[NaCl SDK] nacl_io: handle null irt function pointers

native_client_sdk/src/libraries/nacl_io/kernel_wrap_bionic.cc

Index: native_client_sdk/src/libraries/nacl_io/kernel_wrap_bionic.cc
diff --git a/native_client_sdk/src/libraries/nacl_io/kernel_wrap_bionic.cc b/native_client_sdk/src/libraries/nacl_io/kernel_wrap_bionic.cc
index 7bdf4f9862e29f4d03cbd011ed95cc1f87ae8152..3b8cb64482b7621a76b3705ba636ea92e330000c 100644
--- a/native_client_sdk/src/libraries/nacl_io/kernel_wrap_bionic.cc
+++ b/native_client_sdk/src/libraries/nacl_io/kernel_wrap_bionic.cc
@@ -436,7 +436,7 @@ int _real_lseek(int fd, int64_t offset, int whence, int64_t* new_offset) {
 
 int _real_lstat(const char* path, struct stat* buf) {
   struct nacl_abi_stat st;
-  CHECK_REAL(fstat);
+  CHECK_REAL_NOSYS(lstat);
 
   int err = REAL(lstat)(path, (struct stat*)&st);
   if (err) {
@@ -449,7 +449,7 @@ int _real_lstat(const char* path, struct stat* buf) {
 }
 
 int _real_mkdir(const char* pathname, mode_t mode) {
-  CHECK_REAL(mkdir);
+  CHECK_REAL_NOSYS(mkdir);
   return REAL(mkdir)(pathname, mode);
 }
 
@@ -469,12 +469,12 @@ int _real_munmap(void* addr, size_t length) {
 }
 
 int _real_open(const char* pathname, int oflag, mode_t mode, int* newfd) {
-  CHECK_REAL(open);
+  CHECK_REAL_NOSYS(open);
   return REAL(open)(pathname, oflag, mode, newfd);
 }
 
 int _real_open_resource(const char* file, int* fd) {
-  CHECK_REAL(open_resource);
+  CHECK_REAL_NOSYS(open_resource);
   return REAL(open_resource)(file, fd);
 }
 
@@ -484,17 +484,17 @@ int _real_read(int fd, void* buf, size_t count, size_t* nread) {
 }
 
 int _real_readlink(const char* path, char* buf, size_t count, size_t* nread) {
-  CHECK_REAL(readlink);
+  CHECK_REAL_NOSYS(readlink);
   return REAL(readlink)(path, buf, count, nread);
 }
 
 int _real_rmdir(const char* pathname) {
-  CHECK_REAL(rmdir);
+  CHECK_REAL_NOSYS(rmdir);
   return REAL(rmdir)(pathname);
 }
 
 int _real_truncate(const char* pathname, int64_t len) {
-  CHECK_REAL(truncate);
+  CHECK_REAL_NOSYS(truncate);
   return REAL(truncate)(pathname, len);
 }