1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
use core::fmt::{self, Debug, Formatter};

use super::signal::*;
use super::AuxvEntry;
use super::AuxvType;
use super::TaskContext;
use super::{pid_alloc, KernelStack, PidHandle};
use crate::fs::{open, DiskInodeType, File, FileDescriptor, FileLike, OSInode, OpenFlags, TTY, open_root_inode};
use crate::mm::PageTable;
use crate::mm::{MemorySet, PhysPageNum, VirtAddr, KERNEL_SPACE};
use crate::syscall::errno::*;
use crate::task::current_task;
use crate::timer::TICKS_PER_SEC;
use crate::timer::{ITimerVal, TimeVal};
use crate::trap::{trap_handler, TrapContext};
use crate::{config::*, show_frame_consumption};
use alloc::boxed::Box;
use alloc::collections::BTreeMap;
use alloc::string::String;
use alloc::string::ToString;
use alloc::sync::{Arc, Weak};
use alloc::vec;
use alloc::vec::Vec;
use log::{debug, error, info, trace, warn};
use riscv::register::scause::{Interrupt, Trap};
use spin::{Mutex, MutexGuard};

pub struct TaskControlBlock {
    // immutable
    pub pid: PidHandle,
    pub kernel_stack: KernelStack,
    // mutable
    inner: Mutex<TaskControlBlockInner>,
}

pub type FdTable = Vec<Option<FileDescriptor>>;
pub struct TaskControlBlockInner {
    pub working_inode: Arc<OSInode>,
    pub working_dir: String,
    pub sigmask: Signals,
    pub trap_cx_ppn: PhysPageNum,
    pub base_size: usize,
    pub task_cx_ptr: usize,
    pub task_status: TaskStatus,
    pub memory_set: MemorySet,
    pub parent: Option<Weak<TaskControlBlock>>,
    pub children: Vec<Arc<TaskControlBlock>>,
    pub exit_code: u32,
    pub fd_table: FdTable,
    pub address: ProcAddress,
    pub heap_bottom: usize,
    pub heap_pt: usize,
    pub siginfo: SigInfo,
    pub pgid: usize,
    pub rusage: Rusage,
    pub clock: ProcClock,
    pub timer: [ITimerVal; 3],
}

pub struct ProcClock {
    last_enter_u_mode: TimeVal,
    last_enter_s_mode: TimeVal,
}

impl ProcClock {
    pub fn new() -> Self {
        let now = TimeVal::now();
        Self {
            last_enter_u_mode: now,
            last_enter_s_mode: now,
        }
    }
}

#[allow(unused)]
#[derive(Clone, Copy)]
pub struct Rusage {
    pub ru_utime: TimeVal, /* user CPU time used */
    pub ru_stime: TimeVal, /* system CPU time used */
    ru_maxrss: isize,      // NOT IMPLEMENTED /* maximum resident set size */
    ru_ixrss: isize,       // NOT IMPLEMENTED /* integral shared memory size */
    ru_idrss: isize,       // NOT IMPLEMENTED /* integral unshared data size */
    ru_isrss: isize,       // NOT IMPLEMENTED /* integral unshared stack size */
    ru_minflt: isize,      // NOT IMPLEMENTED /* page reclaims (soft page faults) */
    ru_majflt: isize,      // NOT IMPLEMENTED /* page faults (hard page faults) */
    ru_nswap: isize,       // NOT IMPLEMENTED /* swaps */
    ru_inblock: isize,     // NOT IMPLEMENTED /* block input operations */
    ru_oublock: isize,     // NOT IMPLEMENTED /* block output operations */
    ru_msgsnd: isize,      // NOT IMPLEMENTED /* IPC messages sent */
    ru_msgrcv: isize,      // NOT IMPLEMENTED /* IPC messages received */
    ru_nsignals: isize,    // NOT IMPLEMENTED /* signals received */
    ru_nvcsw: isize,       // NOT IMPLEMENTED /* voluntary context switches */
    ru_nivcsw: isize,      // NOT IMPLEMENTED /* involuntary context switches */
}

