[UPDATED] Unofficial TWRP for OnePlus 7/7 Pro/5G Download

Unofficial TWRP for OnePlus 7/7 Pro/5G - TWRP that's been modified for true dual booting by splitting userdata into a/b slots (also does the same for metadata for encryption support). The installer script repartitions userdata for dualboot or stock based on your input.

This has only been tested on the Oneplus 7 Pro - 256gb. Although it should theoretically work on other OP7's I haven't formally tested it. So if you are on one of these devices, make a post with the output of this command:
su -c sgdisk /dev/block/sda --print

■ Features TWRP OnePlus

• Same as mauronofrio's TWRP
• Can choose between stock layout, a/b userdata, or a/b/c userdata where 'c' is a common data partition that'll show up in both roms - it's quite handy
• Option to choose between ext4 and f2fs
• Disables verity - fstabs are modified for dual boot and so this is a must unless you choose stock layout in which case it's optional
• Option to disable forced encryption
• Option to install magisk - this is mandatory with a/b/c layout

■ Common Data

I recommend the a/b/c layout which includes this common data partition

• If you choose a/b/c layout - you'll have a/b userdata, but you'll also get a 3rd userdata partition I call 'Common Data'
• The name 'Common Data' gives away its purpose - to store files that you'll access on both slots/roms. So stuff like zips, pictures, music, TWRP backups, etc.
• In TWRP, this shows up as another storage option for backup/restore and on your pc as well - your phone will have 'Common Storage' and 'Internal Storage'
• In order to be accessible when booted, some parts of the system are modified so that the it'll be accessible WITHOUT root by the following mechanisms:

- The common data partition is mounted to /sdcard/CommonData
- Furthermore, if your use case is like mine where my music files are in common data, all FOLDERS are mounted over top of sdcard. So for example:
/datacommon/Music -> /sdcard/Music
+ This of course overwrites anything there so make sure that you don't have the same folder in both datacommon and regular data
+ Note that there are 3 exceptions to this folder mounting rule:
1 )Android
2) lost+found
+ The reasoning should be obvious - lost+found isn't something you should need to mess with and Android is for regular data partition only - that's OS specific and should be on separate slots

■ Flashing Instructions

You MUST be booted into TWRP already when flashing this zip. You can grab a bootable twrp img from here
Since this modifies data - the zip CANNOT be on sdcard or data at all.
- If you flash from data, the zip will copy itself to /tmp and instruct you to flash it from there
- You could do the above or copy it to a place like /dev or /tmp and flash it from there
- Alternatively, you can adb sideload it
Read through ALL the prompts - there's lots of options
Note that if you change partition layout, THIS WILL WIPE ALL DATA INCLUDING INTERNAL STORAGE

■ How to Flash Roms - If you're NOT stock layout

Nothing changes here except ONLY FLASH IN TWRP
- Roms always flash to the opposite slot. Keep that in mind and you'll be fine
- So don't take an OTA while booted - boot into twrp, switch slots, reboot into twrp, flash rom
Normal flash procedure:
1) Boot into twrp
2) reboot into twrp selecting slot you do NOT want rom installed to
3) Flash rom
4) Flash this zip
5) Reboot into twrp
6) Flash everything else

■ How to Manually Repartition Back to Stock
In the event any step in the repartioning fails, the entire installer aborts. The good news is that this prevents a potential brick. The bad is that you need to manually revert back. See the README on github for the procedure. Note that if the install went fine and you want to switch back to stock later, just flash the installer again and choose stock layout

■ Limitation
If you set a password, regardless of encryption status, it'll corrupt the other slot if it's also password protected.
Either don't use a password on one slot, or leave one slot (I'll use 'a' in this example) unencrypted and:
Setup rom, password, and everything on slot a
Boot back into twrp, choose common data as storage, and backup userdata (if not using a/b/c layout, backup TWRP folder to your computer)
Setup rom, password, and everything on the other slot (b)
Boot back into twrp, switch back to slot a (reboot back into twrp), and restore the twrp backup
If you messed this up and are unencrypted - delete the /data/system/locksettings.db file
If you messed this up and are encrypted - you lost the data on that slot:[LIST][*]Unmount metadata in twrp gui[*]Format metadata with this command:
Code:
mke2fs -t ext4 -b 4096 /dev/block/sda$metadata_partnum
where metadata_partnum is the partition number of the current metadata partition (you can find this with
Code:
sgdisk /dev/block/sda --print
). DO NOT FORGET THE PARTITION NUMBER. If you do, you'll format all of sda which results in a brick[*]Reboot into twrp and format data in gui