libcruft-util/paths.hpp

54 lines
1.5 KiB
C++

/*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/.
*
* Copyright 2022, Danny Robson <danny@nerdcruft.net>
*/
#pragma once
#include "concepts/named.hpp"
#include <filesystem>
#include <optional>
///////////////////////////////////////////////////////////////////////////////
namespace cruft::paths {
/// Return the path to the system's temporary directory.
std::filesystem::path temp (void);
/// Expand paths that contain platform specific variables
///
/// eg, "$TMPDIR/foo" and "%HOMEPATH%/foo"
std::filesystem::path
expand (std::filesystem::path const&);
/// Given a relative path, and a collection of candidate base paths,
/// return the first path that exists.
///
/// Or, if none do, return the relative path itself (if it exists).
///
/// Else throw a runtime_error.
///
/// Note: there's a good chance if you're using this then it's likely
/// you'll run into TOCTOU errors.
template <cruft::concepts::named::container ContainerT>
std::filesystem::path
resolve_first (std::filesystem::path const &relative, ContainerT bases)
{
for (auto const &base: bases) {
auto const candidate = base / relative;
if (std::filesystem::exists (candidate))
return candidate;
}
if (exists (relative))
return relative;
throw std::runtime_error ("no path");
}
}