[Bug]: SSH_FXP_STAT fails with S3 backend

[ivaradi]

⚠️ This issue respects the following points: ⚠️

• This is a bug, not a question or a configuration issue.
• This issue is not already reported on Github (I've searched it).

Bug description

Hi,

I have a program that uploads files to an SFTP server and changes its mode bits. This program works with several SFTP servers, but fails with SFTPGo when using an S3 backend (MinIO). The following SFTP requests are sent:

1. SSH_FXP_OPEN to open the file for writing
2. one or more SSH_FXP_WRITE requests to write data into it
3. SSH_FXP_STAT to query the current file attributes for modification
   ...

However, the SSH_FXP_STAT request fails with a "no such file" error, if the file does not exist before uploading.

Steps to reproduce

See the description.

Expected behavior

SSH_FXP_STAT should work for the file.

SFTPGo version

2.6.6

Data provider

SQLite

Installation method

Community Docker image

Configuration

Added administrative user, normal user and setup a bucket on the MinIO backend (RELEASE.2025-06-13T11-33-47Z) as a virtual folder mapped for the user.

Relevant log output

What are you using SFTPGo for?

Private user, home usecase (home backup/VPS)

Additional info

No response

[playworker]

I don't think you can change the mode of a file when using S3 as a backend - I'm not the developer so I could be wrong though :)

sftpgo/internal/vfs/s3fs.go

Line 410 in 9d20f17

// Chmod changes the mode of the named file to mode.

// Chmod changes the mode of the named file to mode.
func (*S3Fs) Chmod(_ string, _ os.FileMode) error {
	return ErrVfsUnsupported
}