xref: /DragonOS/kernel/src/process/mod.rs (revision c3dc6f2ff9169c309d1cbf47dcb9e4528d509b2f)
1 use core::{
2     hash::Hash,
3     hint::spin_loop,
4     intrinsics::{likely, unlikely},
5     mem::ManuallyDrop,
6     sync::atomic::{compiler_fence, AtomicBool, AtomicIsize, AtomicUsize, Ordering},
7 };
8 
9 use alloc::{
10     string::{String, ToString},
11     sync::{Arc, Weak},
12     vec::Vec,
13 };
14 use hashbrown::HashMap;
15 use system_error::SystemError;
16 
17 use crate::{
18     arch::{
19         ipc::signal::{AtomicSignal, SigSet, Signal},
20         process::ArchPCBInfo,
21         sched::sched,
22         CurrentIrqArch,
23     },
24     driver::tty::tty_core::TtyCore,
25     exception::InterruptArch,
26     filesystem::{
27         procfs::procfs_unregister_pid,
28         vfs::{file::FileDescriptorVec, FileType},
29     },
30     ipc::signal_types::{SigInfo, SigPending, SignalStruct},
31     kdebug, kinfo,
32     libs::{
33         align::AlignedBox,
34         casting::DowncastArc,
35         futex::{
36             constant::{FutexFlag, FUTEX_BITSET_MATCH_ANY},
37             futex::Futex,
38         },
39         lock_free_flags::LockFreeFlags,
40         rwlock::{RwLock, RwLockReadGuard, RwLockUpgradableGuard, RwLockWriteGuard},
41         spinlock::{SpinLock, SpinLockGuard},
42         wait_queue::WaitQueue,
43     },
44     mm::{percpu::PerCpuVar, set_INITIAL_PROCESS_ADDRESS_SPACE, ucontext::AddressSpace, VirtAddr},
45     net::socket::SocketInode,
46     sched::{
47         completion::Completion,
48         core::{sched_enqueue, CPU_EXECUTING},
49         SchedPolicy, SchedPriority,
50     },
51     smp::{
52         cpu::{AtomicProcessorId, ProcessorId},
53         kick_cpu,
54     },
55     syscall::{user_access::clear_user, Syscall},
56 };
57 
58 use self::kthread::WorkerPrivate;
59 
60 pub mod abi;
61 pub mod c_adapter;
62 pub mod exec;
63 pub mod exit;
64 pub mod fork;
65 pub mod idle;
66 pub mod kthread;
67 pub mod pid;
68 pub mod process;
69 pub mod resource;
70 pub mod syscall;
71 
72 /// 系统中所有进程的pcb
73 static ALL_PROCESS: SpinLock<Option<HashMap<Pid, Arc<ProcessControlBlock>>>> = SpinLock::new(None);
74 
75 pub static mut SWITCH_RESULT: Option<PerCpuVar<SwitchResult>> = None;
76 
77 /// 一个只改变1次的全局变量,标志进程管理器是否已经初始化完成
78 static mut __PROCESS_MANAGEMENT_INIT_DONE: bool = false;
79 
80 #[derive(Debug)]
81 pub struct SwitchResult {
82     pub prev_pcb: Option<Arc<ProcessControlBlock>>,
83     pub next_pcb: Option<Arc<ProcessControlBlock>>,
84 }
85 
86 impl SwitchResult {
87     pub fn new() -> Self {
88         Self {
89             prev_pcb: None,
90             next_pcb: None,
91         }
92     }
93 }
94 
95 #[derive(Debug)]
96 pub struct ProcessManager;
97 impl ProcessManager {
98     #[inline(never)]
99     fn init() {
100         static INIT_FLAG: AtomicBool = AtomicBool::new(false);
101         if INIT_FLAG
102             .compare_exchange(false, true, Ordering::SeqCst, Ordering::SeqCst)
103             .is_err()
104         {
105             panic!("ProcessManager has been initialized!");
106         }
107 
108         unsafe {
109             compiler_fence(Ordering::SeqCst);
110             kdebug!("To create address space for INIT process.");
111             // test_buddy();
112             set_INITIAL_PROCESS_ADDRESS_SPACE(
113                 AddressSpace::new(true).expect("Failed to create address space for INIT process."),
114             );
115             kdebug!("INIT process address space created.");
116             compiler_fence(Ordering::SeqCst);
117         };
118 
119         ALL_PROCESS.lock_irqsave().replace(HashMap::new());
120         Self::arch_init();
121         kdebug!("process arch init done.");
122         Self::init_idle();
123         kdebug!("process idle init done.");
124 
125         unsafe { __PROCESS_MANAGEMENT_INIT_DONE = true };
126         kinfo!("Process Manager initialized.");
127     }
128 
129     /// 判断进程管理器是否已经初始化完成
130     pub fn initialized() -> bool {
131         unsafe { __PROCESS_MANAGEMENT_INIT_DONE }
132     }
133 
134     /// 获取当前进程的pcb
135     pub fn current_pcb() -> Arc<ProcessControlBlock> {
136         if unlikely(unsafe { !__PROCESS_MANAGEMENT_INIT_DONE }) {
137             kerror!("unsafe__PROCESS_MANAGEMENT_INIT_DONE == false");
138             loop {
139                 spin_loop();
140             }
141         }
142         return ProcessControlBlock::arch_current_pcb();
143     }
144 
145     /// 获取当前进程的pid
146     ///
147     /// 如果进程管理器未初始化完成,那么返回0
148     pub fn current_pid() -> Pid {
149         if unlikely(unsafe { !__PROCESS_MANAGEMENT_INIT_DONE }) {
150             return Pid(0);
151         }
152 
153         return ProcessManager::current_pcb().pid();
154     }
155 
156     /// 增加当前进程的锁持有计数
157     #[inline(always)]
158     pub fn preempt_disable() {
159         if likely(unsafe { __PROCESS_MANAGEMENT_INIT_DONE }) {
160             ProcessManager::current_pcb().preempt_disable();
161         }
162     }
163 
164     /// 减少当前进程的锁持有计数
165     #[inline(always)]
166     pub fn preempt_enable() {
167         if likely(unsafe { __PROCESS_MANAGEMENT_INIT_DONE }) {
168             ProcessManager::current_pcb().preempt_enable();
169         }
170     }
171 
172     /// 根据pid获取进程的pcb
173     ///
174     /// ## 参数
175     ///
176     /// - `pid` : 进程的pid
177     ///
178     /// ## 返回值
179     ///
180     /// 如果找到了对应的进程,那么返回该进程的pcb,否则返回None
181     pub fn find(pid: Pid) -> Option<Arc<ProcessControlBlock>> {
182         return ALL_PROCESS.lock_irqsave().as_ref()?.get(&pid).cloned();
183     }
184 
185     /// 向系统中添加一个进程的pcb
