Implement the memset_s(3) function as specified by the C11 ISO/IEC

9899:2011 Appendix K 3.7.4.1.

Other needed supporting types, defines and constraint_handler
infrastructure is added as specified in the C11 spec.

Submitted by:	Tom Rix <trix@juniper.net>
Sponsored by:	Juniper Networks
Discussed with:	ed
MFC after:	3 weeks
Differential revision:	https://reviews.freebsd.org/D9903
Differential revision:	https://reviews.freebsd.org/D10161

include/stddef.h

@@ -72,4 +72,12 @@ typedef	__max_align_t	max_align_t;
 
 #define	offsetof(type, member)	__offsetof(type, member)
 
+#if __EXT1_VISIBLE
+/* ISO/IEC 9899:2011 K.3.3.2 */
+#ifndef _RSIZE_T_DEFINED
+#define _RSIZE_T_DEFINED
+typedef size_t rsize_t;
+#endif
+#endif /* __EXT1_VISIBLE */
+
 #endif /* _STDDEF_H_ */

include/stdlib.h

@@ -323,6 +323,26 @@ __uint64_t
 
 extern char *suboptarg;			/* getsubopt(3) external variable */
 #endif /* __BSD_VISIBLE */
+
+#if __EXT1_VISIBLE
+
+#ifndef _ERRNO_T_DEFINED
+#define _ERRNO_T_DEFINED
+typedef int errno_t;
+#endif
+
+/* K.3.6 */
+typedef void (*constraint_handler_t)(const char * __restrict,
+    void * __restrict, errno_t);
+/* K.3.6.1.1 */
+constraint_handler_t set_constraint_handler_s(constraint_handler_t handler);
+/* K.3.6.1.2 */
+_Noreturn void abort_handler_s(const char * __restrict, void * __restrict,
+    errno_t);
+/* K3.6.1.3 */
+void ignore_handler_s(const char * __restrict, void * __restrict, errno_t);
+#endif /* __EXT1_VISIBLE */
+
 __END_DECLS
 __NULLABILITY_PRAGMA_POP
 

include/string.h

@@ -141,6 +141,22 @@ int	 timingsafe_memcmp(const void *, const void *, size_t);
 #if __POSIX_VISIBLE >= 200809 || defined(_XLOCALE_H_)
 #include <xlocale/_string.h>
 #endif
+
+#if __EXT1_VISIBLE
+
+#ifndef _RSIZE_T_DEFINED
+#define _RSIZE_T_DEFINED
+typedef size_t rsize_t;
+#endif
+
+#ifndef _ERRNO_T_DEFINED
+#define _ERRNO_T_DEFINED
+typedef int errno_t;
+#endif
+
+/* ISO/IEC 9899:2011 K.3.7.4.1.1 */
+errno_t memset_s(void *, rsize_t, int, rsize_t);
+#endif /* __EXT1_VISIBLE */
 __END_DECLS
 
 #endif /* _STRING_H_ */

lib/libc/include/libc_private.h

@@ -404,4 +404,6 @@ void __libc_map_stacks_exec(void);
 void	_pthread_cancel_enter(int);
 void	_pthread_cancel_leave(int);
 
+void __throw_constraint_handler_s(const char * restrict msg, int error);
+
 #endif /* _LIBC_PRIVATE_H_ */

lib/libc/stdlib/Makefile.inc

@@ -13,8 +13,8 @@ MISRCS+=C99_Exit.c a64l.c abort.c abs.c atexit.c atof.c atoi.c atol.c atoll.c \
 	insque.c l64a.c labs.c ldiv.c llabs.c lldiv.c lsearch.c \
 	merge.c mergesort_b.c ptsname.c qsort.c qsort_r.c quick_exit.c \
 	radixsort.c rand.c \
-	random.c reallocarray.c reallocf.c realpath.c remque.c strfmon.c \
+	random.c reallocarray.c reallocf.c realpath.c remque.c \
-	strtoimax.c \
+	set_constraint_handler_s.c strfmon.c strtoimax.c \
 	strtol.c strtoll.c strtoq.c strtoul.c strtonum.c strtoull.c \
         strtoumax.c strtouq.c system.c tdelete.c tfind.c tsearch.c twalk.c
 

lib/libc/stdlib/Symbol.map

@@ -119,6 +119,9 @@ FBSD_1.4 {
 FBSD_1.5 {
 	__cxa_thread_atexit;
 	__cxa_thread_atexit_impl;
+	abort_handler_s;
+	ignore_handler_s;
+	set_constraint_handler_s;
 };
 