impl Rusage {
    pub fn new() -> Self {
        Self {
            ru_utime: TimeVal::new(),
            ru_stime: TimeVal::new(),
            ru_maxrss: 0,
            ru_ixrss: 0,
            ru_idrss: 0,
            ru_isrss: 0,
            ru_minflt: 0,
            ru_majflt: 0,
            ru_nswap: 0,
            ru_inblock: 0,
            ru_oublock: 0,
            ru_msgsnd: 0,
            ru_msgrcv: 0,
            ru_nsignals: 0,
            ru_nvcsw: 0,
            ru_nivcsw: 0,
        }
    }
}

impl Debug for Rusage {
    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
        f.write_fmt(format_args!(
            "(ru_utime:{:?}, ru_stime:{:?})",
            self.ru_utime, self.ru_stime
        ))
    }
}

impl TaskControlBlockInner {
    pub fn get_task_cx_ptr2(&self) -> *const usize {
        &self.task_cx_ptr as *const usize
    }
    pub fn get_trap_cx(&self) -> &'static mut TrapContext {
        self.trap_cx_ppn.get_mut()
    }
    pub fn get_user_token(&self) -> usize {
        self.memory_set.token()
    }
    fn get_status(&self) -> TaskStatus {
        self.task_status
    }
    pub fn is_zombie(&self) -> bool {
        self.get_status() == TaskStatus::Zombie
    }
    /// Try to alloc the lowest valid fd in `fd_table`
    pub fn alloc_fd(&mut self) -> Option<usize> {
        self.alloc_fd_at(0)
    }
    /// Try to alloc fd at `hint`, if `hint` is allocated, will alloc lowest valid fd above.
    pub fn alloc_fd_at(&mut self, hint: usize) -> Option<usize> {
        // [Warning] temporarily use hardcoded implementation, should adapt to `prlimit()` in future
        const FD_LIMIT: usize = 128;
        if hint < self.fd_table.len() {
            if let Some(fd) = (hint..self.fd_table.len()).find(|fd| self.fd_table[*fd].is_none()) {
                Some(fd)
            } else {
                if self.fd_table.len() < FD_LIMIT {
                    self.fd_table.push(None);
                    Some(self.fd_table.len() - 1)
                } else {
                    None
                }
            }
        } else {
            if hint < FD_LIMIT {
                self.fd_table.resize(hint + 1, None);
                Some(hint)
            } else {
                None
            }
        }
    }
    pub fn add_signal(&mut self, signal: Signals) {
        self.siginfo.signal_pending.insert(signal);
    }
    pub fn update_process_times_enter_trap(&mut self) {
        let now = TimeVal::now();
        self.clock.last_enter_s_mode = now;
        let diff = now - self.clock.last_enter_u_mode;
        self.rusage.ru_utime = self.rusage.ru_utime + diff;
        self.update_itimer_virtual_if_exists(diff);
        self.update_itimer_prof_if_exists(diff);
    }
    pub fn update_process_times_leave_trap(&mut self, scause: Trap) {
        let now = TimeVal::now();
        self.update_itimer_real_if_exists(now - self.clock.last_enter_u_mode);
        if scause != Trap::Interrupt(Interrupt::SupervisorTimer) {
            let diff = now - self.clock.last_enter_s_mode;
            self.rusage.ru_stime = self.rusage.ru_stime + diff;
            self.update_itimer_prof_if_exists(diff);
        }
        self.clock.last_enter_u_mode = now;
    }
    pub fn update_itimer_real_if_exists(&mut self, diff: TimeVal) {
        if !self.timer[0].it_value.is_zero() {
            self.timer[0].it_value = self.timer[0].it_value - diff;
            if self.timer[0].it_value.is_zero() {
                self.add_signal(Signals::SIGALRM);
                self.timer[0].it_value = self.timer[0].it_interval;
            }
        }
    }
    pub fn update_itimer_virtual_if_exists(&mut self, diff: TimeVal) {
        if !self.timer[1].it_value.is_zero() {
            self.timer[1].it_value = self.timer[1].it_value - diff;
            if self.timer[1].it_value.is_zero() {
                self.add_signal(Signals::SIGVTALRM);
                self.timer[1].it_value = self.timer[1].it_interval;
            }
        }
    }
    pub fn update_itimer_prof_if_exists(&mut self, diff: TimeVal) {
        if !self.timer[2].it_value.is_zero() {
            self.timer[2].it_value = self.timer[2].it_value - diff;
            if self.timer[2].it_value.is_zero() {
                self.add_signal(Signals::SIGPROF);
                self.timer[2].it_value = self.timer[2].it_interval;
            }
        }
    }
}

