@@ -18,6 +18,9 @@ Major new features:
a dump of information related to IFUNC resolver operation and
glibc-hwcaps subdirectory selection.
+* On Linux, the close_range function has been added. It allows efficiently
+ closing a range of file descriptors on recent kernels (version 5.9).
+
Deprecated and removed features, and other changes affecting compatibility:
[Add deprecations, removals and changes affecting compatibility here]
new file mode 100644
@@ -0,0 +1,6 @@
+#include_next <bits/unistd_ext.h>
+
+#ifndef _ISOMAC
+extern int __close_range (unsigned int lowfd, unsigned int highfd, int flags);
+libc_hidden_proto (__close_range);
+#endif
@@ -284,6 +284,48 @@ of trying to close its underlying file descriptor with @code{close}.
This flushes any buffered output and updates the stream object to
indicate that it is closed.
+@deftypefun int close_range (unsigned int @var{lowfd}, unsigned int @var{maxfd}, int @var{flags})
+@standards{Linux, unistd.h}
+@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{@acsfd{}}}
+@c This is a syscall for Linux v5.9. There is no fallback emulation for
+@c older kernels.
+
+The function @code{close_range} closes the file descriptor from @var{lowfd}
+to @var{maxfd} (inclusive). This function is similar to call @code{close} in
+specified file descriptor range depending on the @var{flags}.
+
+This is function is only supportted on recent Linux versions and @theglibc{}
+does not provide any fallback (the application will need to handle possible
+@code{ENOSYS}).
+
+The @var{flags} add options on how the files are closes. Linux currently
+supports:
+
+@vtable @code
+@item CLOSE_RANGE_UNSHARE
+Unshare the file descriptor table before closing file descriptors.
+@end vtable
+
+The normal return value from @code{close_range} is @math{0}; a value
+of @math{-1} is returned in case of failure. The following @code{errno} error
+conditions are defined for this function:
+
+@table @code
+@item EINVAL
+The @var{lowfd} value is larger than @var{maxfd} or an unsupported @var{flags}
+is used.
+
+@item ENOMEM
+Either there is not enough memory for the operation, or the process is
+out of address space.
+
+@item EMFILE
+The process has too many files open.
+The maximum number of file descriptors is controlled by the
+@end table
+@end deftypefun
+
+
@node I/O Primitives
@section Input and Output Primitives
@@ -108,7 +108,7 @@ tests += tst-clone tst-clone2 tst-clone3 tst-fanotify tst-personality \
