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// Copyright 2011-2022, Molecular Matters GmbH <[email protected]>
// See LICENSE.txt for licensing details (2-clause BSD License: https://opensource.org/licenses/BSD-2-Clause)
#include "Examples_PCH.h"
#include "ExampleMemoryMappedFile.h"
MemoryMappedFile::Handle MemoryMappedFile::Open(const char* path)
{
#ifdef _WIN32
void* file = CreateFileA(path, GENERIC_READ, FILE_SHARE_READ, nullptr, OPEN_EXISTING, FILE_ATTRIBUTE_READONLY, nullptr);
if (file == INVALID_HANDLE_VALUE)
{
return Handle { INVALID_HANDLE_VALUE, INVALID_HANDLE_VALUE, nullptr, 0 };
}
void* fileMapping = CreateFileMappingW(file, nullptr, PAGE_READONLY, 0, 0, nullptr);
if (fileMapping == nullptr)
{
CloseHandle(file);
return Handle { INVALID_HANDLE_VALUE, INVALID_HANDLE_VALUE, nullptr, 0 };
}
void* baseAddress = MapViewOfFile(fileMapping, FILE_MAP_READ, 0, 0, 0);
if (baseAddress == nullptr)
{
CloseHandle(fileMapping);
CloseHandle(file);
return Handle { INVALID_HANDLE_VALUE, INVALID_HANDLE_VALUE, nullptr, 0 };
}
BY_HANDLE_FILE_INFORMATION fileInformation;
const bool getInformationResult = GetFileInformationByHandle(file, &fileInformation);
if (!getInformationResult)
{
UnmapViewOfFile(baseAddress);
CloseHandle(fileMapping);
CloseHandle(file);
return Handle { INVALID_HANDLE_VALUE, INVALID_HANDLE_VALUE, nullptr, 0 };
}
const size_t fileSizeHighBytes = static_cast<size_t>(fileInformation.nFileSizeHigh) << 32;
const size_t fileSizeLowBytes = fileInformation.nFileSizeLow;
const size_t fileSize = fileSizeHighBytes | fileSizeLowBytes;
return Handle { file, fileMapping, baseAddress, fileSize };
#else
struct stat fileSb;
int file = open(path, O_RDONLY);
if (file == INVALID_HANDLE_VALUE)
{
return Handle { INVALID_HANDLE_VALUE, nullptr, 0 };
}
if (fstat(file, &fileSb) == -1)
{
close(file);
return Handle { INVALID_HANDLE_VALUE, nullptr, 0 };
}
void* baseAddress = mmap(nullptr, fileSb.st_size, PROT_READ, MAP_PRIVATE, file, 0);
if (baseAddress == MAP_FAILED)
{
close(file);
return Handle { INVALID_HANDLE_VALUE, nullptr, 0 };
}
return Handle { file, baseAddress, static_cast<size_t>(fileSb.st_size) };
#endif
}
void MemoryMappedFile::Close(Handle& handle)
{
#ifdef _WIN32
UnmapViewOfFile(handle.baseAddress);
CloseHandle(handle.fileMapping);
CloseHandle(handle.file);
handle.file = nullptr;
handle.fileMapping = nullptr;
#else
munmap(handle.baseAddress, handle.len);
close(handle.file);
handle.file = 0;
#endif
handle.baseAddress = nullptr;
}
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