[API] ISO download does not work if ISO has 255 chars name

[OlegChuev]

problem

Low-priority edge case: when I try to download an ISO with a 255-character name, it fails with a 530 error code.

Error details:

Unable to create a link for entity at ... on ssvm
Error in linking  err=ln: failed to access ... File name too long

versions

4.20.1.0

The steps to reproduce the bug

1. Create ISO with 255 characters name

2. Click download ISO

http://acs/client/api/?id=4c9b4c93-f619-4c51-b31c-cadd1c1b87c5&zoneid=b4ea7028-40ff-465f-a4a4-57a599dbf988&mode=HTTP_DOWNLOAD&command=extractIso&response=json

3. Check response

{
  "accountid": "fd3e34a9-2a85-11f0-ac08-02420a000a3d",
  "account": "admin",
  "domainid": "da3cc579-2a85-11f0-ac08-02420a000a3d",
  "domainpath": "ROOT",
  "userid": "fd3f18a1-2a85-11f0-ac08-02420a000a3d",
  "cmd": "org.apache.cloudstack.api.command.user.iso.ExtractIsoCmd",
  "jobstatus": 2,
  "jobprocstatus": 0,
  "jobresultcode": 530,
  "jobresulttype": "object",
  "jobresult": {
    "errorcode": 530,
    "errortext": "Unable to create a link for entity at template/tmpl/8/321/321-8-51a8ff71-e1e8-37b8-a498-30c164def1a7.iso on ssvm, Error in linking  err=ln: failed to access '/var/www/html/userdata/a6df0ad8-7046-4a8b-8b26-e718ab89aa15/P3B5tC3uv5BJMDRQWa7wo001l9WI9cmtVn4yDSQcOUu8ACSzzaC966P6Rgpu0rzQU0uikKKRIfLfLRDiUiSRiegUundPK6Zwmlrb9MHYhxFHOu7IV4aygBXLMnXPNCKKbBU4XtrwLUcyb3V3nu0HsSnma8SkTQUAIUneRweW0Eq5rFLS1e9mcdbpnlvTcjULAtnWC1HQYkemaTSfjlkkFhhuXq7mLNhhj670ulBFCdhNeibm0E2Nyv5Al5eHV.iso': File name too long"
  },
  "jobinstancetype": "Iso",
  "jobinstanceid": "4c9b4c93-f619-4c51-b31c-cadd1c1b87c5",
  "created": "2025-09-26T07:41:49+0000",
  "completed": "2025-09-26T07:41:49+0000",
  "jobid": "24edb09b-f9c9-4179-8fc7-46dd2ed5f392"
}

What to do about it?

Either limit the ISO/Template name/description to fewer characters (I’d suggest 100 should be more than enough), or update the system to allow longer filenames and handle this case properly