lib: utils: Add is_a_tty()

This is a portable version of POSIX's isatty(). Windows has its own
version, called _isatty(). UHD thus gains its own, portable version.
The underscores aren't beautiful, but they're necessary so we can
distinguish the POSIX version from the UHD version.

1 files changed, 55 insertions, 0 deletions

diff --git a/host/lib/include/uhdlib/utils/isatty.hpp b/host/lib/include/uhdlib/utils/isatty.hpp
new file mode 100644
index 000000000..1ae2c8de4
--- /dev/null
+++ b/host/lib/include/uhdlib/utils/isatty.hpp
@@ -0,0 +1,55 @@
+//
+// Copyright 2019 Ettus Research, a National Instruments Brand
+//
+// SPDX-License-Identifier: GPL-3.0-or-later
+//
+
+#ifndef INCLUDED_UHDLIB_UTILS_ISATTY_HPP
+#define INCLUDED_UHDLIB_UTILS_ISATTY_HPP
+
+#include <uhd/config.hpp>
+
+namespace uhd {
+
+#ifdef UHD_PLATFORM_WIN32
+
+#   include <io.h>
+
+    /*! Portable version of isatty()
+     *
+     * We call it is_a_tty() to distinguish from the from the POSIX version.
+     * Also, we simply return a Boolean since the Windows version doesn't set
+     * errno.
+     */
+    bool is_a_tty(const int fd)
+    {
+        return _isatty(fd);
+    }
+
+#elif _POSIX_C_SOURCE >= _200112L
+
+#    include <unistd.h>
+
+    /*! Portable version of isatty()
+     *
+     * We call it is_a_tty() to distinguish from the from the POSIX version.
+     * Also, we simply return a Boolean since the Windows version doesn't set
+     * errno.
+     */
+    bool is_a_tty(const int fd)
+    {
+        return isatty(fd);
+    }
+
+#else
+
+    bool is_a_tty(const int fd)
+    {
+        return false;
+    }
+
+#endif
+
+} /* namespace uhd */
+
+#endif /* INCLUDED_UHDLIB_UTILS_ISATTY_HPP */