Add additional instance info to log

When an instance can't be found, we now log the available instances.
This can help debugging when the instance name is misspelled or the
manifest fragment file wasn't included.

Test: launch_cvd && and logcat | grep "Could not find"
Test: atest servicemanager_test
Bug: 302147119
Change-Id: Iad85903d82bbd45c012b007ba1fcf059c5cd5c4a
diff --git a/cmds/servicemanager/ServiceManager.cpp b/cmds/servicemanager/ServiceManager.cpp
index cae9684..facb8b1 100644
--- a/cmds/servicemanager/ServiceManager.cpp
+++ b/cmds/servicemanager/ServiceManager.cpp
@@ -18,6 +18,7 @@
 
 #include <android-base/logging.h>
 #include <android-base/properties.h>
+#include <android-base/strings.h>
 #include <binder/BpBinder.h>
 #include <binder/IPCThreadState.h>
 #include <binder/ProcessState.h>
@@ -112,10 +113,26 @@
     });
 
     if (!found) {
+        std::set<std::string> instances;
+        forEachManifest([&](const ManifestWithDescription& mwd) {
+            std::set<std::string> res = mwd.manifest->getAidlInstances(aname.package, aname.iface);
+            instances.insert(res.begin(), res.end());
+            return true;
+        });
+
+        std::string available;
+        if (instances.empty()) {
+            available = "No alternative instances declared in VINTF";
+        } else {
+            // for logging only. We can't return this information to the client
+            // because they may not have permissions to find or list those
+            // instances
+            available = "VINTF declared instances: " + base::Join(instances, ", ");
+        }
         // Although it is tested, explicitly rebuilding qualified name, in case it
         // becomes something unexpected.
-        ALOGI("Could not find %s.%s/%s in the VINTF manifest.", aname.package.c_str(),
-              aname.iface.c_str(), aname.instance.c_str());
+        ALOGI("Could not find %s.%s/%s in the VINTF manifest. %s.", aname.package.c_str(),
+              aname.iface.c_str(), aname.instance.c_str(), available.c_str());
     }
 
     return found;