POSIX: Add a macro for handling EINTR.

base/eintr_wrappers.h

Index: base/eintr_wrappers.h
diff --git a/base/eintr_wrappers.h b/base/eintr_wrappers.h
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+++ b/base/eintr_wrappers.h
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+// Copyright (c) 2009 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.
+
+// This provides a wrapper around system calls which may be interrupted by a
+// signal and return EINTR. See man 7 signal.
+//
+// On Windows, this wrapper macro does nothing.
+
+#ifndef BASE_EINTR_WRAPPERS_H_
+#define BASE_EINTR_WRAPPERS_H_
+
+#include "build/build_config.h"
+
+#if defined(OS_POSIX)
+
+#include <errno.h>
+
+#define HANDLE_EINTR(x) ({ \
+  typeof(x) ret; \
+  do { \
+    ret = x; \
+  } while (x == -1 && errno == EINTR); \
+  ret;\
+})
+
+#else
+
+#define HANDLE_EINTR(x) x
+
+#endif  // OS_POSIX
+
+#endif  // !BASE_EINTR_WRAPPERS_H_