atomicio.hh

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/*
 * Copyright (c) 2008 The Hewlett-Packard Development Company
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met: redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer;
 * redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution;
 * neither the name of the copyright holders nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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#ifndef __BASE_ATOMICIO_HH__
#define __BASE_ATOMICIO_HH__

#include <unistd.h>

// These functions keep reading/writing, if possible, until all data
// has been transferred.  Basically, try again when there's no error,
// but there is data left also retry on EINTR.
// This function blocks until it is done.

ssize_t atomic_read(int fd, void *s, size_t n);
ssize_t atomic_write(int fd, const void *s, size_t n);

#define STATIC_MSG(fd, m)                                       \
    do {                                                        \
        static const char msg[] = m;                            \
        atomic_write(fd, msg, sizeof(msg) - 1);                 \
    } while (0)

#define STATIC_ERR(m) STATIC_MSG(STDERR_FILENO, m)

#endif // __BASE_ATOMICIO_HH__