Assets can not be resolved on SSP (symlinked assets folder)

[robbieaverill]

In a site hosted on SSP, none of the assets will load.

Uploading a new image shows the preview, then when you navigate away and back again it is gone.

The network browser tells me that the thumbnails it tries to load are just my root domain, no filename included. I don't see assets/ as a prefix to the filenames that are returned in the GraphQL, just for example Uploads/filename.jpg

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I can replicate this locally by changing my assets directory to a symlink. Note: the underlying league/flysystem package does not support symlinks.

[robbieaverill]

cc @marcello-silverstripe

[tractorcow]

Answer is in thephpleague/flysystem#599 (comment); We just need a realpath in AssetAdapter::findRoot to ensure we work with the symlinked path as the root, rather than the symlink alias.

[tractorcow]

ok, after much debugging, we found the bug is in PublicAssetAdapter::getPublicURL()

It uses realpath($this->getPathPrefix), which may not be within BASE_PATH once resolved from a symlink.

The fix is to store a logicalPathPrefix when we construct the adapter, and compare this to base_path (without realpath).

Also, instead of falling back to returning null, we can assume $dir === ASSET_DIR instead. :D

[tractorcow]

Updated fix at silverstripe/silverstripe-framework#6565