添加rtthread相关代码

riscv/rtthread/components/libc/compilers/common/cunistd.c

@@ -0,0 +1,34 @@
+/*
+ * Copyright (c) 2006-2022, RT-Thread Development Team
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Change Logs:
+ * Date           Author       Notes
+ * 2023-08-16     Meco Man     first version
+ */
+
+#include <rtthread.h>
+#include <unistd.h>
+#include <sys/errno.h>
+
+int isatty(int fd)
+{
+#if defined(RT_USING_CONSOLE) && defined(RT_USING_DEVICE)
+    if(fd == STDOUT_FILENO || fd == STDERR_FILENO)
+    {
+        return 1;
+    }
+#endif /* defined(RT_USING_CONSOLE) && defined(RT_USING_DEVICE) */
+
+#ifdef RT_USING_POSIX_STDIO
+    if(fd == STDIN_FILENO)
+    {
+        return 1;
+    }
+#endif /* RT_USING_POSIX_STDIO */
+
+    rt_set_errno(ENOTTY);
+    return 0;
+}
+RTM_EXPORT(isatty);