Instance: add method FindPartition()

src/Instance.cxx

@@ -39,6 +39,16 @@ Instance::Instance()
 {
 }
 
+Partition *
+Instance::FindPartition(const char *name)
+{
+	for (auto &partition : partitions)
+		if (partition.name == name)
+			return &partition;
+
+	return nullptr;
+}
+
 #ifdef ENABLE_DATABASE
 
 const Database &

src/Instance.hxx

@@ -106,6 +106,13 @@ struct Instance final
 		idle_monitor.OrMask(mask);
 	}
 
+	/**
+	 * Find a #Partition with the given name.  Returns nullptr if
+	 * no such partition was found.
+	 */
+	gcc_pure
+	Partition *FindPartition(const char *name);
+
 #ifdef ENABLE_DATABASE
 	/**
 	 * Returns the global #Database instance.  May return nullptr

src/command/PartitionCommands.cxx

@@ -58,13 +58,9 @@ IsValidPartitionName(const char *name)
 
 gcc_pure
 static bool
-HasPartitionNamed(const Instance &instance, const char *name)
+HasPartitionNamed(Instance &instance, const char *name)
 {
-	for (const auto &partition : instance.partitions)
+	return instance.FindPartition(name) != nullptr;
-		if (partition.name == name)
-			return true;
-
-	return false;
 }
 
 CommandResult