Replace fdisk -l with sysfs-based disk enumeration for better busybox compatibility

fdisk -l is unreliable in busybox environments due to 2TB max size based on max
sector assumption.

Changes:
- Add list_block_devices() helper function to initrd/etc/functions and
  initrd/etc/gui_functions that uses sysfs to enumerate all block devices
  (SATA, NVMe, VirtIO, IDE)

- Update show_system_info() in initrd/etc/gui_functions to use sysfs for
  disk size reporting instead of parsing fdisk output

- Update show_system_info() in initrd/bin/oem-system-info-xx30 to use sysfs
  for disk size reporting

- Replace device_has_partitions() in initrd/etc/functions to check for
  partition entries in sysfs instead of parsing fdisk output

- Replace is_gpt_bios_grub() in initrd/etc/functions to use sysfs partition
  attributes (PARTTYPENAME) instead of fdisk parsing. Improves reliability
  for GPT disk detection while maintaining backward compatibility.

- Update detect_boot_device() in initrd/etc/functions to use list_block_devices()

- Update boot device selection in initrd/bin/config-gui.sh to use
  list_block_devices()

- Update root device selection in initrd/bin/config-gui.sh to use
  list_block_devices()

- Update root device detection in initrd/bin/root-hashes-gui.sh to use
  list_block_devices()

Benefits:
- Fixes disk detection failures with virtio block devices (qcow2 disks)
- Works reliably in busybox environments
- More robust than fdisk output parsing
- Supports all block device types (sd*, nvme*, vd*, hd*)
- Improves debuggability with explicit logging

Note: Interactive partitioning in initrd/etc/luks-functions still uses fdisk
for actually writing partition tables, which is its legitimate use case.

Tested with debian-13 with root hashes. I guess it should still work with PureOS.

Signed-off-by: Thierry Laurion <insurgo@riseup.net>

Author: tlaurion

initrd/bin/config-gui.sh

@@ -119,8 +119,9 @@ while true; do
 		exit 0
 		;;
 	"b")
+		#Change /boot device
 		CURRENT_OPTION="$(load_config_value CONFIG_BOOT_DEV)"
-		if ! fdisk -l 2>/dev/null | grep "Disk /dev/" | cut -f2 -d " " | cut -f1 -d ":" >/tmp/disklist.txt; then
+		if ! list_block_devices >/tmp/disklist.txt; then
 			whiptail_error --title 'ERROR: No bootable devices found' \
 				--msgbox "    $ERROR\n\n" 0 80
 			exit 1
@@ -214,8 +215,9 @@ while true; do
 		fi
 		;;
 	"R")
+		#Change the root device for hashing
 		CURRENT_OPTION="$(load_config_value CONFIG_ROOT_DEV)"
-		fdisk -l 2>/dev/null | grep "Disk /dev/" | cut -f2 -d " " | cut -f1 -d ":" >/tmp/disklist.txt
+		list_block_devices >/tmp/disklist.txt
 		# filter out extraneous options
 		>/tmp/root_device_list.txt
 		for i in $(cat /tmp/disklist.txt); do

initrd/bin/oem-factory-reset

@@ -503,7 +503,7 @@ select_thumb_drive_for_key_material() {
 		if [ $(cat /tmp/usb_disk_list | wc -l) -gt 0 ] &&
 			file_selector --show-size "/tmp/usb_disk_list" "Select USB device to partition" &&
 			[ -n "$FILE" ]; then
-			# Obtain size of thumb drive to be wiped with fdisk
+			# Obtain size of selected thumb drive in bytes
 			disk_size_bytes="$(blockdev --getsize64 "$FILE")"
 			if [ "$disk_size_bytes" -lt "$((128 * 1024 * 1024))" ]; then
 				warn "Thumb drive size is less than 128MB!"

initrd/bin/oem-system-info-xx30

@@ -50,6 +50,10 @@ kernel=$(uname -s -r)
 
