From 62d38f289daee37a2317fc1afe03c891f69aa466 Mon Sep 17 00:00:00 2001
From: Furisto <24721048+Furisto@users.noreply.github.com>
Date: Fri, 9 Jul 2021 23:54:19 +0200
Subject: [PATCH] Add support for /proc/<pid>/ns

---
 src/process/mod.rs        |  3 ++
 src/process/namespaces.rs | 75 +++++++++++++++++++++++++++++++++++++++
 support.md                |  2 +-
 3 files changed, 79 insertions(+), 1 deletion(-)
 create mode 100644 src/process/namespaces.rs

diff --git a/src/process/mod.rs b/src/process/mod.rs
index ea186cf7..bfb1854c 100644
--- a/src/process/mod.rs
+++ b/src/process/mod.rs
@@ -76,6 +76,9 @@ pub use stat::*;
 mod mount;
 pub use mount::*;
 
+mod namespaces;
+pub use namespaces::*;
+
 mod status;
 pub use status::*;
 
diff --git a/src/process/namespaces.rs b/src/process/namespaces.rs
new file mode 100644
index 00000000..59244fda
--- /dev/null
+++ b/src/process/namespaces.rs
@@ -0,0 +1,75 @@
+use std::{
+    ffi::{CString, OsString},
+    fs::{self},
+    os::unix::prelude::OsStrExt,
+    path::PathBuf,
+};
+
+use crate::ProcResult;
+
+use super::Process;
+
+impl Process {
+    /// Describes namespaces to which the process with the corresponding PID belongs.
+    /// Doc reference: https://man7.org/linux/man-pages/man7/namespaces.7.html
+    pub fn namespaces(&self) -> ProcResult<Vec<Namespace>> {
+        let ns = self.root.join("ns");
+        let mut namespaces = Vec::new();
+        for entry in fs::read_dir(ns)? {
+            let entry = entry?;
+            let path = entry.path();
+            let ns_type = entry.file_name();
+            let cstr = CString::new(path.as_os_str().as_bytes()).unwrap();
+
+            let mut stat = unsafe { std::mem::zeroed() };
+            if unsafe { libc::stat(cstr.as_ptr(), &mut stat) } != 0 {
+                return Err(build_internal_error!(format!("Unable to stat {:?}", path)));
+            }
+
+            namespaces.push(Namespace {
+                ns_type,
+                path,
+                identifier: stat.st_ino,
+                device_id: stat.st_dev,
+            })
+        }
+
+        Ok(namespaces)
+    }
+}
+
+/// Information about a namespace
+///
+/// See also the [Process::namespaces()] method
+#[derive(Debug, Clone)]
+pub struct Namespace {
+    /// Namespace type
+    pub ns_type: OsString,
+    /// Handle to the namespace
+    pub path: PathBuf,
+    /// Namespace identifier (inode number)
+    pub identifier: u64,
+    /// Device id of the namespace
+    pub device_id: u64,
+}
+
+impl PartialEq for Namespace {
+    fn eq(&self, other: &Self) -> bool {
+        // see https://lore.kernel.org/lkml/87poky5ca9.fsf@xmission.com/
+        self.identifier == other.identifier && self.device_id == other.device_id
+    }
+}
+
+impl Eq for Namespace {}
+
+#[cfg(test)]
+mod tests {
+    use crate::process::Process;
+
+    #[test]
+    fn test_namespaces() {
+        let myself = Process::myself().unwrap();
+        let namespaces = myself.namespaces().unwrap();
+        print!("{:?}", namespaces);
+    }
+}
diff --git a/support.md b/support.md
index 4337ebde..32fcfa4a 100644
--- a/support.md
+++ b/support.md
@@ -32,7 +32,7 @@ This is an approximate list of all the files under the `/proc` mount, and an ind
   * [x] `/proc/[pid]/mountinfo`
   * [ ] `/proc/[pid]/mounts`
   * [x] `/proc/[pid]/mountstats`
-  * [ ] `/proc/[pid]/ns/`
+  * [x] `/proc/[pid]/ns/`
   * [ ] `/proc/[pid]/numa_maps`
   * [ ] `/proc/[pid]/oom_adj`
   * [x] `/proc/[pid]/oom_score`