[NaCl SDK] Change KernelProxy::GetCWD() to allocate path.

native_client_sdk/src/libraries/nacl_io/kernel_proxy.cc

 // Copyright (c) 2012 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/kernel_proxy.h"
 
 #include <assert.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <limits.h>
@@ skipping 252 matching lines @@
   if (error) {
     errno = error;
     return -1;
   }
   return 0;
 }
 
 char* KernelProxy::getcwd(char* buf, size_t size) {
   std::string cwd = GetCWD();
 
-  if (size <= 0) {
-    errno = EINVAL;
-    return NULL;
-  }
-
   // If size is 0, allocate as much as we need.
   if (size == 0) {
     size = cwd.size() + 1;
   }
 
   // Verify the buffer is large enough
   if (size <= cwd.size()) {
     errno = ERANGE;
     return NULL;
   }
@@ skipping 1313 matching lines @@
     errno = ENOTSOCK;
     return -1;
   }
 
   return 0;
 }
 
 #endif  // PROVIDES_SOCKET_API
 
 }  // namespace_nacl_io