From 04c2e61f1854c6583cf45849be051c1f31d24110 Mon Sep 17 00:00:00 2001
From: Tyler Saunders <tylersaunders@google.com>
Date: Mon, 19 Oct 2026 09:59:58 +0000
Subject: [PATCH] fix(fs): enable openat2 without linux-raw-sys

`rustix::fs::openat2` and its libc backend implementation were gated on
`#[cfg(linux_raw_dep)]` in commit fda7cbe6 ("rustix: on Linux, support
a build without linux-raw-sys (#1478)") because
`backend::fs::syscalls::openat2` imported
`linux_raw_sys::general::open_how`. Meanwhile, the supporting
`ResolveFlags` bitflags and `SYS_OPENAT2` constant in the libc backend
remained gated on `#[cfg(linux_kernel)]`.

Because `libc::open_how` is not defined for `target_os = "android"` and
is marked `#[non_exhaustive]` on `target_os = "linux"`, define
`#[repr(C)] struct open_how` locally in `backend::fs::syscalls::openat2`
when `#[cfg(not(linux_raw_dep))]` and gate `openat2` on
`#[cfg(linux_kernel)]`. This makes `rustix::fs::openat2` usable on
Android and Linux when building with `--cfg=rustix_no_linux_raw`.
---
 src/backend/libc/fs/syscalls.rs | 12 +++++++++++-
 src/fs/mod.rs                   |  4 ++--
 tests/fs/main.rs                |  2 +-
 3 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/src/backend/libc/fs/syscalls.rs b/src/backend/libc/fs/syscalls.rs
index 07000f3dc..4c04ffad8 100644
--- a/src/backend/libc/fs/syscalls.rs
+++ b/src/backend/libc/fs/syscalls.rs
@@ -1868,7 +1868,7 @@ pub(crate) fn memfd_create(name: &CStr, flags: MemfdFlags) -> io::Result<OwnedFd
     unsafe { ret_owned_fd(memfd_create(c_str(name), bitflags_bits!(flags))) }
 }
 
-#[cfg(linux_raw_dep)]
+#[cfg(linux_kernel)]
 pub(crate) fn openat2(
     dirfd: BorrowedFd<'_>,
     path: &CStr,
@@ -1876,8 +1876,18 @@ pub(crate) fn openat2(
     mode: Mode,
     resolve: ResolveFlags,
 ) -> io::Result<OwnedFd> {
+    #[cfg(linux_raw_dep)]
     use linux_raw_sys::general::open_how;
 
+    #[cfg(not(linux_raw_dep))]
+    #[repr(C)]
+    #[derive(Debug, Copy, Clone)]
+    struct open_how {
+        flags: u64,
+        mode: u64,
+        resolve: u64,
+    }
+
     syscall! {
         fn openat2(
             base_dirfd: c::c_int,
diff --git a/src/fs/mod.rs b/src/fs/mod.rs
index baf9d7e14..ccac0486e 100644
--- a/src/fs/mod.rs
+++ b/src/fs/mod.rs
@@ -46,7 +46,7 @@ mod ioctl;
 mod makedev;
 #[cfg(any(linux_kernel, target_os = "freebsd"))]
 mod memfd_create;
-#[cfg(linux_raw_dep)]
+#[cfg(linux_kernel)]
 mod openat2;
 #[cfg(linux_kernel)]
 mod raw_dir;
@@ -112,7 +112,7 @@ pub use ioctl::*;
 pub use makedev::*;
 #[cfg(any(linux_kernel, target_os = "freebsd"))]
 pub use memfd_create::memfd_create;
-#[cfg(linux_raw_dep)]
+#[cfg(linux_kernel)]
 pub use openat2::openat2;
 #[cfg(linux_kernel)]
 pub use raw_dir::{RawDir, RawDirEntry};
diff --git a/tests/fs/main.rs b/tests/fs/main.rs
index 84ac2aef3..869190df6 100644
--- a/tests/fs/main.rs
+++ b/tests/fs/main.rs
@@ -34,7 +34,7 @@ mod mknodat;
 mod negative_timestamp;
 #[cfg(linux_kernel)]
 mod openat;
-#[cfg(linux_raw_dep)]
+#[cfg(linux_kernel)]
 mod openat2;
 #[cfg(not(target_os = "redox"))]
 mod readdir;