impl TaskControlBlock {
    pub fn acquire_inner_lock(&self) -> MutexGuard<TaskControlBlockInner> {
        self.inner.lock()
    }
    /// !!!!!!!!!!!!!!!!WARNING!!!!!!!!!!!!!!!!!!!!!
    /// Currently used for initproc loading only. bin_path must be used changed if used elsewhere.
    pub fn new(elf_data: &[u8]) -> Self {
        // memory_set with elf program headers/trampoline/trap context/user stack
        let (memory_set, user_sp, user_heap, elf_info) = MemorySet::from_elf(elf_data);

        crate::mm::KERNEL_SPACE
            .lock()
            .remove_area_with_start_vpn(VirtAddr::from(elf_data.as_ptr() as usize).floor())
            .unwrap();
        let trap_cx_ppn = memory_set
            .translate(VirtAddr::from(TRAP_CONTEXT).into())
            .unwrap()
            .ppn();
        // alloc a pid and a kernel stack in kernel space
        let pid_handle = pid_alloc();
        let pgid = pid_handle.0;
        let kernel_stack = KernelStack::new(&pid_handle);
        let kernel_stack_top = kernel_stack.get_top();
        // push a task context which goes to trap_return to the top of kernel stack
        let task_cx_ptr = kernel_stack.push_on_top(TaskContext::goto_trap_return());
        let task_control_block = Self {
            pid: pid_handle,
            kernel_stack,
            inner: Mutex::new(TaskControlBlockInner {
                working_inode: open_root_inode(),
                working_dir: "/".to_string(),
                trap_cx_ppn,
                pgid,
                sigmask: Signals::empty(),
                base_size: user_sp,
                task_cx_ptr: task_cx_ptr as usize,
                task_status: TaskStatus::Ready,
                memory_set,
                parent: None,
                children: Vec::new(),
                exit_code: 0,
                fd_table: vec![
                    // 0 -> stdin
                    Some(FileDescriptor::new(false, FileLike::Abstract(TTY.clone()))),
                    // 1 -> stdout
                    Some(FileDescriptor::new(false, FileLike::Abstract(TTY.clone()))),
                    // 2 -> stderr
                    Some(FileDescriptor::new(false, FileLike::Abstract(TTY.clone()))),
                ],
                address: ProcAddress::new(),
                heap_bottom: user_heap,
                heap_pt: user_heap,
                siginfo: SigInfo::new(),
                rusage: Rusage::new(),
                clock: ProcClock::new(),
                timer: [ITimerVal::new(); 3],
            }),
        };
        // prepare TrapContext in user space
        let trap_cx = task_control_block.acquire_inner_lock().get_trap_cx();
        *trap_cx = TrapContext::app_init_context(
            elf_info.entry,
            user_sp,
            KERNEL_SPACE.lock().token(),
            kernel_stack_top,
            trap_handler as usize,
        );
        task_control_block
    }

    pub fn load_elf(&self, elf_data: &[u8], argv_vec: &Vec<String>, envp_vec: &Vec<String>) {
        // memory_set with elf program headers/trampoline/trap context/user stack
        let (memory_set, mut user_sp, program_break, elf_info) = MemorySet::from_elf(elf_data);
        let token = (&memory_set).token();

