Fix Android build: enable linux-raw-sys and exclude Android-unsupported Linux userspace features (#1528)

* Fix tests: exclude Android from preadv2/pwritev2 tests that require RWF_* constants

* Fix Android build by enabling linux_raw_dep and excluding unsupported features

* Enabled target_os=android for libc backend

Author: HemantKArya

Cargo.toml

@@ -45,11 +45,11 @@ libc = { version = "0.2.177", default-features = false, optional = true }
 libc_errno = { package = "errno", version = "0.3.10", default-features = false }
 libc = { version = "0.2.177", default-features = false }
 
-# Additional dependencies for Linux with the libc backend:
+# Additional dependencies for Linux and Android with the libc backend:
 #
 # Some syscalls do not have libc wrappers, such as in `io_uring`. For these,
 # the libc backend uses the linux-raw-sys ABI and `libc::syscall`.
-[target.'cfg(all(any(target_os = "linux"), any(rustix_use_libc, miri, not(all(target_os = "linux", any(target_endian = "little", any(target_arch = "s390x", target_arch = "powerpc")), any(target_arch = "arm", all(target_arch = "aarch64", target_pointer_width = "64"), target_arch = "riscv64", all(rustix_use_experimental_asm, target_arch = "powerpc"), all(rustix_use_experimental_asm, target_arch = "powerpc64"), all(rustix_use_experimental_asm, target_arch = "s390x"), all(rustix_use_experimental_asm, target_arch = "mips"), all(rustix_use_experimental_asm, target_arch = "mips32r6"), all(rustix_use_experimental_asm, target_arch = "mips64"), all(rustix_use_experimental_asm, target_arch = "mips64r6"), target_arch = "x86", all(target_arch = "x86_64", target_pointer_width = "64")))))))'.dependencies]
+[target.'cfg(all(any(target_os = "linux", target_os = "android"), any(rustix_use_libc, miri, not(all(target_os = "linux", any(target_endian = "little", any(target_arch = "s390x", target_arch = "powerpc")), any(target_arch = "arm", all(target_arch = "aarch64", target_pointer_width = "64"), target_arch = "riscv64", all(rustix_use_experimental_asm, target_arch = "powerpc"), all(rustix_use_experimental_asm, target_arch = "powerpc64"), all(rustix_use_experimental_asm, target_arch = "s390x"), all(rustix_use_experimental_asm, target_arch = "mips"), all(rustix_use_experimental_asm, target_arch = "mips32r6"), all(rustix_use_experimental_asm, target_arch = "mips64"), all(rustix_use_experimental_asm, target_arch = "mips64r6"), target_arch = "x86", all(target_arch = "x86_64", target_pointer_width = "64")))))))'.dependencies]
 linux-raw-sys = { version = "0.11.0", default-features = false, features = ["general", "ioctl", "no_std"] }
 
 # For the libc backend on Windows, use the Winsock API in windows-sys.

build.rs

@@ -117,7 +117,7 @@ fn main() {
             || arch.starts_with("mips"))
             && !rustix_use_experimental_asm);
     if libc {
-        if os != "android" && os == "linux" && !cfg_no_linux_raw {
+        if (os == "linux" || os == "android") && !cfg_no_linux_raw {
             use_feature("linux_raw_dep");
         }
 

src/backend/libc/c.rs

@@ -503,6 +503,7 @@ mod statx_flags {
     linux_like,
     linux_raw_dep,
     not(any(
+        target_os = "android",
         target_os = "emscripten",
         target_env = "gnu",
         all(target_arch = "loongarch64", target_env = "musl")

src/backend/libc/mod.rs

@@ -109,7 +109,7 @@ pub(crate) mod event;
 #[cfg(feature = "fs")]
 pub(crate) mod fs;
 pub(crate) mod io;
-#[cfg(linux_kernel)]
+#[cfg(all(linux_kernel, not(target_os = "android")))]
 #[cfg(feature = "io_uring")]
 pub(crate) mod io_uring;
 #[cfg(not(any(

src/backend/libc/net/sockopt.rs

@@ -82,7 +82,7 @@ use c::TCP_KEEPALIVE as TCP_KEEPIDLE;
 use c::TCP_KEEPIDLE;
 use core::mem::{size_of, MaybeUninit};
 use core::time::Duration;
-#[cfg(linux_raw_dep)]
+#[cfg(all(linux_raw_dep, target_os = "linux"))]
 use linux_raw_sys::xdp::{xdp_mmap_offsets, xdp_statistics, xdp_statistics_v1};
 
 #[inline]
@@ -1153,7 +1153,7 @@ pub(crate) fn set_xdp_rx_ring_size(fd: BorrowedFd<'_>, value: u32) -> io::Result
     setsockopt(fd, c::SOL_XDP, c::XDP_RX_RING, value)
 }
 
