libefiwrapper/conin: implement a simple ReadKeyStroke()

This patch implements the SIMPLE_INPUT_INTERFACE ReadKeyStroke()
function using the POSIX getchar() function.

Change-Id: I9cf513d7baf5ff7e36ca94f60ea84da528687730
Signed-off-by: Jeremy Compostella <[email protected]>

Author: jeremy-compostella

include/libefiwrapper/external.h

@@ -77,6 +77,7 @@ int strncmp(const char *s1, const char *s2, size_t n);
 /* stdio.h */
 int printf(const char *format, ...);
 int snprintf(char *str, size_t size, const char *fmt, ...);
+int getchar(void);
 
 /* libpayload.h */
 void ndelay(unsigned int n);

libefiwrapper/conin.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016, Intel Corporation
+ * Copyright (c) 2016-2020, Intel Corporation
  * All rights reserved.
  *
  * Author: Jérémy Compostella <[email protected]>
@@ -41,9 +41,10 @@ conin_reset(__attribute__((__unused__)) struct _SIMPLE_INPUT_INTERFACE *This,
 
 static EFIAPI EFI_STATUS
 conin_read_key(__attribute__((__unused__)) struct _SIMPLE_INPUT_INTERFACE *This,
-	       __attribute__((__unused__)) EFI_INPUT_KEY *Key)
+	       EFI_INPUT_KEY *Key)
 {
-	return EFI_NOT_FOUND;
+	Key->UnicodeChar = getchar();
+	return EFI_SUCCESS;
 }
 
 static EFI_GUID guid = SIMPLE_TEXT_OUTPUT_PROTOCOL;