android_fopen.c

/*
 * Copyright (C) 2016 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

// The original code is from https://github.com/netguy204/gambit-game-lib
#include "android_fopen.h"
#include <errno.h>
#include <android/asset_manager.h>

static int android_read(void* cookie, char* buf, int size) {
    return AAsset_read((AAsset*)cookie, buf, size);
}

static int android_write(void* cookie, const char* buf, int size) {
    return EACCES; // can't provide write access to the apk
}

static fpos_t android_seek(void* cookie, fpos_t offset, int whence) {
    return AAsset_seek((AAsset*)cookie, offset, whence);
}

static int android_close(void* cookie) {
    AAsset_close((AAsset*)cookie);
    return 0;
}

// must be established by someone else...
static AAssetManager* android_asset_manager = NULL;
void android_fopen_set_asset_manager(AAssetManager* manager) {
    android_asset_manager = manager;
}

FILE* android_fopen(const char* fname, const char* mode) {
    if(mode[0] == 'w') return NULL;

    AAsset* asset = AAssetManager_open(android_asset_manager, fname, 0);
    if(!asset) return NULL;

    return funopen(asset, android_read, android_write, android_seek, android_close);
}