Index: kernel/generic/src/lib/str_error.c
===================================================================
--- kernel/generic/src/lib/str_error.c	(revision dad8d2dc1df4b9f6323029dbdda0fb3d1b862c9c)
+++ kernel/generic/src/lib/str_error.c	(revision dad8d2dc1df4b9f6323029dbdda0fb3d1b862c9c)
@@ -0,0 +1,99 @@
+/*
+ * Copyright (c) 2010 Martin Decky
+ * Copyright (c) 2017 CZ.NIC, z.s.p.o.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ * - 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.
+ * - The name of the author may not be used to endorse or promote products
+ *   derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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 <errno.h>
+#include <str.h>
+
+/* The arrays below are automatically generated from the same file that
+ * errno.h constants are generated from. Triple-include of the same list
+ * with redefinitions of __errno() macro are used to ensure that the
+ * information cannot get out of synch. This is inpired by musl libc.
+ */
+
+#undef __errno_entry
+#define __errno_entry(name, num, desc) num,
+
+static const int err_num[] = {
+#include <abi/errno.in>
+};
+
+#undef __errno_entry
+#define __errno_entry(name, num, desc) #name,
+
+static const char* err_name[] = {
+#include <abi/errno.in>
+};
+
+#undef __errno_entry
+#define __errno_entry(name, num, desc) "[" #name "]" desc,
+
+static const char* err_desc[] = {
+#include <abi/errno.in>
+};
+
+/* Returns index corresponding to the given errno, or -1 if not found. */
+static int find_errno(errno_t e)
+{
+	/* Just a dumb linear search.
+	 * There too few entries to warrant anything smarter.
+	 */
+
+	int len = sizeof(err_num) / sizeof(errno_t);
+
+	for (int i = 0; i < len; i++) {
+		if (err_num[i] == e) {
+			return i;
+		}
+	}
+
+	return -1;
+}
+
+const char *str_error_name(errno_t e)
+{
+	int i = find_errno(e);
+
+	if (i >= 0) {
+		return err_name[i];
+	}
+
+	return "(unknown)";
+}
+
+const char *str_error(errno_t e)
+{
+	int i = find_errno(e);
+
+	if (i >= 0) {
+		return err_desc[i];
+	}
+
+	return "Unknown error code";
+}
+