 FB_OPTIONS=""
 if whiptail --version | grep "fbwhiptail"; then FB_OPTIONS="--text-size 12"; fi
+
+# Build disk information using shared sysfs helper
+disk_info="$(disk_info_sysfs)"
+
 # make sure we know the EC version too, populate if not already set
 if [ -z "$EC_VER" ]; then
 	EC_VER=$(ec_version)
@@ -60,4 +64,4 @@ ec_ver_line=""
 [ -n "$EC_VER" ] && ec_ver_line="\nEC_VER: ${EC_VER}"
 
 whiptail_type $BG_COLOR_MAIN_MENU $FB_OPTIONS --title 'System Info' \
-	--msgbox "${BOARD_NAME}\nFW_VER: ${FW_VER}${ec_ver_line}\nKernel: ${kernel}\nCPU: ${cpustr}  RAM: ${memtotal} GB $battery_status\n$(fdisk -l | grep -e '/dev/sd.:' -e '/dev/nvme.*:' | sed 's/B,.*/B/')\n\n$(cat /tmp/devices_usb_pci)" 0 80
+	--msgbox "${BOARD_NAME}\nFW_VER: ${FW_VER}${ec_ver_line}\nKernel: ${kernel}\nCPU: ${cpustr}  RAM: ${memtotal} GB $battery_status\n${disk_info}\n$(cat /tmp/devices_usb_pci)" 0 80

initrd/bin/root-hashes-gui.sh

@@ -164,21 +164,29 @@ check_root_checksums() {
 open_block_device_lvm() {
   TRACE_FUNC
   local VG="$1"
+  local LV
+  local MAPPER_VG
 
   if ! lvm vgchange -ay "$VG"; then
     DEBUG "Can't open LVM VG: $VG"
     return 1
   fi
 
-  # Use the LV 'root'.  This is the default name used by Qubes.  There's no
-  # way to configure this at the moment.
-  if ! [ -e "/dev/mapper/$VG-root" ]; then
+  # Use the LV 'root'.  This is the default name used by Qubes.  Try both the
+  # canonical /dev/<vg>/<lv> path and mapper path (with dash escaping).
+  LV="/dev/$VG/root"
+  if ! [ -e "$LV" ]; then
+    MAPPER_VG="${VG//-/--}"
+    LV="/dev/mapper/$MAPPER_VG-root"
+  fi
+
+  if ! [ -e "$LV" ]; then
     DEBUG "LVM volume group does not have 'root' logical volume"
     return 1
   fi
 
   # Use the root LV now
-  open_block_device_layers "/dev/mapper/$VG-root"
+  open_block_device_layers "$LV"
 }
 
 # Open a LUKS device, then continue looking for more layers.
@@ -269,9 +277,16 @@ open_root_device_no_clean_up() {
 close_block_device_lvm() {
   TRACE_FUNC
   local VG="$1"
+  local LV
+  local MAPPER_VG
+
+  # We always use the LV 'root' currently.  Try canonical and mapper paths.
+  LV="/dev/$VG/root"
+  if ! [ -e "$LV" ]; then
+    MAPPER_VG="${VG//-/--}"
+    LV="/dev/mapper/$MAPPER_VG-root"
+  fi
 
-  # We always use the LV 'root' currently
-  local LV="/dev/mapper/$VG-root"
   if [ -e "$LV" ]; then
     close_block_device_layers "$LV"
   fi
@@ -367,7 +382,7 @@ detect_root_device()
   fi
 
   # generate list of possible boot devices
-  fdisk -l 2>/dev/null | grep "Disk /dev/" | cut -f2 -d " " | cut -f1 -d ":" > /tmp/disklist
+  list_block_devices > /tmp/disklist
 
