gss200610 / erofs

Simple utility to tinker with erofs images

OPlus image utilities

Prerequisites

• Linux running kernel 5.4 or up (check with uname -r)

Image rebuilding

• Used to rebuild read-only erofs images into EXT4 mountable images. Usage: sudo ./erofs.sh <path to original image> <image partition name> For example, if I'm trying to make system_ext image ext4, I'll use the following command: sudo ./erofs.sh system_ext.img system_ext

• IF you're running into issues like "not enough space to setup filesystem", specify filesystem size by adding the size (I recommend 64MB) after $2.

Product image rebuilding

• OPlus (previously oppo) has been being a jerk and adding a butt ton of useless so-called "optimizations" (porting killers). This is one of them.
• In Android 12 (OxygenOS 12 at least), OPlus has added OPLUS_FEATURE_OVERLAY_MOUNT to "mount product partition from existing my_* partitions" (to save image space? idk). With this going on, the product image shipped with OTAs is a dummy image that could not be mounted.
• Non-OPlus devices does NOT have OPLUS_FEATURE_OVERLAY_MOUNT implementation (and it is highly unrecommended to use it, as someone has bricked their devices before after implementing it). However, product image should NOT be empty (there is a system symlink pointing to /product). Therefore, this script is written to merge the my_* partitions into a single product image to replicate the /product behavior on OPlus devices.

Usage: sudo ./product-merge.sh

OPlus custom partition merging

• We will still have to merge my_* partitions after building the product image (as not all files exist in product image). The script will automatically merge the my_* partitions into system.

Usage: sudo ./oplus-merge.sh

Notes

• All images (especially system) must be the dir that the script is ran.

To-Do

• Remove dependency of system file_contexts to build all images (we currently cat system filecontexts to the working file contexts to make the image resign properly)
• Run checks on mounting image (It is reported by Velosh that sometimes mounting erofs images without -o loop -t erofs does not work. However it works on my PC, that's why I introduced this commit. Will work on checks for it later.)

Credits and Thanks

Amack

Erfan Abdi

Velosh

Piraterex

Xiaoxindada

And all those I forgot to mention.