AndroidApiWrapper.cc

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/*
 * Android API wrapper
 *
 * It makes a few Android functions available for the android flavour of openMSX
 *
 */

#include "build-info.hh"
#include "AndroidApiWrapper.hh"

#if PLATFORM_ANDROID

#include "openmsx.hh"
#include <cstdlib>
#include <cstring>
#include <jni.h>

// The jniVM parameter gets set by the JNI mechanism directly after loading the
// shared lib containing openMSX by invoking a method with following
// signature if it exists in the shared lib:
//   JNIEXPORT jint JNICALL JNI_OnLoad(JavaVM *vm, void *reserved)
// This method is defined at the end of this source file and must be able to
// initialize this jniVM parameter, hence it must exist outside the openmsx
// namespace
static JavaVM* jniVM = nullptr;

namespace openmsx {

std::string AndroidApiWrapper::getStorageDirectory()
{
        JNIEnv* jniEnv = nullptr;
        jniVM->AttachCurrentThread(&jniEnv, nullptr);
        if (!jniEnv) {
                throw JniException("Java VM AttachCurrentThread() failed");
        }
        jclass cls = jniEnv->FindClass("android/os/Environment");
        if (cls == 0) {
                throw JniException("Cant find class android/os/Environment");
        }
        jmethodID mid = jniEnv->GetStaticMethodID(cls, "getExternalStorageDirectory", "()Ljava/io/File;");
        if (mid == 0) {
                throw JniException("Cant find getExternalStorageDirectory method");
        }
        jobject storageDirectory = jniEnv->CallStaticObjectMethod(cls, mid);
        if (storageDirectory == 0) {
                throw JniException("Cant get storageDirectory");
        }
        cls = jniEnv->GetObjectClass(storageDirectory);
        if (cls == 0) {
                throw JniException("Cant find class for storageDirectory object");
        }
        mid = jniEnv->GetMethodID(cls, "getAbsolutePath", "()Ljava/lang/String;");
        if (mid == 0) {
                throw JniException("Cant find getAbsolutePath method");
        }
        jstring storageDirectoryName = static_cast<jstring>(jniEnv->CallObjectMethod(storageDirectory, mid));
        if (storageDirectoryName == 0) {
                throw JniException("Cant get storageDirectoryName");
        }
        const char* str = jniEnv->GetStringUTFChars(storageDirectoryName, nullptr);
        if (str == nullptr) {
                throw JniException("Cant convert storageDirectoryName to C format");
        }
        std::string rslt(str);
        jniEnv->ReleaseStringUTFChars(storageDirectoryName, str);
        return rslt;
}

} // namespace openmsx

JNIEXPORT jint JNICALL JNI_OnLoad(JavaVM* vm, void* /*reserved*/)
{
        // Store the reference to the JVM so that the JNI calls can use it
        jniVM = vm;
        return JNI_VERSION_1_2;
}

JNIEXPORT void JNICALL JNI_OnUnload(JavaVM* /*vm*/, void* /*reserved*/)
{
        // Nothing to do
}

#endif