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/*
* This source code is released into the public domain.
*/
/*
* Exec providers for spawn().
*/
#ifndef LFJAIL_EXEC_HH
#define LFJAIL_EXEC_HH
#include <unistd.h>
#include "argv.hh"
#include "exec_error.hh"
#include "fd.hh"
#include "guard.hh"
#include "path.hh"
namespace lfjail::exec {
/*
* A concept to mark spawn executors.
*/
struct exec_tag{};
template<typename T>
concept executor =
requires (T e) {
std::same_as<exec_tag, typename 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).
*/
struct fexecv final {
using tag = exec_tag;
fexecv(fd &&execfd, argv &&args) noexcept;
[[noreturn]] auto exec(this fexecv &self) noexcept -> void;
// Movable
fexecv(fexecv &&) noexcept = default;
auto operator=(this fexecv &, fexecv &&) noexcept -> fexecv& = default;
// Not copyable (because we hold the open fd object)
fexecv(fexecv const &) = delete;
auto operator=(this fexecv &, fexecv const &) -> fexecv& = delete;
private:
fd _execfd;
argv _args;
};
static_assert(executor<fexecv>);
/*
* execv: equivalent to fexecv(), except the command is passed as
* a pathname instead of a file descriptor. Does not search $PATH.
*/
auto execv(std::string path, argv &&argv) -> fexecv;
/*
* 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.
*/
auto execvp(std::string file, argv &&argv) -> fexecv;
/*
* execl: equivalent to execv, except the arguments are passed as a
* variadic pack of string-like objects.
*/
auto execl(std::string path, auto &&...args) {
return execv(std::move(path),
argv::from_args({std::string_view(args)...}));
}
/*
* execlp: equivalent to execvp, except the arguments are passed as a
* variadic pack of string-like objects.
*/
auto execlp(std::string file, auto &&...args) {
return execvp(std::move(file),
argv::from_args({std::string_view(args)...}));
}
/*
* shell: run the process by invoking /bin/sh -c with the single argument,
* equivalent to system(3).
*/
auto shell(std::string command) -> fexecv;
} // namespace lfjail
#endif // LFJAIL_EXEC_HH
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