From ece39a9a1859be150e874754755213e264f3be8a Mon Sep 17 00:00:00 2001
From: Jan Nieuwenhuizen <janneke@gnu.org>
Date: Sun, 22 Apr 2018 11:47:44 +0200
Subject: [PATCH] mlibc: Add isatty.

* lib/libc.c (isatty): New function.
* include/unistd.h: Declare it.
---
 include/unistd.h | 1 +
 lib/libc.c       | 8 ++++++++
 2 files changed, 9 insertions(+)

diff --git a/include/unistd.h b/include/unistd.h
index 5c6426e3..1c4086ad 100644
--- a/include/unistd.h
+++ b/include/unistd.h
@@ -51,6 +51,7 @@ int access (char const *s, int mode);
 int close (int fd);
 int execvp (char const *file, char *const argv[]);
 char *getcwd (char *buf, size_t size);
+int isatty (int fd);
 off_t lseek (int fd, off_t offset, int whence);
 int read (int fd, void* buf, size_t n);
 int unlink (char const *file_name);
diff --git a/lib/libc.c b/lib/libc.c
index bfef3eec..97565c31 100644
--- a/lib/libc.c
+++ b/lib/libc.c
@@ -18,6 +18,7 @@
  * along with Mes.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include <sys/ioctl.h>
 #include <stdarg.h>
 #include <stdlib.h>
 
@@ -419,4 +420,11 @@ sprintf (char *str, char const* format, ...)
   va_end (ap);
   return r;
 }
+
+int
+isatty (int fd)
+{
+  return ioctl (fd, TCGETS, 0) == -14; // MAGIC
+}
+
 #endif //!POSIX