/*
 * This source code is released into the public domain.
 */

#include <ranges>

#include <fcntl.h>
#include <paths.h>
#include <unistd.h>

#include "getenv.hh"
#include "path.hh"

using namespace std::literals;

namespace lfjail {

auto find_in_path(std::string const &file) -> std::optional<fd> {
	if (file.empty())
		return {};

	auto try_open = [](std::string const &path) -> std::optional<fd> {
		auto const ret = ::open(path.c_str(), O_EXEC);
		if (ret == -1)
			return {};
		return fd(ret);
	};

	// Absolute pathname skips the search.
	if (file[0] == '/')
		return try_open(file);

	auto path = getenv("PATH").value_or(_PATH_DEFPATH);

	for (auto &&dir : std::views::split(path, ':')) {
		// An empty $PATH element means cwd.
		auto sdir = std::string_view(dir);
		if (sdir.empty())
			sdir = ".";

		auto const path = std::format("{}/{}", sdir, file);
		if (auto ret = try_open(path); ret)
			return ret;
	}

	return {};
}

} // namespace lfjail