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Commit 4418030f authored by Jerry Zhang's avatar Jerry Zhang
Browse files

Fix GetPartialObject on FFS 

Linux apps use GetPartialObject to access
MTP files directly. Fix file offset handling
as well as lengths shorter than packet size.

Bug: 34822471
Test: Attach photos in Gmail, open directly from device
Change-Id: I9986cd8c70ed261f07e8f96a72e53b87341dd93f
parent 3f6419d0

media/mtp/MtpFfsHandle.cpp

+7 −4
Original line number Diff line number Diff line
@@ -583,7 +583,7 @@ int MtpFfsHandle::sendFile(mtp_file_range mfr) { 
    uint64_t file_length = mfr.length;

    uint32_t given_length = std::min(static_cast<uint64_t>(MAX_MTP_FILE_SIZE),

            file_length + sizeof(mtp_data_header));

    uint64_t offset = 0;

    uint64_t offset = mfr.offset;

    struct usb_endpoint_descriptor mBulkIn_desc;

    int packet_size;
@@ -594,7 +594,10 @@ int MtpFfsHandle::sendFile(mtp_file_range mfr) { 
        packet_size = mBulkIn_desc.wMaxPacketSize;

    }



    int init_read_len = packet_size - sizeof(mtp_data_header);

    // If file_length is larger than a size_t, truncating would produce the wrong comparison.

    // Instead, promote the left side to 64 bits, then truncate the small result.

    int init_read_len = std::min(

            static_cast<uint64_t>(packet_size - sizeof(mtp_data_header)), file_length);



    char *data = mBuffer1.data();

    char *data2 = mBuffer2.data();
@@ -620,10 +623,10 @@ int MtpFfsHandle::sendFile(mtp_file_range mfr) { 
    if (TEMP_FAILURE_RETRY(pread(mfr.fd, reinterpret_cast<char*>(data) +

                    sizeof(mtp_data_header), init_read_len, offset))

            != init_read_len) return -1;

    if (writeHandle(mBulkIn, data, sizeof(mtp_data_header) + init_read_len) == -1) return -1;

    if (file_length == static_cast<unsigned>(init_read_len)) return 0;

    file_length -= init_read_len;

    offset += init_read_len;

    if (writeHandle(mBulkIn, data, packet_size) == -1) return -1;

    if (file_length == 0) return 0;



    // Break down the file into pieces that fit in buffers

    while(file_length > 0) {