 FBSDprivate_1.0 {

lib/libc/stdlib/set_constraint_handler_s.c

@@ -0,0 +1,95 @@
+/*-
+ * Copyright (c) 2017 Juniper Networks.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include "namespace.h"
+#include <sys/types.h>
+#include <machine/atomic.h>
+#include <errno.h>
+#include <pthread.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include "un-namespace.h"
+#include "libc_private.h"
+
+/*
+ * Rationale recommends allocating new memory each time.
+ */
+static constraint_handler_t *_ch = NULL;
+static pthread_mutex_t ch_lock = PTHREAD_MUTEX_INITIALIZER;
+
+constraint_handler_t
+set_constraint_handler_s(constraint_handler_t handler)
+{
+	constraint_handler_t *new, *old, ret;
+
+	new = malloc(sizeof(constraint_handler_t));
+	if (new == NULL)
+		return (NULL);
+	*new = handler;
+	if (__isthreaded)
+		_pthread_mutex_lock(&ch_lock);
+	old = _ch;
+	_ch = new;
+	if (__isthreaded)
+		_pthread_mutex_unlock(&ch_lock);
+	if (old == NULL) {
+		ret = NULL;
+	} else {
+		ret = *old;
+		free(old);
+	}
+	return (ret);
+}
+
+void
+__throw_constraint_handler_s(const char * restrict msg, errno_t error)
+{
+	constraint_handler_t ch;
+
+	if (__isthreaded)
+		_pthread_mutex_lock(&ch_lock);
+	ch = _ch != NULL ? *_ch : NULL;
+	if (__isthreaded)
+		_pthread_mutex_unlock(&ch_lock);
+	if (ch != NULL)
+		ch(msg, NULL, error);
+}
+
+void
+abort_handler_s(const char * restrict msg __unused,
+    void * restrict ptr __unused, errno_t error __unused)
+{
+
+	abort();
+}
+
+void
+ignore_handler_s(const char * restrict msg __unused,
+    void * restrict ptr __unused, errno_t error __unused)
+{
+}

lib/libc/string/Makefile.inc

@@ -10,7 +10,7 @@ CFLAGS+= -I${LIBC_SRCTOP}/locale
 MISRCS+=bcmp.c bcopy.c bzero.c explicit_bzero.c \
 	ffs.c ffsl.c ffsll.c fls.c flsl.c flsll.c \
 	memccpy.c memchr.c memrchr.c memcmp.c \
-	memcpy.c memmem.c memmove.c memset.c \
+	memcpy.c memmem.c memmove.c memset.c memset_s.c \
 	stpcpy.c stpncpy.c strcasecmp.c \
 	strcat.c strcasestr.c strchr.c strchrnul.c strcmp.c strcoll.c strcpy.c\
 	strcspn.c strdup.c strerror.c strlcat.c strlcpy.c strlen.c strmode.c \

lib/libc/string/Symbol.map

@@ -105,6 +105,7 @@ FBSD_1.4 {
 };
 
