if ((pData[i] == 0xFF) && (pData[i + 1] == 0xD8) && (pData[i + 2] == 0xFF) && (pData[i + 3] == 0xE0)) {
    i += 4;

    // Check for valid JPEG header (null terminated JFIF)
    if ((pData[i + 2] == 'J') && (pData[i + 3] == 'F') && (pData[i + 4] == 'I') && (pData[i + 5] == 'F')
            && (pData[i + 6] == 0x00)) {

        //Retrieve the block length of the first block since the first block will not contain the size of file
        unsigned short block_length = pData[i] * 256 + pData[i + 1];

        while (i < FileSizeLow) {
            //Increase the file index to get to the next block
            i += block_length;

            if (i >= FileSizeLow) {
                //Check to protect against segmentation faults
                return -1;
            }

            if (pData[i] != 0xFF) {
                return -2;
            }

            if (pData[i + 1] == 0xC0) {
                //0xFFC0 is the "Start of frame" marker which contains the file size
                //The structure of the 0xFFC0 block is quite simple [0xFFC0][ushort length][uchar precision][ushort x][ushort y]
                *pHeight = pData[i + 5] * 256 + pData[i + 6];
                *pWidth = pData[i + 7] * 256 + pData[i + 8];

                return 0;
            }
            else {
                i += 2; //Skip the block marker

                //Go to the next block
                block_length = pData[i] * 256 + pData[i + 1];
            }
        }

        //If this point is reached then no size was found
        return -3;
    }
    else {
        return -4;
    } //Not a valid JFIF string
}
else {
    return -5;
} //Not a valid SOI header

return -6;

f = open("filename.jpg", "r")
s = f.read()
start = s.find("xffxe0")
end = s.rfind("xffxd9")
imagesize = end - start