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// This source code is released into the public domain.
module;
// progname: wrappers for getprogname and setprogname.
//
// setprogname() doesn't copy the provided name, which makes it awkward to provide
// dynamic values (e.g., std::string). We solve this by making setprogname a guard
// object which resets the previous progname when it's destroyed. This also happens
// to be useful in cases like nihil.cli where we want to temporarily set the progname.
#include <stdlib.h> // NOLINT
export module nihil.posix:progname;
import nihil.std;
namespace nihil {
// Get the current program name. We could return std::string_view here, but since
// the current program name can change unexpectedly, we don't.
export [[nodiscard]] auto getprogname() -> std::optional<std::string>
{
if (auto const *progname = ::getprogname(); progname != nullptr)
return {progname};
return {};
}
// Set the progname name to a new value for the lifetime of this object.
// Reset it to the previous value when the object is destroyed.
export struct setprogname final
{
// Set the program name.
explicit setprogname(std::string_view const progname)
: m_progname(progname)
, m_old_progname(::getprogname())
{
::setprogname(m_progname.data());
}
// Restore the old name on destruction.
~setprogname()
{
if (m_old_progname != nullptr)
::setprogname(m_old_progname);
}
// Restore the old program name immediately.
auto release() -> void
{
if (m_old_progname != nullptr) {
::setprogname(m_old_progname);
m_old_progname = nullptr;
}
}
// Not copyable.
setprogname(setprogname const &) = delete;
auto operator=(setprogname const &) -> setprogname & = delete;
// Not movable.
setprogname(setprogname &&) = delete;
auto operator=(setprogname &&) -> setprogname & = delete;
private:
std::string m_progname;
char const *m_old_progname;
};
} // namespace nihil
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