[erlang-bugs] Suspicious callback when using an SFTP server-side file handler

[Rabbe Fogelholm]

I have set up an SFTP service, using OTP SSH, where I configure a custom
ssh_sftpd_file_api module.

The service is started with a subsystem_spec() roughly like this:

{"sftp",
  {mySftpd,
   [{cwd,"/aaa/bbb"},
    {root,"/aaa/bbb"},
    {file_handler,myStfpdHandler},
    {sftpd_vsn,3}]}}

The callbacks generally pass paths that are filesystem-absolute. For example,
when myStfpdHandler:is_dir/2 is called the passed path may look like

     "/aaa/bbb/xxx/somefile.txt"

This happens when the callback occurs due to an SFTP client call like this,

    ls /xxx

However, if I instead make the following SFTP client command

    get /xxx/somefile.txt

the path passed to is_dir/2 is instead

    "/xxx/somefile.txt"

This path does not make sense? The default callback module calls filelib:is_dir/1
with the passed path, which is bound to be false all the time.

So, I suspect that there may be a bug, although not a very serious one: The "get"
operation succeeds despite the peculiar call. Anyway, for the passed path to be
useful in is_dir/2 it ought to be filesystem-absolute all the time, just like the
argument name suggests.

_______________
Rabbe fogelholm, Ericsson, Stockholm