db/Configured: store database file in cache directory

Add class Context which wraps the Android/Java Context class and add a
JNI wrapper for method Context.getCacheDir().

Makefile.am

@@ -254,6 +254,7 @@ libjava_a_SOURCES = \
 
 noinst_LIBRARIES += libandroid.a
 libandroid_a_SOURCES = \
+	src/android/Context.cxx src/android/Context.hxx \
 	src/android/Environment.cxx src/android/Environment.hxx
 libandroid_a_CPPFLAGS = $(AM_CPPFLAGS) -Iandroid/build/include
 

android/src/Bridge.java

@@ -19,9 +19,11 @@
 
 package org.musicpd;
 
+import android.content.Context;
+
 /**
  * Bridge to native code.
  */
 public class Bridge {
-	public static native void run();
+	public static native void run(Context context);
 }

android/src/Main.java

@@ -57,6 +57,6 @@ public class Main extends Activity implements Runnable {
 	}
 
 	@Override public void run() {
-		Bridge.run();
+		Bridge.run(this);
 	}
 }

src/Main.cxx

@@ -93,6 +93,7 @@
 #include "java/Global.hxx"
 #include "java/File.hxx"
 #include "android/Environment.hxx"
+#include "android/Context.hxx"
 #include "org_musicpd_Bridge.h"
 #endif
 
@@ -118,6 +119,10 @@ static constexpr unsigned DEFAULT_BUFFER_BEFORE_PLAY = 10;
 
 static constexpr Domain main_domain("main");
 
+#ifdef ANDROID
+Context *context;
+#endif
+
 Instance *instance;
 
 static StateFile *state_file;
@@ -679,14 +684,17 @@ int mpd_main(int argc, char *argv[])
 
 gcc_visibility_default
 JNIEXPORT void JNICALL
-Java_org_musicpd_Bridge_run(JNIEnv *env, jclass)
+Java_org_musicpd_Bridge_run(JNIEnv *env, jclass, jobject _context)
 {
 	Java::Init(env);
 	Java::File::Initialise(env);
 	Environment::Initialise(env);
 
+	context = new Context(env, _context);
+
 	mpd_main(0, nullptr);
 
+	delete context;
 	Environment::Deinitialise(env);
 }
 

src/Main.hxx

@@ -21,8 +21,13 @@
 #define MPD_MAIN_HXX
 
 class EventLoop;
+class Context;
 struct Instance;
 
+#ifdef ANDROID
+extern Context *context;
+#endif
+
 extern Instance *instance;
 
 #ifndef ANDROID

src/android/Context.cxx

@@ -0,0 +1,43 @@
+/*
+ * Copyright (C) 2003-2014 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "config.h"
+#include "Context.hxx"
+#include "java/Class.hxx"
+#include "java/File.hxx"
+#include "fs/AllocatedPath.hxx"
+
+AllocatedPath
+Context::GetCacheDir(JNIEnv *env) const
+{
+	assert(env != nullptr);
+
+	Java::Class cls(env, env->GetObjectClass(Get()));
+	jmethodID method = env->GetMethodID(cls, "getCacheDir",
+					    "()Ljava/io/File;");
+	assert(method);
+
+	jobject file = env->CallObjectMethod(Get(), method);
+	if (file == nullptr) {
+		env->ExceptionClear();
+		return AllocatedPath::Null();
+	}
+
+	return Java::File::ToAbsolutePath(env, file);
+}

src/android/Context.hxx

@@ -0,0 +1,35 @@
+/*
+ * Copyright (C) 2003-2014 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef MPD_ANDROID_CONTEXT_HXX
+#define MPD_ANDROID_CONTEXT_HXX
+
+#include "java/Object.hxx"
+
+class AllocatedPath;
+
+class Context : public Java::Object {
+public:
+	Context(JNIEnv *env, jobject obj):Java::Object(env, obj) {}
+
+	gcc_pure
+	AllocatedPath GetCacheDir(JNIEnv *env) const;
+};
+
+#endif

src/db/Configured.cxx

@@ -26,6 +26,13 @@
 #include "util/Error.hxx"
 #include "Log.hxx"
 
+#ifdef ANDROID
+#include "Main.hxx"
+#include "android/Context.hxx"
+#include "fs/AllocatedPath.hxx"
+#include "plugins/simple/SimpleDatabasePlugin.hxx"
+#endif
+
 Database *
 CreateConfiguredDatabase(EventLoop &loop, DatabaseListener &listener,
 			 Error &error)
@@ -49,8 +56,25 @@ CreateConfiguredDatabase(EventLoop &loop, DatabaseListener &listener,
 		param = allocated;
 	}
 
-	if (param == nullptr)
+	if (param == nullptr) {
+#ifdef ANDROID
+		/* if there is no override, use the Android cache
+		   directory */
+
+		const AllocatedPath cache_dir =
+			context->GetCacheDir(Java::GetEnv());
+		if (cache_dir.IsNull())
+			return nullptr;
+
+		const auto db_file = AllocatedPath::Build(cache_dir, "mpd.db");
+
+		allocated = new config_param("database");
+		allocated->AddBlockParam("path", db_file.c_str(), -1);
+		param = allocated;
+#else
 		return nullptr;
+#endif
+	}
 
 	Database *db = DatabaseGlobalInit(loop, listener, *param,
 					  error);