Add /proc/meminfo support

kernel/aster-nix/src/fs/procfs/meminfo.rs

@@ -0,0 +1,48 @@
+// SPDX-License-Identifier: MPL-2.0
+
+//! This module offers `/proc/meminfo` file support, which tells the user space
+//! about the memory statistics in the entire system. The definition of the
+//! fields are similar to that of Linux's but there exist differences.
+//!
+//! Reference: <https://man7.org/linux/man-pages/man5/proc_meminfo.5.html>
+
+use alloc::format;
+
+use ostd::mm::stat;
+
+use crate::{
+    fs::{
+        procfs::template::{FileOps, ProcFileBuilder},
+        utils::Inode,
+    },
+    prelude::*,
+};
+
+/// Represents the inode at `/proc/meminfo`.
+pub struct MemInfoFileOps;
+
+impl MemInfoFileOps {
+    pub fn new_inode(parent: Weak<dyn Inode>) -> Arc<dyn Inode> {
+        ProcFileBuilder::new(Self).parent(parent).build().unwrap()
+    }
+}
+
+/// Total memory in the entire system in bytes.
+fn mem_total() -> usize {
+    stat::mem_total()
+}
+
+/// An estimation of how much memory is available for starting new
+/// applications, without disk operations.
+fn mem_available() -> usize {
+    stat::mem_available()
+}
+
+impl FileOps for MemInfoFileOps {
+    fn data(&self) -> Result<Vec<u8>> {
+        let total = mem_total();
+        let available = mem_available();
+        let output = format!("MemTotal:\t{}\nMemAvailable:\t{}\n", total, available);
+        Ok(output.into_bytes())
+    }
+}

kernel/aster-nix/src/fs/procfs/mod.rs

@@ -5,6 +5,7 @@ use core::sync::atomic::{AtomicU64, Ordering};
 use sys::SysDirOps;
 
 use self::{
+    meminfo::MemInfoFileOps,
     pid::PidDirOps,
     self_::SelfSymOps,
     template::{DirOps, ProcDir, ProcDirBuilder, ProcSymBuilder, SymOps},
@@ -20,6 +21,7 @@ use crate::{
 };
 
 mod filesystems;
+mod meminfo;
 mod pid;
 mod self_;
 mod sys;
@@ -102,6 +104,8 @@ impl DirOps for RootDirOps {
             SysDirOps::new_inode(this_ptr.clone())
         } else if name == "filesystems" {
             FileSystemsFileOps::new_inode(this_ptr.clone())
+        } else if name == "meminfo" {
+            MemInfoFileOps::new_inode(this_ptr.clone())
         } else if let Ok(pid) = name.parse::<Pid>() {
             let process_ref =
                 process_table::get_process(pid).ok_or_else(|| Error::new(Errno::ENOENT))?;
@@ -123,6 +127,8 @@ impl DirOps for RootDirOps {
         cached_children.put_entry_if_not_found("filesystems", || {
             FileSystemsFileOps::new_inode(this_ptr.clone())
         });
+        cached_children
+            .put_entry_if_not_found("meminfo", || MemInfoFileOps::new_inode(this_ptr.clone()));
 
         for process in process_table::process_table().iter() {
             let pid = process.pid().to_string();