186     ///
187     /// ## 参数
188     ///
189     /// - `pcb` : 进程的pcb
190     ///
191     /// ## 返回值
192     ///
193     /// 无
194     pub fn add_pcb(pcb: Arc<ProcessControlBlock>) {
195         ALL_PROCESS
196             .lock_irqsave()
197             .as_mut()
198             .unwrap()
199             .insert(pcb.pid(), pcb.clone());
200     }
201 
202     /// 唤醒一个进程
203     pub fn wakeup(pcb: &Arc<ProcessControlBlock>) -> Result<(), SystemError> {
204         let _guard = unsafe { CurrentIrqArch::save_and_disable_irq() };
205         let state = pcb.sched_info().inner_lock_read_irqsave().state();
206         if state.is_blocked() {
207             let mut writer = pcb.sched_info().inner_lock_write_irqsave();
208             let state = writer.state();
209             if state.is_blocked() {
210                 writer.set_state(ProcessState::Runnable);
211                 // avoid deadlock
212                 drop(writer);
213 
214                 sched_enqueue(pcb.clone(), true);
215                 return Ok(());
216             } else if state.is_exited() {
217                 return Err(SystemError::EINVAL);
218             } else {
219                 return Ok(());
220             }
221         } else if state.is_exited() {
222             return Err(SystemError::EINVAL);
223         } else {
224             return Ok(());
225         }
226     }
227 
228     /// 唤醒暂停的进程
229     pub fn wakeup_stop(pcb: &Arc<ProcessControlBlock>) -> Result<(), SystemError> {
230         let _guard = unsafe { CurrentIrqArch::save_and_disable_irq() };
231         let state = pcb.sched_info().inner_lock_read_irqsave().state();
232         if let ProcessState::Stopped = state {
233             let mut writer = pcb.sched_info().inner_lock_write_irqsave();
234             let state = writer.state();
235             if let ProcessState::Stopped = state {
236                 writer.set_state(ProcessState::Runnable);
237                 // avoid deadlock
238                 drop(writer);
239 
240                 sched_enqueue(pcb.clone(), true);
241                 return Ok(());
242             } else if state.is_runnable() {
243                 return Ok(());
244             } else {
245                 return Err(SystemError::EINVAL);
246             }
247         } else if state.is_runnable() {
248             return Ok(());
249         } else {
250             return Err(SystemError::EINVAL);
251         }
252     }
253 
254     /// 标志当前进程永久睡眠,但是发起调度的工作,应该由调用者完成
255     ///
256     /// ## 注意
257     ///
258     /// - 进入当前函数之前,不能持有sched_info的锁
259     /// - 进入当前函数之前,必须关闭中断
260     /// - 进入当前函数之后必须保证逻辑的正确性,避免被重复加入调度队列
261     pub fn mark_sleep(interruptable: bool) -> Result<(), SystemError> {
262         assert_eq!(
263             CurrentIrqArch::is_irq_enabled(),
264             false,
265             "interrupt must be disabled before enter ProcessManager::mark_sleep()"
266         );
267 
268         let pcb = ProcessManager::current_pcb();
269         let mut writer = pcb.sched_info().inner_lock_write_irqsave();
270         if !matches!(writer.state(), ProcessState::Exited(_)) {
271             writer.set_state(ProcessState::Blocked(interruptable));
272             pcb.flags().insert(ProcessFlags::NEED_SCHEDULE);
273             drop(writer);
274 
275             return Ok(());
276         }
277         return Err(SystemError::EINTR);
278     }
279 
280     /// 标志当前进程为停止状态,但是发起调度的工作,应该由调用者完成
281     ///
282     /// ## 注意
283     ///
284     /// - 进入当前函数之前,不能持有sched_info的锁
285     /// - 进入当前函数之前,必须关闭中断
286     pub fn mark_stop() -> Result<(), SystemError> {
287         assert_eq!(
288             CurrentIrqArch::is_irq_enabled(),
289             false,
290             "interrupt must be disabled before enter ProcessManager::mark_stop()"
291         );
292 
293         let pcb = ProcessManager::current_pcb();
294         let mut writer = pcb.sched_info().inner_lock_write_irqsave();
295         if !matches!(writer.state(), ProcessState::Exited(_)) {
296             writer.set_state(ProcessState::Stopped);
297             pcb.flags().insert(ProcessFlags::NEED_SCHEDULE);
298             drop(writer);
299 
300             return Ok(());
301         }
302         return Err(SystemError::EINTR);
303     }
304     /// 当子进程退出后向父进程发送通知
305     fn exit_notify() {
306         let current = ProcessManager::current_pcb();
307         // 让INIT进程收养所有子进程
308         if current.pid() != Pid(1) {
309             unsafe {
310                 current
311                     .adopt_childen()
312                     .unwrap_or_else(|e| panic!("adopte_childen failed: error: {e:?}"))
313             };
314             let r = current.parent_pcb.read().upgrade();
315             if r.is_none() {
316                 return;
317             }
318             let parent_pcb = r.unwrap();
319             let r = Syscall::kill(parent_pcb.pid(), Signal::SIGCHLD as i32);
320             if r.is_err() {
321                 kwarn!(
322                     "failed to send kill signal to {:?}'s parent pcb {:?}",
323                     current.pid(),
324                     parent_pcb.pid()
325                 );
326             }
327             // todo: 这里需要向父进程发送SIGCHLD信号
328             // todo: 这里还需要根据线程组的信息,决定信号的发送
329         }
330     }
331 
332     /// 退出当前进程
333     ///
334     /// ## 参数
335     ///
336     /// - `exit_code` : 进程的退出码
337     pub fn exit(exit_code: usize) -> ! {
338         // 关中断
339         unsafe { CurrentIrqArch::interrupt_disable() };
340         let pcb = ProcessManager::current_pcb();
341         pcb.sched_info
