Added bindings for wasm32-wali-linux-musl target

Author: arjunr2

src/lib.rs

@@ -1,6 +1,8 @@
 //! libc - Raw FFI bindings to platforms' system libraries
 #![crate_name = "libc"]
 #![crate_type = "rlib"]
+#![feature(c_variadic)]
+#![feature(concat_idents)]
 #![allow(
     renamed_and_removed_lints, // Keep this order.
     unknown_lints, // Keep this order.

src/unix/linux_like/linux/arch/generic/mod.rs

@@ -291,7 +291,8 @@ cfg_if! {
         target_arch = "riscv64",
         target_arch = "aarch64",
         target_arch = "s390x",
-        target_arch = "loongarch64"
+        target_arch = "loongarch64",
+        target_arch = "wasm32"
     ))] {
         pub const FS_IOC_GETFLAGS: Ioctl = 0x80086601;
         pub const FS_IOC_SETFLAGS: Ioctl = 0x40086602;

src/unix/linux_like/linux/mod.rs

@@ -6432,7 +6432,7 @@ extern "C" {
     pub fn vhangup() -> c_int;
     pub fn sync();
     pub fn syncfs(fd: c_int) -> c_int;
-    pub fn syscall(num: c_long, ...) -> c_long;
+
     pub fn sched_getaffinity(
         pid: crate::pid_t,
         cpusetsize: size_t,
@@ -6839,6 +6839,23 @@ extern "C" {
     pub fn ioctl(fd: c_int, request: Ioctl, ...) -> c_int;
 }
 
+// Syscall libc stub for non-wasm32 (WALI) targets
+//
+// For wasm32, all syscalls are name-bound and typed.
+// The 'syscall' implementation from C library is avoided since
+// higher level libraries do not explicitly typecast arguments to
+// 64-bit register sizes, which is expected of C variadic arguments.
+// To overcome this, a wrapper 'syscall' method is implemented,
+// which binds the syscall types statically at compile time
+// and binds their numbers at runtime
+cfg_if!(
+    if #[cfg(not(target_arch = "wasm32"))] {
+        extern "C" {
+            pub fn syscall(num: c_long, ...) -> c_long;
+        }
+    }
+);
+
 // LFS64 extensions
 //
 // * musl has 64-bit versions only so aliases the LFS64 symbols to the standard ones

src/unix/linux_like/linux/musl/b64/mod.rs

@@ -109,6 +109,9 @@ cfg_if! {
     } else if #[cfg(any(target_arch = "loongarch64"))] {
         mod loongarch64;
         pub use self::loongarch64::*;
+    } else if #[cfg(any(target_arch = "wasm32"))] {
+        mod wasm32;
+        pub use self::wasm32::*;
     } else {
         // Unknown target_arch
     }