Add close_range(3) function

distrib/sets/lists/debug/mi

@@ -2037,6 +2037,7 @@
 ./usr/libdata/debug/usr/tests/lib/libc/gen/t_arc4random.debug		tests-lib-debug		debug,atf,compattestfile
 ./usr/libdata/debug/usr/tests/lib/libc/gen/t_assert.debug		tests-lib-debug		debug,atf,compattestfile
 ./usr/libdata/debug/usr/tests/lib/libc/gen/t_basedirname.debug		tests-lib-debug		debug,atf,compattestfile
+./usr/libdata/debug/usr/tests/lib/libc/gen/t_close_range.debug		tests-lib-debug		debug,atf,compattestfile
 ./usr/libdata/debug/usr/tests/lib/libc/gen/t_closefrom.debug		tests-lib-debug		debug,atf,compattestfile
 ./usr/libdata/debug/usr/tests/lib/libc/gen/t_cpuset.debug		tests-lib-debug		debug,atf,compattestfile
 ./usr/libdata/debug/usr/tests/lib/libc/gen/t_ctype.debug		tests-lib-debug		debug,atf,compattestfile

distrib/sets/lists/tests/mi

@@ -3096,6 +3096,7 @@
 ./usr/tests/lib/libc/gen/t_arc4random			tests-lib-tests		compattestfile,atf
 ./usr/tests/lib/libc/gen/t_assert			tests-lib-tests		compattestfile,atf
 ./usr/tests/lib/libc/gen/t_basedirname			tests-lib-tests		compattestfile,atf
+./usr/tests/lib/libc/gen/t_close_range			tests-lib-tests		compattestfile,atf
 ./usr/tests/lib/libc/gen/t_closefrom			tests-lib-tests		compattestfile,atf
 ./usr/tests/lib/libc/gen/t_cpuset			tests-lib-tests		compattestfile,atf
 ./usr/tests/lib/libc/gen/t_ctype			tests-lib-tests		compattestfile,atf

include/unistd.h

@@ -338,6 +338,7 @@ int	 pipe2(int *, int);
 #if defined(_NETBSD_SOURCE)
 int	 acct(const char *);
 int	 closefrom(int);
+int	 close_range(unsigned int, unsigned int, int);
 int	 des_cipher(const char *, char *, long, int);
 int	 des_setkey(const char *);
 void	 endusershell(void);

lib/libc/gen/close_range.3

@@ -0,0 +1,62 @@
+.Dd July 19, 2025
+.Dt CLOSE_RANGE 3
+.Os
+.Sh NAME
+.Nm close_range
+.Nd delete open file descriptors
+.Sh LIBRARY
+.Lb libc
+.Sh SYNOPSIS
+.In unistd.h
+.Ft int
+.Fn close_range "u_int first" "u_int last" "int flags"
+.Sh DESCRIPTION
+The
+.Fn close_range
+function deletes all open file descriptors between
+.Fa first
+and
+.Fa last
+inclusive, clamped to the range of open file descriptors.
+Any errors encountered while closing file descriptors are ignored.
+Supported
+.Fa flags :
+.Bl -tag -width ".Dv CLOSE_RANGE_CLOEXEC"
+.It Dv CLOSE_RANGE_CLOEXEC
+Set the close-on-exec flag on descriptors in the range instead of closing them.
+.It Dv CLOSE_RANGE_CLOFORK
+Set the close-on-fork flag on descriptors in the range instead of closing them.
+.El
+.Sh RETURN VALUES
+Upon successful completion,
+.Fn close_range
+returns a value
+of 0.
+Otherwise, a value of -1 is returned and the global variable
+.Va errno
+is set to indicate the error.
+.Sh ERRORS
+The
+.Fn close_range
+function
+will fail if:
+.Bl -tag -width Er
+.It Bq Er EINVAL
+The
+.Fa last
+argument is lower than the
+.Fa first
+argument.
+.It Bq Er EINVAL
+An invalid flag was set.
+.El
+.Sh SEE ALSO
+.Xr close 2
+.Xr closefrom 3
+.Sh HISTORY
+The
+.Fn close_range
+function comes from Linux and first appeared in
+.Fx 8.0
+and
+.Nx 11.0 .