342             .inner_lock_write_irqsave()
343             .set_state(ProcessState::Exited(exit_code));
344         pcb.wait_queue.wakeup(Some(ProcessState::Blocked(true)));
345 
346         // 进行进程退出后的工作
347         let thread = pcb.thread.write();
348         if let Some(addr) = thread.set_child_tid {
349             unsafe { clear_user(addr, core::mem::size_of::<i32>()).expect("clear tid failed") };
350         }
351 
352         if let Some(addr) = thread.clear_child_tid {
353             if Arc::strong_count(&pcb.basic().user_vm().expect("User VM Not found")) > 1 {
354                 let _ =
355                     Futex::futex_wake(addr, FutexFlag::FLAGS_MATCH_NONE, 1, FUTEX_BITSET_MATCH_ANY);
356             }
357             unsafe { clear_user(addr, core::mem::size_of::<i32>()).expect("clear tid failed") };
358         }
359 
360         // 如果是vfork出来的进程,则需要处理completion
361         if thread.vfork_done.is_some() {
362             thread.vfork_done.as_ref().unwrap().complete_all();
363         }
364         drop(thread);
365         unsafe { pcb.basic_mut().set_user_vm(None) };
366         drop(pcb);
367         ProcessManager::exit_notify();
368         unsafe { CurrentIrqArch::interrupt_enable() };
369 
370         sched();
371         loop {}
372     }
373 
374     pub unsafe fn release(pid: Pid) {
375         let pcb = ProcessManager::find(pid);
376         if pcb.is_some() {
377             // let pcb = pcb.unwrap();
378             // 判断该pcb是否在全局没有任何引用
379             // TODO: 当前,pcb的Arc指针存在泄露问题,引用计数不正确,打算在接下来实现debug专用的Arc,方便调试,然后解决这个bug。
380             //          因此目前暂时注释掉,使得能跑
381             // if Arc::strong_count(&pcb) <= 2 {
382             //     drop(pcb);
383             //     ALL_PROCESS.lock().as_mut().unwrap().remove(&pid);
384             // } else {
385             //     // 如果不为1就panic
386             //     let msg = format!("pcb '{:?}' is still referenced, strong count={}",pcb.pid(),  Arc::strong_count(&pcb));
387             //     kerror!("{}", msg);
388             //     panic!()
389             // }
390 
391             ALL_PROCESS.lock_irqsave().as_mut().unwrap().remove(&pid);
392         }
393     }
394 
395     /// 上下文切换完成后的钩子函数
396     unsafe fn switch_finish_hook() {
397         // kdebug!("switch_finish_hook");
398         let prev_pcb = SWITCH_RESULT
399             .as_mut()
400             .unwrap()
401             .get_mut()
402             .prev_pcb
403             .take()
404             .expect("prev_pcb is None");
405         let next_pcb = SWITCH_RESULT
406             .as_mut()
407             .unwrap()
408             .get_mut()
409             .next_pcb
410             .take()
411             .expect("next_pcb is None");
412 
413         // 由于进程切换前使用了SpinLockGuard::leak(),所以这里需要手动释放锁
414         prev_pcb.arch_info.force_unlock();
415         next_pcb.arch_info.force_unlock();
416     }
417 
418     /// 如果目标进程正在目标CPU上运行,那么就让这个cpu陷入内核态
419     ///
420     /// ## 参数
421     ///
422     /// - `pcb` : 进程的pcb
423     #[allow(dead_code)]
424     pub fn kick(pcb: &Arc<ProcessControlBlock>) {
425         ProcessManager::current_pcb().preempt_disable();
426         let cpu_id = pcb.sched_info().on_cpu();
427 
428         if let Some(cpu_id) = cpu_id {
429             let cpu_id = cpu_id;
430 
431             if pcb.pid() == CPU_EXECUTING.get(cpu_id) {
432                 kick_cpu(cpu_id).expect("ProcessManager::kick(): Failed to kick cpu");
433             }
434         }
435 
436         ProcessManager::current_pcb().preempt_enable();
437     }
438 }
439 
440 /// 上下文切换的钩子函数,当这个函数return的时候,将会发生上下文切换
441 #[cfg(target_arch = "x86_64")]
442 pub unsafe extern "sysv64" fn switch_finish_hook() {
443     ProcessManager::switch_finish_hook();
444 }
445 #[cfg(target_arch = "riscv64")]
446 pub unsafe extern "C" fn switch_finish_hook() {
447     ProcessManager::switch_finish_hook();
448 }
449 
450 int_like!(Pid, AtomicPid, usize, AtomicUsize);
451 
452 impl Pid {
453     pub fn to_string(&self) -> String {
454         self.0.to_string()
455     }
456 }
457 
458 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
459 pub enum ProcessState {
460     /// The process is running on a CPU or in a run queue.
461     Runnable,
462     /// The process is waiting for an event to occur.
463     /// 其中的bool表示该等待过程是否可以被打断。
464     /// - 如果该bool为true,那么,硬件中断/信号/其他系统事件都可以打断该等待过程,使得该进程重新进入Runnable状态。
465     /// - 如果该bool为false,那么,这个进程必须被显式的唤醒,才能重新进入Runnable状态。
466     Blocked(bool),
467     /// 进程被信号终止
468     Stopped,
469     /// 进程已经退出,usize表示进程的退出码
470     Exited(usize),
471 }
472 
473 #[allow(dead_code)]
474 impl ProcessState {
475     #[inline(always)]
476     pub fn is_runnable(&self) -> bool {
477         return matches!(self, ProcessState::Runnable);
478     }
479 
480     #[inline(always)]
481     pub fn is_blocked(&self) -> bool {
482         return matches!(self, ProcessState::Blocked(_));
483     }
484 
485     #[inline(always)]
486     pub fn is_blocked_interruptable(&self) -> bool {
487         return matches!(self, ProcessState::Blocked(true));
488     }
489 
490     /// Returns `true` if the process state is [`Exited`].
491     #[inline(always)]
492     pub fn is_exited(&self) -> bool {
493         return matches!(self, ProcessState::Exited(_));
494     }
495 
496     /// Returns `true` if the process state is [`Stopped`].
497     ///
498     /// [`Stopped`]: ProcessState::Stopped
499     #[inline(always)]
500     pub fn is_stopped(&self) -> bool {
501         matches!(self, ProcessState::Stopped)
502     }
503 
504     /// Returns exit code if the process state is [`Exited`].
