Add trait implementations for Rust binder crate

Implements Error for StatusCode in the bindgen generated bindings, which
makes usage simpler. Implements Eq for SpIBinder. Exposes a method to
promote weak binder references to strong ones.

Bug: 161559357
Test: m libbinder_rs
Change-Id: Ia2f891c2f0f84ed0454039169ed42ab20401c1a4

6 files changed, 76 insertions, 14 deletions

diff --git a/libs/binder/rust/Android.bp b/libs/binder/rust/Android.bp
index 16811eebe4..0234820b02 100644
--- a/libs/binder/rust/Android.bp
+++ b/libs/binder/rust/Android.bp
@@ -3,12 +3,24 @@ rust_library {
     crate_name: "binder",
     srcs: ["src/lib.rs"],
     shared_libs: [
-        "libbinder_ndk",
         "libutils",
     ],
     rustlibs: [
         "liblibc",
-        "libbinder_ndk_bindgen",
+        "libbinder_ndk_sys",
+    ],
+    host_supported: true,
+}
+
+rust_library {
+    name: "libbinder_ndk_sys",
+    crate_name: "binder_ndk_sys",
+    srcs: [
+        "sys/lib.rs",
+        ":libbinder_ndk_bindgen",
+    ],
+    shared_libs: [
+        "libbinder_ndk",
     ],
     host_supported: true,
 }
@@ -16,8 +28,8 @@ rust_library {
 rust_bindgen {
     name: "libbinder_ndk_bindgen",
     crate_name: "binder_ndk_bindgen",
-    wrapper_src: "BinderBindings.h",
-    source_stem: "ndk_bindings",
+    wrapper_src: "sys/BinderBindings.h",
+    source_stem: "bindings",
     cflags: [
         "-x c++",
     ],
@@ -69,6 +81,6 @@ rust_test {
     ],
     rustlibs: [
         "liblibc",
-        "libbinder_ndk_bindgen",
+        "libbinder_ndk_sys",
     ],
 }
diff --git a/libs/binder/rust/src/error.rs b/libs/binder/rust/src/error.rs
index 289b1573db..4492cf72f4 100644
--- a/libs/binder/rust/src/error.rs
+++ b/libs/binder/rust/src/error.rs
@@ -43,14 +43,6 @@ pub fn status_result(status: status_t) -> Result<()> {
     }
 }
 
-// impl Display for StatusCode {
-//     fn fmt(&self, f: &mut Formatter) -> FmtResult {
-//         write!(f, "StatusCode::{:?}", self)
-//     }
-// }
-
-// impl error::Error for StatusCode {}
-
 fn parse_status_code(code: i32) -> StatusCode {
     match code {
         e if e == StatusCode::OK as i32 => StatusCode::OK,
diff --git a/libs/binder/rust/src/lib.rs b/libs/binder/rust/src/lib.rs
index 4b9cccf41b..8ee6a62180 100644
--- a/libs/binder/rust/src/lib.rs
+++ b/libs/binder/rust/src/lib.rs
@@ -102,7 +102,7 @@ mod error;
 mod native;
 mod state;
 
-use binder_ndk_bindgen as sys;
+use binder_ndk_sys as sys;
 
 pub mod parcel;
 
diff --git a/libs/binder/rust/src/proxy.rs b/libs/binder/rust/src/proxy.rs
index f9519b4d01..13e5619237 100644
--- a/libs/binder/rust/src/proxy.rs
+++ b/libs/binder/rust/src/proxy.rs
@@ -122,6 +122,14 @@ impl AssociateClass for SpIBinder {
     }
 }
 
+impl PartialEq for SpIBinder {
+    fn eq(&self, other: &Self) -> bool {
+        ptr::eq(self.0, other.0)
+    }
+}
+
+impl Eq for SpIBinder {}
+
 impl Clone for SpIBinder {
     fn clone(&self) -> Self {
         unsafe {
@@ -363,6 +371,18 @@ impl WpIBinder {
         assert!(!ptr.is_null());
         Self(ptr)
     }
+
+    /// Promote this weak reference to a strong reference to the binder object.
+    pub fn promote(&self) -> Option<SpIBinder> {
+        unsafe {
+            // Safety: `WpIBinder` always contains a valid weak reference, so we
+            // can pass this pointer to `AIBinder_Weak_promote`. Returns either
+            // null or an AIBinder owned by the caller, both of which are valid
+            // to pass to `SpIBinder::from_raw`.
+            let ptr = sys::AIBinder_Weak_promote(self.0);
+            SpIBinder::from_raw(ptr)
+        }
+    }
 }
 
 /// Rust wrapper around DeathRecipient objects.
diff --git a/libs/binder/rust/BinderBindings.h b/libs/binder/rust/sys/BinderBindings.h
index c7a06d9a1c..c7a06d9a1c 100644
--- a/libs/binder/rust/BinderBindings.h
+++ b/libs/binder/rust/sys/BinderBindings.h
diff --git a/libs/binder/rust/sys/lib.rs b/libs/binder/rust/sys/lib.rs
new file mode 100644
index 0000000000..9095af29e0
--- /dev/null
+++ b/libs/binder/rust/sys/lib.rs
@@ -0,0 +1,38 @@
+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+//! Generated Rust bindings to libbinder_ndk
+
+#![allow(
+    non_camel_case_types,
+    non_snake_case,
+    non_upper_case_globals,
+    unused,
+    improper_ctypes,
+    missing_docs
+)]
+use std::error::Error;
+use std::fmt;
+
+include!(concat!(env!("OUT_DIR"), "/bindings.rs"));
+
+impl Error for android_c_interface_StatusCode {}
+
+impl fmt::Display for android_c_interface_StatusCode {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "StatusCode::{:?}", self)
+    }
+}