[NaCl SDK] nacl_io: Enable isatty running under sel_ldr.

native_client_sdk/src/libraries/nacl_io/passthroughfs/passthrough_fs.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "nacl_io/passthroughfs/passthrough_fs.h"
 
 #include <errno.h>
 
 #include "nacl_io/kernel_handle.h"
 #include "nacl_io/kernel_wrap_real.h"
@@ skipping 72 matching lines @@
     return nread;
   }
 
   virtual Error GetStat(struct stat* stat) {
     int err = _real_fstat(real_fd_, stat);
     if (err)
       return err;
     return 0;
   }
 
+  virtual Error Isatty() {
+#ifdef __GLIBC__
+    // isatty is not yet hooked up to the IRT interface under glibc.
+    return ENOTTY;
+#else
+    int result = 0;
+    int err = _real_isatty(real_fd_, &result);
+    if (err)
+      return err;
+    return 0;
+#endif
+  }
+
   Error MMap(void* addr,
              size_t length,
              int prot,
              int flags,
              size_t offset,
              void** out_addr) {
     *out_addr = addr;
     int err = _real_mmap(out_addr, length, prot, flags, real_fd_, offset);
     if (err)
       return err;
@@ skipping 58 matching lines @@
   // Not implemented by NaCl.
   return ENOSYS;
 }
 
 Error PassthroughFs::Rename(const Path& path, const Path& newpath) {
   // Not implemented by NaCl.
   return ENOSYS;
 }
 
 }  // namespace nacl_io