fix: run Commands when set by "cmds add" cli (#655)

[dannyp11]

Description

Hello, I came across the exact issue #655 in that when adding cmds via filebrowser cli instead of in web UI, filebrowser fails to run the command due to leading whitespace (eg. input command is "echo hello" but filebrowser will run " echo hello")

To reproduce

rm -f filebrowser.db
filebrowser config init
filebrowser cmds add "before_upload" "echo hello world"
filebrowser -r .

Try to upload 1 file

• Expected: file is uploaded successfully, hello world is printed to stdout
• Actual: no such file or directory error due to running " echo hello world" instead of "echo hello world"

2020/10/03 15:00:59 [INFO] Blocking Command: " echo hello world"
2020/10/03 15:00:59 /service-runner: 404 127.0.0.1 fork/exec : no such file or directory

Root cause

• Settings.Shell is initiated as []string{""} instead of []string{} due to strings.Split() expected behavior
• that will result in len(Shell) always >= 1
• that leads to command = append(s.Shell, raw) which is ["", "echo hello world"] which leads to cmd := exec.Command("", "echo", "hello", "world") here
  => runs exec command " echo hello world" instead of "echo hello world"

Testing

1. Try reproduce step
2. File is uploaded successfully and "hello world" is printed

2020/10/03 15:03:07 [INFO] Blocking Command: "echo hello world"
hello world

🚨 I have followed all the below:

• DO make sure you are requesting to pull a topic/feature/bugfix branch (right side). Don't request your master!
• DO make sure you are making a pull request against the master branch (left side). Also you should start your branch off our master.
• DO make sure that File Browser can be successfully built. See builds and development.
• DO make sure that related issues are opened in other repositories. I.e., the frontend, caddy plugins or the web page need to be updated accordingly.
• AVOID breaking the continuous integration build.

❤️ Thank you!

[o1egl]

Good catch!

[dannyp11]

Revision 2

• Addressed @o1egl comment

Testing passed

2020/10/04 13:52:28 [INFO] Blocking Command: "echo hello world"
hello world

[dannyp11]

Revision 3

• Fix same bug in config_set.go
• Move cmd string split into cmd/utils.go

Testing passed

2020/10/04 14:28:38 [INFO] Blocking Command: "echo hello world"
hello world

Side note

@o1egl why don't we have any unit test? I'm happy to setup simple one in separate PR if the team is ok with it, where can I bring this up?

[o1egl]

@dannyp11 I think due to historical reason. I'm trying to add unit test on new code. At the moment I'm working on refactoring which will be released as v3 and after that unit tests will be required for PRs

[o1egl]

LGTM