Add dwm config

hosts/fw/config/dwm/util.c

@@ -0,0 +1,37 @@
+/* See LICENSE file for copyright and license details. */
+#include <errno.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "util.h"
+
+void
+die(const char *fmt, ...)
+{
+	va_list ap;
+	int saved_errno;
+
+	saved_errno = errno;
+
+	va_start(ap, fmt);
+	vfprintf(stderr, fmt, ap);
+	va_end(ap);
+
+	if (fmt[0] && fmt[strlen(fmt)-1] == ':')
+		fprintf(stderr, " %s", strerror(saved_errno));
+	fputc('\n', stderr);
+
+	exit(1);
+}
+
+void *
+ecalloc(size_t nmemb, size_t size)
+{
+	void *p;
+
+	if (!(p = calloc(nmemb, size)))
+		die("calloc:");
+	return p;
+}