Patch from Eric Norum:

With this in place, it is possible to fdopen a TCP stream socket and
  getc/fprintf/etc. on the STDIO stream!

c/src/exec/libcsupport/src/termios.c

@@ -113,6 +113,7 @@ struct rtems_termios_tty {
 	int		(*read)(int minor);
 	int		(*write)(int minor, const char *buf, int len);
 };
+
 static struct rtems_termios_tty *ttyHead, *ttyTail;
 static rtems_id ttyMutex;
 

c/src/lib/libc/Makefile.in

@@ -30,7 +30,7 @@ SRCS=$(C_FILES) $(H_FILES) $(SYS_H_FILES) $(RTEMS_H_FILES) $(PRIVATE_H_FILES)
 OBJS=$(C_O_FILES)
 
 include $(RTEMS_CUSTOM)
-include $(PROJECT_ROOT)/make/lib.cfg
+include $(RTEMS_ROOT)/make/lib.cfg
 
 #
 # Add local stuff here using +=

c/src/lib/libc/syscalls.c

@@ -26,6 +26,7 @@
 #include <stdio.h>  /* only for puts */
 
 #include <rtems.h>
+#include <rtems/libio.h>
 
 #ifdef RTEMS_NEWLIB
 /*
@@ -35,20 +36,36 @@
 
 int __rtems_fstat(int _fd, struct stat* _sbuf)
 {
-  if ( _fd > 2 ) {
-    puts( "__rtems_fstat -- only stdio supported" );
-    assert( 0 );
-  }
-  _sbuf->st_mode = S_IFCHR;
 #ifdef HAVE_BLKSIZE
   _sbuf->st_blksize = 0;
 #endif
+
+  /*
+   * For now assume stdin/stdout/stderr are always a TTY line
+   */
+  if (_fd <= 2) {
+    _sbuf->st_mode = S_IFCHR;
+  } else {
+    switch (rtems_file_descriptor_type (_fd)) {
+    case RTEMS_FILE_DESCRIPTOR_TYPE_SOCKET:
+      _sbuf->st_mode = S_IFSOCK;
+      break;
+
+    default:
+      puts( "__rtems_fstat -- unknown socket type" );
+      assert( 0 );
+    }
+  }
   return 0;
 }
 
 int __rtems_isatty(int _fd)
 {
-  return 1;
+  struct stat st;
+
+  if (__rtems_fstat(_fd, &st) < 0)
+    return 0;
+  return S_ISCHR (st.st_mode);
 }
 
 #if !defined(RTEMS_UNIX)

c/src/lib/libc/termios.c

@@ -113,6 +113,7 @@ struct rtems_termios_tty {
 	int		(*read)(int minor);
 	int		(*write)(int minor, const char *buf, int len);
 };
+
 static struct rtems_termios_tty *ttyHead, *ttyTail;
 static rtems_id ttyMutex;
 

cpukit/libcsupport/src/termios.c

@@ -113,6 +113,7 @@ struct rtems_termios_tty {
 	int		(*read)(int minor);
 	int		(*write)(int minor, const char *buf, int len);
 };
+
 static struct rtems_termios_tty *ttyHead, *ttyTail;
 static rtems_id ttyMutex;