[Bug]: adding a share-link breaks encryption after upgrade to v27

[dsweberr]

⚠️ This issue respects the following points: ⚠️

• This is a bug, not a question or a configuration/webserver/proxy issue.
• This issue is not already reported on Github OR Nextcloud Community Forum (I've searched it).
• Nextcloud Server is up to date. See Maintenance and Release Schedule for supported versions.
• I agree to follow Nextcloud's Code of Conduct.

Bug description

adding a share via link to existing files breaks encryption by deleting all encryption keys

https://github.com/nextcloud/server/blob/v27.0.0/apps/encryption/lib/Crypto/Encryption.php#L444
$this->path is empty and causes exception after deleting all keys in #L441

changing to $path appears to fix the issue

Steps to reproduce

enable encryption, do multiple major version upgrades, add share via link to file

Expected behavior

link to file should work and not break existing files

Installation method

Community Manual installation with Archive

Nextcloud Server version

27

Operating system

Debian/Ubuntu

PHP engine version

PHP 8.2

Web server

Apache (supported)

Database engine version

PostgreSQL

Is this bug present after an update or on a fresh install?

Upgraded to a MAJOR version (ex. 22 to 23)

Are you using the Nextcloud Server Encryption module?

Encryption is Enabled

What user-backends are you using?

• Default user-backend (database)
• LDAP/ Active Directory
• SSO - SAML
• Other

Configuration report

No response

List of activated Apps

No response

Nextcloud Signing status

No response

Nextcloud Logs

"exception": {
        "Exception": "BadMethodCallException",
        "Message": "path needs to be relative to the system wide data folder and point to a user specific file",
        "Code": 0,
        "Trace": [
            {
                "file": "/var/www/nextcloud/lib/private/Encryption/Keys/Storage.php",
                "line": 366,
                "function": "getUidAndFilename",
                "class": "OC\\Encryption\\Util",
                "type": "->"
            },
            {
                "file": "/var/www/nextcloud/lib/private/Encryption/Keys/Storage.php",
                "line": 138,
                "function": "getFileKeyDir",
                "class": "OC\\Encryption\\Keys\\Storage",
                "type": "->"
            },
            {
                "file": "/var/www/nextcloud/apps/encryption/lib/KeyManager.php",
                "line": 381,
                "function": "setFileKey",
                "class": "OC\\Encryption\\Keys\\Storage",
                "type": "->"
            },
            {
                "file": "/var/www/nextcloud/apps/encryption/lib/Crypto/Encryption.php",
                "line": 444,
                "function": "setShareKey",
                "class": "OCA\\Encryption\\KeyManager",
                "type": "->"
            },
---
call to setShareKey() with empty path

Additional info

No response

[dsweberr]

appears to be fixed in
d7ef87c

[joshtrichards]

Fixed in #39447 / similar to #39034