path.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/path.hpp>
#include <winapi/utf8.hpp>
 
#include <windows.h>
 
#include <cstddef>
#include <limits>
#include <stdexcept>
#include <string>
#include <vector>
 
namespace winapi {
namespace {
 
std::wstring do_canonicalize(const std::wstring& path) {
    static constexpr std::size_t init_buffer_size = MAX_PATH;
    static_assert(init_buffer_size > 0, "init_buffer_size must be positive");
 
    std::vector<wchar_t> buffer;
    buffer.resize(init_buffer_size);
 
    while (true) {
        if (buffer.size() > std::numeric_limits<DWORD>::max())
            throw std::range_error{"Path buffer is too large"};
        const auto nch = ::GetFullPathNameW(
            path.c_str(), static_cast<DWORD>(buffer.size()), buffer.data(), NULL);
 
        if (nch == 0) {
            throw error::windows(GetLastError(), "GetFullPathNameW");
        }
 
        if (nch < buffer.size()) {
            return {buffer.data(), nch};
        }
 
        if (nch > buffer.size()) {
            buffer.resize(2 * buffer.size());
        }
    }
}
 
} // namespace
 
CanonicalPath::CanonicalPath(const std::string& path) : m_path(canonicalize(path)) {}
 
std::string CanonicalPath::canonicalize(const std::string& path) {
    return narrow(do_canonicalize(widen(path)));
}
 
} // namespace winapi