[NaCl SDK] nacl_io: handle null irt function pointers

native_client_sdk/src/libraries/nacl_io/kernel_wrap_glibc.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 <sys/types.h>  // Include something that will define __GLIBC__.
 
 // The entire file is wrapped in this #if. We do this so this .cc file can be
 // compiled, even on a non-glibc build.
 #if defined(__native_client__) && defined(__GLIBC__)
 
@@ skipping 506 matching lines @@
 }
 
 static void assign_real_pointers() {
   static bool assigned = false;
   if (!assigned) {
     EXPAND_SYMBOL_LIST_OPERATION(ASSIGN_REAL_PTR)
     assigned = true;
   }
 }
 
-#define CHECK_REAL(func) \
-  if (!REAL(func))       \
-    assign_real_pointers();
-
-#define CHECK_REAL_NOSYS(func)  \
-  CHECK_REAL(func)              \
-  if (!REAL(func))              \
-    return ENOSYS;
+#define CHECK_REAL(func)    \
+  if (!REAL(func)) {        \
+    assign_real_pointers(); \
+    if (!REAL(func))        \
+      return ENOSYS;        \
+  }
 
 // "real" functions, i.e. the unwrapped original functions.
 
 int _real_close(int fd) {
   CHECK_REAL(close);
   return REAL(close)(fd);
 }
 
 void _real_exit(int status) {
-  CHECK_REAL(exit);
+  if (!REAL(exit))
+    assign_real_pointers();
   REAL(exit)(status);
 }
 
 int _real_fstat(int fd, struct stat* buf) {
   struct nacl_abi_stat st;
   CHECK_REAL(fstat);
   int err = REAL(fstat)(fd, &st);
   if (err) {
     errno = err;
     return -1;
@@ skipping 77 matching lines @@
   CHECK_REAL(rmdir);
   return REAL(rmdir)(pathname);
 }
 
 int _real_write(int fd, const void* buf, size_t count, size_t* nwrote) {
   CHECK_REAL(write);
   return REAL(write)(fd, buf, count, nwrote);
 }
 
 int _real_getcwd(char* pathname, size_t len) {
-  CHECK_REAL_NOSYS(getcwd);
+  CHECK_REAL(getcwd);
   return REAL(getcwd)(pathname, len);
 }
 
 static bool s_wrapped = false;
 void kernel_wrap_init() {
   if (!s_wrapped) {
     LOG_TRACE("kernel_wrap_init");
     assign_real_pointers();
     EXPAND_SYMBOL_LIST_OPERATION(USE_WRAP)
     s_wrapped = true;
   }
 }
 
 void kernel_wrap_uninit() {
   if (s_wrapped) {
     LOG_TRACE("kernel_wrap_uninit");
     EXPAND_SYMBOL_LIST_OPERATION(USE_REAL)
     s_wrapped = false;
   }
 }
 
 EXTERN_C_END
 
 #endif  // defined(__native_client__) && defined(__GLIBC__)