From 0bbf3c3e71e613801583222ae782fae866ecd5d8 Mon Sep 17 00:00:00 2001
From: Aaron Ball <nullspoon@oper.io>
Date: Sat, 4 Mar 2023 22:03:20 -0700
Subject: Refactor to support udev block device loading

Previously block device aliases did not load correctly, so the direct
`/dev/nvme*` path for example was required as `/dev/disk/by-*` was not
available at all for mounting by partlabel or uuid.

This adds the udevadm and udevd binaries so the /dev/disk directory tree
can be populated during init, allowing for block device aliases. This
also does some cleanup and organization to improve the over code
quality.
---
 init        | 63 +++++++++++++++++++++----------------------------------------
 mkinitramfs | 21 +++++++++++++++------
 2 files changed, 37 insertions(+), 47 deletions(-)

diff --git a/init b/init
index 36dde80..7babfd2 100755
--- a/init
+++ b/init
@@ -121,7 +121,7 @@ parse_cmdline() {
 #
 setup_encrypted() {
   local path="${1}"
-  local name="$(echo ${path} | tr / _)"
+  local name="${path//\//_}"
 
   # Decrypted block dev path is /dev/mapper/${name}
   cryptsetup luksOpen ${path} ${name}
@@ -144,35 +144,18 @@ setup_encrypted() {
 }
 
 
-#
-# Waits up to a threshold (in seconds) for the specified path to appear as a
-# block device. A check for device presence occurs once per second.
-#
-# If the device appears within the threshold time, the function returns early
-# with error code 0 (all is well - no need to wait more).
-#
-# If the block device fails to appear within the threshold time, the function
-# returns code 2 (not found)
-#
-# @param dev     Path to the device to wait for
-# @param timeout Maximum time (in seconds) to wait for the device to appear
-#
-wait_dev() {
-  local dev=${1}
-  local timeout=${2}
-
-  local wait=0
-
-  while [ ${wait} -lt ${timeout} ]; do
-    # If the path exists as a block device, exit the wait loop
-    [ -b "${dev}" ] && return 0
-    # Increment the wait counter
-    wait=$(( wait + 1 ))
-    # Wait another second for the device to appear
-    sleep 1
-  done
+udev_populate() {
+  # Start udevd if not already running
+  pidof -s udevd > /dev/null || /sbin/udevd --daemon
 
-  return 2
+  /sbin/udevadm trigger --type=subsystems --action=add
+  /sbin/udevadm trigger --type=devices --action=add --subsystem-match=block
+  /sbin/udevadm trigger --type=devices --action=add --subsystem-match=input
+  /sbin/udevadm settle
+
+  # Shut down udevd once devices are populated so main init can handle udevd to
+  # finish booting
+  kill $(pidof udevd)
 }
 
 
@@ -182,30 +165,27 @@ wait_dev() {
 #
 main() {
   # Mount the /proc and /sys filesystems.
-  mount -t tmpfs                        none    /run
-  mount -t sysfs -o nodev,noexec,nosuid sysfs   /sys
-  mount -t proc  -o nodev,noexec,nosuid proc    /proc
-  mount -t devtmpfs                     none    /dev
-  mount -t devpts                       devpts  /dev/pts
-  mount -t tmpfs                        shm     /dev/shm
+  mount -t tmpfs -o mode=0755,nousid,nodev none   /run
+  mount -t sysfs -o nodev,noexec,nosuid    sysfs  /sys
+  mount -t proc  -o nodev,noexec,nosuid    proc   /proc
+  mount -t tmpfs                           shm    /dev/shm
+  mount -t devtmpfs -o exec,nosuid,noatime dev    /dev
+  mount -t devpts                          devpts /dev/pts
 
   local fakeroot='/mnt/root'
 
   if [ ! -d "${fakeroot}" ]; then
-    log INFO "Fake root location ${fakeroot} does not exist. Creating."
-    mkdir ${fakeroot}
+    log INFO "Fake root location ${fakeroot} does not exist. Cannot boot."
   fi
 
   parse_cmdline "$(cat /proc/cmdline)"
 
   # display fanciful boot image
   screen_init
+  udev_populate
 
   log INFO "Root device: ${ROOTDEV}"
 
-  log INFO "Waiting up to 10 seconds for root device to appear."
-  wait_dev "${ROOTDEV}" 10
-
   # Drop to maintenance shell if root device does not exist.
   if [ "$?" -ne 0 ]; then
     log ERROR "ERROR: Root device ${ROOTDEV} does not exist or can not be accessed."
@@ -215,7 +195,8 @@ main() {
   fi
 
   # Modprobe atkbd to ensure user can type password
-  for i in dm-crypt i8042 atkbd; do
+  # dm-crypt
+  for i in i8042 atkbd; do
     printf 'Loading required module [%s]\n' "${i}"
     modprobe "${i}" || printf 'Failed loading %s\n' "${i}"
   done
diff --git a/mkinitramfs b/mkinitramfs
index 52e0165..5d35386 100755
--- a/mkinitramfs
+++ b/mkinitramfs
@@ -36,7 +36,7 @@ function resolve_bins {
   local args=${@}
 
   for i in ${args[@]}; do
-    local path=$(which ${i} 2>/dev/null)
+    local path=$(type -p ${i} 2>/dev/null)
 
     if [[ $? -gt 0 ]]; then
       echo "Could not find binary ${i}. Is it installed?"
@@ -114,7 +114,7 @@ function mkcpio {
 
 #
 # Sets up cache dir for later writing to an archive (via cpio).
-# Performs simple operations like creating a basic directory structure, 
+# Performs simple operations like creating a basic directory structure,
 #
 # @param cache Path to the cache directory. Will be created if not exists
 #
@@ -203,10 +203,15 @@ function main {
   fi
 
   # List of binaries to exist in the new initramfs
-  resolve_bins \
-    bash cat echo ls cryptsetup chmod chown mount sleep umount clear cut \
-    grep less tr which blkid partprobe reboot shutdown switch_root modprobe \
-    rmmod
+  # Standard shell binaries
+  resolve_bins bash cat pidof ps ls clear cut grep less blkid switch_root kill
+  # Module management
+  resolve_bins udevadm udevd modprobe rmmod
+  # For encrypted and block device support
+  resolve_bins partprobe dmsetup mount umount cryptsetup
+
+  # For debugging
+  #resolve_bins sleep mkdir chmod chown tr
 
   # Set up the archive source dir.
   cache_dir_setup ${cache}
@@ -218,6 +223,10 @@ function main {
   install -v -D /usr/lib/libgcc_s.so   "${cache}/usr/lib/libgcc_s.so"
   install -v -D /usr/lib/libgcc_s.so.1 "${cache}/usr/lib/libgcc_s.so.1"
 
+  # Install udev rules for block devices
+  mkdir -p "${cache}/lib/udev"
+  cp -rv /lib/udev/rules.d "${cache}/lib/udev/rules.d"
+
   # Copy binary and dependencies to cache dir
   for bin in ${fqbins[@]}; do
     # Copy the binary of interest
-- 
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