// mcpp.fallback.xpkg_copy — copy xpkg payload from global ~/.xlings/ to sandbox.

//

// Workaround: xlings may extract large packages (e.g. LLVM) into its

// global data dir instead of the mcpp sandbox, because the extraction

// subprocess doesn't always inherit XLINGS_HOME. This module detects

// the global copy and mirrors it into the sandbox so mcpp remains

// self-contained.

module;

#include <cstdlib>

export module mcpp.fallback.xpkg_copy;

import std;

import mcpp.log;

export namespace mcpp::fallback {

// Try to copy an xpkg verdir from the global xlings home into the

// sandbox. Returns true if the copy succeeded (verdir now exists).

bool copy_xpkg_from_global(const std::filesystem::path& sandboxVerdir) {

if (std::filesystem::exists(sandboxVerdir)) return true;

mcpp::log::verbose("fallback", "verdir not in sandbox, checking global xlings");

const char* xhome = nullptr;

#if defined(_WIN32)

xhome = std::getenv("USERPROFILE");

#endif

if (!xhome) xhome = std::getenv("HOME");

if (!xhome) return false;

mcpp::log::debug("fallback", std::format("HOME={}", xhome));

// xlings stores xpkgs at <home>/.xlings/data/xpkgs/ or

// <home>/.xlings/subos/default/data/xpkgs/

auto pkgDir = sandboxVerdir.parent_path().filename().string();

auto verName = sandboxVerdir.filename().string();

std::filesystem::path candidates[] = {

std::filesystem::path(xhome) / ".xlings" / "data" / "xpkgs" / pkgDir / verName,

std::filesystem::path(xhome) / ".xlings" / "subos" / "default" / "data" / "xpkgs" / pkgDir / verName,

};

for (auto& src : candidates) {

std::error_code ec;

bool srcExists = std::filesystem::exists(src, ec) && std::filesystem::is_directory(src, ec);

mcpp::log::debug("fallback", std::format(

"candidate '{}' exists={}", src.string(), srcExists));

if (srcExists) {

std::filesystem::create_directories(sandboxVerdir.parent_path(), ec);

std::filesystem::copy(src, sandboxVerdir,

std::filesystem::copy_options::recursive

| std::filesystem::copy_options::overwrite_existing, ec);

mcpp::log::verbose("fallback", std::format(

"copied from global xlings: ec={}", ec.message()));

if (!ec) return true;

}

}

return false;

}

} // namespace mcpp::fallback