--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/xmalloc.c	Tue Dec 06 13:51:55 2022 +0000
@@ -0,0 +1,147 @@
+/* $OpenBSD: xmalloc.c,v 1.11 2016/11/17 10:06:08 nicm Exp $ */
+
+/*
+ * Author: Tatu Ylonen <ylo@cs.hut.fi>
+ * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
+ *                    All rights reserved
+ * Versions of malloc and friends that check their results, and never return
+ * failure (they call fatalx if they encounter an error).
+ *
+ * As far as I am concerned, the code I have written for this software
+ * can be used freely for any purpose.  Any derived versions of this
+ * software must be clearly marked as such, and if the derived work is
+ * incompatible with the protocol description in the RFC file, it must be
+ * called by a name other than "ssh" or "Secure Shell".
+ */
+
+#include <err.h>
+#include <errno.h>
+#include <limits.h>
+#include <stdarg.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "xmalloc.h"
+
+void *
+xmalloc(size_t size)
+{
+	void *ptr;
+
+	if (size == 0)
+		errx(1, "xmalloc: zero size");
+	ptr = malloc(size);
+	if (ptr == NULL)
+		err(1, "xmalloc: allocating %zu bytes", size);
+	return ptr;
+}
+
+void *
+xcalloc(size_t nmemb, size_t size)
+{
+	void *ptr;
+
+	if (size == 0 || nmemb == 0)
+		errx(1, "xcalloc: zero size");
+	ptr = calloc(nmemb, size);
+	if (ptr == NULL)
+		err(1, "xcalloc: allocating %zu * %zu bytes", nmemb, size);
+	return ptr;
+}
+
+void *
+xrealloc(void *ptr, size_t size)
+{
+	return xreallocarray(ptr, 1, size);
+}
+
+void *
+xreallocarray(void *ptr, size_t nmemb, size_t size)
+{
+	void *new_ptr;
+
+	if (nmemb == 0 || size == 0)
+		errx(1, "xreallocarray: zero size");
+	new_ptr = reallocarray(ptr, nmemb, size);
+	if (new_ptr == NULL)
+		err(1, "xreallocarray: allocating %zu * %zu bytes",
+		    nmemb, size);
+	return new_ptr;
+}
+
+char *
+xstrdup(const char *str)
+{
+	char *cp;
+
+	if ((cp = strdup(str)) == NULL)
+		err(1, "xstrdup");
+	return cp;
+}
+
+char *
+xstrndup(const char *str, size_t maxlen)
+{
+	char *cp;
+
+	if ((cp = strndup(str, maxlen)) == NULL)
+		err(1, "xstrndup");
+	return cp;
+}
+
+int
+xasprintf(char **ret, const char *fmt, ...)
+{
+	va_list ap;
+	int i;
+
+	va_start(ap, fmt);
+	i = xvasprintf(ret, fmt, ap);
+	va_end(ap);
+
+	return i;
+}
+
+int
+xvasprintf(char **ret, const char *fmt, va_list ap)
+{
+	int i;
+
+	i = vasprintf(ret, fmt, ap);
+
+	if (i < 0 || *ret == NULL)
+		err(1, "xasprintf");
+
+	return i;
+}
+
+int
+xsnprintf(char *str, size_t len, const char *fmt, ...)
+{
+	va_list ap;
+	int i;
+
+	va_start(ap, fmt);
+	i = xvsnprintf(str, len, fmt, ap);
+	va_end(ap);
+
+	return i;
+}
+
+int
+xvsnprintf(char *str, size_t len, const char *fmt, va_list ap)
+{
+	int i;
+
+	if (len > INT_MAX)
+		errx(1, "xsnprintf: len > INT_MAX");
+
+	i = vsnprintf(str, len, fmt, ap);
+
+	if (i < 0 || i >= (int)len)
+		errx(1, "xsnprintf: overflow");
+
+	return i;
+}