Fix false "invalid file size" error on boards with unlimited attachment size

[ECYaz]

Problem

Uploading a custom verification badge fails with "The image you uploaded has an invalid file size." on some boards, for every file and file type.

In acp/settings_module.php, the size check compares the upload against $config['max_filesize'] directly:

$max_size = $config[ 'max_filesize' ];

if ( '0' !== $file_upload[ 'error' ] || 1 > $file_upload[ 'size' ] || $max_size < $file_upload[ 'size' ] ) {

In phpBB, an attachment max_filesize of 0 means "no limit" (that's how the core attachment settings treat it). On any board configured that way, $max_size < $file_upload['size'] is 0 < <size>, which is always true, so the size check rejects every upload before the file-type check is even reached. Boards left on the default limit (262144) with a small badge are unaffected — which is why it only happens on some installs, and why it looks like it applies to all file types.

Fix

Cast the setting to int and only enforce the maximum when it is greater than zero:

$max_size = (int) $config[ 'max_filesize' ];

if ( '0' !== $file_upload[ 'error' ] || 1 > $file_upload[ 'size' ] || ( 0 < $max_size && $max_size < $file_upload[ 'size' ] ) ) {

Behaviour before/after (size gate only):

Case	Before	After
default limit, small badge	allow	allow
unlimited (max_filesize = 0), small badge	reject	allow
admin limit set, badge under limit	allow	allow
admin limit set, badge over limit	reject	reject

The change only affects the max_filesize == 0 case; a genuinely oversized upload against a set limit is still rejected.

Scoped to this one issue — no other changes.