 FBSD_1.5 {
+	memset_s;
 	timingsafe_bcmp;
 	timingsafe_memcmp;
 };

lib/libc/string/memset_s.c

@@ -0,0 +1,63 @@
+/*-
+ * Copyright (c) 2017 Juniper Networks.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <errno.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <string.h>
+#include "libc_private.h"
+
+/* ISO/IEC 9899:2011 K.3.7.4.1 */
+errno_t
+memset_s(void *s, rsize_t smax, int c, rsize_t n)
+{
+	errno_t ret;
+	rsize_t lim;
+	unsigned char v;
+	volatile unsigned char *dst;
+
+	ret = EINVAL;
+	lim = smax;
+	v = (unsigned char)c;
+	dst = (unsigned char *)s;
+	if (s == NULL) {
+		__throw_constraint_handler_s("memset_s : s is NULL", ret);
+	} else if (smax > RSIZE_MAX) {
+		__throw_constraint_handler_s("memset_s : smax > RSIZE_MAX",
+		     ret);
+	} else if (n > RSIZE_MAX) {
+		__throw_constraint_handler_s("memset_s : n > RSIZE_MAX", ret);
+	} else {
+		if (n < smax)
+			lim = n;
+		while (lim > 0)
+			dst[--lim] = v;
+		ret = 0;
+	}
+	return (ret);
+}

lib/libc/tests/stdlib/Makefile

@@ -5,6 +5,7 @@
 ATF_TESTS_C+=		heapsort_test
 ATF_TESTS_C+=		mergesort_test
 ATF_TESTS_C+=		qsort_test
+ATF_TESTS_C+=		set_constraint_handler_s_test
 ATF_TESTS_C+=		tsearch_test
 .if ${COMPILER_FEATURES:Mc++11}
 ATF_TESTS_CXX+=		cxa_thread_atexit_test

lib/libc/tests/stdlib/set_constraint_handler_s_test.c

@@ -0,0 +1,63 @@
+/*-
+ * Copyright (c) 2017 Juniper Networks.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <assert.h>
+#include <stdlib.h>
+
+#include <atf-c.h>
+
+/* null */
+ATF_TC_WITHOUT_HEAD(null_handler);
+ATF_TC_BODY(null_handler, tc)
+{
+	assert(set_constraint_handler_s(abort_handler_s) == NULL);
+}
+
+/* abort handler */
+ATF_TC_WITHOUT_HEAD(abort_handler);
+ATF_TC_BODY(abort_handler, tc)
+{
+	set_constraint_handler_s(abort_handler_s);
+	assert(set_constraint_handler_s(ignore_handler_s) == abort_handler_s);
+}
+
+/* ignore handler */
+ATF_TC_WITHOUT_HEAD(ignore_handler);
+ATF_TC_BODY(ignore_handler, tc)
+{
+	set_constraint_handler_s(ignore_handler_s);
+	assert(set_constraint_handler_s(abort_handler_s) == ignore_handler_s);
+}
+
+ATF_TP_ADD_TCS(tp)
+{
+	ATF_TP_ADD_TC(tp, null_handler);
+	ATF_TP_ADD_TC(tp, abort_handler);
+	ATF_TP_ADD_TC(tp, ignore_handler);
+	return (atf_no_error());
+}

lib/libc/tests/string/Makefile

@@ -1,6 +1,7 @@
 # $FreeBSD$
 
 ATF_TESTS_C+=		memcmp_test
+ATF_TESTS_C+=		memset_s_test
 ATF_TESTS_C+=		stpncpy_test
 ATF_TESTS_C+=		strerror2_test
 ATF_TESTS_C+=		wcscasecmp_test

