Added bindings for wasm32-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

@@ -231,7 +231,8 @@ 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;
         pub const FS_IOC_GETVERSION: ::Ioctl = 0x80087601;

src/unix/linux_like/linux/mod.rs

@@ -5201,7 +5201,7 @@ 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: ::pid_t, cpusetsize: ::size_t, cpuset: *mut cpu_set_t)
         -> ::c_int;
     pub fn sched_setaffinity(
@@ -5622,6 +5622,24 @@ extern "C" {
     ) -> ::ssize_t;
 }
 
+
+// Syscall libc stub for non Wasm32-WALI targets
+// In wasm32-linux, 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

@@ -160,6 +160,9 @@ 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
     }