[NaCl SDK] nacl_io: Make IRT intercepts (and their test code) more robust.

native_client_sdk/src/libraries/nacl_io/kernel_wrap.h

 // 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.
 
 #ifndef LIBRARIES_NACL_IO_KERNEL_WRAP_H_
 #define LIBRARIES_NACL_IO_KERNEL_WRAP_H_
 
+#include <assert.h>
 #include <signal.h>
 #include <stdint.h>
 #include <stdlib.h>
 #include <sys/fcntl.h>
 #include <sys/ioctl.h>
 #include <sys/types.h>
 
 #include "nacl_io/ossocket.h"
 #include "nacl_io/ostypes.h"
 #include "nacl_io/osutime.h"
 #include "sdk_util/macros.h"
 
 #if defined(__GLIBC__)
 #include <sys/cdefs.h>
 #define NOTHROW __THROW
 #else
 #define NOTHROW
 #endif
 
+// Most kernel intercept functions (ki_*) return -1 and set the global errno.
+// However, the IRT wrappers are expected to return errno on failure. These
+// macros are used in the wrappers to check that the ki_ function actually
+// set errno and to its value.
+#define RTN_ERRNO_IF(cond) \
+  if (cond) { \
+    assert(errno != 0); \
+    return errno; \
+  }
+
+#define ERRNO_RTN(cond) \
+  RTN_ERRNO_IF(cond < 0); \
+  return 0;
+
 #if defined(WIN32)
 typedef int chmod_mode_t;
 typedef int getcwd_size_t;
 typedef int read_ssize_t;
 typedef int write_ssize_t;
 #define NAME(x) _##x
 #else
 typedef mode_t chmod_mode_t;
 typedef size_t getcwd_size_t;
 typedef ssize_t read_ssize_t;
@@ skipping 88 matching lines @@
 int setsockopt(int fd, int lvl, int optname, const void* optval,
                socklen_t len);
 int shutdown(int fd, int how);
 int socket(int domain, int type, int protocol);
 int socketpair(int domain, int type, int protocl, int* sv);
 #endif  // PROVIDES_SOCKET_API
 
 EXTERN_C_END
 
 #endif  // LIBRARIES_NACL_IO_KERNEL_WRAP_H_