lib/libc/tests/string/memset_s_test.c

@@ -0,0 +1,195 @@
+/*-
+ * Copyright (c) 2017 Juniper Networks.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <assert.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <atf-c.h>
+
+static errno_t e;
+static const char * restrict m;
+
+void
+h(const char * restrict msg, void * restrict ptr __unused, errno_t error)
+{
+	e = error;
+	m = msg;
+}
+
+/* null ptr */
+ATF_TC_WITHOUT_HEAD(null_ptr);
+ATF_TC_BODY(null_ptr, tc)
+{
+	assert(memset_s(0, 1, 1, 1) != 0);
+}
+
+/* smax > rmax */
+ATF_TC_WITHOUT_HEAD(smax_gt_rmax);
+ATF_TC_BODY(smax_gt_rmax, tc)
+{
+	char b;
+
+	assert(memset_s(&b, RSIZE_MAX + 1, 1, 1) != 0);
+}
+
+/* smax < 0 */
+ATF_TC_WITHOUT_HEAD(smax_lt_zero);
+ATF_TC_BODY(smax_lt_zero, tc)
+{
+	char b;
+
+	assert(memset_s(&b, -1, 1, 1) != 0);
+}
+
+/* normal */
+ATF_TC_WITHOUT_HEAD(normal);
+ATF_TC_BODY(normal, tc)
+{
+	char b;
+
+	b = 3;
+	assert(memset_s(&b, 1, 5, 1) == 0);
+	assert(b == 5);
+}
+
+/* n > rmax */
+ATF_TC_WITHOUT_HEAD(n_gt_rmax);
+ATF_TC_BODY(n_gt_rmax, tc)
+{
+	char b;
+
+	assert(memset_s(&b, 1, 1, RSIZE_MAX + 1) != 0);
+}
+
+/* n < 0 */
+ATF_TC_WITHOUT_HEAD(n_lt_zero);
+ATF_TC_BODY(n_lt_zero, tc)
+{
+	char b;
+
+	assert(memset_s(&b, 1, 1, -1) != 0);
+}
+
+/* n < smax */
+ATF_TC_WITHOUT_HEAD(n_lt_smax);
+ATF_TC_BODY(n_lt_smax, tc)
+{
+	char b[3] = {1, 2, 3};
+
+	assert(memset_s(&b[0], 3, 9, 1) == 0);
+	assert(b[0] == 9);
+	assert(b[1] == 2);
+	assert(b[2] == 3);
+}
+
+/* n > smax */
+ATF_TC_WITHOUT_HEAD(n_gt_smax);
+ATF_TC_BODY(n_gt_smax, tc)
+{
+	char b[3] = {1, 2, 3};
+
+	assert(memset_s(&b[0], 1, 9, 3) == 0);
+	assert(b[0] == 9);
+	assert(b[1] == 2);
+	assert(b[2] == 3);
+}
+
+/* smax > rmax, handler */
+ATF_TC_WITHOUT_HEAD(smax_gt_rmax_handler);
+ATF_TC_BODY(smax_gt_rmax_handler, tc)
+{
+	char b;
+
+	e = 0;
+	m = NULL;
+	set_constraint_handler_s(h);
+	assert(memset_s(&b, RSIZE_MAX + 1, 1, 1) != 0);
+	assert(e > 0);
+	assert(strcmp(m, "memset_s : smax > RSIZE_MAX") == 0);
+}
+
+/* smax < 0, handler */
+ATF_TC_WITHOUT_HEAD(smax_lt_zero_handler);
+ATF_TC_BODY(smax_lt_zero_handler, tc)
+{
+	char b;
+
+	e = 0;
+	m = NULL;
+	set_constraint_handler_s(h);
+	assert(memset_s(&b, -1, 1, 1) != 0);
+	assert(e > 0);
+	assert(strcmp(m, "memset_s : smax > RSIZE_MAX") == 0);
+}
+
+/* n > rmax, handler */
+ATF_TC_WITHOUT_HEAD(n_gt_rmax_handler);
+ATF_TC_BODY(n_gt_rmax_handler, tc)
+{
+	char b;
+
+	e = 0;
+	m = NULL;
+	set_constraint_handler_s(h);
+	assert(memset_s(&b, 1, 1, RSIZE_MAX + 1) != 0);
+	assert(e > 0);
+	assert(strcmp(m, "memset_s : n > RSIZE_MAX") == 0);
+}
+
+/* n < 0, handler */
+ATF_TC_WITHOUT_HEAD(n_lt_zero_handler);
+ATF_TC_BODY(n_lt_zero_handler, tc)
+{
+	char b;
+
+	e = 0;
+	m = NULL;
+	set_constraint_handler_s(h);
+	assert(memset_s(&b, 1, 1, -1) != 0);
+	assert(e > 0);
+	assert(strcmp(m, "memset_s : n > RSIZE_MAX") == 0);
+}
+
+ATF_TP_ADD_TCS(tp)
+{
+	ATF_TP_ADD_TC(tp, null_ptr);
+	ATF_TP_ADD_TC(tp, smax_gt_rmax);
+	ATF_TP_ADD_TC(tp, smax_lt_zero);
+	ATF_TP_ADD_TC(tp, normal);
+	ATF_TP_ADD_TC(tp, n_gt_rmax);
+	ATF_TP_ADD_TC(tp, n_lt_zero);
+	ATF_TP_ADD_TC(tp, n_gt_smax);
+	ATF_TP_ADD_TC(tp, n_lt_smax);
+	ATF_TP_ADD_TC(tp, smax_gt_rmax_handler);
+	ATF_TP_ADD_TC(tp, smax_lt_zero_handler);
+	ATF_TP_ADD_TC(tp, n_gt_rmax_handler);
+	ATF_TP_ADD_TC(tp, n_lt_zero_handler);
+	return (atf_no_error());
+}

