From 0ca2a2a6bd37beb32404c1b148e72e24759affd3 Mon Sep 17 00:00:00 2001
From: David Carlier <devnexen@gmail.com>
Date: Sat, 20 Apr 2024 10:14:38 +0100
Subject: [PATCH] sys::prctl: Adding set_addr_name.

to set a name for an `anonymous` region for Linux/Android.
---
 changelog/2378.added.md |  1 +
 src/sys/prctl.rs        | 15 ++++++++++++++-
 test/sys/test_prctl.rs  | 34 ++++++++++++++++++++++++++++++++++
 3 files changed, 49 insertions(+), 1 deletion(-)
 create mode 100644 changelog/2378.added.md

diff --git a/changelog/2378.added.md b/changelog/2378.added.md
new file mode 100644
index 0000000000..21ad0b90f6
--- /dev/null
+++ b/changelog/2378.added.md
@@ -0,0 +1 @@
+Add prctl function `prctl_set_vma_anon_name` for Linux/Android.
diff --git a/src/sys/prctl.rs b/src/sys/prctl.rs
index 42324beab2..fc3cbc7e99 100644
--- a/src/sys/prctl.rs
+++ b/src/sys/prctl.rs
@@ -9,9 +9,11 @@ use crate::errno::Errno;
 use crate::sys::signal::Signal;
 use crate::Result;
 
-use libc::{c_int, c_ulong};
+use libc::{c_int, c_ulong, c_void};
 use std::convert::TryFrom;
 use std::ffi::{CStr, CString};
+use std::num::NonZeroUsize;
+use std::ptr::NonNull;
 
 libc_enum! {
     /// The type of hardware memory corruption kill policy for the thread.
@@ -213,3 +215,14 @@ pub fn set_thp_disable(flag: bool) -> Result<()> {
 pub fn get_thp_disable() -> Result<bool> {
     prctl_get_bool(libc::PR_GET_THP_DISABLE)
 }
+
+/// Set an identifier (or reset it) to the address memory range.
+pub fn set_vma_anon_name(addr: NonNull<c_void>, length: NonZeroUsize, name: Option<&CStr>) -> Result<()> {
+    let nameref = match name {
+        Some(n) => n.as_ptr(),
+        _ => std::ptr::null_mut()
+    };
+    let res = unsafe { libc::prctl(libc::PR_SET_VMA, libc::PR_SET_VMA_ANON_NAME, addr.as_ptr(), length, nameref) };
+
+    Errno::result(res).map(drop)
+}
diff --git a/test/sys/test_prctl.rs b/test/sys/test_prctl.rs
index 351213b7ef..b409735af6 100644
--- a/test/sys/test_prctl.rs
+++ b/test/sys/test_prctl.rs
@@ -122,4 +122,38 @@ mod test_prctl {
 
         prctl::set_thp_disable(original).unwrap();
     }
+
+    #[test]
+    fn test_set_vma_anon_name() {
+        use nix::errno::Errno;
+        use nix::sys::mman;
+        use std::num::NonZeroUsize;
+
+        const ONE_K: libc::size_t = 1024;
+        let sz = NonZeroUsize::new(ONE_K).unwrap();
+        let ptr = unsafe {
+            mman::mmap_anonymous(
+                None,
+                sz,
+                mman::ProtFlags::PROT_READ,
+                mman::MapFlags::MAP_SHARED,
+            )
+            .unwrap()
+        };
+        let err = prctl::set_vma_anon_name(
+            ptr,
+            sz,
+            Some(CStr::from_bytes_with_nul(b"[,$\0").unwrap()),
+        )
+        .unwrap_err();
+        assert_eq!(err, Errno::EINVAL);
+        // `CONFIG_ANON_VMA_NAME` kernel config might not be set
+        prctl::set_vma_anon_name(
+            ptr,
+            sz,
+            Some(CStr::from_bytes_with_nul(b"Nix\0").unwrap()),
+        )
+        .unwrap_or_default();
+        prctl::set_vma_anon_name(ptr, sz, None).unwrap_or_default();
+    }
 }