505     #[inline(always)]
506     pub fn exit_code(&self) -> Option<usize> {
507         match self {
508             ProcessState::Exited(code) => Some(*code),
509             _ => None,
510         }
511     }
512 }
513 
514 bitflags! {
515     /// pcb的标志位
516     pub struct ProcessFlags: usize {
517         /// 当前pcb表示一个内核线程
518         const KTHREAD = 1 << 0;
519         /// 当前进程需要被调度
520         const NEED_SCHEDULE = 1 << 1;
521         /// 进程由于vfork而与父进程存在资源共享
522         const VFORK = 1 << 2;
523         /// 进程不可被冻结
524         const NOFREEZE = 1 << 3;
525         /// 进程正在退出
526         const EXITING = 1 << 4;
527         /// 进程由于接收到终止信号唤醒
528         const WAKEKILL = 1 << 5;
529         /// 进程由于接收到信号而退出.(Killed by a signal)
530         const SIGNALED = 1 << 6;
531         /// 进程需要迁移到其他cpu上
532         const NEED_MIGRATE = 1 << 7;
533         /// 随机化的虚拟地址空间,主要用于动态链接器的加载
534         const RANDOMIZE = 1 << 8;
535     }
536 }
537 
538 #[derive(Debug)]
539 pub struct ProcessControlBlock {
540     /// 当前进程的pid
541     pid: Pid,
542     /// 当前进程的线程组id(这个值在同一个线程组内永远不变)
543     tgid: Pid,
544 
545     basic: RwLock<ProcessBasicInfo>,
546     /// 当前进程的自旋锁持有计数
547     preempt_count: AtomicUsize,
548 
549     flags: LockFreeFlags<ProcessFlags>,
550     worker_private: SpinLock<Option<WorkerPrivate>>,
551     /// 进程的内核栈
552     kernel_stack: RwLock<KernelStack>,
553 
554     /// 系统调用栈
555     syscall_stack: RwLock<KernelStack>,
556 
557     /// 与调度相关的信息
558     sched_info: ProcessSchedulerInfo,
559     /// 与处理器架构相关的信息
560     arch_info: SpinLock<ArchPCBInfo>,
561     /// 与信号处理相关的信息(似乎可以是无锁的)
562     sig_info: RwLock<ProcessSignalInfo>,
563     /// 信号处理结构体
564     sig_struct: SpinLock<SignalStruct>,
565     /// 退出信号S
566     exit_signal: AtomicSignal,
567 
568     /// 父进程指针
569     parent_pcb: RwLock<Weak<ProcessControlBlock>>,
570     /// 真实父进程指针
571     real_parent_pcb: RwLock<Weak<ProcessControlBlock>>,
572 
573     /// 子进程链表
574     children: RwLock<Vec<Pid>>,
575 
576     /// 等待队列
577     wait_queue: WaitQueue,
578 
579     /// 线程信息
580     thread: RwLock<ThreadInfo>,
581 }
582 
583 impl ProcessControlBlock {
584     /// Generate a new pcb.
585     ///
586     /// ## 参数
587     ///
588     /// - `name` : 进程的名字
589     /// - `kstack` : 进程的内核栈
590     ///
591     /// ## 返回值
592     ///
593     /// 返回一个新的pcb
594     pub fn new(name: String, kstack: KernelStack) -> Arc<Self> {
595         return Self::do_create_pcb(name, kstack, false);
596     }
597 
598     /// 创建一个新的idle进程
599     ///
600     /// 请注意,这个函数只能在进程管理初始化的时候调用。
601     pub fn new_idle(cpu_id: u32, kstack: KernelStack) -> Arc<Self> {
602         let name = format!("idle-{}", cpu_id);
603         return Self::do_create_pcb(name, kstack, true);
604     }
605 
606     #[inline(never)]
607     fn do_create_pcb(name: String, kstack: KernelStack, is_idle: bool) -> Arc<Self> {
608         let (pid, ppid, cwd) = if is_idle {
609             (Pid(0), Pid(0), "/".to_string())
610         } else {
611             let ppid = ProcessManager::current_pcb().pid();
612             let cwd = ProcessManager::current_pcb().basic().cwd();
613             (Self::generate_pid(), ppid, cwd)
614         };
615 
616         let basic_info = ProcessBasicInfo::new(Pid(0), ppid, name, cwd, None);
617         let preempt_count = AtomicUsize::new(0);
618         let flags = unsafe { LockFreeFlags::new(ProcessFlags::empty()) };
619 
620         let sched_info = ProcessSchedulerInfo::new(None);
621         let arch_info = SpinLock::new(ArchPCBInfo::new(&kstack));
622 
623         let ppcb: Weak<ProcessControlBlock> = ProcessManager::find(ppid)
624             .map(|p| Arc::downgrade(&p))
625             .unwrap_or_else(|| Weak::new());
626 
627         let pcb = Self {
628             pid,
629             tgid: pid,
630             basic: basic_info,
631             preempt_count,
632             flags,
633             kernel_stack: RwLock::new(kstack),
634             syscall_stack: RwLock::new(KernelStack::new().unwrap()),
635             worker_private: SpinLock::new(None),
636             sched_info,
637             arch_info,
638             sig_info: RwLock::new(ProcessSignalInfo::default()),
639             sig_struct: SpinLock::new(SignalStruct::new()),
640             exit_signal: AtomicSignal::new(Signal::SIGCHLD),
641             parent_pcb: RwLock::new(ppcb.clone()),
642             real_parent_pcb: RwLock::new(ppcb),
643             children: RwLock::new(Vec::new()),
644             wait_queue: WaitQueue::INIT,
645             thread: RwLock::new(ThreadInfo::new()),
646         };
647 
648         // 初始化系统调用栈
649         #[cfg(target_arch = "x86_64")]
650         pcb.arch_info
651             .lock()
652             .init_syscall_stack(&pcb.syscall_stack.read());
653 
654         let pcb = Arc::new(pcb);
655 
656         // 设置进程的arc指针到内核栈和系统调用栈的最低地址处
657         unsafe {
658             pcb.kernel_stack
659                 .write()
660                 .set_pcb(Arc::downgrade(&pcb))
661                 .unwrap();
662 
663             pcb.syscall_stack
664                 .write()
665                 .set_pcb(Arc::downgrade(&pcb))
666                 .unwrap()
667         };
668 
669         // 将当前pcb加入父进程的子进程哈希表中
670         if pcb.pid() > Pid(1) {
