Refactor magic mount

[yujincheng08]

Mirror was previously used for accessing the original file during magic mount when we are using a tmpfs to cover the target. However, since we introduce atomic mount, we switch all tmpfs mount in worker and then move to the target at once. It means that we can still access the original file when we are constructing the tmpfs mount point. Thus we no longer need mirror.

[reiryuki]

My magisk modules are detecting some original files from mirror while installing whether the rom is already have it or not.

if we cannot detect the original files, then the second installations after reboot will produce wrong detections which result in my modules will think the rom is already have the file (even the file is from the module at the first installation, not from the original rom), the the module will not use the file again. In result, the second installation will lose the file.

[vvb2060]

Magisk/docs/details.md

Lines 17 to 18 in a0b8aa4

	# Magisk internal stuffs
	INTERNALDIR=$MAGISKTMP/.magisk

.magisk is an internal directory, modules should not depend on it. I think it's better for the module to fix its incorrect behavior than to prevent magisk from developing

[vvb2060]

For your case, you can use magisk --denylist exec ls. Or fix the install logic, such as checking whether the file exists in both the system and module dir.

[reiryuki]

but magisk --path command will still available right?

and magisk --path/mirror dir

[yujincheng08]

yes. but note that magisk --path does not point to the internal directory.

[vvb2060]

This command is deprecated but retained for compatibility reasons. You can replace it with the following script, which behave the same but support KSU.

MAGISKTMP=/sbin
[ -d /sbin ] || MAGISKTMP=/debug_ramdisk

[vvb2060]

I think it can fix #6914

[osm0sis]

I just wanted to make one final comment on the mirror removal matter...

This is kinda too bad, since the mirror was an easy way to access and change the real partitions using root on devices that allow that, for both stock and custom ROMs.

That's quite a loss of function for the affected older Android versions, or any ROM not using ext4-dedup/erofs and could still allow rw system. Yes, it was an "internal" feature, but it is a loss for root nonetheless.

[vvb2060]

Just unmount all magic mounts in a new private mount namespace. I believe a developer using magisk's internal details should be able to do it. Because this is easier than using mirror and is a documented, supported method.

[osm0sis]

Just unmount all magic mounts in a new private mount namespace. I believe a developer using magisk's internal details should be able to do it. Because this is easier than using mirror and is a documented, supported method.

Hmm what about in a module post-fs-data.sh or other script?

[vvb2060]

magisk --denylist exec sh

[osm0sis]

Oh wow, that's a very cool feature. Wasn't aware of it! Thanks! 🙌