sys/sys/cdefs.h

@@ -750,24 +750,38 @@
 #define	__XSI_VISIBLE		0
 #define	__BSD_VISIBLE		0
 #define	__ISO_C_VISIBLE		1990
+#define	__EXT1_VISIBLE		0
 #elif defined(_C99_SOURCE)	/* Localism to specify strict C99 env. */
 #define	__POSIX_VISIBLE		0
 #define	__XSI_VISIBLE		0
 #define	__BSD_VISIBLE		0
 #define	__ISO_C_VISIBLE		1999
+#define	__EXT1_VISIBLE		0
 #elif defined(_C11_SOURCE)	/* Localism to specify strict C11 env. */
 #define	__POSIX_VISIBLE		0
 #define	__XSI_VISIBLE		0
 #define	__BSD_VISIBLE		0
 #define	__ISO_C_VISIBLE		2011
+#define	__EXT1_VISIBLE		0
 #else				/* Default environment: show everything. */
 #define	__POSIX_VISIBLE		200809
 #define	__XSI_VISIBLE		700
 #define	__BSD_VISIBLE		1
 #define	__ISO_C_VISIBLE		2011
+#define	__EXT1_VISIBLE		1
 #endif
 #endif
 
+/* User override __EXT1_VISIBLE */
+#if defined(__STDC_WANT_LIB_EXT1__)
+#undef	__EXT1_VISIBLE
+#if __STDC_WANT_LIB_EXT1__
+#define	__EXT1_VISIBLE		1
+#else
+#define	__EXT1_VISIBLE		0
+#endif
+#endif /* __STDC_WANT_LIB_EXT1__ */
+
 #if defined(__mips) || defined(__powerpc64__) || defined(__riscv__)
 #define	__NO_TLS 1
 #endif

sys/sys/errno.h

@@ -193,4 +193,12 @@ __END_DECLS
 #define	ERELOOKUP	(-5)		/* retry the directory lookup */
 #endif
 
+#if __EXT1_VISIBLE
+/* ISO/IEC 9899:2011 K.3.2.2 */
+#ifndef _ERRNO_T_DEFINED
+#define _ERRNO_T_DEFINED
+typedef int errno_t;
+#endif
+#endif /* __EXT1_VISIBLE */
+
 #endif

sys/sys/stdint.h

@@ -66,4 +66,11 @@ typedef	__uint_fast64_t		uint_fast64_t;
 #define	WCHAR_MIN	__WCHAR_MIN
 #define	WCHAR_MAX	__WCHAR_MAX
 
+#if __EXT1_VISIBLE
+/* ISO/IEC 9899:2011 K.3.4.4 */
+#ifndef RSIZE_MAX
+#define RSIZE_MAX (SIZE_MAX >> 1)
+#endif
+#endif /* __EXT1_VISIBLE */
+
 #endif /* !_SYS_STDINT_H_ */