tst-rlimit-infinity tst-ofdlocks tst-gettid tst-gettid-kill \
tst-tgkill tst-sysvsem-linux tst-sysvmsg-linux tst-sysvshm-linux \
tst-timerfd tst-ppoll tst-futimens tst-utime tst-utimes \
- tst-clock_adjtime tst-adjtimex tst-ntp_adjtime
+ tst-clock_adjtime tst-adjtimex tst-ntp_adjtime tst-close_range
# Test for the symbol version of fcntl that was replaced in glibc 2.28.
ifeq ($(have-GLIBC_2.27)$(build-shared),yesyes)
@@ -169,6 +169,9 @@ libc {
}
GLIBC_2.32 {
}
+ GLIBC_2.34 {
+ close_range;
+ }
GLIBC_PRIVATE {
# functions used in other libraries
__syscall_rt_sigqueueinfo;
@@ -2172,3 +2172,4 @@ GLIBC_2.33 mknodat F
GLIBC_2.33 stat F
GLIBC_2.33 stat64 F
GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 close_range F
@@ -2254,6 +2254,7 @@ GLIBC_2.33 mknodat F
GLIBC_2.33 stat F
GLIBC_2.33 stat64 F
GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 close_range F
GLIBC_2.4 _IO_fprintf F
GLIBC_2.4 _IO_printf F
GLIBC_2.4 _IO_sprintf F
@@ -1932,3 +1932,4 @@ GLIBC_2.33 mknodat F
GLIBC_2.33 stat F
GLIBC_2.33 stat64 F
GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 close_range F
@@ -156,6 +156,7 @@ GLIBC_2.33 mknodat F
GLIBC_2.33 stat F
GLIBC_2.33 stat64 F
GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 close_range F
GLIBC_2.4 _Exit F
GLIBC_2.4 _IO_2_1_stderr_ D 0xa0
GLIBC_2.4 _IO_2_1_stdin_ D 0xa0
@@ -153,6 +153,7 @@ GLIBC_2.33 mknodat F
GLIBC_2.33 stat F
GLIBC_2.33 stat64 F
GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 close_range F
GLIBC_2.4 _Exit F
GLIBC_2.4 _IO_2_1_stderr_ D 0xa0
GLIBC_2.4 _IO_2_1_stdin_ D 0xa0
@@ -33,4 +33,22 @@
not detached and has not been joined. */
extern __pid_t gettid (void) __THROW;
+/* Unshare the file descriptor table before closing file descriptors. */
+#ifdef __has_include
+# if __has_include ("linux/close_range.h")
+# include "linux/close_range.h"
+# endif
#endif
+#ifndef CLOSE_RANGE_UNSHARE
+# define CLOSE_RANGE_UNSHARE (1U << 1)
+#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. 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 */
@@ -2116,3 +2116,4 @@ GLIBC_2.33 mknodat F
GLIBC_2.33 stat F
GLIBC_2.33 stat64 F
GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 close_range F
@@ -2075,6 +2075,7 @@ GLIBC_2.33 mknodat F
GLIBC_2.33 stat F
GLIBC_2.33 stat64 F
GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 close_range F
GLIBC_2.4 __confstr_chk F
GLIBC_2.4 __fgets_chk F
GLIBC_2.4 __fgets_unlocked_chk F
@@ -2242,6 +2242,7 @@ GLIBC_2.33 mknodat F
GLIBC_2.33 stat F
GLIBC_2.33 stat64 F
GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 close_range F
GLIBC_2.4 __confstr_chk F
GLIBC_2.4 __fgets_chk F
GLIBC_2.4 __fgets_unlocked_chk F
@@ -2107,6 +2107,7 @@ GLIBC_2.33 mknodat F
GLIBC_2.33 stat F
GLIBC_2.33 stat64 F
GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 close_range F
GLIBC_2.4 __confstr_chk F
GLIBC_2.4 __fgets_chk F
GLIBC_2.4 __fgets_unlocked_chk F
@@ -157,6 +157,7 @@ GLIBC_2.33 mknodat F
GLIBC_2.33 stat F
GLIBC_2.33 stat64 F
GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 close_range F
GLIBC_2.4 _Exit F
GLIBC_2.4 _IO_2_1_stderr_ D 0x98
GLIBC_2.4 _IO_2_1_stdin_ D 0x98
@@ -2187,6 +2187,7 @@ GLIBC_2.33 mknodat F
GLIBC_2.33 stat F
GLIBC_2.33 stat64 F
GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 close_range F
GLIBC_2.4 __confstr_chk F
GLIBC_2.4 __fgets_chk F
GLIBC_2.4 __fgets_unlocked_chk F
@@ -2167,3 +2167,4 @@ GLIBC_2.33 mknodat F
GLIBC_2.33 stat F
GLIBC_2.33 stat64 F
GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 close_range F
@@ -2164,3 +2164,4 @@ GLIBC_2.33 mknodat F
GLIBC_2.33 stat F
GLIBC_2.33 stat64 F
GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 close_range F
@@ -2158,6 +2158,7 @@ GLIBC_2.33 mknodat F
