include: ssp: don't shadow the mempcpy builtin

GCC emits a warning about shadowing a builtin with our mempcpy
declaration, so switch it to using the same model as memcpy() and
use the apparently-existing __builtin___mempcpy_chk().

Reviewed by:	kib (earlier version), markj
Sponsored by:	Klara, Inc.
Sponsored by:	Stormshield
Differential Revision:	https://reviews.freebsd.org/D45976

include/ssp/string.h

@@ -106,6 +106,7 @@ __ ## fun ## _ichk(type1 __restrict dst, type2 __restrict src) { \
 
 __BEGIN_DECLS
 __ssp_bos_icheck3_restrict(memcpy, void *, const void *)
+__ssp_bos_icheck3_restrict(mempcpy, void *, const void *)
 __ssp_bos_icheck3(memmove, void *, const void *)
 __ssp_bos_icheck3(memset, void *, int)
 __ssp_bos_icheck2_restrict(stpcpy, char *, const char *)
@@ -116,23 +117,10 @@ __ssp_redirect0(int, strerror_r, (int __errnum, char *__buf, size_t __len),
     (__errnum, __buf, __len));
 __ssp_bos_icheck3_restrict(strncpy, char *, const char *)
 __ssp_bos_icheck3_restrict(strncat, char *, const char *)
-
-__ssp_redirect_raw_impl(void *, mempcpy, mempcpy,
-    (void *__restrict buf, const void *__restrict src, size_t len))
-{
-	const size_t slen = __ssp_bos(buf);
-
-	if (len > slen)
-		__chk_fail();
-
-	if (__ssp_overlap(src, buf, len))
-		__chk_fail();
-
-	return (__ssp_real(mempcpy)(buf, src, len));
-}
 __END_DECLS
 
 #define memcpy(dst, src, len) __ssp_bos_check3(memcpy, dst, src, len)
+#define mempcpy(dst, src, len) __ssp_bos_check3(mempcpy, dst, src, len)
 #define memmove(dst, src, len) __ssp_bos_check3(memmove, dst, src, len)
 #define memset(dst, val, len) \
     __ssp_bos_check3_typed(memset, void *, dst, int, val, len)

include/string.h

@@ -68,7 +68,7 @@ void	*memmem(const void *, size_t, const void *, size_t) __pure;
 #endif
 void	*(memmove)(void *, const void *, size_t);
 #if __BSD_VISIBLE
-void	*mempcpy(void * __restrict, const void * __restrict, size_t);
+void	*(mempcpy)(void * __restrict, const void * __restrict, size_t);
 #endif
 void	*(memset)(void *, int, size_t);
 #if __POSIX_VISIBLE >= 200809

lib/libc/secure/Makefile.inc

@@ -4,7 +4,7 @@
 .PATH: ${LIBC_SRCTOP}/secure
 
 # _FORTIFY_SOURCE
-SRCS+=	fgets_chk.c memcpy_chk.c memmove_chk.c memset_chk.c \
+SRCS+=	fgets_chk.c memcpy_chk.c memmove_chk.c mempcpy_chk.c memset_chk.c \
 	snprintf_chk.c sprintf_chk.c stpcpy_chk.c stpncpy_chk.c \
 	strcat_chk.c strcpy_chk.c strlcat_chk.c strncat_chk.c strlcpy_chk.c \
 	strncpy_chk.c vsnprintf_chk.c vsprintf_chk.c

lib/libc/secure/Symbol.map

@@ -8,6 +8,7 @@ FBSD_1.8 {
 	__fgets_chk;
 	__memcpy_chk;
 	__memmove_chk;
+	__mempcpy_chk;
 	__memset_chk;
 	__snprintf_chk;
 	__sprintf_chk;

lib/libc/secure/mempcpy_chk.c

@@ -0,0 +1,49 @@
+/*-
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2006 The NetBSD Foundation, Inc.
+ * All rights reserved.
+ *
+ * This code is derived from software contributed to The NetBSD Foundation
+ * by Christos Zoulas.
+ *
+ * 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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 <string.h>
+
+#include <ssp/string.h>
+#undef mempcpy
+
+void *
+__mempcpy_chk(void * __restrict dst, const void * __restrict src, size_t len,
+    size_t slen)
+{
+	if (len > slen)
+		__chk_fail();
+
+	if (__ssp_overlap(src, dst, len))
+		__chk_fail();
+
+	return (mempcpy(dst, src, len));
+}

lib/libc/string/mempcpy.c

@@ -32,7 +32,7 @@
 #include <ssp/ssp.h>
 
 void *
-__ssp_real(mempcpy)(void *__restrict dst, const void *__restrict src,
+(mempcpy)(void *__restrict dst, const void *__restrict src,
     size_t len)
 {
 	return ((char *)memcpy(dst, src, len) + len);