microdroid_manager: initial impl

It is started by init in microdroid and executes a command specified in
a VM payload config.

Bug: 189301496
Test: MicrodroidHostTestCases
  (in a microdroid, run /system/bin/microdroid_manager manulally)
Change-Id: I85c7e370d4a0dcf58b4aafbe6e9fba73e69c2a44
diff --git a/microdroid/Android.bp b/microdroid/Android.bp
index 85b5e0c..30fec88 100644
--- a/microdroid/Android.bp
+++ b/microdroid/Android.bp
@@ -48,6 +48,7 @@
         "microdroid_build_prop",
         "microdroid_init_rc",
         "microdroid_launcher",
+        "microdroid_manager",
         "ueventd.rc",
         "libbinder",
         "libbinder_ndk",
diff --git a/microdroid/init.rc b/microdroid/init.rc
index 121afaa..8458291 100644
--- a/microdroid/init.rc
+++ b/microdroid/init.rc
@@ -110,6 +110,9 @@
 
     perform_apex_config
 
+    # TODO(b/185991357) start this earlier
+    start microdroid_manager
+
     exec_start derive_sdk
 
     start adbd
diff --git a/microdroid/microdroid_file_contexts b/microdroid/microdroid_file_contexts
index b033110..fc5e456 100644
--- a/microdroid/microdroid_file_contexts
+++ b/microdroid/microdroid_file_contexts
@@ -368,6 +368,7 @@
 /system/bin/snapuserd            u:object_r:snapuserd_exec:s0
 /system/bin/zipfuse              u:object_r:zipfuse_exec:s0
 /system/bin/microdroid_launcher  u:object_r:microdroid_launcher_exec:s0
+/system/bin/microdroid_manager   u:object_r:microdroid_manager_exec:s0
 
 #############################
 # Vendor files
diff --git a/microdroid/signature/Android.bp b/microdroid/signature/Android.bp
index 35c4e9e..1ce7805 100644
--- a/microdroid/signature/Android.bp
+++ b/microdroid/signature/Android.bp
@@ -38,6 +38,14 @@
     ],
 }
 
+rust_protobuf {
+    name: "libmicrodroid_signature_proto_rust",
+    crate_name: "microdroid_signature",
+    protos: ["microdroid_signature.proto"],
+    source_stem: "microdroid_signature",
+    host_supported: true,
+}
+
 cc_binary {
     name: "mk_payload",
     srcs: [
diff --git a/microdroid/signature/microdroid_signature.proto b/microdroid/signature/microdroid_signature.proto
index 8816aa8..6ae3756 100644
--- a/microdroid/signature/microdroid_signature.proto
+++ b/microdroid/signature/microdroid_signature.proto
@@ -27,6 +27,8 @@
   repeated ApexSignature apexes = 2;
 
   ApkSignature apk = 3;
+
+  string payload_config_path = 4;
 }
 
 message ApexSignature {
@@ -54,4 +56,4 @@
 
   string payload_partition_name = 2;
   string idsig_partition_name = 3;
-}
\ No newline at end of file
+}
diff --git a/microdroid/signature/mk_payload.cc b/microdroid/signature/mk_payload.cc
index a3501d4..9caf788 100644
--- a/microdroid/signature/mk_payload.cc
+++ b/microdroid/signature/mk_payload.cc
@@ -97,6 +97,7 @@
     std::vector<std::string> system_apexes;
     std::vector<ApexConfig> apexes;
     std::optional<ApkConfig> apk;
+    std::optional<std::string> payload_config_path;
 };
 
 #define DO(expr) \
@@ -120,6 +121,16 @@
     return ParseJson(value, *s);
 }
 
+template <typename T>
+Result<void> ParseJson(const Json::Value& values, std::vector<T>& parsed) {
+    for (const Json::Value& value : values) {
+        T t;
+        DO(ParseJson(value, t));
+        parsed.push_back(std::move(t));
+    }
+    return {};
+}
+
 Result<void> ParseJson(const Json::Value& value, ApexConfig& apex_config) {
     DO(ParseJson(value["name"], apex_config.name));
     DO(ParseJson(value["path"], apex_config.path));
@@ -134,20 +145,11 @@
     return {};
 }
 
-template <typename T>
-Result<void> ParseJson(const Json::Value& values, std::vector<T>& parsed) {
-    for (const Json::Value& value : values) {
-        T t;
-        DO(ParseJson(value, t));
-        parsed.push_back(std::move(t));
-    }
-    return {};
-}
-
 Result<void> ParseJson(const Json::Value& value, Config& config) {
     DO(ParseJson(value["system_apexes"], config.system_apexes));
     DO(ParseJson(value["apexes"], config.apexes));
     DO(ParseJson(value["apk"], config.apk));
+    DO(ParseJson(value["payload_config_path"], config.payload_config_path));
     return {};
 }
 
@@ -232,6 +234,10 @@
         // TODO(jooyung): set idsig partition as well
     }
 
+    if (config.payload_config_path.has_value()) {
+        *signature.mutable_payload_config_path() = config.payload_config_path.value();
+    }
+
     std::ofstream out(filename);
     return WriteMicrodroidSignature(signature, out);
 }