   # filter out extraneous options
   > /tmp_root_device_list

initrd/etc/functions

@@ -802,24 +802,77 @@ enable_usb_storage() {
 
 device_has_partitions() {
 	local DEVICE="$1"
-	# fdisk normally says "doesn't contain a valid partition table" for
-	# devices that lack a partition table - except for FAT32.
-	#
-	# FAT32 devices have a volume boot record that looks enough like an MBR
-	# to satisfy fdisk.  In that case, fdisk prints a partition table header
-	# but no partitions.
-	#
-	# This check covers that: [ $(fdisk -l "$b" | wc -l) -eq 5 ]
-	# In both cases the output is 5 lines: 3 about device info, 1 empty line
-	# and the 5th will be the table header or the invalid message.
-	local DISK_DATA=$(fdisk -l "$DEVICE" 2>/dev/null)
-	if echo "$DISK_DATA" | grep -q "doesn't contain a valid partition table" ||
-		[ "$(echo "$DISK_DATA" | wc -l)" -eq 5 ]; then
-		# No partition table
+	# Check if device has any partitions by checking sysfs
+	# A device with partitions will have entries like /sys/block/sda/sda1, /sys/block/vda/vda1, etc
+	local device_name=$(basename "$DEVICE")
+
+	if [ ! -e "/sys/block/$device_name" ]; then
+		# Device doesn't exist
 		return 1
 	fi
-	# There is a partition table
-	return 0
+
+	# Count partitions - handle nvme partition naming (nvme0n1p1) and traditional (sda1, vda1, hda1)
+	if [ -n "$(ls -1 /sys/block/$device_name/ 2>/dev/null | grep -E "^${device_name}(p)?[0-9]")" ]; then
+		# There is a partition table
+		return 0
+	fi
+	# No partition table
+	return 1
+}
+
+# List all block devices using sysfs
+# Outputs one device path per line (e.g., /dev/sda, /dev/vda, /dev/nvme0n1)
+list_block_devices() {
+	TRACE_FUNC
+	for dev in /sys/block/sd* /sys/block/nvme* /sys/block/vd* /sys/block/hd*; do
+		if [ -e "$dev" ]; then
+			echo "/dev/$(basename "$dev")"
+		fi
+	done | sort
+}
+
+# Build displayable disk information using sysfs (vs current busybox's 2tb limit per https://bugs.busybox.net/show_bug.cgi?id=16276)
+# Output format: "Disk /dev/<name>: <GB> GB" per line
+disk_info_sysfs() {
+	TRACE_FUNC
+	local disk_info=""
+	DEBUG "disk_info_sysfs: Starting disk enumeration"
+	for dev in /sys/block/sd* /sys/block/nvme* /sys/block/vd* /sys/block/hd*; do
+		if [ -e "$dev" ]; then
+			local devname=$(basename "$dev")
+			DEBUG "disk_info_sysfs: Found device $dev (devname=$devname)"
+			local size_bytes=$(cat "$dev/size" 2>/dev/null)
+			DEBUG "disk_info_sysfs: /dev/${devname} reports size_bytes=$size_bytes sectors from $dev/size"
+			if [ -n "$size_bytes" ] && [ "$size_bytes" -gt 0 ]; then
+				# Determine sector size for this device from sysfs; prefer hw_sector_size
+				local sector_size=512
+				if [ -r "$dev/queue/hw_sector_size" ]; then
+					sector_size=$(cat "$dev/queue/hw_sector_size" 2>/dev/null || echo 512)
+					DEBUG "disk_info_sysfs: /dev/${devname} using hw_sector_size=$sector_size from $dev/queue/hw_sector_size"
+				elif [ -r "$dev/queue/logical_block_size" ]; then
+					sector_size=$(cat "$dev/queue/logical_block_size" 2>/dev/null || echo 512)
+					DEBUG "disk_info_sysfs: /dev/${devname} using logical_block_size=$sector_size from $dev/queue/logical_block_size"
+				else
+					DEBUG "disk_info_sysfs: /dev/${devname} using default sector_size=$sector_size (no queue info available)"
+				fi
+				# Convert from sectors * sector_size to bytes, then to decimal GB.
+				#
+				# Explanation of the constants:
+				# - We divide by 1,000,000,000 (1000000000) to report decimal GB (10^9 bytes),
+				#   which matches the historical output used elsewhere in Heads.
+				# - Shell arithmetic is integer-only, so to round to the nearest GB we add
+				#   half the divisor (500,000,000) before dividing. This implements
+				#   rounding instead of truncation.
+				#	If you prefer binary GiB (1024^3), replace the divisor and half-divisor
+				#	with 1073741824 and 536870912 respectively, or use `awk`/`printf`
+				#	for fractional output.
+				local size_gb=$(((size_bytes * sector_size + 500000000) / 1000000000))
+				disk_info="${disk_info}Disk /dev/${devname}: ${size_gb} GB\n"
+				DEBUG "disk_info_sysfs: /dev/${devname} calculated as ${size_gb} GB (${size_bytes} sectors * ${sector_size} bytes/sector = $((size_bytes * sector_size)) bytes)"
+			fi
+		fi
+	done
+	echo -n "$disk_info"
 }
 