671             if let Some(ppcb_arc) = pcb.parent_pcb.read().upgrade() {
672                 let mut children = ppcb_arc.children.write_irqsave();
673                 children.push(pcb.pid());
674             } else {
675                 panic!("parent pcb is None");
676             }
677         }
678 
679         return pcb;
680     }
681 
682     /// 生成一个新的pid
683     #[inline(always)]
684     fn generate_pid() -> Pid {
685         static NEXT_PID: AtomicPid = AtomicPid::new(Pid(1));
686         return NEXT_PID.fetch_add(Pid(1), Ordering::SeqCst);
687     }
688 
689     /// 返回当前进程的锁持有计数
690     #[inline(always)]
691     pub fn preempt_count(&self) -> usize {
692         return self.preempt_count.load(Ordering::SeqCst);
693     }
694 
695     /// 增加当前进程的锁持有计数
696     #[inline(always)]
697     pub fn preempt_disable(&self) {
698         self.preempt_count.fetch_add(1, Ordering::SeqCst);
699     }
700 
701     /// 减少当前进程的锁持有计数
702     #[inline(always)]
703     pub fn preempt_enable(&self) {
704         self.preempt_count.fetch_sub(1, Ordering::SeqCst);
705     }
706 
707     #[inline(always)]
708     pub unsafe fn set_preempt_count(&self, count: usize) {
709         self.preempt_count.store(count, Ordering::SeqCst);
710     }
711 
712     #[inline(always)]
713     pub fn flags(&self) -> &mut ProcessFlags {
714         return self.flags.get_mut();
715     }
716 
717     /// 请注意,这个值能在中断上下文中读取,但不能被中断上下文修改
718     /// 否则会导致死锁
719     #[inline(always)]
720     pub fn basic(&self) -> RwLockReadGuard<ProcessBasicInfo> {
721         return self.basic.read();
722     }
723 
724     #[inline(always)]
725     pub fn set_name(&self, name: String) {
726         self.basic.write().set_name(name);
727     }
728 
729     #[inline(always)]
730     pub fn basic_mut(&self) -> RwLockWriteGuard<ProcessBasicInfo> {
731         return self.basic.write_irqsave();
732     }
733 
734     /// # 获取arch info的锁,同时关闭中断
735     #[inline(always)]
736     pub fn arch_info_irqsave(&self) -> SpinLockGuard<ArchPCBInfo> {
737         return self.arch_info.lock_irqsave();
738     }
739 
740     /// # 获取arch info的锁,但是不关闭中断
741     ///
742     /// 由于arch info在进程切换的时候会使用到,
743     /// 因此在中断上下文外,获取arch info 而不irqsave是不安全的.
744     ///
745     /// 只能在以下情况下使用这个函数:
746     /// - 在中断上下文中(中断已经禁用),获取arch info的锁。
747     /// - 刚刚创建新的pcb
748     #[inline(always)]
749     pub unsafe fn arch_info(&self) -> SpinLockGuard<ArchPCBInfo> {
750         return self.arch_info.lock();
751     }
752 
753     #[inline(always)]
754     pub fn kernel_stack(&self) -> RwLockReadGuard<KernelStack> {
755         return self.kernel_stack.read();
756     }
757 
758     #[inline(always)]
759     #[allow(dead_code)]
760     pub fn kernel_stack_mut(&self) -> RwLockWriteGuard<KernelStack> {
761         return self.kernel_stack.write();
762     }
763 
764     #[inline(always)]
765     pub fn sched_info(&self) -> &ProcessSchedulerInfo {
766         return &self.sched_info;
767     }
768 
769     #[inline(always)]
770     pub fn worker_private(&self) -> SpinLockGuard<Option<WorkerPrivate>> {
771         return self.worker_private.lock();
772     }
773 
774     #[inline(always)]
775     pub fn pid(&self) -> Pid {
776         return self.pid;
777     }
778 
779     #[inline(always)]
780     pub fn tgid(&self) -> Pid {
781         return self.tgid;
782     }
783 
784     /// 获取文件描述符表的Arc指针
785     #[inline(always)]
786     pub fn fd_table(&self) -> Arc<RwLock<FileDescriptorVec>> {
787         return self.basic.read().fd_table().unwrap();
788     }
789 
790     /// 根据文件描述符序号,获取socket对象的Arc指针
791     ///
792     /// ## 参数
793     ///
794     /// - `fd` 文件描述符序号
795     ///
796     /// ## 返回值
797     ///
798     /// Option(&mut Box<dyn Socket>) socket对象的可变引用. 如果文件描述符不是socket,那么返回None
799     pub fn get_socket(&self, fd: i32) -> Option<Arc<SocketInode>> {
800         let binding = ProcessManager::current_pcb().fd_table();
801         let fd_table_guard = binding.read();
802 
803         let f = fd_table_guard.get_file_by_fd(fd)?;
804         drop(fd_table_guard);
805 
806         let guard = f.lock();
807         if guard.file_type() != FileType::Socket {
808             return None;
809         }
810         let socket: Arc<SocketInode> = guard
811             .inode()
812             .downcast_arc::<SocketInode>()
813             .expect("Not a socket inode");
814         return Some(socket);
815     }
816 
817     /// 当前进程退出时,让初始进程收养所有子进程
818     unsafe fn adopt_childen(&self) -> Result<(), SystemError> {
819         match ProcessManager::find(Pid(1)) {
820             Some(init_pcb) => {
821                 let childen_guard = self.children.write();
822                 let mut init_childen_guard = init_pcb.children.write();
823 
824                 childen_guard.iter().for_each(|pid| {
825                     init_childen_guard.push(*pid);
826                 });
827 
828                 return Ok(());
829             }
830             _ => Err(SystemError::ECHILD),
831         }
832     }
833 
834     /// 生成进程的名字
835     pub fn generate_name(program_path: &str, args: &Vec<String>) -> String {
836         let mut name = program_path.to_string();
837         for arg in args {
838             name.push(' ');
839             name.push_str(arg);
840         }
841         return name;
