Sharees list with user.search_min_length set to 0 returns users in incorrect format

[dpakach]

Steps to reproduce

1. set system config user.search_min_length to 0
2. Get the list of sharees with empty search or without search

curl http://localhost/ocs/v1.php/apps/files_sharing/api/v1/sharees\?itemType\=file -u admin:admin

Expected behaviour

The response should return with empty exact searches and all users in the users section

Actual behaviour

Some users are returned in the exact section

curl http://localhost/ocs/v1.php/apps/files_sharing/api/v1/sharees\?itemType\=file\&format\=json -u admin:admin | jq 
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100   552  100   552    0     0   2453      0 --:--:-- --:--:-- --:--:--  2442
{
  "ocs": {
    "meta": {
      "status": "ok",
      "statuscode": 100,
      "message": "OK",
      "totalitems": "",
      "itemsperpage": ""
    },
    "data": {
      "exact": {
        "users": [
          {
            "label": "test123",
            "value": {
              "shareType": 0,
              "shareWith": "test123",
              "userType": 0
            }
          },
          {
            "label": "testABC",
            "value": {
              "shareType": 0,
              "shareWith": "testABC",
              "userType": 0
            }
          }
        ],
        "groups": [],
        "remotes": []
      },
      "users": [
        {
          "label": "admin",
          "value": {
            "shareType": 0,
            "shareWith": "admin",
            "userType": 0
          }
        },
        {
          "label": "tu1",
          "value": {
            "shareType": 0,
            "shareWith": "tu1",
            "userType": 0
          }
        }
      ],
      "groups": [
        {
          "label": "admin",
          "value": {
            "shareType": 1,
            "shareWith": "admin"
          }
        }
      ],
      "remotes": []
    }
  }
}

Server configuration

Operating system: ubuntu 20.04

Web server: apache

Database: mysql

PHP version: 7.4

ownCloud version: (see ownCloud admin page) latest git

Updated from an older ownCloud or fresh install: fresh

Where did you install ownCloud from: git

[dpakach]

Looks like only the users which dont have email set are returned in the exact section.
If the email field is empty they are returned under regular users
In the above example admin and tu have email set while test123 and testABC dont have email set.

[IljaN]

Could be related to #38489 But probability is low as our code "only" adds an empty return.

core/apps/files_sharing/lib/Controller/ShareesController.php

Lines 168 to 171 in 2edf9bd

	if (\strlen(\trim($search)) === 0 && $this->userSearch->getSearchMinLength() > 0) {
	$this->result['users'] = [];
	return;
	}

We should test tough to be 100% sure.

[IljaN]

Tested it have the same behaviour before #38489