 list_usb_storage() {
@@ -1278,12 +1331,19 @@ is_gpt_bios_grub() {
 
 	NUMBER="${BASH_REMATCH[1]}"
 
-	# Now we know the device and partition number, get the type.  This is
-	# specific to GPT disks, MBR disks are shown differently by fdisk.
-	TRACE "$PART_DEV is partition $NUMBER of $DEVICE"
-	if [ "$(fdisk -l "/dev/$DEVICE" 2>/dev/null | awk '$1 == '"$NUMBER"' {print $5}')" == grub ]; then
-		return 0
+	# Check partition type using sysfs if available, otherwise check for grub type
+	# For GPT disks, check /sys/class/block/<dev>/<partition>/uevent for PARTTYPENAME
+	local part_sys="/sys/class/block/$DEVICE/$(basename "$PART_DEV")"
+	if [ -e "$part_sys/uevent" ]; then
+		if grep -q "PARTTYPENAME=BIOS boot" "$part_sys/uevent"; then
+			TRACE "$PART_DEV is a GPT BIOS grub partition"
+			return 0
+		fi
 	fi
+
+	# Fallback: try to detect using other sysfs attributes if available
+	# For MBR disks, we would need to check partition type differently
+	DEBUG "$PART_DEV - unable to confirm it's a bios-grub partition via sysfs"
 	return 1
 }
 
@@ -1354,7 +1414,7 @@ detect_boot_device() {
 	fi
 
 	# generate list of possible boot devices
-	fdisk -l 2>/dev/null | grep "Disk /dev/" | cut -f2 -d " " | cut -f1 -d ":" >/tmp/disklist
+	list_block_devices >/tmp/disklist
 
 	# Check each possible boot device
 	for i in $(cat /tmp/disklist); do

initrd/etc/gui_functions

@@ -93,7 +93,7 @@ display_block_device_size() {
 	local block_dev disk_size_bytes
 	block_dev="$1"
 
-	# Obtain size of thumb drive to be wiped with fdisk
+	# Obtain size of the selected block device in bytes
 	if ! disk_size_bytes="$(blockdev --getsize64 "$block_dev")"; then
 		exit 1
 	fi
@@ -178,6 +178,9 @@ show_system_info() {
 	cpustr=$(cat /proc/cpuinfo | grep 'model name' | uniq | sed -r 's/\(R\)//;s/\(TM\)//;s/CPU //;s/model name.*: //')
 	kernel=$(uname -s -r)
 
+	# Get disk information using the shared sysfs helper from functions
+	local disk_info="$(disk_info_sysfs)"
+
 	local ec_ver_line=""
 	[ -n "$EC_VER" ] && ec_ver_line="
 	EC_VER: ${EC_VER}"
@@ -191,8 +194,7 @@ show_system_info() {
 	Microcode: $(cat /proc/cpuinfo | grep microcode | uniq | cut -d':' -f2 | tr -d ' ')
 	RAM: ${memtotal} GB
 	$battery_status
-	$(fdisk -l 2>/dev/null | grep -e '/dev/sd.:' -e '/dev/nvme.*:' | sed 's/B,.*/B/')
-	"
+	${disk_info}"
 
 	local msgbox_rm_tabs=$(echo "$msgbox" | tr -d "\t")