Help with standard function to find ubi device number?

For Developers
1

Ok so I'm trying to capture the UBI device number to pass it onto mount a factory data partition containing my source mac binary.
I have modified a pervious device specific script on the same platform, so it does not assume anything and make it more universal.

see here for my commit:
Qualcommax: IPQ807x: Add support for TP-Link Deco X80-5G by professor-jonny · Pull Request #16329 · openwrt/openwrt

I'm just not sure on the factory function find_mtd_index in the standard functions in /lib/functions.sh and, I could not figure out how to debug preinit to get stdout etc...

Is there a help file or something that explains what these standard functions do ? or anyone able to offer advice ?

As I don't know if it will parse on the correct string ubi$ubi_num into the mount command

I'm not really clued up enough to understand how to decipher and understand the standard functions work as there is no notes in the code or notes on the wiki as far as I can tell.

I could use awk to capture the output of the ubiattatch command to get the ubi device number something like below I just do not know if there is a standard function to mount a ubi formatted device:

	
local ubi_num=$(ubiattach --dev-path="$mtd_path" | \
		awk -F',' '/UBI device number [0-9]{1,}/{print $1}' | \
		awk '{print $4}')

The other thing I could do is parse on the device number in the case command using --devn=$ubi_device_number in the ubiattach command by specifying it in the string but this has the potential for failure as one could accidentally type in a ubi device number that is in use.

2

Ok so I thought of another potential way to grep the mtd id number from proc/mtd
This will mean the mtd number and the ubi number will match, setting the id rather than reading it after the ubiatatch command to use it in the mount command string.

preinit_mount_factory_data() {
	local part_name="$1"
	local mtd_path
	local ubi_num

		mtd_path=$(find_mtd_chardev "$part_name")
		ubi_num=$(grep $part_name /proc/mtd | cut -c 1-5 | grep -o '[0-9]*')
		ubiattach --dev-path="$mtd_path" --devn=$ubi_num
		mkdir /tmp/$part_name
		mount -o ro,noatime -t ubifs ubi$ubi_num:ubi_$part_name /tmp/$part_name
}