From b82b8f84b48616c124e1d1421a985328c1df53dc Mon Sep 17 00:00:00 2001
From: Steven Moreland <smoreland@google.com>
Date: Mon, 28 Oct 2019 10:52:34 -0700
Subject: ServiceManager: add isDeclared

Most of the time, AIDL services exist in client/service pairs. In this
context, `while(true) getService` or `waitForService` makes sense.
However, for VINTF services, this client/server coupling isn't
guaranteed. A device may or may not have specific hardware. So, now
IServiceManager can tell a client when a server will exist so it will
know if it needs to wait for this service during boot-up. The function
waitForDeclaredService is provided for this.

These functions are generic (not referring to VINTF specifically)
because they may be expanded to include information about APEX services
in the future OR the infrastructure may be made generic to work, if
desired, on system services.

Bug: 141828236
Test: binderStabilityTest, using waitForDeclaredService function
Change-Id: Ia230625e44e1685cc3fa9230ece8f0a25c88585e
---
 cmds/servicemanager/ServiceManager.cpp | 29 ++++++++++++++++++++++++-----
 1 file changed, 24 insertions(+), 5 deletions(-)

(limited to 'cmds/servicemanager/ServiceManager.cpp')

diff --git a/cmds/servicemanager/ServiceManager.cpp b/cmds/servicemanager/ServiceManager.cpp
index 934646da41..91e89ae7e8 100644
--- a/cmds/servicemanager/ServiceManager.cpp
+++ b/cmds/servicemanager/ServiceManager.cpp
@@ -34,11 +34,7 @@ using ::android::internal::Stability;
 namespace android {
 
 #ifndef VENDORSERVICEMANAGER
-static bool meetsDeclarationRequirements(const sp<IBinder>& binder, const std::string& name) {
-    if (!Stability::requiresVintfDeclaration(binder)) {
-        return true;
-    }
-
+static bool isVintfDeclared(const std::string& name) {
     size_t firstSlash = name.find('/');
     size_t lastDot = name.rfind('.', firstSlash);
     if (firstSlash == std::string::npos || lastDot == std::string::npos) {
@@ -62,6 +58,14 @@ static bool meetsDeclarationRequirements(const sp<IBinder>& binder, const std::s
                << " in the VINTF manifest.";
     return false;
 }
+
+static bool meetsDeclarationRequirements(const sp<IBinder>& binder, const std::string& name) {
+    if (!Stability::requiresVintfDeclaration(binder)) {
+        return true;
+    }
+
+    return isVintfDeclared(name);
+}
 #endif  // !VENDORSERVICEMANAGER
 
 ServiceManager::ServiceManager(std::unique_ptr<Access>&& access) : mAccess(std::move(access)) {}
@@ -270,6 +274,21 @@ Status ServiceManager::unregisterForNotifications(
     return Status::ok();
 }
 
+Status ServiceManager::isDeclared(const std::string& name, bool* outReturn) {
+    auto ctx = mAccess->getCallingContext();
+
+    if (!mAccess->canFind(ctx, name)) {
+        return Status::fromExceptionCode(Status::EX_SECURITY);
+    }
+
+    *outReturn = false;
+
+#ifndef VENDORSERVICEMANAGER
+    *outReturn = isVintfDeclared(name);
+#endif
+    return Status::ok();
+}
+
 void ServiceManager::removeCallback(const wp<IBinder>& who,
                                     CallbackMap::iterator* it,
                                     bool* found) {
-- 
cgit v1.2.3-59-g8ed1b