GLIBC_2.33 stat F
GLIBC_2.33 stat64 F
GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 close_range F
GLIBC_2.4 __confstr_chk F
GLIBC_2.4 __fgets_chk F
GLIBC_2.4 __fgets_unlocked_chk F
@@ -2156,6 +2156,7 @@ GLIBC_2.33 mknodat F
GLIBC_2.33 stat F
GLIBC_2.33 stat64 F
GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 close_range F
GLIBC_2.4 __confstr_chk F
GLIBC_2.4 __fgets_chk F
GLIBC_2.4 __fgets_unlocked_chk F
@@ -2164,6 +2164,7 @@ GLIBC_2.33 mknodat F
GLIBC_2.33 stat F
GLIBC_2.33 stat64 F
GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 close_range F
GLIBC_2.4 __confstr_chk F
GLIBC_2.4 __fgets_chk F
GLIBC_2.4 __fgets_unlocked_chk F
@@ -2158,6 +2158,7 @@ GLIBC_2.33 mknodat F
GLIBC_2.33 stat F
GLIBC_2.33 stat64 F
GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 close_range F
GLIBC_2.4 __confstr_chk F
GLIBC_2.4 __fgets_chk F
GLIBC_2.4 __fgets_unlocked_chk F
@@ -2205,3 +2205,4 @@ GLIBC_2.33 mknodat F
GLIBC_2.33 stat F
GLIBC_2.33 stat64 F
GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 close_range F
@@ -2214,6 +2214,7 @@ GLIBC_2.33 mknodat F
GLIBC_2.33 stat F
GLIBC_2.33 stat64 F
GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 close_range F
GLIBC_2.4 _IO_fprintf F
GLIBC_2.4 _IO_printf F
GLIBC_2.4 _IO_sprintf F
@@ -2247,6 +2247,7 @@ GLIBC_2.33 mknodat F
GLIBC_2.33 stat F
GLIBC_2.33 stat64 F
GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 close_range F
GLIBC_2.4 _IO_fprintf F
GLIBC_2.4 _IO_printf F
GLIBC_2.4 _IO_sprintf F
@@ -2077,6 +2077,7 @@ GLIBC_2.33 mknodat F
GLIBC_2.33 stat F
GLIBC_2.33 stat64 F
GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 close_range F
GLIBC_2.4 _IO_fprintf F
GLIBC_2.4 _IO_printf F
GLIBC_2.4 _IO_sprintf F
@@ -2367,3 +2367,4 @@ GLIBC_2.33 mknodat F
GLIBC_2.33 stat F
GLIBC_2.33 stat64 F
GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 close_range F
@@ -1934,3 +1934,4 @@ GLIBC_2.33 write F
GLIBC_2.33 writev F
GLIBC_2.33 wscanf F
GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 close_range F
@@ -2134,3 +2134,4 @@ GLIBC_2.33 mknodat F
GLIBC_2.33 stat F
GLIBC_2.33 stat64 F
GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 close_range F
@@ -2212,6 +2212,7 @@ GLIBC_2.33 mknodat F
GLIBC_2.33 stat F
GLIBC_2.33 stat64 F
GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 close_range F
GLIBC_2.4 _IO_fprintf F
GLIBC_2.4 _IO_printf F
GLIBC_2.4 _IO_sprintf F
@@ -2113,6 +2113,7 @@ GLIBC_2.33 mknodat F
GLIBC_2.33 stat F
GLIBC_2.33 stat64 F
GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 close_range F
GLIBC_2.4 _IO_fprintf F
GLIBC_2.4 _IO_printf F
GLIBC_2.4 _IO_sprintf F
@@ -2082,6 +2082,7 @@ GLIBC_2.33 mknodat F
GLIBC_2.33 stat F
GLIBC_2.33 stat64 F
GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 close_range F
GLIBC_2.4 __confstr_chk F
GLIBC_2.4 __fgets_chk F
GLIBC_2.4 __fgets_unlocked_chk F
@@ -2079,6 +2079,7 @@ GLIBC_2.33 mknodat F
GLIBC_2.33 stat F
GLIBC_2.33 stat64 F
GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 close_range F
GLIBC_2.4 __confstr_chk F
GLIBC_2.4 __fgets_chk F
GLIBC_2.4 __fgets_unlocked_chk F
@@ -2203,6 +2203,7 @@ GLIBC_2.33 mknodat F
GLIBC_2.33 stat F
GLIBC_2.33 stat64 F
GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 close_range F
GLIBC_2.4 _IO_fprintf F
GLIBC_2.4 _IO_printf F
GLIBC_2.4 _IO_sprintf F
@@ -2130,6 +2130,7 @@ GLIBC_2.33 mknodat F
GLIBC_2.33 stat F
GLIBC_2.33 stat64 F
GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 close_range F
GLIBC_2.4 __confstr_chk F
GLIBC_2.4 __fgets_chk F
GLIBC_2.4 __fgets_unlocked_chk F
@@ -101,3 +101,4 @@ 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
new file mode 100644
@@ -0,0 +1,226 @@
+/* Test for the close_range system call.