        // go down to the stack page (important!) and align
        user_sp -= 2 * core::mem::size_of::<usize>();

        // because size of parameters is almost never more than PAGE_SIZE,
        // so I decide to use physical address directly for better performance
        let mut phys_user_sp = PageTable::from_token(token)
            .translate_va(VirtAddr::from(user_sp))
            .unwrap()
            .0;
        // we can add this to a phys addr to get corresponding virt addr
        let virt_phys_offset = user_sp - phys_user_sp;
        let phys_start = phys_user_sp;

        // unsafe code is efficient code! here we go!
        fn copy_to_user_string_unchecked(src: &str, dst: *mut u8) {
            let size = src.len();
            unsafe {
                core::slice::from_raw_parts_mut(dst, size)
                    .copy_from_slice(core::slice::from_raw_parts(src.as_ptr(), size));
                // adapt to C-style string
                *dst.add(size) = b'\0';
            }
        }

        // we don't care about the order of env...
        let mut envp_user = Vec::<*const u8>::new();
        for env in envp_vec.iter() {
            phys_user_sp -= env.len() + 1;
            envp_user.push((phys_user_sp + virt_phys_offset) as *const u8);
            copy_to_user_string_unchecked(env, phys_user_sp as *mut u8);
        }
        envp_user.push(core::ptr::null());

        // we don't care about the order of arg, too...
        let mut argv_user = Vec::<*const u8>::new();
        for arg in argv_vec.iter() {
            phys_user_sp -= arg.len() + 1;
            argv_user.push((phys_user_sp + virt_phys_offset) as *const u8);
            copy_to_user_string_unchecked(arg, phys_user_sp as *mut u8);
        }
        argv_user.push(core::ptr::null());

        // align downward to usize (64bit)
        phys_user_sp &= !0x7;

        // 16 random bytes
        phys_user_sp -= 2 * core::mem::size_of::<usize>();
        // should be virt addr!
        let random_bits_ptr = phys_user_sp + virt_phys_offset;
        unsafe {
            *(phys_user_sp as *mut usize) = 0xdeadbeefcafebabe;
            *(phys_user_sp as *mut usize).add(1) = 0xdeadbeefcafebabe;
        }

        // padding
        phys_user_sp -= core::mem::size_of::<usize>();
        unsafe {
            *(phys_user_sp as *mut usize) = 0x0000000000000000;
        }

        let auxv = [
            // AuxvEntry::new(AuxvType::SYSINFO_EHDR, vDSO_mapping);
            // AuxvEntry::new(AuxvType::L1I_CACHESIZE, 0);
            // AuxvEntry::new(AuxvType::L1I_CACHEGEOMETRY, 0);
            // AuxvEntry::new(AuxvType::L1D_CACHESIZE, 0);
            // AuxvEntry::new(AuxvType::L1D_CACHEGEOMETRY, 0);
            // AuxvEntry::new(AuxvType::L2_CACHESIZE, 0);
            // AuxvEntry::new(AuxvType::L2_CACHEGEOMETRY, 0);
            // `0x112d` means IMADZifenciC, aka gc
            AuxvEntry::new(AuxvType::HWCAP, 0x112d),
            AuxvEntry::new(AuxvType::PAGESZ, PAGE_SIZE),
            AuxvEntry::new(AuxvType::CLKTCK, TICKS_PER_SEC),
            AuxvEntry::new(AuxvType::PHDR, elf_info.phdr),
            AuxvEntry::new(AuxvType::PHENT, elf_info.phent),
            AuxvEntry::new(AuxvType::PHNUM, elf_info.phnum),
            AuxvEntry::new(AuxvType::BASE, 0),
            AuxvEntry::new(AuxvType::FLAGS, 0),
            AuxvEntry::new(AuxvType::ENTRY, elf_info.entry),
            AuxvEntry::new(AuxvType::UID, 0),
            AuxvEntry::new(AuxvType::EUID, 0),
            AuxvEntry::new(AuxvType::GID, 0),
            AuxvEntry::new(AuxvType::EGID, 0),
            AuxvEntry::new(AuxvType::SECURE, 0),
            AuxvEntry::new(AuxvType::RANDOM, random_bits_ptr as usize),
            AuxvEntry::new(
                AuxvType::EXECFN,
                argv_user.first().copied().unwrap() as usize,
            ),
            AuxvEntry::new(AuxvType::NULL, 0),
        ];
        phys_user_sp -= auxv.len() * core::mem::size_of::<AuxvEntry>();
        unsafe {
            core::slice::from_raw_parts_mut(phys_user_sp as *mut AuxvEntry, auxv.len())
                .copy_from_slice(auxv.as_slice());
        }

