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/*
* This source code is released into the public domain.
*/
module;
/*
* Exec providers, mostly used for spawn().
*/
#include <expected>
#include <string>
export module nihil.posix:exec;
import nihil.error;
import :argv;
import :fd;
namespace nihil {
/*
* A concept to mark spawn executors.
*/
export struct exec_tag{};
export template<typename T>
concept executor =
requires (T e) {
std::same_as<exec_tag, typename std::remove_cvref_t<T>::tag>;
{ e.exec() };
};
/*
* fexecv: use a file descriptor and an argument vector to call ::fexecve().
* This is the lowest-level executor which all others are implemented
* in terms of.
*
* TODO: Should have a way to pass the environment (envp).
*/
export struct fexecv final {
using tag = exec_tag;
fexecv(fd &&execfd, argv &&args) noexcept;
[[nodiscard]] auto exec(this fexecv &self)
-> std::expected<void, error>;
// Movable
fexecv(fexecv &&) noexcept;
auto operator=(this fexecv &, fexecv &&) noexcept -> fexecv&;
// Not copyable (because we hold the open fd object)
fexecv(fexecv const &) = delete;
auto operator=(this fexecv &, fexecv const &) -> fexecv& = delete;
private:
fd m_execfd;
argv m_args;
};
/*
* execv: equivalent to fexecv(), except the command is passed as
* a pathname instead of a file descriptor. Does not search $PATH.
*/
export [[nodiscard]] auto execv(std::string_view path, argv &&argv)
-> std::expected<fexecv, error>;
/*
* execvp: equivalent to fexecv(), except the command is passed as
* a filename instead of a file descriptor. If the filename is not
* an absolute path, it will be searched for in $PATH.
*/
export [[nodiscard]] auto execvp(std::string_view file, argv &&argv)
-> std::expected<fexecv, error>;
/*
* execl: equivalent to execv, except the arguments are passed as a
* variadic pack of string-like objects.
*/
export [[nodiscard]] auto execl(std::string_view path, auto &&...args)
-> std::expected<fexecv, error>
{
return execv(path, argv({std::string_view(args)...}));
}
/*
* execlp: equivalent to execvp, except the arguments are passed as a
* variadic pack of string-like objects.
*/
export [[nodiscard]] auto execlp(std::string_view file, auto &&...args)
-> std::expected<fexecv, error>
{
return execvp(file, argv({std::string_view(args)...}));
}
/*
* shell: run the process by invoking /bin/sh -c with the single argument,
* equivalent to system(3).
*/
export [[nodiscard]] auto shell(std::string_view const &command)
-> std::expected<fexecv, error>;
} // namespace nihil
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