+ 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 <dirent.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <getopt.h>
+#include <signal.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <stdint.h>
+
+#include <array_length.h>
+#include <support/capture_subprocess.h>
+#include <support/check.h>
+#include <support/descriptors.h>
+#include <support/support.h>
+#include <support/xsched.h>
+#include <support/xunistd.h>
+
+#define NFDS 100
+
+static int
+open_multiple_temp_files (void)
+{
+ /* Check if the temporary file descriptor has no no gaps. */
+ int lowfd = xopen ("/dev/null", O_RDONLY, 0600);
+ for (int i = 1; i <= NFDS; i++)
+ TEST_COMPARE (xopen ("/dev/null", O_RDONLY, 0600),
+ lowfd + i);
+ return lowfd;
+}
+
+static void
+close_range_test_max_upper_limit (void)
+{
+ struct support_descriptors *descrs = support_descriptors_list ();
+
+ int lowfd = open_multiple_temp_files ();
+
+ {
+ int r = close_range (lowfd, ~0U, 0);
+ if (r == -1 && errno == ENOSYS)
+ FAIL_UNSUPPORTED ("close_range not supported");
+ TEST_COMPARE (r, 0);
+ }
+
+ support_descriptors_check (descrs);
+ support_descriptors_free (descrs);
+}
+
+static void
+close_range_test_common (int lowfd, unsigned int flags)
+{
+ const int maximum_fd = lowfd + NFDS;
+ const int half_fd = lowfd + NFDS / 2;
+ const int gap_1 = maximum_fd - 8;
+
+ /* Close half of the descriptors and check result. */
+ TEST_COMPARE (close_range (lowfd, half_fd, flags), 0);
+ for (int i = lowfd; i <= half_fd; i++)
+ {
+ TEST_COMPARE (fcntl (i, F_GETFL), -1);
+ TEST_COMPARE (errno, EBADF);
+ }
+ for (int i = half_fd + 1; i < maximum_fd; i++)
+ TEST_VERIFY (fcntl (i, F_GETFL) > -1);
+
+ /* Create some gaps, close up to a threshold, and check result. */
+ xclose (lowfd + 57);
+ xclose (lowfd + 78);
+ xclose (lowfd + 81);
+ xclose (lowfd + 82);
+ xclose (lowfd + 84);
+ xclose (lowfd + 90);
+
+ TEST_COMPARE (close_range (half_fd + 1, gap_1, flags), 0);
+ for (int i = half_fd + 1; i < gap_1; i++)
+ {
+ TEST_COMPARE (fcntl (i, F_GETFL), -1);
+ TEST_COMPARE (errno, EBADF);
+ }
+ for (int i = gap_1 + 1; i < maximum_fd; i++)
+ TEST_VERIFY (fcntl (i, F_GETFL) > -1);
+
+ /* Close the remaining but the last one. */
+ TEST_COMPARE (close_range (gap_1 + 1, maximum_fd - 1, flags), 0);
+ for (int i = gap_1 + 1; i < maximum_fd - 1; i++)
+ {
+ TEST_COMPARE (fcntl (i, F_GETFL), -1);
+ TEST_COMPARE (errno, EBADF);
+ }
+ TEST_VERIFY (fcntl (maximum_fd, F_GETFL) > -1);
+
+ /* Close the last one. */
+ TEST_COMPARE (close_range (maximum_fd, maximum_fd, flags), 0);
+ TEST_COMPARE (fcntl (maximum_fd, F_GETFL), -1);
+ TEST_COMPARE (errno, EBADF);
+}
+
+/* Basic tests: check if the syscall close ranges with and without gaps. */
+static void
+close_range_test (void)
+{
+ struct support_descriptors *descrs = support_descriptors_list ();
+
+ /* Check if the temporary file descriptor has no no gaps. */
+ int lowfd = open_multiple_temp_files ();
+
+ close_range_test_common (lowfd, 0);
+
+ /* Double check by check the /proc. */
