使用图像流确定扩展类型

Question

I am developing an API system for my uploading service (in PHP). At the current moment I support the option to send image data as binary data from file_get_contents, fread, etc, or by encoding it with 64 based system. I am attempting to determine the extension type of the image being uploaded to my service from this binary/base64 data. If it is base64 then I decode it and then process it.

I have the following at the moment:

// We need to figure it out ourselves
if ($type === "")
{
    // Let's see if it is a base64 file
    $base64 = $this->checkBase64Encoded($file_data);

    // We got a 64 based file or binary
    $type = $base64 === TRUE ? "base64" : "binary";
}

if ($type == "binary")
{
    $im = imagecreatefromstring($file_data);

}

I want to see if it is possible to determine the image extension type for saving the file. What do you guys suggest? I read something about using getimagesize()? Although I am not sure about this. Is there no way to get around temporarily saving the file, processing it, and then renaming it?

I also planned to use this to test that the image was a valid image before i checked for extension but I wasn't exactly sure how to use the getimagesize() function:

try
        {
            // Get the width and height from the uploaded image
            list($width, $height) = getimagesize($file['tmp_name']); // I'm not sure what to put here instead of $file['tmp_name']
        }
        catch (ErrorException $e)
        {
            // Ignore read errors
        }

        if (empty($width) OR empty($height))
        {
            // Cannot get image size, cannot validate
            return FALSE;
        }

Please feel free to ask for any clarifications if I was unclear. Thanks so much :)

Answer 1

You're looking for the fileinfo functions, particularly finfo_buffer().