[wifi] "Link Quality" field is missing unless "sudo"

[lihebi]

When I enable wifi in mode-line by "%I", I got "The value NIL is not of type VECTOR" in the mode line.

Diving into the code, I found the following code cause the bug:

(qual (multiple-value-bind (match? sub)
                         (cl-ppcre:scan-to-strings "Link Quality=(\\d+)/(\\d+)" iwconfig)
                       (truncate (float (* (/ (parse-integer (aref sub 0))
                                              (parse-integer (aref sub 1)))
                                           100)))))

The cause is iwconfig does not report "Link Quality" unless run as root.

I'm using a macbook, thus not sure if this is the case for other hardware, but I guess so. The fix might be:
Option 1. remove the Link Quality
Option 2. run the command iwconfig in root priviliage

[kriyative]

@lihebi - is this on MacOS? I'm running with the %I formatter on Ubuntu Linux and it works without root privilege. Your Option 1 is pretty drastic - displaying the signal strength in the modeline is quite useful IMHO. For your Option 2, you could try:

(setq *iwconfig-path* "sudo /sbin/iwconfig")

and edit /etc/sudoers to permit /sbin/iwconfig to run without password.

[PuercoPop]

Option 3. Use handle-{case,bind} to handle the condition gracefully. Maybe print a red square or a short message in the status bar?

Something along the lines of 9369f5b but in this case it probably wouldn't be a need for interactive handling of the condition as the causes for the module failing are too many.

[lihebi]

Thanks for the help, Ram.
Sorry about the improper description of "option 1", what I meant was to add another option, say %X, to present only ESSID.
I'm using macbook pro as hardware, but running archlinux natively. So it should not be a macOS problem. To be precise, on arch, the iwconfig gives me:

wlp3s0    IEEE 802.11  ESSID:"IASTATE"  
          Mode:Managed  Frequency:2.412 GHz  Access Point: 64:F6:9D:66:4F:20   
          Retry short limit:7   RTS thr:off   Fragment thr:off
          Power Management:off

While sudo iwconfig gives me

wlp3s0    IEEE 802.11  ESSID:"IASTATE"  
          Mode:Managed  Frequency:2.412 GHz  Access Point: 64:F6:9D:66:4F:20   
          Bit Rate=216.5 Mb/s   Tx-Power=200 dBm   
          Retry short limit:7   RTS thr:off   Fragment thr:off
          Encryption key:off
          Power Management:off
          Link Quality=46/70  Signal level=-64 dBm  
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:0  Invalid misc:0   Missed beacon:0

I believe this is a root privilege issue.

I tried your suggestion for setting *iwconfig-path* to a sudo command. It worked, but only if I modify it in the original wifi.lisp file. Setting the variable *iwconfig-path* in my configuration file does not work.
I'm not sure why. Evaluating the *iwconfig-path* in stumpwm gives me unbounded variable error. I do see the variable is exported in package.lisp. I'm learning common lisp, I cannot tell what was exactly happening yet ..

[kriyative]

@lihebi - ah, I think this may help: (setq wifi:*iwconfig-path* "sudo /sbin/iwconfig")

[lihebi]

Here we go, this works, thanks!

[lihebi]

Hi, I encounter some exceptions even if I added sudo privilege. Sometimes (on my archlinux machine), sudo iwconfig still miss "Link Quality" section.

Instead of just printing multiple line "The value NIL is not of type VECTOR" in the mode line, it might be better to just give user options to retrieve link quality or not. For me, I don't think the link quality is important, but I really need to know whether I connected to the right wifi.

I propose two ways:

1. for backward compatibility, keep %I as ESSID + Quality, and add a new formatter %i as ESSID only. Something like this commit
2. add %i for ESSID, %j for Quality, so user can use %i %j to achieve the original %I, while also has the flexibility to use %i only