fixup: some tests started to fail - fix some, document some

Author: gnzlbg

libc-test/build.rs

@@ -1538,12 +1538,16 @@ fn test_freebsd(target: &str) {
             // Just pass all these through, no need for a "struct" prefix
             "FILE" | "fd_set" | "Dl_info" | "DIR" => ty.to_string(),
 
+            // FIXME: ?
             "sighandler_t" => "sig_t".to_string(),
 
             t if is_union => format!("union {}", t),
 
             t if t.ends_with("_t") => t.to_string(),
 
+            // sigval is a struct in Rust, but a union in C:
+            "sigval" => format!("union sigval"),
+
             // put `struct` in front of all structs:.
             t if is_struct => format!("struct {}", t),
 
@@ -1565,16 +1569,6 @@ fn test_freebsd(target: &str) {
         }
     });
 
-    cfg.skip_struct(move |ty| {
-        match ty {
-            // This is actually a union, not a struct
-            // FIXME: still required?
-            "sigval" => true,
-
-            _ => false,
-        }
-    });
-
     cfg.skip_signededness(move |c| {
         match c {
             // FIXME: still required?
@@ -1639,6 +1633,24 @@ fn test_freebsd(target: &str) {
         }
     });
 
+    cfg.volatile_item(|i| {
+        use ctest::VolatileItemKind::*;
+        match i {
+            // aio_buf is a volatile void** but since we cannot express that in
+            // Rust types, we have to explicitly tell the checker about it here:
+            StructField(ref n, ref f) if n == "aiocb" && f == "aio_buf" => {
+                true
+            }
+            _ => false,
+        }
+    });
+
+    cfg.skip_field(move |struct_, field| {
+        // FIXME: `sa_sigaction` has type `sighandler_t` but that type is
+        // incorrect, see: https://github.com/rust-lang/libc/issues/1359
+        (struct_ == "sigaction" && field == "sa_sigaction")
+    });
+
     cfg.generate("../src/lib.rs", "main.rs");
 }