libcruft-util/io_posix.cpp

/*
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * Copyright 2010-2014 Danny Robson <danny@nerdcruft.net>
 */

#include "io.hpp"

#include "debug.hpp"
#include "except.hpp"

#include <fcntl.h>
#include <sys/stat.h>
#include <sys/types.h>

using util::detail::posix::mapped_file;

//////////////////////////////////////////////////////////////////////////////
mapped_file::mapped_file (const char *_path, int fflags, int mflags):
    m_fd (_path, fflags)
{
    try {
        load_fd (mflags);
    } catch (const errno_error &e) {
        // ignore zero length mapping error
        if (e.code () == EINVAL && m_size == 0)
            return;
    }
}


//----------------------------------------------------------------------------
mapped_file::~mapped_file ()
{
    CHECK (m_data != NULL);
    munmap (m_data, m_size);
}


//----------------------------------------------------------------------------
void
mapped_file::load_fd (int mflags) {
    struct stat meta;
    if (fstat (m_fd, &meta) < 0)
        throw errno_error ();

    m_size = (size_t)meta.st_size;
    m_data = (uint8_t *)mmap (NULL, m_size, mflags, MAP_SHARED, m_fd, 0);
    if (m_data == MAP_FAILED)
        throw errno_error ();
}


//----------------------------------------------------------------------------
size_t
mapped_file::size (void) const
{
    return m_size;
}


//-----------------------------------------------------------------------------
bool
mapped_file::empty (void) const
{
    return size () == 0;
}


//----------------------------------------------------------------------------
uint8_t*
mapped_file::data (void) {
    CHECK (m_size > 0);
    CHECK (m_data != NULL);

    return m_data;
}


//----------------------------------------------------------------------------
const uint8_t*
mapped_file::data (void) const {
    CHECK (m_size > 0);
    CHECK (m_data != NULL);

    return m_data;
}


//----------------------------------------------------------------------------
uint8_t*
mapped_file::begin (void) {
    return data ();
}


//----------------------------------------------------------------------------
uint8_t*
mapped_file::end (void) {
    return data () + size ();
}


//----------------------------------------------------------------------------
const uint8_t*
mapped_file::cbegin (void) const {
    return data ();
}


//----------------------------------------------------------------------------
const uint8_t*
mapped_file::cend (void) const {
    return data () + size ();
}