        phys_user_sp -= envp_user.len() * core::mem::size_of::<usize>();
        unsafe {
            core::slice::from_raw_parts_mut(phys_user_sp as *mut *const u8, envp_user.len())
                .copy_from_slice(envp_user.as_slice());
        }

        phys_user_sp -= argv_user.len() * core::mem::size_of::<usize>();
        unsafe {
            core::slice::from_raw_parts_mut(phys_user_sp as *mut *const u8, argv_user.len())
                .copy_from_slice(argv_user.as_slice());
        }

        phys_user_sp -= core::mem::size_of::<usize>();
        unsafe {
            *(phys_user_sp as *mut usize) = argv_vec.len();
        }

        user_sp = phys_user_sp + virt_phys_offset;

        // unlikely, if `start` and `end` are in different pages, we should panic
        assert_eq!(phys_start & !0xfff, phys_user_sp & !0xfff);

        // print user stack
        let mut phys_addr = phys_user_sp & !0xf;
        while phys_start >= phys_addr {
            info!(
                "0x{:0>16X}:    {:0>16X}  {:0>16X}",
                phys_addr + virt_phys_offset,
                unsafe { *(phys_addr as *mut usize) },
                unsafe { *((phys_addr + core::mem::size_of::<usize>()) as *mut usize) }
            );
            phys_addr += 2 * core::mem::size_of::<usize>();
        }

