/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */

/*

 * This file is part of the LibreOffice project.

 *

 * This Source Code Form is subject to the terms of the Mozilla Public

 * License, v. 2.0. If a copy of the MPL was not distributed with this

 * file, You can obtain one at http://mozilla.org/MPL/2.0/.

 */

#include <sal/config.h>

#include <algorithm>

#include <cassert>

#include <cstddef>

#include <errno.h>

#include <limits>

#include <unistd.h>

#include "readwrite_helper.hxx"

namespace {

std::size_t cap_ssize_t(std::size_t value) {

    return std::min(value, std::size_t(std::numeric_limits<ssize_t>::max()));

}

}

bool safeWrite(int fd, void* data, std::size_t dataSize)

{

    auto nToWrite = dataSize;

    unsigned char* dataToWrite = static_cast<unsigned char *>(data);

    while ( nToWrite ) {

        auto nWritten = write(fd, dataToWrite, cap_ssize_t(nToWrite));

        if ( nWritten < 0 ) {

            if ( errno == EINTR )

                continue;

            return false;

        }

        assert(nWritten > 0);

        nToWrite -= nWritten;

        dataToWrite += nWritten;

    }

    return true;

}

bool safeRead( int fd, void* buffer, std::size_t count )

{

    auto nToRead = count;

    unsigned char* bufferForReading = static_cast<unsigned char *>(buffer);

    while ( nToRead ) {

        auto nRead = read(fd, bufferForReading, cap_ssize_t(nToRead));

        if ( nRead < 0 ) {

            // We were interrupted before reading, retry.

            if (errno == EINTR)

                continue;

            return false;

        }

        // If we reach the EOF, we consider this a partial transfer and thus

        // an error.

        if ( nRead == 0 )

            return false;

        nToRead -= nRead;

        bufferForReading += nRead;

    }

    return true;

}

/* vim:set shiftwidth=4 softtabstop=4 expandtab: */