(c2rust-analyze) Add known_fns! for declaring the permissions on ptrs in known (i.e. libc) UnknownDef fns

c2rust-analyze/Cargo.toml

@@ -24,6 +24,7 @@ env_logger = "0.10.0"
 log = "0.4.17"
 backtrace = "0.3.67"
 itertools = "0.10"
+libc = "0.2.147"
 
 [build-dependencies]
 c2rust-build-paths = { path = "../c2rust-build-paths", version = "0.18.0" }

c2rust-analyze/src/context.rs

@@ -134,6 +134,17 @@ impl PermissionSet {
     //
     // `.union` is used here since it's a `const fn`, unlike `BitOr::bitor`.
     pub const STRING_LITERAL: Self = Self::READ.union(Self::OFFSET_ADD);
+
+    #[cfg(test)]
+    pub const fn union_all<const N: usize>(a: [Self; N]) -> Self {
+        let mut this = Self::empty();
+        let mut i = 0;
+        while i < N {
+            this = this.union(a[i]);
+            i += 1;
+        }
+        this
+    }
 }
 
 bitflags! {