842     }
843 
844     pub fn sig_info(&self) -> RwLockReadGuard<ProcessSignalInfo> {
845         self.sig_info.read()
846     }
847 
848     pub fn sig_info_irqsave(&self) -> RwLockReadGuard<ProcessSignalInfo> {
849         self.sig_info.read_irqsave()
850     }
851 
852     pub fn try_siginfo(&self, times: u8) -> Option<RwLockReadGuard<ProcessSignalInfo>> {
853         for _ in 0..times {
854             if let Some(r) = self.sig_info.try_read() {
855                 return Some(r);
856             }
857         }
858 
859         return None;
860     }
861 
862     pub fn sig_info_mut(&self) -> RwLockWriteGuard<ProcessSignalInfo> {
863         self.sig_info.write_irqsave()
864     }
865 
866     pub fn try_siginfo_mut(&self, times: u8) -> Option<RwLockWriteGuard<ProcessSignalInfo>> {
867         for _ in 0..times {
868             if let Some(r) = self.sig_info.try_write() {
869                 return Some(r);
870             }
871         }
872 
873         return None;
874     }
875 
876     pub fn sig_struct(&self) -> SpinLockGuard<SignalStruct> {
877         self.sig_struct.lock()
878     }
879 
880     pub fn try_sig_struct_irq(&self, times: u8) -> Option<SpinLockGuard<SignalStruct>> {
881         for _ in 0..times {
882             if let Ok(r) = self.sig_struct.try_lock_irqsave() {
883                 return Some(r);
884             }
885         }
886 
887         return None;
888     }
889 
890     pub fn sig_struct_irqsave(&self) -> SpinLockGuard<SignalStruct> {
891         self.sig_struct.lock_irqsave()
892     }
893 }
894 
895 impl Drop for ProcessControlBlock {
896     fn drop(&mut self) {
897         // 在ProcFS中,解除进程的注册
898         procfs_unregister_pid(self.pid())
899             .unwrap_or_else(|e| panic!("procfs_unregister_pid failed: error: {e:?}"));
900 
901         if let Some(ppcb) = self.parent_pcb.read().upgrade() {
902             ppcb.children.write().retain(|pid| *pid != self.pid());
903         }
904     }
905 }
906 
907 /// 线程信息
908 #[derive(Debug)]
909 pub struct ThreadInfo {
910     // 来自用户空间记录用户线程id的地址,在该线程结束时将该地址置0以通知父进程
911     clear_child_tid: Option<VirtAddr>,
912     set_child_tid: Option<VirtAddr>,
913 
914     vfork_done: Option<Arc<Completion>>,
915     /// 线程组的组长
916     group_leader: Weak<ProcessControlBlock>,
917 }
918 
919 impl ThreadInfo {
920     pub fn new() -> Self {
921         Self {
922             clear_child_tid: None,
923             set_child_tid: None,
924             vfork_done: None,
925             group_leader: Weak::default(),
926         }
927     }
928 
929     pub fn group_leader(&self) -> Option<Arc<ProcessControlBlock>> {
930         return self.group_leader.upgrade();
931     }
932 }
933 
934 /// 进程的基本信息
935 ///
936 /// 这个结构体保存进程的基本信息,主要是那些不会随着进程的运行而经常改变的信息。
937 #[derive(Debug)]
938 pub struct ProcessBasicInfo {
939     /// 当前进程的进程组id
940     pgid: Pid,
941     /// 当前进程的父进程的pid
942     ppid: Pid,
943     /// 进程的名字
944     name: String,
945 
946     /// 当前进程的工作目录
947     cwd: String,
948 
949     /// 用户地址空间
950     user_vm: Option<Arc<AddressSpace>>,
951 
952     /// 文件描述符表
953     fd_table: Option<Arc<RwLock<FileDescriptorVec>>>,
954 }
955 
956 impl ProcessBasicInfo {
957     #[inline(never)]
958     pub fn new(
959         pgid: Pid,
960         ppid: Pid,
961         name: String,
962         cwd: String,
963         user_vm: Option<Arc<AddressSpace>>,
964     ) -> RwLock<Self> {
965         let fd_table = Arc::new(RwLock::new(FileDescriptorVec::new()));
966         return RwLock::new(Self {
967             pgid,
968             ppid,
969             name,
970             cwd,
971             user_vm,
972             fd_table: Some(fd_table),
973         });
974     }
975 
976     pub fn pgid(&self) -> Pid {
977         return self.pgid;
978     }
979 
980     pub fn ppid(&self) -> Pid {
981         return self.ppid;
982     }
983 
984     pub fn name(&self) -> &str {
985         return &self.name;
986     }
987 
988     pub fn set_name(&mut self, name: String) {
989         self.name = name;
990     }
991 
992     pub fn cwd(&self) -> String {
993         return self.cwd.clone();
994     }
995     pub fn set_cwd(&mut self, path: String) {
996         return self.cwd = path;
997     }
998 
999     pub fn user_vm(&self) -> Option<Arc<AddressSpace>> {
1000         return self.user_vm.clone();
1001     }
1002 
1003     pub unsafe fn set_user_vm(&mut self, user_vm: Option<Arc<AddressSpace>>) {
1004         self.user_vm = user_vm;
1005     }
1006 
1007     pub fn fd_table(&self) -> Option<Arc<RwLock<FileDescriptorVec>>> {
1008         return self.fd_table.clone();
1009     }
1010 
1011     pub fn set_fd_table(&mut self, fd_table: Option<Arc<RwLock<FileDescriptorVec>>>) {
1012         self.fd_table = fd_table;
1013     }
1014 }
1015 
1016 #[derive(Debug)]
1017 pub struct ProcessSchedulerInfo {
1018     /// 当前进程所在的cpu
1019     on_cpu: AtomicProcessorId,
1020     /// 如果当前进程等待被迁移到另一个cpu核心上(也就是flags中的PF_NEED_MIGRATE被置位),
1021     /// 该字段存储要被迁移到的目标处理器核心号
1022     migrate_to: AtomicProcessorId,
1023     inner_locked: RwLock<InnerSchedInfo>,
1024     /// 进程的调度优先级
1025     priority: SchedPriority,
1026     /// 当前进程的虚拟运行时间
1027     virtual_runtime: AtomicIsize,
1028     /// 由实时调度器管理的时间片
1029     rt_time_slice: AtomicIsize,
1030 }
1031 