-#[cfg(linux_raw_dep)]
+#[cfg(all(linux_raw_dep, target_os = "linux"))]
 #[inline]
 pub(crate) fn xdp_mmap_offsets(fd: BorrowedFd<'_>) -> io::Result<XdpMmapOffsets> {
     // The kernel will write `xdp_mmap_offsets` or `xdp_mmap_offsets_v1` to the
@@ -1240,7 +1240,7 @@ pub(crate) fn xdp_mmap_offsets(fd: BorrowedFd<'_>) -> io::Result<XdpMmapOffsets>
     }
 }
 
-#[cfg(linux_raw_dep)]
+#[cfg(all(linux_raw_dep, target_os = "linux"))]
 #[inline]
 pub(crate) fn xdp_statistics(fd: BorrowedFd<'_>) -> io::Result<XdpStatistics> {
     let mut optlen = size_of::<xdp_statistics>().try_into().unwrap();

src/lib.rs

@@ -225,7 +225,7 @@ pub mod ffi;
 #[cfg_attr(docsrs, doc(cfg(feature = "fs")))]
 pub mod fs;
 pub mod io;
-#[cfg(linux_kernel)]
+#[cfg(all(linux_kernel, not(target_os = "android")))]
 #[cfg(feature = "io_uring")]
 #[cfg_attr(docsrs, doc(cfg(feature = "io_uring")))]
 pub mod io_uring;

src/net/sockopt.rs

@@ -1774,7 +1774,7 @@ pub fn set_xdp_rx_ring_size<Fd: AsFd>(fd: Fd, value: u32) -> io::Result<()> {
 ///   - [Linux]
 ///
 /// [Linux]: https://www.kernel.org/doc/html/next/networking/af_xdp.html
-#[cfg(linux_raw_dep)]
+#[cfg(all(linux_raw_dep, target_os = "linux"))]
 #[doc(alias = "XDP_MMAP_OFFSETS")]
 pub fn xdp_mmap_offsets<Fd: AsFd>(fd: Fd) -> io::Result<XdpMmapOffsets> {
     backend::net::sockopt::xdp_mmap_offsets(fd.as_fd())
@@ -1786,7 +1786,7 @@ pub fn xdp_mmap_offsets<Fd: AsFd>(fd: Fd) -> io::Result<XdpMmapOffsets> {
 ///   - [Linux]
 ///
 /// [Linux]: https://www.kernel.org/doc/html/next/networking/af_xdp.html#xdp-statistics-getsockopt
-#[cfg(linux_raw_dep)]
+#[cfg(all(linux_raw_dep, target_os = "linux"))]
 #[doc(alias = "XDP_STATISTICS")]
 pub fn xdp_statistics<Fd: AsFd>(fd: Fd) -> io::Result<XdpStatistics> {
     backend::net::sockopt::xdp_statistics(fd.as_fd())

tests/io/read_write.rs

@@ -202,7 +202,7 @@ fn test_rwf_values() {
     );
 }
 
-#[cfg(linux_raw_dep)]
+#[cfg(all(linux_raw_dep, not(target_os = "android")))]
 #[cfg(feature = "fs")]
 #[test]
 fn test_pwritev2() {
@@ -256,7 +256,7 @@ fn test_pwritev2() {
     assert_eq!(&buf, b"world");
 }
 
-#[cfg(linux_raw_dep)]
+#[cfg(all(linux_raw_dep, not(target_os = "android")))]
 #[cfg(all(feature = "net", feature = "pipe"))]
 #[test]
 fn test_preadv2_nowait() {
@@ -308,7 +308,7 @@ fn test_preadv2_nowait() {
 fn test_p_offsets() {
     use rustix::fs::{openat, Mode, OFlags, CWD};
     use rustix::io::{pread, preadv, pwrite, pwritev};
-    #[cfg(linux_raw_dep)]
+    #[cfg(all(linux_raw_dep, not(target_os = "android")))]
     use rustix::io::{preadv2, pwritev2, ReadWriteFlags};
 
     let mut buf = [0_u8; 5];
@@ -343,7 +343,7 @@ fn test_p_offsets() {
         Ok(_) => {}
         Err(e) => panic!("pwritev failed with an unexpected error: {:?}", e),
     }
-    #[cfg(linux_raw_dep)]
+    #[cfg(all(linux_raw_dep, not(target_os = "android")))]
     {
         match preadv2(
             &f,
@@ -393,7 +393,7 @@ fn test_p_offsets() {
                 Err(e) => panic!("pwritev failed with an unexpected error: {:?}", e),
             }
         }
-        #[cfg(linux_raw_dep)]
+        #[cfg(all(linux_raw_dep, not(target_os = "android")))]
         {
             match preadv2(
                 &f,