base/posix/eintr_wrapper.h

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 // This provides a wrapper around system calls which may be interrupted by a
   6 // signal and return EINTR. See man 7 signal.
   7 // To prevent long-lasting loops (which would likely be a bug, such as a signal
   8 // that should be masked) to go unnoticed, there is a limit after which the
   9 // caller will nonetheless see an EINTR in Debug builds.
  10 //
  11 // On Windows, this wrapper macro does nothing.
  12 //
  13 // Don't wrap close calls in HANDLE_EINTR. Use IGNORE_EINTR if the return
  14 // value of close is significant. See http://crbug.com/269623.
  15
  16 #ifndef BASE_POSIX_EINTR_WRAPPER_H_
  17 #define BASE_POSIX_EINTR_WRAPPER_H_
  18
  19 #include "build/build_config.h"
  20
  21 #if defined(OS_POSIX)
  22
  23 #include <errno.h>
  24
  25 #if defined(NDEBUG)
  26
  27 #define HANDLE_EINTR(x) ({ \
  28   decltype(x) eintr_wrapper_result; \
  29   do { \
  30     eintr_wrapper_result = (x); \
  31   } while (eintr_wrapper_result == -1 && errno == EINTR); \
  32   eintr_wrapper_result; \
  33 })
  34
  35 #else
  36
  37 #define HANDLE_EINTR(x) ({ \
  38   int eintr_wrapper_counter = 0; \
  39   decltype(x) eintr_wrapper_result; \
  40   do { \
  41     eintr_wrapper_result = (x); \
  42   } while (eintr_wrapper_result == -1 && errno == EINTR && \
  43            eintr_wrapper_counter++ < 100); \
  44   eintr_wrapper_result; \
  45 })
  46
  47 #endif  // NDEBUG
  48
  49 #define IGNORE_EINTR(x) ({ \
  50   decltype(x) eintr_wrapper_result; \
  51   do { \
  52     eintr_wrapper_result = (x); \
  53     if (eintr_wrapper_result == -1 && errno == EINTR) { \
  54       eintr_wrapper_result = 0; \
  55     } \
  56   } while (0); \
  57   eintr_wrapper_result; \
  58 })
  59
  60 #else
  61
  62 #define HANDLE_EINTR(x) (x)
  63 #define IGNORE_EINTR(x) (x)
  64
  65 #endif  // OS_POSIX
  66
  67 #endif  // BASE_POSIX_EINTR_WRAPPER_H_