Checks the interface inheritance hierarchy in init_rc files.

Bug: 118016875
Test: Added 'interface' lines to an init_rc file and observed errors
when misspelled or missing entire inheritance hierarchy.
Change-Id: I681420f15539742d8415808b2a0dcbf0bf6faaf1
diff --git a/init/service_parser.cpp b/init/service_parser.cpp
index ba35104..88ce364 100644
--- a/init/service_parser.cpp
+++ b/init/service_parser.cpp
@@ -18,6 +18,9 @@
 
 #include <linux/input.h>
 
+#include <algorithm>
+#include <sstream>
+
 #include <android-base/logging.h>
 #include <android-base/parseint.h>
 #include <android-base/strings.h>
@@ -152,12 +155,6 @@
         return Error() << "Interface name must not be a value name '" << interface_name << "'";
     }
 
-    if (known_interfaces_ && known_interfaces_->count(interface_name) == 0) {
-        return Error() << "Interface is not in the known set of hidl_interfaces: '"
-                       << interface_name << "'. Please ensure the interface is built "
-                       << "by a hidl_interface target.";
-    }
-
     const std::string fullname = interface_name + "/" + instance_name;
 
     for (const auto& svc : *service_list_) {
@@ -540,6 +537,37 @@
         return {};
     }
 
+    if (interface_inheritance_hierarchy_) {
+        std::set<std::string> interface_names;
+        for (const std::string& intf : service_->interfaces()) {
+            interface_names.insert(Split(intf, "/")[0]);
+        }
+        std::ostringstream error_stream;
+        for (const std::string& intf : interface_names) {
+            if (interface_inheritance_hierarchy_->count(intf) == 0) {
+                error_stream << "\nInterface is not in the known set of hidl_interfaces: '" << intf
+                             << "'. Please ensure the interface is spelled correctly and built "
+                             << "by a hidl_interface target.";
+                continue;
+            }
+            const std::set<std::string>& required_interfaces =
+                    (*interface_inheritance_hierarchy_)[intf];
+            std::set<std::string> diff;
+            std::set_difference(required_interfaces.begin(), required_interfaces.end(),
+                                interface_names.begin(), interface_names.end(),
+                                std::inserter(diff, diff.begin()));
+            if (!diff.empty()) {
+                error_stream << "\nInterface '" << intf << "' requires its full inheritance "
+                             << "hierarchy to be listed in this init_rc file. Missing "
+                             << "interfaces: [" << base::Join(diff, " ") << "]";
+            }
+        }
+        const std::string& errors = error_stream.str();
+        if (!errors.empty()) {
+            return Error() << errors;
+        }
+    }
+
     Service* old_service = service_list_->FindService(service_->name());
     if (old_service) {
         if (!service_->is_override()) {