1032 #[derive(Debug)]
1033 pub struct InnerSchedInfo {
1034     /// 当前进程的状态
1035     state: ProcessState,
1036     /// 进程的调度策略
1037     sched_policy: SchedPolicy,
1038 }
1039 
1040 impl InnerSchedInfo {
1041     pub fn state(&self) -> ProcessState {
1042         return self.state;
1043     }
1044 
1045     pub fn set_state(&mut self, state: ProcessState) {
1046         self.state = state;
1047     }
1048 
1049     pub fn policy(&self) -> SchedPolicy {
1050         return self.sched_policy;
1051     }
1052 }
1053 
1054 impl ProcessSchedulerInfo {
1055     #[inline(never)]
1056     pub fn new(on_cpu: Option<ProcessorId>) -> Self {
1057         let cpu_id = on_cpu.unwrap_or(ProcessorId::INVALID);
1058         return Self {
1059             on_cpu: AtomicProcessorId::new(cpu_id),
1060             migrate_to: AtomicProcessorId::new(ProcessorId::INVALID),
1061             inner_locked: RwLock::new(InnerSchedInfo {
1062                 state: ProcessState::Blocked(false),
1063                 sched_policy: SchedPolicy::CFS,
1064             }),
1065             virtual_runtime: AtomicIsize::new(0),
1066             rt_time_slice: AtomicIsize::new(0),
1067             priority: SchedPriority::new(100).unwrap(),
1068         };
1069     }
1070 
1071     pub fn on_cpu(&self) -> Option<ProcessorId> {
1072         let on_cpu = self.on_cpu.load(Ordering::SeqCst);
1073         if on_cpu == ProcessorId::INVALID {
1074             return None;
1075         } else {
1076             return Some(on_cpu);
1077         }
1078     }
1079 
1080     pub fn set_on_cpu(&self, on_cpu: Option<ProcessorId>) {
1081         if let Some(cpu_id) = on_cpu {
1082             self.on_cpu.store(cpu_id, Ordering::SeqCst);
1083         } else {
1084             self.on_cpu.store(ProcessorId::INVALID, Ordering::SeqCst);
1085         }
1086     }
1087 
1088     pub fn migrate_to(&self) -> Option<ProcessorId> {
1089         let migrate_to = self.migrate_to.load(Ordering::SeqCst);
1090         if migrate_to == ProcessorId::INVALID {
1091             return None;
1092         } else {
1093             return Some(migrate_to);
1094         }
1095     }
1096 
1097     pub fn set_migrate_to(&self, migrate_to: Option<ProcessorId>) {
1098         if let Some(data) = migrate_to {
1099             self.migrate_to.store(data, Ordering::SeqCst);
1100         } else {
1101             self.migrate_to
1102                 .store(ProcessorId::INVALID, Ordering::SeqCst)
1103         }
1104     }
1105 
1106     pub fn inner_lock_write_irqsave(&self) -> RwLockWriteGuard<InnerSchedInfo> {
1107         return self.inner_locked.write_irqsave();
1108     }
1109 
1110     pub fn inner_lock_read_irqsave(&self) -> RwLockReadGuard<InnerSchedInfo> {
1111         return self.inner_locked.read_irqsave();
1112     }
1113 
1114     pub fn inner_lock_try_read_irqsave(
1115         &self,
1116         times: u8,
1117     ) -> Option<RwLockReadGuard<InnerSchedInfo>> {
1118         for _ in 0..times {
1119             if let Some(r) = self.inner_locked.try_read_irqsave() {
1120                 return Some(r);
1121             }
1122         }
1123 
1124         return None;
1125     }
1126 
1127     pub fn inner_lock_try_upgradable_read_irqsave(
1128         &self,
1129         times: u8,
1130     ) -> Option<RwLockUpgradableGuard<InnerSchedInfo>> {
1131         for _ in 0..times {
1132             if let Some(r) = self.inner_locked.try_upgradeable_read_irqsave() {
1133                 return Some(r);
1134             }
1135         }
1136 
1137         return None;
1138     }
1139 
1140     pub fn virtual_runtime(&self) -> isize {
1141         return self.virtual_runtime.load(Ordering::SeqCst);
1142     }
1143 
1144     pub fn set_virtual_runtime(&self, virtual_runtime: isize) {
1145         self.virtual_runtime
1146             .store(virtual_runtime, Ordering::SeqCst);
1147     }
1148     pub fn increase_virtual_runtime(&self, delta: isize) {
1149         self.virtual_runtime.fetch_add(delta, Ordering::SeqCst);
1150     }
1151 
1152     pub fn rt_time_slice(&self) -> isize {
1153         return self.rt_time_slice.load(Ordering::SeqCst);
1154     }
1155 
1156     pub fn set_rt_time_slice(&self, rt_time_slice: isize) {
1157         self.rt_time_slice.store(rt_time_slice, Ordering::SeqCst);
1158     }
1159 
1160     pub fn increase_rt_time_slice(&self, delta: isize) {
1161         self.rt_time_slice.fetch_add(delta, Ordering::SeqCst);
1162     }
1163 
1164     pub fn priority(&self) -> SchedPriority {
1165         return self.priority;
1166     }
1167 }
1168 
1169 #[derive(Debug, Clone)]
1170 pub struct KernelStack {
1171     stack: Option<AlignedBox<[u8; KernelStack::SIZE], { KernelStack::ALIGN }>>,
1172     /// 标记该内核栈是否可以被释放
1173     can_be_freed: bool,
1174 }
1175 
1176 impl KernelStack {
1177     pub const SIZE: usize = 0x4000;
1178     pub const ALIGN: usize = 0x4000;
1179 
1180     pub fn new() -> Result<Self, SystemError> {
1181         return Ok(Self {
1182             stack: Some(
1183                 AlignedBox::<[u8; KernelStack::SIZE], { KernelStack::ALIGN }>::new_zeroed()?,
1184             ),
1185             can_be_freed: true,
1186         });
1187     }
1188 
1189     /// 根据已有的空间,构造一个内核栈结构体
1190     ///
1191     /// 仅仅用于BSP启动时,为idle进程构造内核栈。其他时候使用这个函数,很可能造成错误!
