A way to get ApplicationInfo when app start

/*
 * content manager for Android
 */

#include <android/log.h>
#include <stdio.h>

#include "murmurhash3.h"
#include "unzip.h"

#include "content_manager.h"

#define ACTIVITYTHREAD_CLASSNAME        "android/app/ActivityThread"
#define APPBINDDATA_CLASSNAME           ACTIVITYTHREAD_CLASSNAME"$AppBindData"
#define APPLICATIONINFO_CLASSNAME       "android/content/pm/ApplicationInfo"
#define ENVIRONMENT_CLASSNAME           "android/os/Environment"
#define FILE_CLASSNAME                  "java/io/File"
#define STRING_CLASSNAME                "java/lang/String"

#define ACTIVITYTHREAD_CLASS_SIGNATURE  "L"ACTIVITYTHREAD_CLASSNAME";"
#define APPBINDDATA_CLASS_SIGNATURE     "L"APPBINDDATA_CLASSNAME";"
#define APPLICATIONINFO_CLASS_SIGNATURE "L"APPLICATIONINFO_CLASSNAME";"
#define STRING_CLASS_SIGNATURE          "L"STRING_CLASSNAME";"
#define FILE_CLASS_SIGNATURE            "L"FILE_CLASSNAME";"

#define DATA_DIRECTORY                  "/Android/data"
#define MEDIA_DIRECTORY                 "/Android/media"
#define OBB_DIRECTORY                   "/Android/obb"

#define LOG_TAG                         "ContentManager"

#ifndef NDEBUG
    #define LOGD(...)   __android_log_print(ANDROID_LOG_DEBUG, LOG_TAG, __VA_ARGS__)
    #define LOGE(...)   __android_log_print(ANDROID_LOG_ERROR, LOG_TAG, __VA_ARGS__)
    #define LOGW(...)   __android_log_print(ANDROID_LOG_WARN,  LOG_TAG, __VA_ARGS__)
    #define LOGI(...)   __android_log_print(ANDROID_LOG_INFO,  LOG_TAG, __VA_ARGS__)
#else
    #define LOGD(...)   do {} while (0)
    #define LOGE(...)   do {} while (0)
    #define LOGW(...)   do {} while (0)
    #define LOGI(...)   do {} while (0)
#endif

#define STRING_BUFFERSIZE               512

static char PackageName[STRING_BUFFERSIZE]              = {0};
static char DataDir[STRING_BUFFERSIZE]                  = {0};
static char SourceDir[STRING_BUFFERSIZE]                = {0};
static char ExternalDirectory[STRING_BUFFERSIZE]        = {0};
static char ExternalDataDirectory[STRING_BUFFERSIZE]    = {0};
static char ExternalMediaDirectory[STRING_BUFFERSIZE]   = {0};
static char ExternalOBBDirectory[STRING_BUFFERSIZE]     = {0};

static unzFile APKFile = 0;

typedef struct
{
    unz64_file_pos file_pos;
    uLong uncompressed_size;
} Content;

static jclass cm_get_jclass(const char *class_name, JNIEnv *env)
{
    jclass clazz = 0;

    if (env)
    {
        clazz = (*env)->FindClass(env, class_name);

        if ((*env)->ExceptionCheck(env))
            (*env)->ExceptionClear(env);
    }

    return clazz;
}

static jmethodID cm_get_jmethod(jclass clazz, const char *method_name, const char *signature, JNIEnv *env)
{
    jmethodID methodId = 0;

    if (env)
    {
        methodId = (*env)->GetMethodID(env, clazz, method_name, signature);

        if ((*env)->ExceptionCheck(env))
            (*env)->ExceptionClear(env);
    }

    return methodId;
}

static jmethodID cm_get_static_jmethod(jclass clazz, const char *method_name, const char *signature, JNIEnv *env)
{
    jmethodID methodId = 0;

    if (env)
    {
        methodId = (*env)->GetStaticMethodID(env, clazz, method_name, signature);

        if ((*env)->ExceptionCheck(env))
            (*env)->ExceptionClear(env);
    }

    return methodId;
}

static jfieldID cm_get_jfield(jclass clazz, const char *field_name, const char *signature, JNIEnv *env)
{
    jfieldID fieldId = 0;

    if (env)
    {
        fieldId = (*env)->GetFieldID(env, clazz, field_name, signature);

        if ((*env)->ExceptionCheck(env))
            (*env)->ExceptionClear(env);
    }

    return fieldId;
}

int cm_initialize(JNIEnv *env)
{
    int ret = 0;

    jclass jcActivityThread = 0, jcAppBindData = 0, jcApplicationInfo = 0, jcEnvironment = 0, jcFile = 0;
    jstring jsString = 0;
    jobject joActivityThread = 0, joAppBindData = 0, joAppInfo = 0, joFile = 0;

    jmethodID jmCurrentActivityThread, jmGetExtStorageDir, jmGetAbsolutePath;
    jfieldID jfAppInfo, jfBoundApplication, jfSourceDir, jfDataDir, jfPackageName;

