Improve /proc/{PID}/stat

kernel/src/fs/procfs/pid/stat.rs

@@ -8,7 +8,6 @@ use crate::{
         utils::Inode,
     },
     prelude::*,
-    process::posix_thread::AsPosixThread,
     Process,
 };
 
@@ -16,6 +15,59 @@ use crate::{
 /// The fields are the same as the ones in `/proc/[pid]/status`. But the format is different.
 /// See https://github.com/torvalds/linux/blob/ce1c54fdff7c4556b08f5b875a331d8952e8b6b7/fs/proc/array.c#L467
 /// FIXME: Some fields are not implemented yet.
+///
+/// Fields:
+/// - pid              : Process ID.
+/// - comm             : Process name.
+/// - state            : Process state (R: running, S: sleeping, Z: zombie).
+/// - ppid             : Parent process ID.
+/// - pgrp             : Process group ID.
+/// - session          : Session ID.
+/// - tty_nr           : Terminal associated with the process.
+/// - tpgid            : Foreground process group ID.
+/// - flags            : Kernel flags determining process behavior.
+/// - minflt           : Minor page faults (no I/O needed).
+/// - cminflt          : Cumulative minor faults of child processes.
+/// - majflt           : Major page faults (I/O required).
+/// - cmajflt          : Cumulative major faults of child processes.
+/// - utime            : Time spent in user mode (clock ticks).
+/// - stime            : Time spent in kernel mode (clock ticks).
+/// - cutime           : Child processes' user mode time.
+/// - cstime           : Child processes' kernel mode time.
+/// - priority         : Process priority or nice value.
+/// - nice             : Nice value (-20 to 19; lower is higher priority).
+/// - num_threads      : Number of threads.
+/// - starttime        : Process start time since boot (clock ticks).
+/// - vsize            : Virtual memory size (bytes).
+/// - rss              : Resident Set Size (pages in real memory).
+/// - rsslim           : Soft memory limit (bytes).
+/// - startcode        : Start address of executable code.
+/// - endcode          : End address of executable code.
+/// - startstack       : Bottom address of process stack.
+/// - kstkesp          : Current stack pointer (ESP).
+/// - kstkeip          : Current instruction pointer (EIP).
+/// - signal           : Bitmap of pending signals.
+/// - blocked          : Bitmap of blocked signals.
+/// - sigignore        : Bitmap of ignored signals.
+/// - sigcatch         : Bitmap of caught signals.
+/// - wchan            : Address where the process is waiting.
+/// - nswap            : Number of pages swapped (deprecated).
+/// - cnswap           : Cumulative swapped pages of children.
+/// - exit_signal      : Signal sent to parent on termination.
+/// - processor        : Last CPU the process executed on.
+/// - rt_priority      : Real-time scheduling priority (1-99, 0 otherwise).
+/// - policy           : Scheduling policy (e.g., SCHED_NORMAL, SCHED_FIFO).
+/// - delayacct_blkio_ticks : Block I/O delays (clock ticks).
+/// - guest_time       : Time spent as a guest in virtual CPU.
+/// - cguest_time      : Guest time of child processes.
+/// - start_data       : Start address of initialized/uninitialized data.
+/// - end_data         : End address of initialized/uninitialized data.
+/// - start_brk        : Address above which the heap expands.
+/// - arg_start        : Start address of command-line arguments.
+/// - arg_end          : End address of command-line arguments.
+/// - env_start        : Start address of environment variables.
+/// - env_end          : End address of environment variables.
+/// - exit_code        : Process exit code as returned by waitpid(2).
 pub struct StatFileOps(Arc<Process>);
 
 impl StatFileOps {
@@ -30,20 +82,26 @@ impl StatFileOps {
 impl FileOps for StatFileOps {
     fn data(&self) -> Result<Vec<u8>> {
         let process = &self.0;
-        let main_thread = process.main_thread();
-        let file_table = main_thread.as_posix_thread().unwrap().file_table();
+
+        let pid = process.pid();
+        let comm = process.executable_path();
+        let ppid = process.parent().pid();
+        let state = if process.status().is_zombie() {
+            'Z'
+        } else {
+            'R'
+        };
+        let pgrp = if let Some(pgrp) = process.process_group() {
+            pgrp.pgid()
+        } else {
+            0
+        };
 
         let mut stat_output = String::new();
         writeln!(
             stat_output,
-            "{} {} {} {} {} {} {}",
-            process.executable_path(),
-            process.pid(),
-            process.pid(),
-            process.parent().pid(),
-            process.parent().pid(),
-            file_table.lock().len(),
-            process.tasks().lock().as_slice().len(),
+            "{} ({}) {} {} {}",
+            pid, comm, state, ppid, pgrp
         )
         .unwrap();
         Ok(stat_output.into_bytes())