1192     pub unsafe fn from_existed(base: VirtAddr) -> Result<Self, SystemError> {
1193         if base.is_null() || base.check_aligned(Self::ALIGN) == false {
1194             return Err(SystemError::EFAULT);
1195         }
1196 
1197         return Ok(Self {
1198             stack: Some(
1199                 AlignedBox::<[u8; KernelStack::SIZE], { KernelStack::ALIGN }>::new_unchecked(
1200                     base.data() as *mut [u8; KernelStack::SIZE],
1201                 ),
1202             ),
1203             can_be_freed: false,
1204         });
1205     }
1206 
1207     /// 返回内核栈的起始虚拟地址(低地址)
1208     pub fn start_address(&self) -> VirtAddr {
1209         return VirtAddr::new(self.stack.as_ref().unwrap().as_ptr() as usize);
1210     }
1211 
1212     /// 返回内核栈的结束虚拟地址(高地址)(不包含该地址)
1213     pub fn stack_max_address(&self) -> VirtAddr {
1214         return VirtAddr::new(self.stack.as_ref().unwrap().as_ptr() as usize + Self::SIZE);
1215     }
1216 
1217     pub unsafe fn set_pcb(&mut self, pcb: Weak<ProcessControlBlock>) -> Result<(), SystemError> {
1218         // 将一个Weak<ProcessControlBlock>放到内核栈的最低地址处
1219         let p: *const ProcessControlBlock = Weak::into_raw(pcb);
1220         let stack_bottom_ptr = self.start_address().data() as *mut *const ProcessControlBlock;
1221 
1222         // 如果内核栈的最低地址处已经有了一个pcb,那么,这里就不再设置,直接返回错误
1223         if unlikely(unsafe { !(*stack_bottom_ptr).is_null() }) {
1224             kerror!("kernel stack bottom is not null: {:p}", *stack_bottom_ptr);
1225             return Err(SystemError::EPERM);
1226         }
1227         // 将pcb的地址放到内核栈的最低地址处
1228         unsafe {
1229             *stack_bottom_ptr = p;
1230         }
1231 
1232         return Ok(());
1233     }
1234 
1235     /// 清除内核栈的pcb指针
1236     ///
1237     /// ## 参数
1238     ///
1239     /// - `force` : 如果为true,那么,即使该内核栈的pcb指针不为null,也会被强制清除而不处理Weak指针问题
1240     pub unsafe fn clear_pcb(&mut self, force: bool) {
1241         let stack_bottom_ptr = self.start_address().data() as *mut *const ProcessControlBlock;
1242         if unlikely(unsafe { (*stack_bottom_ptr).is_null() }) {
1243             return;
1244         }
1245 
1246         if !force {
1247             let pcb_ptr: Weak<ProcessControlBlock> = Weak::from_raw(*stack_bottom_ptr);
1248             drop(pcb_ptr);
1249         }
1250 
1251         *stack_bottom_ptr = core::ptr::null();
1252     }
1253 
1254     /// 返回指向当前内核栈pcb的Arc指针
1255     #[allow(dead_code)]
1256     pub unsafe fn pcb(&self) -> Option<Arc<ProcessControlBlock>> {
1257         // 从内核栈的最低地址处取出pcb的地址
1258         let p = self.stack.as_ref().unwrap().as_ptr() as *const *const ProcessControlBlock;
1259         if unlikely(unsafe { (*p).is_null() }) {
1260             return None;
1261         }
1262 
1263         // 为了防止内核栈的pcb指针被释放,这里需要将其包装一下,使得Arc的drop不会被调用
1264         let weak_wrapper: ManuallyDrop<Weak<ProcessControlBlock>> =
1265             ManuallyDrop::new(Weak::from_raw(*p));
1266 
1267         let new_arc: Arc<ProcessControlBlock> = weak_wrapper.upgrade()?;
1268         return Some(new_arc);
1269     }
1270 }
1271 
1272 impl Drop for KernelStack {
1273     fn drop(&mut self) {
1274         if !self.stack.is_none() {
1275             let ptr = self.stack.as_ref().unwrap().as_ptr() as *const *const ProcessControlBlock;
1276             if unsafe { !(*ptr).is_null() } {
1277                 let pcb_ptr: Weak<ProcessControlBlock> = unsafe { Weak::from_raw(*ptr) };
1278                 drop(pcb_ptr);
1279             }
1280         }
1281         // 如果该内核栈不可以被释放,那么,这里就forget,不调用AlignedBox的drop函数
1282         if !self.can_be_freed {
1283             let bx = self.stack.take();
1284             core::mem::forget(bx);
1285         }
1286     }
1287 }
1288 
1289 pub fn process_init() {
1290     ProcessManager::init();
1291 }
1292 
1293 #[derive(Debug)]
1294 pub struct ProcessSignalInfo {
1295     // 当前进程
1296     sig_block: SigSet,
1297     // sig_pending 中存储当前线程要处理的信号
1298     sig_pending: SigPending,
1299     // sig_shared_pending 中存储当前线程所属进程要处理的信号
1300     sig_shared_pending: SigPending,
1301     // 当前进程对应的tty
1302     tty: Option<Arc<TtyCore>>,
1303 }
1304 
1305 impl ProcessSignalInfo {
1306     pub fn sig_block(&self) -> &SigSet {
1307         &self.sig_block
1308     }
1309 
1310     pub fn sig_pending(&self) -> &SigPending {
1311         &self.sig_pending
1312     }
1313 
1314     pub fn sig_pending_mut(&mut self) -> &mut SigPending {
1315         &mut self.sig_pending
1316     }
1317 
1318     pub fn sig_block_mut(&mut self) -> &mut SigSet {
1319         &mut self.sig_block
1320     }
1321 
1322     pub fn sig_shared_pending_mut(&mut self) -> &mut SigPending {
1323         &mut self.sig_shared_pending
1324     }
1325 
1326     pub fn sig_shared_pending(&self) -> &SigPending {
1327         &self.sig_shared_pending
1328     }
1329 
1330     pub fn tty(&self) -> Option<Arc<TtyCore>> {
1331         self.tty.clone()
1332     }
1333 
1334     pub fn set_tty(&mut self, tty: Arc<TtyCore>) {
1335         self.tty = Some(tty);
1336     }
1337 
1338     /// 从 pcb 的 siginfo中取出下一个要处理的信号,先处理线程信号,再处理进程信号
1339     ///
1340     /// ## 参数
1341     ///
1342     /// - `sig_mask` 被忽略掉的信号
1343     ///
1344     pub fn dequeue_signal(&mut self, sig_mask: &SigSet) -> (Signal, Option<SigInfo>) {
1345         let res = self.sig_pending.dequeue_signal(sig_mask);
1346         if res.0 != Signal::INVALID {
1347             return res;
1348         } else {
1349             return self.sig_shared_pending.dequeue_signal(sig_mask);
1350         }
1351     }
1352 }
1353 
1354 impl Default for ProcessSignalInfo {
1355     fn default() -> Self {
1356         Self {
1357             sig_block: SigSet::empty(),
1358             sig_pending: SigPending::default(),
1359             sig_shared_pending: SigPending::default(),
1360             tty: None,
1361         }
1362     }
1363 }
1364