        // initialize trap_cx
        let trap_cx = TrapContext::app_init_context(
            elf_info.entry,
            user_sp,
            KERNEL_SPACE.lock().token(),
            self.kernel_stack.get_top(),
            trap_handler as usize,
        );
        // trap_cx.x[10] = args_vec.len();
        // trap_cx.x[11] = argv_base;
        // trap_cx.x[12] = envp_base;
        // trap_cx.x[13] = auxv_base;
        // **** hold current PCB lock
        let mut inner = self.acquire_inner_lock();
        // update trap_cx ppn
        inner.trap_cx_ppn = (&memory_set)
            .translate(VirtAddr::from(TRAP_CONTEXT).into())
            .unwrap()
            .ppn();
        *inner.get_trap_cx() = trap_cx;
        // substitute memory_set
        inner.memory_set = memory_set;
        inner.heap_bottom = program_break;
        inner.heap_pt = program_break;
        // flush signal handler
        inner.siginfo.signal_handler = BTreeMap::new();
        // flush cloexec fd
        inner.fd_table.iter_mut().for_each(|fd| match fd {
            Some(file) => {
                if file.get_cloexec() {
                    *fd = None;
                }
            }
            None => (),
        });
        // **** release current PCB lock
    }
    pub fn fork(self: &Arc<TaskControlBlock>) -> Arc<TaskControlBlock> {
        // ---- hold parent PCB lock
        let mut parent_inner = self.acquire_inner_lock();
        // copy user space(include trap context)
        let memory_set = MemorySet::from_existed_user(&mut parent_inner.memory_set);
        let trap_cx_ppn = memory_set
            .translate(VirtAddr::from(TRAP_CONTEXT).into())
            .unwrap()
            .ppn();
        // alloc a pid and a kernel stack in kernel space
        let pid_handle = pid_alloc();
        let kernel_stack = KernelStack::new(&pid_handle);
        let kernel_stack_top = kernel_stack.get_top();
        // push a goto_trap_return task_cx on the top of kernel stack
        let task_cx_ptr = kernel_stack.push_on_top(TaskContext::goto_trap_return());
        // copy fd table
        let mut new_fd_table: FdTable = Vec::new();
        for fd in parent_inner.fd_table.iter() {
            if let Some(file) = fd {
                new_fd_table.push(Some(file.clone()));
            } else {
                new_fd_table.push(None);
            }
        }
        let task_control_block = Arc::new(TaskControlBlock {
            pid: pid_handle,
            kernel_stack,
            inner: Mutex::new(TaskControlBlockInner {
                //inherited
                pgid: parent_inner.pgid,
                base_size: parent_inner.base_size,
                heap_bottom: parent_inner.heap_bottom,
                heap_pt: parent_inner.heap_pt,
                //cloned(usu. still inherited)
                working_inode: parent_inner.working_inode.clone(),
                working_dir: parent_inner.working_dir.clone(),
                siginfo: parent_inner.siginfo.clone(),
                //new/empty
                parent: Some(Arc::downgrade(self)),
                children: Vec::new(),
                rusage: Rusage::new(),
                clock: ProcClock::new(),
                address: ProcAddress::new(),
                timer: [ITimerVal::new(); 3],
                sigmask: Signals::empty(),
                //computed
                fd_table: new_fd_table,
                task_cx_ptr: task_cx_ptr as usize,
                task_status: TaskStatus::Ready,
                trap_cx_ppn,
                memory_set,
                //constants
                exit_code: 0,
            }),
        });
        // add child
        parent_inner.children.push(task_control_block.clone());
        // modify kernel_sp in trap_cx
        // **** acquire child PCB lock
        let trap_cx = task_control_block.acquire_inner_lock().get_trap_cx();
        // **** release child PCB lock
        trap_cx.kernel_sp = kernel_stack_top;
        // return
        task_control_block
        // ---- release parent PCB lock
    }
    pub fn getpid(&self) -> usize {
        self.pid.0
    }
    pub fn setpgid(&self, pgid: usize) -> isize {
        if (pgid as isize) < 0 {
            return -1;
        }
        let mut inner = self.acquire_inner_lock();
        inner.pgid = pgid;
        0
        //Temporarily suspend. Because the type of 'self' is 'Arc', which can't be borrow as mutable.
    }
    pub fn getpgid(&self) -> usize {
        let inner = self.acquire_inner_lock();
        inner.pgid
    }
}

fn elf_exec(file: Arc<OSInode>, argv_vec: &Vec<String>, envp_vec: &Vec<String>) -> isize {
    let size = file.size();
    let start: usize = MMAP_BASE;
    let buffer = unsafe { core::slice::from_raw_parts_mut(start as *mut u8, size) };
    show_frame_consumption! {
        "push_elf_area";
        if crate::mm::push_elf_area(file.clone()).is_err() {
            file.kread(None, buffer);
        } else {
            info!("[elf_exec] Hit ELF cache, no alloc");
        };
    }
    let task = current_task().unwrap();
    show_frame_consumption! {
        "task_exec";
        task.load_elf(buffer, argv_vec, envp_vec);
    }
    // remove elf area
    crate::mm::KERNEL_SPACE
        .lock()
        .remove_area_with_start_vpn(VirtAddr::from(MMAP_BASE).floor())
        .unwrap();
    // should return 0 in success
    SUCCESS
}

