writeprivate.hpp

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//    OpenVPN -- An application to securely tunnel IP networks
//               over a single port, with support for SSL/TLS-based
//               session authentication and key exchange,
//               packet encryption, packet authentication, and
//               packet compression.
//
//    Copyright (C) 2012- OpenVPN Inc.
//
//    SPDX-License-Identifier: MPL-2.0 OR AGPL-3.0-only WITH openvpn3-openssl-exception
//
 
#pragma once
 
#include <string>
 
#include <openvpn/common/platform.hpp>
 
#if !defined(OPENVPN_PLATFORM_WIN)
#include <sys/types.h> // for open(), ftruncate()
#include <sys/stat.h>  // for open()
#include <fcntl.h>     // for open()
#include <unistd.h>    // for write(), ftruncate()
#include <errno.h>
#endif
 
#include <openvpn/common/exception.hpp>
#include <openvpn/common/size.hpp>
#include <openvpn/buffer/buffer.hpp>
 
#if !defined(OPENVPN_PLATFORM_WIN)
#include <openvpn/common/scoped_fd.hpp>
#include <openvpn/common/write.hpp>
#include <openvpn/common/strerror.hpp>
#endif
 
namespace openvpn {
 
#if defined(OPENVPN_PLATFORM_WIN)
 
inline void write_private(const std::string &path, const void *buf, size_t count)
{
    OPENVPN_THROW_EXCEPTION("write_private('" << path << "') : not implemented on Windows yet");
}
 
#else
 
inline void write_private(const std::string &path, const void *buf, ssize_t count)
{
    ScopedFD fd(::open(path.c_str(), O_WRONLY | O_CREAT | O_CLOEXEC, S_IRUSR | S_IWUSR));
    if (!fd.defined())
    {
        const int eno = errno;
        OPENVPN_THROW_EXCEPTION(path << " : open error : " << strerror_str(eno));
    }
    if (::ftruncate(fd(), 0) < 0)
    {
        const int eno = errno;
        OPENVPN_THROW_EXCEPTION(path << " : truncate error : " << strerror_str(eno));
    }
    const ssize_t len = write_retry(fd(), buf, count);
    if (len == -1)
    {
        const int eno = errno;
        OPENVPN_THROW_EXCEPTION(path << " : write error : " << strerror_str(eno));
    }
    else if (len != count)
        OPENVPN_THROW_EXCEPTION(path << " : unexpected write size");
    if (!fd.close())
    {
        const int eno = errno;
        OPENVPN_THROW_EXCEPTION(path << " : close error : " << strerror_str(eno));
    }
}
 
#endif
 
inline void write_private(const std::string &path, const Buffer &buf)
{
    write_private(path, buf.c_data(), buf.size());
}
 
inline void write_private(const std::string &path, const std::string &str)
{
    write_private(path, str.c_str(), str.length());
}
 
} // namespace openvpn