    const char *package_name, *source_dir, *data_dir, *ext_storage_dir;

    if (!env)
        goto cm_initialize_error_;

    if ((*env)->PushLocalFrame(env, 10))
        goto cm_initialize_error_;

    if (!(jcActivityThread = cm_get_jclass(ACTIVITYTHREAD_CLASSNAME, env)))
        goto cm_initialize_error;

    if (!(jcAppBindData = cm_get_jclass(APPBINDDATA_CLASSNAME, env)))
        goto cm_initialize_error;

    if (!(jcApplicationInfo = cm_get_jclass(APPLICATIONINFO_CLASSNAME, env)))
        goto cm_initialize_error;

    if (!(jcEnvironment = cm_get_jclass(ENVIRONMENT_CLASSNAME, env)))
        goto cm_initialize_error;

    if (!(jcFile = cm_get_jclass(FILE_CLASSNAME, env)))
        goto cm_initialize_error;

    if (!(jmCurrentActivityThread = cm_get_static_jmethod(jcActivityThread, "currentActivityThread", "()"ACTIVITYTHREAD_CLASS_SIGNATURE, env)))
        goto cm_initialize_error;

    if (!(jmGetExtStorageDir = cm_get_static_jmethod(jcEnvironment, "getExternalStorageDirectory", "()"FILE_CLASS_SIGNATURE, env)))
        goto cm_initialize_error;

    if (!(jmGetAbsolutePath = cm_get_jmethod(jcFile, "getAbsolutePath", "()"STRING_CLASS_SIGNATURE, env)))
        goto cm_initialize_error;

    if (!(jfBoundApplication = cm_get_jfield(jcActivityThread, "mBoundApplication", APPBINDDATA_CLASS_SIGNATURE, env)))
        goto cm_initialize_error;

    if (!(jfAppInfo = cm_get_jfield(jcAppBindData, "appInfo", APPLICATIONINFO_CLASS_SIGNATURE, env)))
        goto cm_initialize_error;

    if (!(jfPackageName = cm_get_jfield(jcApplicationInfo, "packageName", STRING_CLASS_SIGNATURE, env)))
        goto cm_initialize_error;

    if (!(jfSourceDir = cm_get_jfield(jcApplicationInfo, "sourceDir", STRING_CLASS_SIGNATURE, env)))
        goto cm_initialize_error;

    if (!(jfDataDir = cm_get_jfield(jcApplicationInfo, "dataDir", STRING_CLASS_SIGNATURE, env)))
            goto cm_initialize_error;

    if (!(joActivityThread = (*env)->CallStaticObjectMethod(env, jcActivityThread, jmCurrentActivityThread)))
        goto cm_initialize_error;

    if (!(joAppBindData = (*env)->GetObjectField(env, joActivityThread, jfBoundApplication)))
        goto cm_initialize_error;

    if (!(joAppInfo = (*env)->GetObjectField(env, joAppBindData, jfAppInfo)))
        goto cm_initialize_error;

    if (!(joFile = (*env)->CallStaticObjectMethod(env, jcEnvironment, jmGetExtStorageDir)))
        goto cm_initialize_error;

    // get packagename
    if (!(jsString = (*env)->GetObjectField(env, joAppInfo, jfPackageName)))
        goto cm_initialize_error;

    if (!(package_name = (*env)->GetStringUTFChars(env, jsString, 0)))
        goto cm_initialize_error;

    snprintf(PackageName, STRING_BUFFERSIZE, "%s", package_name);
    (*env)->ReleaseStringUTFChars(env, jsString, package_name);
    (*env)->DeleteLocalRef(env, jsString);

    // get sourceDir
    if (!(jsString = (*env)->GetObjectField(env, joAppInfo, jfSourceDir)))
        goto cm_initialize_error;

    if (!(source_dir = (*env)->GetStringUTFChars(env, jsString, 0)))
        goto cm_initialize_error;

    snprintf(SourceDir, STRING_BUFFERSIZE, "%s", source_dir);
    (*env)->ReleaseStringUTFChars(env, jsString, source_dir);
    (*env)->DeleteLocalRef(env, jsString);

    // get dataDir
    if (!(jsString = (*env)->GetObjectField(env, joAppInfo, jfDataDir)))
        goto cm_initialize_error;

    if (!(data_dir = (*env)->GetStringUTFChars(env, jsString, 0)))
        goto cm_initialize_error;

    snprintf(DataDir, STRING_BUFFERSIZE, "%s", data_dir);
    (*env)->ReleaseStringUTFChars(env, jsString, data_dir);
    (*env)->DeleteLocalRef(env, jsString);

