base/posix/eintr_wrapper.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.

// This provides a wrapper around system calls which may be interrupted by a
// signal and return EINTR. See man 7 signal.
// To prevent long-lasting loops (which would likely be a bug, such as a signal
// that should be masked) to go unnoticed, there is a limit after which the
// caller will nonetheless see an EINTR in Debug builds.
//
// On Windows and Fuchsia, this wrapper macro does nothing because there are no
// signals.
//
// Don't wrap close calls in HANDLE_EINTR. Use IGNORE_EINTR if the return
// value of close is significant. See http://crbug.com/269623.

#ifndef BASE_POSIX_EINTR_WRAPPER_H_
#define BASE_POSIX_EINTR_WRAPPER_H_

#include "util/build_config.h"

#if defined(OS_POSIX) && !defined(OS_FUCHSIA)

#include <errno.h>

#if defined(NDEBUG)

#define HANDLE_EINTR(x)                                     \
  ({                                                        \
    decltype(x) eintr_wrapper_result;                       \
    do {                                                    \
      eintr_wrapper_result = (x);                           \
    } while (eintr_wrapper_result == -1 && errno == EINTR); \
    eintr_wrapper_result;                                   \
  })

#else

#define HANDLE_EINTR(x)                                      \
  ({                                                         \
    int eintr_wrapper_counter = 0;                           \
    decltype(x) eintr_wrapper_result;                        \
    do {                                                     \
      eintr_wrapper_result = (x);                            \
    } while (eintr_wrapper_result == -1 && errno == EINTR && \
             eintr_wrapper_counter++ < 100);                 \
    eintr_wrapper_result;                                    \
  })

#endif  // NDEBUG

#define IGNORE_EINTR(x)                                   \
  ({                                                      \
    decltype(x) eintr_wrapper_result;                     \
    do {                                                  \
      eintr_wrapper_result = (x);                         \
      if (eintr_wrapper_result == -1 && errno == EINTR) { \
        eintr_wrapper_result = 0;                         \
      }                                                   \
    } while (0);                                          \
    eintr_wrapper_result;                                 \
  })

#else  // !OS_POSIX || OS_FUCHSIA

#define HANDLE_EINTR(x) (x)
#define IGNORE_EINTR(x) (x)

#endif  // !OS_POSIX || OS_FUCHSIA

#endif  // BASE_POSIX_EINTR_WRAPPER_H_