move the get_cgroup utility function into the library

1 files changed, 11 insertions, 0 deletions

diff --git a/linuxnamespaces/__init__.py b/linuxnamespaces/__init__.py
index a2c7985..cd30498 100644
--- a/linuxnamespaces/__init__.py
+++ b/linuxnamespaces/__init__.py
@@ -367,6 +367,17 @@ def bind_mount(
         mount(srcloc, tgtloc, None, mflags)
 
 
+def get_cgroup(pid: int = -1) -> pathlib.PurePath:
+    """Look up the cgroup that the given pid or the current process belongs
+    to.
+    """
+    return pathlib.PurePath(
+        pathlib.Path(
+            f"/proc/{pid}/cgroup" if pid > 0 else "/proc/self/cgroup"
+        ).read_text().split(":", 2)[2].strip()
+    )
+
+
 _P = typing.ParamSpec("_P")
 
 class _ExceptionExitCallback: