementations in light of such divergence, I think.  If the Hurd
> developers don't object, it should be fine, though..

This was used before, we still have some leftovers from it:

nscd/nscd.c:306:# ifndef __ASSUME_IN_NONBLOCK
resolv/res_send.c:1035:#ifndef __ASSUME_SENDMMSG
resolv/res_send.c:1081:#ifndef __ASSUME_SENDMMSG
resolv/res_send.c:1100:#ifndef __ASSUME_SENDMMSG

You have also cleanup some other assumes from Hurd: dup3 (b48061e1a534a242),
O_CLOEXEC (cef9b65376a04430), and accept4 (e92030239abb4038).

Re: [PATCH v2] io: Refactor close_range and closefrom

[Adhemerval Zanella via Libc-alpha]

On 24/11/2021 09:20, Adhemerval Zanella wrote:
> 
> 
> On 24/11/2021 09:03, Florian Weimer wrote:
>> * Adhemerval Zanella:
>>
>>>> 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
>>>
>>> It does add it here (I also checked with a build for i688-gnu).
>>
>> Hmm, this doesn't match existing practice.  We haven't unified
>> implementations in light of such divergence, I think.  If the Hurd
>> developers don't object, it should be fine, though..
> 
> This was used before, we still have some leftovers from it:
> 
> nscd/nscd.c:306:# ifndef __ASSUME_IN_NONBLOCK

On a side note, I think we can just remove it since it is only used
with inotify_init1 (which is only supported on Linux and currently
on all minimum supported kernel).

> resolv/res_send.c:1035:#ifndef __ASSUME_SENDMMSG
> resolv/res_send.c:1081:#ifndef __ASSUME_SENDMMSG
> resolv/res_send.c:1100:#ifndef __ASSUME_SENDMMSG

And we might remove it by implementing sendmmsg/recvmmsg on top of
sendmsg/recvmsg on generic implementations.

> 
> You have also cleanup some other assumes from Hurd: dup3 (b48061e1a534a242),
> O_CLOEXEC (cef9b65376a04430), and accept4 (e92030239abb4038).
>