Export /proc/[pid]/task and /proc/[pid]/task/[tid]

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

@@ -1,6 +1,8 @@
 // SPDX-License-Identifier: MPL-2.0
 
-use self::{cmdline::CmdlineFileOps, comm::CommFileOps, exe::ExeSymOps, fd::FdDirOps};
+use self::{
+    cmdline::CmdlineFileOps, comm::CommFileOps, exe::ExeSymOps, fd::FdDirOps, task::TaskDirOps,
+};
 use super::template::{DirOps, ProcDir, ProcDirBuilder};
 use crate::{
     events::Observer,
@@ -18,6 +20,7 @@ mod exe;
 mod fd;
 mod stat;
 mod status;
+mod task;
 
 /// Represents the inode at `/proc/[pid]`.
 pub struct PidDirOps(Arc<Process>);
@@ -56,6 +59,7 @@ impl DirOps for PidDirOps {
             "cmdline" => CmdlineFileOps::new_inode(self.0.clone(), this_ptr.clone()),
             "status" => status::StatusFileOps::new_inode(self.0.clone(), this_ptr.clone()),
             "stat" => stat::StatFileOps::new_inode(self.0.clone(), this_ptr.clone()),
+            "task" => TaskDirOps::new_inode(self.0.clone(), this_ptr.clone()),
             _ => return_errno!(Errno::ENOENT),
         };
         Ok(inode)
@@ -85,5 +89,8 @@ impl DirOps for PidDirOps {
         cached_children.put_entry_if_not_found("stat", || {
             stat::StatFileOps::new_inode(self.0.clone(), this_ptr.clone())
         });
+        cached_children.put_entry_if_not_found("task", || {
+            TaskDirOps::new_inode(self.0.clone(), this_ptr.clone())
+        });
     }
 }

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

@@ -0,0 +1,84 @@
+// SPDX-License-Identifier: MPL-2.0
+
+use alloc::format;
+
+use super::*;
+use crate::{
+    fs::{
+        procfs::template::{DirOps, ProcDir, ProcDirBuilder},
+        utils::{DirEntryVecExt, Inode},
+    },
+    process::posix_thread::AsPosixThread,
+    Process,
+};
+
+/// Represents the inode at `/proc/[pid]/task`.
+pub struct TaskDirOps(Arc<Process>);
+
+impl TaskDirOps {
+    pub fn new_inode(process_ref: Arc<Process>, parent: Weak<dyn Inode>) -> Arc<dyn Inode> {
+        ProcDirBuilder::new(Self(process_ref))
+            .parent(parent)
+            .build()
+            .unwrap()
+    }
+}
+
+/// Represents the inode at `/proc/[pid]/task/[tid]`.
+struct ThreadDirOps(Arc<Process>);
+
+impl ThreadDirOps {
+    pub fn new_inode(process_ref: Arc<Process>, parent: Weak<dyn Inode>) -> Arc<dyn Inode> {
+        ProcDirBuilder::new(Self(process_ref))
+            .parent(parent)
+            .build()
+            .unwrap()
+    }
+}
+
+impl DirOps for ThreadDirOps {
+    fn lookup_child(&self, this_ptr: Weak<dyn Inode>, name: &str) -> Result<Arc<dyn Inode>> {
+        let inode = match name {
+            "fd" => FdDirOps::new_inode(self.0.clone(), this_ptr.clone()),
+            _ => return_errno!(Errno::ENOENT),
+        };
+        Ok(inode)
+    }
+
+    fn populate_children(&self, this_ptr: Weak<dyn Inode>) {
+        let this = {
+            let this = this_ptr.upgrade().unwrap();
+            this.downcast_ref::<ProcDir<ThreadDirOps>>().unwrap().this()
+        };
+        let mut cached_children = this.cached_children().write();
+        cached_children.put_entry_if_not_found("fd", || {
+            FdDirOps::new_inode(self.0.clone(), this_ptr.clone())
+        });
+    }
+}
+
+impl DirOps for TaskDirOps {
+    fn lookup_child(&self, this_ptr: Weak<dyn Inode>, name: &str) -> Result<Arc<dyn Inode>> {
+        for task in self.0.tasks().lock().iter() {
+            if task.as_posix_thread().unwrap().tid() != name.parse::<u32>().unwrap() {
+                continue;
+            }
+            return Ok(ThreadDirOps::new_inode(self.0.clone(), this_ptr));
+        }
+        return_errno_with_message!(Errno::ENOENT, "No such thread")
+    }
+
+    fn populate_children(&self, this_ptr: Weak<dyn Inode>) {
+        let this = {
+            let this = this_ptr.upgrade().unwrap();
+            this.downcast_ref::<ProcDir<TaskDirOps>>().unwrap().this()
+        };
+        let mut cached_children = this.cached_children().write();
+        for task in self.0.tasks().lock().iter() {
+            cached_children.put_entry_if_not_found(
+                &format!("{}", task.as_posix_thread().unwrap().tid()),
+                || ThreadDirOps::new_inode(self.0.clone(), this_ptr.clone()),
+            );
+        }
+    }
+}