media/mtp/MtpRequestPacket.cpp

/*
 * Copyright (C) 2010 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.
 */

#define LOG_TAG "MtpRequestPacket"

#include <stdio.h>
#include <sys/types.h>
#include <fcntl.h>

#include "MtpRequestPacket.h"

#include <usbhost/usbhost.h>

namespace android {

MtpRequestPacket::MtpRequestPacket()
    :   MtpPacket(512),
        mParameterCount(0)
{
}

MtpRequestPacket::~MtpRequestPacket() {
}

#ifdef MTP_DEVICE
int MtpRequestPacket::read(int fd) {
    int ret = ::read(fd, mBuffer, mBufferSize);
    if (ret < 0) {
        // file read error
        return ret;
    }

    // request packet should have 12 byte header followed by 0 to 5 32-bit arguments
    const size_t read_size = static_cast<size_t>(ret);
    if (read_size >= MTP_CONTAINER_HEADER_SIZE
            && read_size <= MTP_CONTAINER_HEADER_SIZE + 5 * sizeof(uint32_t)
            && ((read_size - MTP_CONTAINER_HEADER_SIZE) & 3) == 0) {
        mPacketSize = read_size;
        mParameterCount = (read_size - MTP_CONTAINER_HEADER_SIZE) / sizeof(uint32_t);
    } else {
        ALOGE("Malformed MTP request packet");
        ret = -1;
    }
    return ret;
}
#endif

#ifdef MTP_HOST
    // write our buffer to the given endpoint (host mode)
int MtpRequestPacket::write(struct usb_request *request)
{
    putUInt32(MTP_CONTAINER_LENGTH_OFFSET, mPacketSize);
    putUInt16(MTP_CONTAINER_TYPE_OFFSET, MTP_CONTAINER_TYPE_COMMAND);
    request->buffer = mBuffer;
    request->buffer_length = mPacketSize;
    return transfer(request);
}
#endif

}  // namespace android