+ support_descriptors_check (descrs);
+ support_descriptors_free (descrs);
+}
+
+_Noreturn static int
+close_range_test_fn (void *arg)
+{
+ int lowfd = (int) ((uintptr_t) arg);
+ close_range_test_common (lowfd, 0);
+ exit (EXIT_SUCCESS);
+}
+
+/* Check if a clone_range on a subprocess created with CLONE_FILES close
+ the shared file descriptor table entries in the parent. */
+static void
+close_range_test_subprocess (void)
+{
+ struct support_descriptors *descrs = support_descriptors_list ();
+
+ /* Check if the temporary file descriptor has no no gaps. */
+ int lowfd = open_multiple_temp_files ();
+
+ struct support_stack stack = support_stack_alloc (4096);
+
+ pid_t pid = xclone (close_range_test_fn, (void*) (uintptr_t) lowfd,
+ stack.stack, stack.size, CLONE_FILES | SIGCHLD);
+ TEST_VERIFY_EXIT (pid > 0);
+ int status;
+ xwaitpid (pid, &status, 0);
+ TEST_VERIFY (WIFEXITED (status));
+ TEST_COMPARE (WEXITSTATUS(status), 0);
+
+ support_stack_free (&stack);
+
+ for (int i = lowfd; i < NFDS; i++)
+ TEST_VERIFY (fcntl (i, F_GETFL) < 0);
+
+ support_descriptors_check (descrs);
+ support_descriptors_free (descrs);
+}
+
+
+_Noreturn static int
+close_range_unshare_test_fn (void *arg)
+{
+ int lowfd = (int) ((uintptr_t) arg);
+ close_range_test_common (lowfd, CLOSE_RANGE_UNSHARE);
+ exit (EXIT_SUCCESS);
+}
+
+/* Check if a close_range with CLOSE_RANGE_UNSHARE issued from a subprocess
+ created with CLONE_FILES does not close the parent file descriptor list. */
+static void
+close_range_unshare_test (void)
+{
+ struct support_descriptors *descrs1 = support_descriptors_list ();
+
+ /* Check if the temporary file descriptor has no no gaps. */
+ int lowfd = open_multiple_temp_files ();
+
+ struct support_descriptors *descrs2 = support_descriptors_list ();
+
+ struct support_stack stack = support_stack_alloc (4096);
+
+ pid_t pid = xclone (close_range_unshare_test_fn, (void*) (uintptr_t) lowfd,
+ stack.stack, stack.size, CLONE_FILES | SIGCHLD);
+ TEST_VERIFY_EXIT (pid > 0);
+ int status;
+ xwaitpid (pid, &status, 0);
+ TEST_VERIFY (WIFEXITED (status));
+ TEST_COMPARE (WEXITSTATUS(status), 0);
+
+ support_stack_free (&stack);
+
+ for (int i = 0; i < NFDS; i++)
+ TEST_VERIFY (fcntl (i, F_GETFL) > -1);
+
+ support_descriptors_check (descrs2);
+ support_descriptors_free (descrs2);
+
+ TEST_COMPARE (close_range (lowfd, lowfd + NFDS, 0), 0);
+
+ support_descriptors_check (descrs1);
+ support_descriptors_free (descrs1);
+}
+
+static int
+do_test (void)
+{
+ close_range_test_max_upper_limit ();
+ close_range_test ();
+ close_range_test_subprocess ();
+ close_range_unshare_test ();
+
+ return 0;
+}
+
+#include <support/test-driver.c>
@@ -2089,6 +2089,7 @@ GLIBC_2.33 mknodat F
GLIBC_2.33 stat F
GLIBC_2.33 stat64 F
GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 close_range F
GLIBC_2.4 __confstr_chk F
GLIBC_2.4 __fgets_chk F
GLIBC_2.4 __fgets_unlocked_chk F
@@ -2186,3 +2186,4 @@ GLIBC_2.33 mknodat F
GLIBC_2.33 stat F
GLIBC_2.33 stat64 F
GLIBC_2.34 __libc_start_main F
+GLIBC_2.34 close_range F