Implement posix_memalign

src/header/stdlib/mod.rs

@@ -582,6 +582,27 @@ pub extern "C" fn nrand48(xsubi: [c_ushort; 3]) -> c_long {
     unimplemented!();
 }
 
+#[no_mangle]
+pub unsafe extern "C" fn posix_memalign(memptr: *mut *mut c_void, alignment: size_t, size: size_t) -> c_int {
+    const void_ptr_size: usize = mem::size_of::<*mut c_void>();
+    
+    /* Check that alignment is:
+     * a) a multiple of sizeof(void *)
+     * b) a power-of-two multiple of sizeof(void *). Integer division as
+     *    below gives the correct result once a) is ensured. */
+    if alignment % void_ptr_size == 0 && (alignment/void_ptr_size).is_power_of_two() {
+        let ptr = platform::alloc_align(size, alignment);
+        if !ptr.is_null() {
+            *memptr = ptr;
+            0
+        } else {
+            ENOMEM
+        }
+    } else {
+        EINVAL
+    }
+}
+
 // #[no_mangle]
 pub extern "C" fn ptsname(fildes: c_int) -> *mut c_char {
     unimplemented!();