libcruft-util/io_win32.cpp

189 lines
4.2 KiB
C++

/*
* 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 2014 Danny Robson <danny@nerdcruft.net>
*/
#include "./io_win32.hpp"
#include "./debug.hpp"
#include "./except.hpp"
#include <windows.h>
using util::detail::win32::mapped_file;
//-----------------------------------------------------------------------------
static constexpr
DWORD
fflags_to_generic (int flags) {
switch (flags) {
case O_RDONLY: return GENERIC_READ;
case O_WRONLY: return GENERIC_WRITE;
case O_RDWR: return GENERIC_READ | GENERIC_WRITE;
}
unreachable ();
}
static constexpr
DWORD
fflags_to_access (int fflags)
{
switch (fflags) {
case O_RDONLY: return FILE_MAP_READ;
case O_WRONLY: return FILE_MAP_WRITE;
case O_RDWR: return FILE_MAP_WRITE;
}
unreachable ();
}
static constexpr
DWORD
mflags_to_protect (int mflags) {
DWORD res = 0;
if (mflags & util::detail::win32::PROT_READ) res |= PAGE_READONLY;
if (mflags & util::detail::win32::PROT_WRITE) res |= PAGE_READWRITE;
if (mflags & util::detail::win32::PROT_EXEC) res |= PAGE_EXECUTE;
return res;
}
//-----------------------------------------------------------------------------
mapped_file::mapped_file (const boost::filesystem::path &path,
int fflags,
int mflags):
m_data (nullptr, UnmapViewOfFile)
{
// Cache the ASCII path to avoid memory scoping issues.
std::string path_str = path.string ();
// Get hold of the file we're attempting to map. Emulate some level of POXIS mmap.
m_file.reset (
CreateFile (
path_str.c_str (),
fflags_to_generic (fflags),
fflags == O_RDONLY ? FILE_SHARE_READ : 0,
nullptr,
OPEN_EXISTING,
FILE_ATTRIBUTE_NORMAL | FILE_FLAG_SEQUENTIAL_SCAN,
nullptr
)
);
if (m_file == INVALID_HANDLE_VALUE)
win32_error::throw_code ();
// I would rather perform checks on filesize after mapping, but mapping
// requires a check for empty files before we perform the mapping to
// detect errors it throws in that specific situation.
DWORD hi_size, lo_size = GetFileSize (m_file, &hi_size);
m_size = (uint64_t)hi_size << 32 | lo_size;
m_mapping.reset (
CreateFileMapping (
m_file,
nullptr,
mflags_to_protect (mflags),
0, 0,
nullptr
)
);
// Apparently Windows lacks the ability to map zero length files; fucking
// hell. Try not to collapse, but instead bail with a null mapping and
// pray the user doesn't do something stupid with the result.
if (!m_mapping) {
auto err = win32_error::last_code ();
if (err == ERROR_FILE_INVALID && m_size == 0)
return;
win32_error::throw_code (err);
}
auto view = MapViewOfFile (
m_mapping,
fflags_to_access (fflags),
0, 0,
0
);
if (!view)
win32_error::throw_code ();
m_data.reset (
static_cast<unsigned char*> (view)
);
}
//-----------------------------------------------------------------------------
const uint8_t*
mapped_file::data (void) const
{
return m_data.get ();
}
uint8_t*
mapped_file::data (void)
{
return m_data.get ();
}
size_t
mapped_file::size (void) const
{
return m_size;
}
bool
mapped_file::empty (void) const
{
return size () == 0;
}
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 ();
}