From e2c12495886ab79973d7f793bcd6ad6d89723346 Mon Sep 17 00:00:00 2001
From: ur4t <46435411+ur4t@users.noreply.github.com>
Date: Tue, 2 Dec 2025 09:01:31 +0000
Subject: [PATCH] Implement `SYS_pidfd_open` for Tokio 1.36+

---
 c-scape/Cargo.toml     |  2 ++
 c-scape/src/syscall.rs | 21 +++++++++++++++++++++
 2 files changed, 23 insertions(+)

diff --git a/c-scape/Cargo.toml b/c-scape/Cargo.toml
index f00a3dd..5c953e7 100644
--- a/c-scape/Cargo.toml
+++ b/c-scape/Cargo.toml
@@ -190,6 +190,7 @@ extra-syscalls = [
     "syscall-syncfs",
     "syscall-sync",
     "syscall-pipe2",
+    "syscall-pidfd_open",
 ]
 syscall-read = []
 syscall-write = []
@@ -206,3 +207,4 @@ syscall-fdatasync = []
 syscall-syncfs = []
 syscall-sync = []
 syscall-pipe2 = []
+syscall-pidfd_open = []
diff --git a/c-scape/src/syscall.rs b/c-scape/src/syscall.rs
index caa3f41..0b80480 100644
--- a/c-scape/src/syscall.rs
+++ b/c-scape/src/syscall.rs
@@ -162,6 +162,27 @@ unsafe extern "C" fn syscall(number: c_long, mut args: ...) -> *mut c_void {
             let flags = args.arg::<c_int>();
             without_provenance_mut(libc::pipe2(pipefd, flags) as isize as usize)
         }
+        #[cfg(feature = "syscall-pidfd_open")]
+        libc::SYS_pidfd_open => {
+            use rustix::fd::IntoRawFd;
+            use rustix::process::{pidfd_open, Pid, PidfdFlags};
+            let pid = args.arg::<c_int>();
+            let flags = args.arg::<libc::c_uint>();
+            let fd = match (Pid::from_raw(pid), PidfdFlags::from_bits(flags)) {
+                (Some(pid), Some(flags)) => match pidfd_open(pid, flags) {
+                    Err(err) => {
+                        set_errno(Errno(err.raw_os_error()));
+                        -1
+                    }
+                    Ok(pidfd) => pidfd.into_raw_fd(),
+                },
+                _ => {
+                    set_errno(Errno(libc::EINVAL));
+                    -1
+                }
+            };
+            without_provenance_mut(fd as isize as usize)
+        }
         libc::SYS_gettid => {
             without_provenance_mut(rustix::thread::gettid().as_raw_nonzero().get() as _)
         }