git: 3dc5429158cf - main - lib/libc/aarch64/string: add strncat SIMD implementation

The branch main has been updated by fuz:

URL: https://cgit.FreeBSD.org/src/commit/?id=3dc5429158cf221374cdbd0bbb728962bff4fb76

commit 3dc5429158cf221374cdbd0bbb728962bff4fb76
Author:     Getz Mikalsen <getz@FreeBSD.org>
AuthorDate: 2024-08-26 18:15:34 +0000
Commit:     Robert Clausecker <fuz@FreeBSD.org>
CommitDate: 2025-01-10 15:02:40 +0000

    lib/libc/aarch64/string: add strncat SIMD implementation
    
    This patch requires D46170 as it depends on strlcpy being labeled
    __memccpy.
    
    It's a direct copy from the amd64 string functions.
    
    Tested by:      fuz (exprun)
    Reviewed by:    fuz, emaste
    Sponsored by:   Google LLC (GSoC 2024)
    PR:             281175
    Differential Revision: https://reviews.freebsd.org/D46292
---
 lib/libc/aarch64/string/Makefile.inc |  3 ++-
 lib/libc/aarch64/string/strncat.c    | 29 +++++++++++++++++++++++++++++
 2 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/lib/libc/aarch64/string/Makefile.inc b/lib/libc/aarch64/string/Makefile.inc
index 78145a17ab85..876ef4257b4c 100644
--- a/lib/libc/aarch64/string/Makefile.inc
+++ b/lib/libc/aarch64/string/Makefile.inc
@@ -28,7 +28,8 @@ MDSRCS+= \
 	strcat.c \
 	strlcpy.S \
 	strncmp.S \
-	memccpy.S
+	memccpy.S \
+	strncat.c
 
 #
 # Add the above functions. Generate an asm file that includes the needed
diff --git a/lib/libc/aarch64/string/strncat.c b/lib/libc/aarch64/string/strncat.c
new file mode 100644
index 000000000000..33b278ac5e04
--- /dev/null
+++ b/lib/libc/aarch64/string/strncat.c
@@ -0,0 +1,29 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2023 Robert Clausecker
+ */
+
+#include <sys/cdefs.h>
+
+#include <string.h>
+
+void *__memccpy(void *restrict, const void *restrict, int, size_t);
+
+char *
+strncat(char *dest, const char *src, size_t n)
+{
+	size_t len;
+	char *endptr;
+
+	len = strlen(dest);
+	endptr = __memccpy(dest + len, src, '\0', n);
+
+	/* avoid an extra branch */
+	if (endptr == NULL)
+		endptr = dest + len + n + 1;
+
+	endptr[-1] = '\0';
+
+	return (dest);
+}