file.cpp

// Copyright (c) 2020 Egor Tensin <Egor.Tensin@gmail.com>
// This file is part of the "winapi-common" project.
// For details, see https://github.com/egor-tensin/winapi-common.
// Distributed under the MIT License.
 
#include <winapi/error.hpp>
#include <winapi/file.hpp>
#include <winapi/handle.hpp>
#include <winapi/path.hpp>
#include <winapi/utf8.hpp>
 
#include <cstddef>
#include <cstdint>
#include <cstring>
#include <stdexcept>
#include <string>
 
namespace winapi {
namespace {
 
std::wstring to_system_path(const std::string& path) {
    return widen(path);
}
 
std::wstring to_system_path(const CanonicalPath& path) {
    return widen(R"(\\?\)" + path.get());
}
 
struct CreateFileParams {
    static CreateFileParams read() {
        CreateFileParams params;
        params.dwDesiredAccess = GENERIC_READ;
        params.dwShareMode = FILE_SHARE_READ;
        params.dwCreationDisposition = OPEN_EXISTING;
        return params;
    }
 
    static CreateFileParams read_attributes() {
        auto params = read();
        params.dwDesiredAccess = FILE_READ_ATTRIBUTES;
        params.dwShareMode = FILE_SHARE_READ | FILE_SHARE_WRITE;
        return params;
    }
 
    static CreateFileParams write() {
        CreateFileParams params;
        params.dwDesiredAccess = GENERIC_WRITE;
        params.dwShareMode = FILE_SHARE_READ;
        params.dwCreationDisposition = OPEN_ALWAYS;
        return params;
    }
 
    DWORD dwDesiredAccess = 0;
    DWORD dwShareMode = 0;
    DWORD dwCreationDisposition = 0;
 
private:
    CreateFileParams() = default;
};
 
File open_file(const std::wstring& path, const CreateFileParams& params) {
    SECURITY_ATTRIBUTES attributes;
    std::memset(&attributes, 0, sizeof(attributes));
    attributes.nLength = sizeof(attributes);
    attributes.bInheritHandle = TRUE;
 
    const auto handle = ::CreateFileW(path.c_str(),
                                      params.dwDesiredAccess,
                                      params.dwShareMode,
                                      &attributes,
                                      params.dwCreationDisposition,
                                      FILE_ATTRIBUTE_NORMAL,
                                      NULL);
 
    if (handle == INVALID_HANDLE_VALUE) {
        throw error::windows(GetLastError(), "CreateFileW");
    }
 
    return File{Handle{handle}};
}
 
void remove_file(const std::wstring& path) {
    const auto ret = ::DeleteFileW(path.c_str());
 
    if (!ret) {
        throw error::windows(GetLastError(), "DeleteFileW");
    }
}
 
} // namespace
 
File File::open_r(const std::string& path) {
    return open_file(to_system_path(path), CreateFileParams::read());
}
 
File File::open_r(const CanonicalPath& path) {
    return open_file(to_system_path(path), CreateFileParams::read());
}
 
File File::open_read_attributes(const std::string& path) {
    return open_file(to_system_path(path), CreateFileParams::read_attributes());
}
 
File File::open_read_attributes(const CanonicalPath& path) {
    return open_file(to_system_path(path), CreateFileParams::read_attributes());
}
 
File File::open_w(const std::string& path) {
    return open_file(to_system_path(path), CreateFileParams::write());
}
 
File File::open_w(const CanonicalPath& path) {
    return open_file(to_system_path(path), CreateFileParams::write());
}
 
void File::remove(const std::string& path) {
    remove_file(to_system_path(path));
}
 
void File::remove(const CanonicalPath& path) {
    remove_file(to_system_path(path));
}
 
std::size_t File::get_size() const {
    LARGE_INTEGER size;
 
    if (!GetFileSizeEx(get(), &size))
        throw error::windows(GetLastError(), "GetFileSizeEx");
 
    if (size.QuadPart < 0 || size.QuadPart > SIZE_MAX)
        throw std::runtime_error{"invalid file size"};
    return static_cast<std::size_t>(size.QuadPart);
}
 
bool operator==(const FILE_ID_128& a, const FILE_ID_128& b) {
    return 0 == std::memcmp(a.Identifier, b.Identifier, sizeof(a.Identifier));
}
 
File::ID File::query_id() const {
    FILE_ID_INFO id;
 
    if (!GetFileInformationByHandleEx(get(), FileIdInfo, &id, sizeof(id)))
        throw error::windows(GetLastError(), "GetFileInformationByHandleEx");
 
    return {id};
}
 
} // namespace winapi