Display upload file size limit on file upload form

[jrtilson]

I've implemented this in a plugin, but I'm thinking this would be useful in the core files plugin.

It's easy enough to get the upload/post max sizes in bytes, ie:

elgg_get_ini_setting_in_bytes('upload_max_filesize');
elgg_get_ini_setting_in_bytes('post_max_size');

The only missing piece of the puzzle is a function to convert bytes to a human
readable/friendly string. There's a ton of different ways to go about this..

I like this method (from: http://stackoverflow.com/questions/2510434/format-bytes-to-kilobytes-megabytes-gigabytes):

function formatBytes($size, $precision = 2) {
    $base = log($size) / log(1024);
    $suffixes = array('', 'k', 'M', 'G', 'T');   

    return round(pow(1024, $base - floor($base)), $precision) . $suffixes[floor($base)];
}

If anyone has a better solution for friendly byte formatting, please comment. I'll work this into a pull request otherwise..

[mrclay]

Seems fine. Display this in its own view/extension so site owners can easily remove it if they like.

[jrtilson]

Few logistical questions:

1. Should I put this in master, or the 1.8 branch?
2. Should the bytes formatting function live in lib/output, ie: elgg_format_bytes
3. Is it worth writing an authoritative function in core to determine the actual file upload limit? upload_max_filesize could be greater than post_max_size (on a misconfigured install)

[Srokap]

The code for formatBytes is from php.net, licensed under CC license and AFAIK it's not compatible with MIT. I think we just need to write custom one.

[mrclay]

1. master
2. elgg_format_bytes in lib/output seems fine
3. Not sure

Do units like KB/MB need to be translated?

[jrtilson]

@Srokap The formatBytes function I referenced is actually the second answer to that SO question (http://stackoverflow.com/a/2510540/1202510)

I've modified it to return false to address the error if you pass 0 or a negative number, as well as using proper (I believe) standard symbols for kB, MB etc:

function elgg_format_bytes($size, $precision = 2) {
    if (!$size || $size < 0) {
        return false;
    }

    $base = log($size) / log(1024);
    $suffixes = array('B', 'kB', 'MB', 'GB', 'TB');   

    return round(pow(1024, $base - floor($base)), $precision) . ' ' . $suffixes[floor($base)];
}

@mrclay I suppose it'd be more flexible to handle any file size unit to/from any other unit size, but that seems a bit beyond the scope of this feature.

[juho-jaakkola]

Already merged to 1.x, so closing.