From ae429ebde2a0f88d1749a3ccd8f6b1251c6623e4 Mon Sep 17 00:00:00 2001
From: Alejandro Colomar <alx@kernel.org>
Date: Sun, 22 Mar 2026 23:36:25 +0100
Subject: [PATCH] lib/: memdup_T(): Add parameter 'n'

I've found this to be useful elsewhere, where we want to duplicate an
array.

We need to implement this through a real memdup() function, because
arrays can't be copied with the assignment operator ('='); we need to
memcpy(3).

Signed-off-by: Alejandro Colomar <alx@kernel.org>
---
 lib/string/strdup/memdup.c |  7 ++++++-
 lib/string/strdup/memdup.h | 40 +++++++++++++++++++++++++++-----------
 lib/utmp.c                 |  2 +-
 3 files changed, 36 insertions(+), 13 deletions(-)

diff --git a/lib/string/strdup/memdup.c b/lib/string/strdup/memdup.c
index c574e3cff9..e4c41c6876 100644
--- a/lib/string/strdup/memdup.c
+++ b/lib/string/strdup/memdup.c
@@ -1,7 +1,12 @@
-// SPDX-FileCopyrightText: 2025, Alejandro Colomar <alx@kernel.org>
+// SPDX-FileCopyrightText: 2025-2026, Alejandro Colomar <alx@kernel.org>
 // SPDX-License-Identifier: BSD-3-Clause
 
 
 #include "config.h"
 
 #include "string/strdup/memdup.h"
+
+#include <stddef.h>
+
+
+extern inline void *memdup(const void *p, size_t size);
diff --git a/lib/string/strdup/memdup.h b/lib/string/strdup/memdup.h
index cbae5158f8..d6df9e032e 100644
--- a/lib/string/strdup/memdup.h
+++ b/lib/string/strdup/memdup.h
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2025, Alejandro Colomar <alx@kernel.org>
+// SPDX-FileCopyrightText: 2025-2026, Alejandro Colomar <alx@kernel.org>
 // SPDX-License-Identifier: BSD-3-Clause
 
 
@@ -9,21 +9,39 @@
 #include "config.h"
 
 #include <stddef.h>
+#include <stdlib.h>
+#include <string.h>
 
 #include "alloc/malloc.h"
+#include "attr.h"
+#include "sizeof.h"
 
 
 // memdup_T - memory duplicate type-safe
-#define memdup_T(p, T)   memdup_T_(p, typeas(T))
-#define memdup_T_(p, T)                                               \
-({                                                                    \
-	T  *new_;                                                     \
-                                                                      \
-	new_ = malloc_T(1, T);                                        \
-	if (new_ != NULL)                                             \
-		*new_ = *(p);                                         \
-	new_;                                                         \
-})
+#define memdup_T(p, n, T)   memdup_T_(p, n, typeas(T))
+#define memdup_T_(p, n, T)                                            \
+(                                                                     \
+	_Generic(p, T *: (void)0, const T *: (void)0),                \
+	(T *){memdup(p, (n) * sizeof(T))}                             \
+)
+
+
+ATTR_MALLOC(free)
+inline void *memdup(const void *p, size_t size);
+
+
+// memdup - memory duplicate
+inline void *
+memdup(const void *p, size_t size)
+{
+	void  *dup;
+
+	dup = malloc(size);
+	if (dup == NULL)
+		return NULL;
+
+	return memcpy(dup, p, size);
+}
 
 
 #endif  // include guard
diff --git a/lib/utmp.c b/lib/utmp.c
index dc9870a7cf..24ef049b9c 100644
--- a/lib/utmp.c
+++ b/lib/utmp.c
@@ -182,7 +182,7 @@ get_current_utmp(pid_t main_pid)
 		ut = ut_by_pid ?: ut_by_line;
 
 	if (NULL != ut)
-		ut = memdup_T(ut, struct utmpx);
+		ut = memdup_T(ut, 1, struct utmpx);
 
 	free(ut_by_line);
 	free(ut_by_pid);