feat(meta): Initial commit

README.md

@@ -1,3 +1,67 @@
 # zbm-syslinux-pacman-hook
 
-Arch Linux pacman hook to automatically recreate syslinux and MBR after updates
+Arch Linux pacman hook to automatically recreate syslinux and MBR after updates
+
+# Setup
+
+Get started like so:
+
+1. Install dependency `rsync`
+1. Clone repo into arbitrary path `<repo>`
+1. Make `pacman-zbm-syslinux-regen.sh` executable
+    ```
+    chmod +x <repo>/pacman-zbm-syslinux-regen.sh
+    ```
+1. Symlink to files, for example
+    ```
+    sudo ln -s <repo>/pacman-zbm-syslinux-regen.sh /usr/local/bin/pacman-zbm-syslinux-regen
+    sudo ln -s <repo>/pacman-zbm-syslinux-regen.hook /usr/share/libalpm/hooks/pacman-zbm-syslinux-regen.hook
+    ```
+    Note that while you may choose an arbitrary location for your shell script symlink `pacman-zbm-syslinux-regen.hook` file references `/usr/local/bin/pacman-zbm-syslinux-regen`. Change that accordingly if you need to.
+
+# What's it do?
+
+In `pacman` whenever the `syslinux` package is getting updated this hook will replace all `*.c32` COMBOOT module files in `/boot/syslinux`, will reinstall newest `extlinux` and write the newest `mbr.bin` Master Boot Record file onto the boot disk.
+
+This happens as a `PostTransaction` in `pacman`.
+
+We identify the boot disk via:
+```
+findmnt --noheadings --target "${boot_dir}" --output 'SOURCE'
+```
+
+Where `"${boot_dir}"` is:
+```
+boot_dir='/boot/syslinux'
+```
+
+If this returns zero or more than one mounted drive we bail, print an error message and do not do any operations.
+
+# Assumptions
+
+This hook is intended to work with [quico.space/quico-os-setup/arch-zbm](https://quico.space/quico-os-setup/arch-zbm), a root on ZFS installation script that uses ZFSBootMenu as its boot loader; it's specifically intended for use on `arch-zbm` machines that use legacy BIOS. Before using this hook for any other purpose please closely review what it does and adapt to your use case as needed.
+
+We do not care about `pacman` events other than a `syslinux` package update. Specifically if ZFSBootMenu gets an update `syslinux` and our Master Boot Record remain unaffected. Kernel update? Same, no change needed since no kernel or module change directly influence the simple and decoupled structure of `syslinux`.
+
+# Development
+
+## Conventional commits
+
+This project uses [Conventional Commits](https://www.conventionalcommits.org/) for its commit messages.
+
+### Commit types
+
+Commit _types_ besides `fix` and `feat` are:
+
+- `build`: Project structure, directory layout, build instructions for roll-out
+- `refactor`: Keeping functionality while streamlining or otherwise improving function flow
+- `test`: Working on test coverage
+- `docs`: Documentation for project or components
+
+### Commit scopes
+
+The following _scopes_ are known for this project. A Conventional Commits commit message may optionally use one of the following scopes or none:
+
+- `script`: Any other script work that doesn't specifically fall into the above scopes
+- `hook`: Configuring the hook(s)
+- `meta`: Affects the project's repo layout, readme content, file names etc.

pacman-zbm-syslinux-regen.hook

@@ -0,0 +1,11 @@
+[Trigger]
+Operation = Upgrade
+Type = Package
+Target = syslinux
+
+[Action]
+Description = Regen syslinux and MBR
+When = PostTransaction
+Exec = /usr/local/bin/pacman-zbm-syslinux-regen
+Depends = rsync
+AbortOnFail

pacman-zbm-syslinux-regen.sh

@@ -0,0 +1,21 @@
+#!/bin/bash
+
+boot_dir='/boot/syslinux'
+boot_dir="${boot_dir%/}"
+boot_disk="$(findmnt --noheadings --target "${boot_dir}" --output 'SOURCE')" || {
+    printf -- '%s\n' \
+        'Unable to identify boot drive for '"'${boot_dir}'"' boot dir.' \
+        'Cowardly exiting. No syslinux files nor MBR were overwritten.'
+    exit 1
+}
+if [[ "$(<<<"${boot_dir}" wc -l)" -gt '1' ]]; then
+    printf -- '%s\n' \
+        'More than one drive mounted at '"'${boot_dir}'"' boot dir.' \
+        'Cowardly exiting. No syslinux files nor MBR were overwritten.'
+    exit 1
+fi
+
+find "${boot_dir}" -type f -iname '*.c32' -delete
+rsync -a '/usr/lib/syslinux/bios/'*'.c32' "${boot_dir}"'/'
+extlinux --install "${boot_dir}"
+dd bs=440 count=1 conv=notrunc if='/usr/lib/syslinux/bios/mbr.bin' of="${boot_disk}"