    // get external storage directory
    if (!(jsString = (*env)->CallObjectMethod(env, joFile, jmGetAbsolutePath)))
        goto cm_initialize_error;

    if (!(ext_storage_dir = (*env)->GetStringUTFChars(env, jsString, 0)))
        goto cm_initialize_error;

    snprintf(ExternalDirectory, STRING_BUFFERSIZE, "%s", ext_storage_dir);
    (*env)->ReleaseStringUTFChars(env, jsString, ext_storage_dir);
    // delete local ref in cm_initialize_error

    snprintf(ExternalDataDirectory, STRING_BUFFERSIZE, "%s%s", ExternalDirectory, DATA_DIRECTORY);
    snprintf(ExternalMediaDirectory, STRING_BUFFERSIZE, "%s%s", ExternalDirectory, MEDIA_DIRECTORY);
    snprintf(ExternalOBBDirectory, STRING_BUFFERSIZE, "%s%s", ExternalDirectory, OBB_DIRECTORY);

    LOGD("package = %s", PackageName);
    LOGD("source dir = %s", SourceDir);
    LOGD("data dir = %s", DataDir);
    LOGD("ext dir = %s", ExternalDirectory);
    LOGD("ext data = %s", ExternalDataDirectory);
    LOGD("ext media = %s", ExternalMediaDirectory);
    LOGD("ext obb = %s", ExternalOBBDirectory);

    if (!(APKFile = unzOpen(SourceDir)))
        goto cm_initialize_error;

    char file_name[STRING_BUFFERSIZE];
    unz_file_info64 file_info;
    unz64_file_pos file_pos;
    unz_global_info64 global_info;

    ZPOS64_T start_pos;
    uLong handle;

    if (unzGetGlobalInfo64(APKFile, &global_info) == UNZ_OK)
    {
        LOGD("entry: %llu", global_info.number_entry);

        do
        {
            if (unzGetCurrentFileInfo64(APKFile, &file_info, file_name, STRING_BUFFERSIZE - 1, 0, 0, 0, 0) == UNZ_OK)
            {
                if (unzGetFilePos64(APKFile, &file_pos) == UNZ_OK)
                {
                    if (unzOpenCurrentFile(APKFile) == UNZ_OK)
                    {
                        start_pos = unzGetCurrentFileZStreamPos64(APKFile);

                        handle = crc32(0, file_name, file_info.size_filename);
                        // MurmurHash3_x86_32(file_name, file_info.size_filename, 0, &handle);

                        LOGD("%s : start 0x%08llx length 0x%08llx 0x%08lx handle = %lu", file_name,
                                                                                         start_pos,
                                                                                         file_info.compressed_size,
                                                                                         handle,
                                                                                         (handle % 32));
                    }
                }
            }
        } while (unzGoToNextFile(APKFile) == UNZ_OK);
    }

    LOGD("end of list file");

    unzGoToFirstFile(APKFile);

    ret = 1;

cm_initialize_error:
    (*env)->DeleteLocalRef(env, jcActivityThread);
    (*env)->DeleteLocalRef(env, jcAppBindData);
    (*env)->DeleteLocalRef(env, jcApplicationInfo);
    (*env)->DeleteLocalRef(env, jcEnvironment);
    (*env)->DeleteLocalRef(env, jcFile);

    (*env)->DeleteLocalRef(env, joActivityThread);
    (*env)->DeleteLocalRef(env, joAppBindData);
    (*env)->DeleteLocalRef(env, joAppInfo);
    (*env)->DeleteLocalRef(env, joFile);

    (*env)->DeleteLocalRef(env, jsString);

    (*env)->PopLocalFrame(env, 0);

cm_initialize_error_:
    return ret;
}

int cm_deinitialize(void)
{
    unzClose(APKFile);
}


// for test
#include <pthread.h>
#define USE_JNI_VERSION JNI_VERSION_1_4

static JavaVM *jvm = 0;

static void jvm_detach_thread(void *arg)
{
    pthread_key_t *jvm_detach_key = (pthread_key_t *)arg;

    if (jvm)
        (*jvm)->DetachCurrentThread(jvm);

    pthread_setspecific(*jvm_detach_key, 0);
    free(jvm_detach_key);
}

int getEnv(JNIEnv **env)
{
    switch ((*jvm)->GetEnv(jvm, (void **)env, USE_JNI_VERSION))
    {
        default:
        {
            return 0;
        }
        case JNI_EDETACHED:
        {
            if ((*jvm)->AttachCurrentThread(jvm, env, 0))
            {
                return 0;
            }

            pthread_key_t *jvm_detach_key = (pthread_key_t *)calloc(1, sizeof(pthread_key_t));

            // attach successfully
            pthread_key_create(jvm_detach_key, jvm_detach_thread);
            pthread_setspecific(*jvm_detach_key, jvm_detach_key);
        }
        case JNI_OK:
        {
            break;
        }
    }

    return 1;
}

jint JNI_OnLoad(JavaVM *vm, void *reserved)
{
    JNIEnv *env;
    jvm = vm;

    if (getEnv(&env) && cm_initialize(env))
        return USE_JNI_VERSION;

    return -1;
}