lib/libc/gen/closefrom.c

@@ -37,6 +37,17 @@ __RCSID("$NetBSD: closefrom.c,v 1.4 2018/01/17 01:24:29 kamil Exp $");
 #include <fcntl.h>
 #include <unistd.h>
 
+int
+close_range(unsigned int first, unsigned int last, int flags)
+{
+	struct fclose_range_args cr = {
+		.last	= last,
+		.flags	= flags
+	};
+
+	return (fcntl(first, F_CLOSE_RANGE, &cr));
+}
+
 int
 closefrom(int fd)
 {

sys/kern/sys_descrip.c

@@ -336,13 +336,39 @@ sys_fcntl(struct lwp *l, const struct sys_fcntl_args *uap, register_t *retval)
 	struct flock fl;
 	bool cloexec = false;
 	bool clofork = false;
+	struct fclose_range_args cr;
 
 	fd = SCARG(uap, fd);
 	cmd = SCARG(uap, cmd);
 	fdp = l->l_fd;
 	error = 0;
 
 	switch (cmd) {
+	case F_CLOSE_RANGE:
+		if (fd < 0)
+			return EINVAL;
+		error = copyin(SCARG(uap, arg), &cr, sizeof(cr));
+		if (error)
+			return error;
+		if (cr.flags & ~(CLOSE_RANGE_CLOEXEC|CLOSE_RANGE_CLOFORK))
+			return EINVAL;
+		if ((unsigned int)fd > cr.last)
+			return EINVAL;
+		cr.last = MIN(cr.last, fdp->fd_lastfile);
+		for (i = fd; i <= (int)cr.last; i++) {
+			fp = fd_getfile(i);
+			if (fp == NULL)
+				continue;
+			if (cr.flags != 0) {
+				fd_set_exclose(l, i,
+				    (cr.flags & CLOSE_RANGE_CLOEXEC) != 0);
+				fd_set_foclose(l, i,
+				    (cr.flags & CLOSE_RANGE_CLOFORK) != 0);
+				fd_putfile(i);
+			} else
+				fd_close(i);
+		}
+		return 0;
 	case F_CLOSEM:
 		if (fd < 0)
 			return EBADF;

sys/sys/fcntl.h

@@ -216,6 +216,14 @@
 #define	F_DUPFD_CLOBOTH	19		/* close on exec/fork duplicated fd */
 #endif
 
+#if defined(_NETBSD_SOURCE)
+#define F_CLOSE_RANGE	20		/* close_range(3) */
+struct fclose_range_args {
+	unsigned int last;		/* last file descriptor */
+	int flags;			/* CLOSE_RANGE_* flags */
+};
+#endif
+
 /* file descriptor flags (F_GETFD, F_SETFD) */
 #define	FD_CLOEXEC	1		/* close-on-exec flag */
 #define	FD_CLOFORK	2		/* close-on-fork flag */

sys/sys/unistd.h

@@ -344,4 +344,10 @@
 /* configurable system strings */
 #define	_CS_PATH			   1
 
+#ifdef _NETBSD_SOURCE
+/* close_range(3) flags */
+#define CLOSE_RANGE_CLOEXEC	(1<<2)
+#define CLOSE_RANGE_CLOFORK	(1<<3)
+#endif
+
 #endif /* !_SYS_UNISTD_H_ */

tests/lib/libc/gen/Makefile

@@ -15,6 +15,7 @@ TESTS_C+=	t_arc4random
 TESTS_C+=	t_assert
 TESTS_C+=	t_basedirname
 TESTS_C+=	t_closefrom
+TESTS_C+=	t_close_range
 TESTS_C+=	t_cpuset
 TESTS_C+=	t_ctype
 TESTS_C+=	t_dir