Add support for MTD ioctls

[kempniu]

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/mtd/mtdchar.c?h=v6.13#n822

A limited subset of these ioctls can be tested without a physical MTD device by running:

sudo modprobe nandsim
sudo chown "${USER}" /dev/mtd1
git clone --depth 1 --recurse-submodules https://github.com/kempniu/yafut.git
cd yafut/
cmake -Bbuild && cmake --build build
dd if=/dev/urandom bs=32k count=1 | tee garbage-in | rr record build/yafut -d /dev/mtd1 -v -v -w -i - -o /garbage   
rr replay -a -M
rr record build/yafut -d /dev/mtd1 -v -v -r -i /garbage -o garbage-out
rr replay -a -M
sha256sum garbage-in garbage-out

[kempniu]

The Android build fails because it uses Android NDK r25c, which was released in July 2022 and therefore does not contain the definitions of the MEMREAD ioctl and struct mtd_read_req, which first appeared in Linux kernel 6.1, which was released in December 2022. AFAICT, Android NDK r25c is no longer supported.

I verified that this PR builds fine with Android NDK r26d (September 2023) or any newer version - the latest stable Android NDK release is r27c (July 2024):

diff --git a/.android/Dockerfile b/.android/Dockerfile
index 62fb2cd5..8557eefc 100644
--- a/.android/Dockerfile
+++ b/.android/Dockerfile
@@ -1,6 +1,6 @@
 FROM ubuntu:latest
 
-ARG ndk_version=r25c
+ARG ndk_version=r27c
 
 RUN apt-get update && apt-get install -y \
     build-essential \

[rocallahan]

Thanks for the PR. I'm a bit swamped so I might need another week to get to it.
We usually deal with new syscalls and types etc by copying their definitions into rr when needed --- kernel_supplement.h for stuff used by rr itself and util.h or the tests themselves when used in tests.

[khuey]

I'll look at bumping Android's NDK version later this week. Thanks for doing the legwork there :)

[khuey]

Alright lets rebase this and verify that CI passes now that we're on r27c.

[khuey]

Thanks!