From 5f48a6b4e0e2753038a839cb10246ba3a159b3c4 Mon Sep 17 00:00:00 2001
From: Lephenixnoir <sebastien.michelland@protonmail.com>
Date: Sun, 16 May 2021 18:10:30 +0200
Subject: [PATCH] errno: add the errno variable and base macros

A <bits/errno.h> file will likely by added later on for each target to
add more specific values.
---
 CMakeLists.txt         |  1 +
 include/errno.h        | 12 ++++++++++++
 src/libc/errno/errno.c |  4 ++++
 3 files changed, 17 insertions(+)
 create mode 100644 include/errno.h
 create mode 100644 src/libc/errno/errno.c

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 0af8e42..dd2baa6 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -73,6 +73,7 @@ set(SOURCES
   src/libc/ctype/isxdigit.c
   src/libc/ctype/tolower.c
   src/libc/ctype/toupper.c
+  src/libc/errno/errno.c
   src/libc/locale/setlocale.c
   src/libc/locale/localeconv.c
   src/libc/stdio/vsnprintf.c
diff --git a/include/errno.h b/include/errno.h
new file mode 100644
index 0000000..41f0201
--- /dev/null
+++ b/include/errno.h
@@ -0,0 +1,12 @@
+#ifndef __ERRNO_H__
+# define __ERRNO_H__
+
+/* Initialized to 0 at startup. Currently not TLS, maybe in the future if
+   threads are supported. */
+extern int errno;
+
+#define EDOM       1
+#define EILSEQ     2
+#define ERANGE     3
+
+#endif /*__ERRNO_H__*/
diff --git a/src/libc/errno/errno.c b/src/libc/errno/errno.c
new file mode 100644
index 0000000..01c99f8
--- /dev/null
+++ b/src/libc/errno/errno.c
@@ -0,0 +1,4 @@
+#include <errno.h>
+
+/* The initial value is 0 at program startup */
+int errno = 0;