[NaCl SDK] nacl_io: handle null irt function pointers

native_client_sdk/src/libraries/nacl_io/kernel_wrap_newlib.cc

Index: native_client_sdk/src/libraries/nacl_io/kernel_wrap_newlib.cc
diff --git a/native_client_sdk/src/libraries/nacl_io/kernel_wrap_newlib.cc b/native_client_sdk/src/libraries/nacl_io/kernel_wrap_newlib.cc
index ebe8dd528bb1d3d61ace938baaed2fe2b291611e..fecd72f9916c816c4a6183cc261cedaefdcace26 100644
--- a/native_client_sdk/src/libraries/nacl_io/kernel_wrap_newlib.cc
+++ b/native_client_sdk/src/libraries/nacl_io/kernel_wrap_newlib.cc
@@ -269,13 +269,11 @@ static void assign_real_pointers() {
 }
 
 #define CHECK_REAL(func)    \
-  if (!REAL(func))          \
-    assign_real_pointers();
-
-#define CHECK_REAL_NOSYS(func)  \
-  CHECK_REAL(func)              \
-  if (!REAL(func))              \
-    return ENOSYS;
+  if (!REAL(func)) {        \
+    assign_real_pointers(); \
+    if (!REAL(func))        \
+      return ENOSYS;        \
+  }
 
 // "real" functions, i.e. the unwrapped original functions.
 
@@ -285,7 +283,8 @@ int _real_close(int fd) {
 }
 
 void _real_exit(int status) {
-  CHECK_REAL(exit);
+  if (!REAL(exit))
+    assign_real_pointers();
   REAL(exit)(status);
 }
 
@@ -360,7 +359,7 @@ int _real_write(int fd, const void* buf, size_t count, size_t* nwrote) {
 }
 
 int _real_getcwd(char* pathname, size_t len) {
-  CHECK_REAL_NOSYS(getcwd);
+  CHECK_REAL(getcwd);
   return REAL(getcwd)(pathname, len);
 }