[libc] Add libc_stdio_get_console .

components/libc/compilers/armlibc/libc.h

@@ -31,6 +31,7 @@
 int libc_system_init(void);
 
 int libc_stdio_set_console(const char* device_name, int mode);
+int libc_stdio_get_console(void);
 int libc_stdio_read (void *buffer, size_t size);
 int libc_stdio_write(const void *buffer, size_t size);
 

components/libc/compilers/armlibc/stdio.c

@@ -58,6 +58,11 @@ int libc_stdio_set_console(const char* device_name, int mode)
     return std_fd;
 }
 
+int libc_stdio_get_console(void)
+{
+    return std_fd;
+}
+
 int libc_stdio_read(void *buffer, size_t size)
 {
     return read(std_fd, buffer, size);

components/libc/compilers/dlib/libc.h

@@ -32,6 +32,7 @@
 int libc_system_init(void);
 
 int libc_stdio_set_console(const char* device_name, int mode);
+int libc_stdio_get_console(void);
 int libc_stdio_read (void *buffer, size_t size);
 int libc_stdio_write(const void *buffer, size_t size);
 

components/libc/compilers/dlib/stdio.c

@@ -58,6 +58,10 @@ int libc_stdio_set_console(const char* device_name, int mode)
     return std_fd;
 }
 
+int libc_stdio_get_console(void) {
+    return std_fd;
+}
+
 int libc_stdio_read(void *buffer, size_t size)
 {
     return read(std_fd, buffer, size);

components/libc/compilers/newlib/libc.h

@@ -38,6 +38,7 @@
 
 int libc_system_init(void);
 int libc_stdio_set_console(const char* device_name, int mode);
+int libc_stdio_get_console(void);
 
 /* some time related function */
 int libc_set_time(const struct timespec *time);

components/libc/compilers/newlib/stdio.c

@@ -83,3 +83,10 @@ int libc_stdio_set_console(const char* device_name, int mode)
 
     return fileno(std_console);
 }
+
+int libc_stdio_get_console(void) {
+    if (std_console)
+        return fileno(std_console);
+    else
+        return -1;
+}