// should return 0 in success
pub fn execve(path: String, mut argv_vec: Vec<String>, envp_vec: Vec<String>) -> isize {
    const DEFAULT_SHELL: &str = "/bin/bash";
    debug!(
        "[exec] argv: {:?} /* {} vars */, envp: {:?} /* {} vars */",
        argv_vec,
        argv_vec.len(),
        envp_vec,
        envp_vec.len()
    );
    let task = current_task().unwrap();
    let inner = task.acquire_inner_lock();
    let working_inode = inner.working_inode.clone();
    drop(inner);

    match open(
        &working_inode,
        path.as_str(),
        OpenFlags::O_RDONLY,
        DiskInodeType::File,
    ) {
        Ok(file) => {
            if file.size() < 4 {
                return ENOEXEC;
            }
            let mut magic_number = Box::<[u8; 4]>::new([0; 4]);
            // this operation may be expensive... I'm not sure
            file.kread(Some(&mut 0usize), magic_number.as_mut_slice());
            match magic_number.as_slice() {
                b"\x7fELF" => elf_exec(file, &argv_vec, &envp_vec),
                b"#!" => {
                    let shell_file = open(
                        &working_inode,
                        DEFAULT_SHELL,
                        OpenFlags::O_RDONLY,
                        DiskInodeType::File,
                    )
                    .unwrap();
                    argv_vec.insert(0, DEFAULT_SHELL.to_string());
                    elf_exec(shell_file, &argv_vec, &envp_vec)
                }
                _ => ENOEXEC,
            }
        }
        Err(_) => ENOENT,
    }
}
// I think it's a little expensive, so I temporarily move it here
// test sh
// if buffer[0..4] != [0x7f, 0x45, 0x4c, 0x46]

// Problem 0: Zero Init. Exec Attempt: Use `busybox sh` as `default` while achieving the following purposes.
// Problem 1: Recursion Redirection Problem: what if the #! gives an X that is NOT a binary.
// problem 2: Invalid Redirection Problem: what if the #! gives an invalid binary? If you redirect it to `busybox sh` directly, will it be an infinitive recursion?

// let path_bin: String;
// let shell: bool = buffer[0..2.min(buffer.len())] == [b'#', b'!']; // see if it tells us the path using #!
// info!("bin_given:{}", shell);
// if shell {
//     let last = buffer[0..85.min(buffer.len())]
//         .iter()
//         .position(|&r| ['\n' as u8, '\0' as u8, 0].contains(&(r)));
//     //assign_to_bin. not done.
//     path_bin = String::from_utf8_lossy(
//         &buffer[2..if last.is_some() { last.unwrap() } else { 2 }], //what if it is #!
//     )
//     .to_string();
//     if path_bin.is_empty() {
//         unmap_exec_buf!(buffer);
//         // #! must be followed by a path or at least a name
//         return ENOEXEC;
//     }
//     info!("path_bin:{}", path_bin);
//     //end of assign_to_bin
//     if ["/bin/sh", "/bin/bash"].contains(&&(path_bin[..])) {
//         info!("[exec]path_bin==/bin/sh");
//         *path = String::from("/bash");
//         args_vec.insert(0, path.to_string());
//     } else {
//         info!("[exec]path_bin!=/bin/sh");
//         let cmd = path_bin.split(' ').collect::<Vec<_>>();
//         //args_vec[0] = path.clone();
//         *path = cmd[0].to_string();
//         let bin_name = path[..]
//             .split('/')
//             .collect::<Vec<_>>()
//             .last()
//             .unwrap()
//             .to_string();
//         if cmd.len() > 1 {
//             for j in (1..cmd.len()).rev() {
//                 args_vec.insert(0, cmd[j].to_string());
//             }
//         }
//         args_vec.insert(0, bin_name);
//         info!("[exec] args_vec{:?}", args_vec);
//     }
//  } else {
// completely no info, fall back to busybox.
// args_vec.insert(0, String::from("busybox"));
// }

#[derive(Copy, Clone, PartialEq, Debug)]
pub enum TaskStatus {
    Ready,
    Running,
    Zombie,
    Interruptible,
}

pub struct ProcAddress {
    pub set_child_tid: usize,
    pub clear_child_tid: usize,
}

impl ProcAddress {
    pub fn new() -> Self {
        Self {
            set_child_tid: 0,
            clear_child_tid: 0,
        }
    }
}