# Create the raw disk image # # The disk image will be created as a bootable disk image supporting booting via EFI and/or Legacy BIOS if the # respective bootloaders are available. This script expects an EFI bootloader to be prepared in advance in a # staging directory. # # If an EFI bootloader has been prepared, $RAWDISK_BOOT_EFI_STAGING_ROOT must point to the EFI staging directory. # ### Check prerequisites local use_syslinux_legacy=no if has_binary syslinux && [[ -z "$SECURE_BOOT_BOOTLOADER" ]]; then if is_true "${RAWDISK_BOOT_EXCLUDE_SYSLINUX_LEGACY:-no}"; then LogPrint "DISABLED: Using syslinux to create a BIOS Legacy bootloader" else use_syslinux_legacy=yes fi fi if ([[ -z "$RAWDISK_BOOT_EFI_STAGING_ROOT" ]] && ! is_true $use_syslinux_legacy); then Error "Creating a raw disk image requires an EFI bootloader or syslinux" fi ### Create an initial disk image # Wait for file systems to settle before trying to determine partition content size sync sleep 3 # should not be strictly necessary as Linux sync(2) waits until data is written # Determine the appropriate size (adding 1 MiB for plus 7% for file system overhead/reserve) local staged_boot_partition_contents=( "$KERNEL_FILE" "$TMP_DIR/$REAR_INITRD_FILENAME" ) [[ -n "$RAWDISK_BOOT_EFI_STAGING_ROOT" ]] && staged_boot_partition_contents+=( "$RAWDISK_BOOT_EFI_STAGING_ROOT" ) local disk_image_size_MiB="$(du -m --summarize --total "${staged_boot_partition_contents[@]}" | awk '$2 == "total" { printf("%.0f\n", 1 + ($1 * 1.07) + .5); }')" local full_disk_name="${RAWDISK_IMAGE_NAME:-rear-$HOSTNAME}.raw" local disk_image="$TMP_DIR/$full_disk_name" LogPrint "Creating $disk_image_size_MiB MiB raw disk image \"$full_disk_name\"" dd if=/dev/zero of="$disk_image" bs=1M count="$disk_image_size_MiB" [ -f "$disk_image" ] || Error "Could not create initial disk image file $disk_image" ### Create a GPT partition table # Determine the configuration for the boot partition local typecode="8300" # Linux partition for non-EFI booting [[ -n "$RAWDISK_BOOT_EFI_STAGING_ROOT" ]] && typecode="ef00" # EFI System partition if an EFI bootloader has been prepared local legacy_boot_option="" is_true $use_syslinux_legacy && legacy_boot_option="--attributes=1:set:2" # mark partition as Legacy BIOS-bootable sgdisk --new 1::0 --typecode=1:"$typecode" --change-name=1:"${RAWDISK_GPT_PARTITION_NAME:-Rescue System}" $legacy_boot_option "$disk_image" StopIfError "Could not create GPT partition table on $disk_image" Log "Raw disk image partition table:" gdisk -l "$disk_image" >&2 ### Create block devices representing the raw disk image local disk_device # separate 'local' statement to avoid losing $(...) exit status - cf. https://stackoverflow.com/a/10397996 # Set up the loop device, trying the '--partscan' option first (introduced in util-linux v2.21) # Trying '--partscan' here first avoids a situation where all of the methods below fail to make the kernel recognize # partitions on the loop device (cf. https://github.com/rear/rear/pull/2071). disk_device="$(losetup --show --find "$disk_image" --partscan || losetup --show --find "$disk_image")" StopIfError "Could not create loop device on $disk_image" AddExitTask "losetup -d $disk_device >&2" local boot_partition="${disk_device}p1" # Try several methods to make the kernel recognize partitions on the loop device, if not already done automatically: # 1. partprobe if [[ ! -b "$boot_partition" ]] && has_binary partprobe; then partprobe "$disk_device" || LogPrintError "partprobe failed to make the kernel recognize loop device partitions" fi # 2. Heuristic: wait [[ ! -b "$boot_partition" ]] && sleep 5 # 3. kpartx local use_kpartx=no if [[ ! -b "$boot_partition" ]]; then if has_binary kpartx; then kpartx -as "$disk_device" # detect partitions, create device nodes - synchronously (wait until done) StopIfError "kpartx could not create loop partition device nodes from loop device $disk_device" AddExitTask "kpartx -d $disk_device >&2" if [[ ! -b "$boot_partition" ]]; then # Some versions of kpartx (as on CentOS 6) do not create partition device nodes under /dev, but leave # them under /dev/mapper instead. This kludge will pick those up. local alternate_boot_partition="/dev/mapper/"$(basename "$boot_partition") [[ -b "$alternate_boot_partition" ]] && boot_partition="$alternate_boot_partition" fi use_kpartx=yes else LogPrintError "It seems that the current linux kernel does not support loop device partitions." LogPrintError "TIP: You might achieve loop device partition support by installing the 'kpartx' tool, if available." fi fi # If unsuccessful, say so. [[ -b "$boot_partition" ]] || Error "Cannot prepare boot file system for the RAWDISK image: Missing OS support for loop device partitions." ### Create and populate the boot file system # Note: Having a small EFI System Partition (ESP) might introduce problems: # - The UEFI spec seems to require a FAT32 EFI System Partition (ESP). # - syslinux/Legacy BIOS fails to install on small FAT32 partitions with "syslinux: zero FAT sectors (FAT12/16)". # - Some firmwares fail to boot from small FAT32 partitions. # - Some firmwares fail to boot from FAT16 partitions. # See: # - http://www.rodsbooks.com/efi-bootloaders/principles.html # - http://lists.openembedded.org/pipermail/openembedded-core/2012-January/055999.html # As there seems to be no silver bullet, let mkfs.vfat choose the 'right' FAT partition type based on partition size # (i.e. do not use the '-F 32' option) and hope for the best... mkfs.vfat $v "$boot_partition" -n "${RAWDISK_FAT_VOLUME_LABEL:-RESCUE SYS}" || Error "Could not create boot file system" local boot_partition_root="$TMP_DIR/boot" mkdir -p "$boot_partition_root" || Error "Could not create boot file system mount point" mount "$boot_partition" "$boot_partition_root" || Error "Could not mount boot file system" AddExitTask "umount $boot_partition_root >&2" # Populate the boot file system with kernel, initrd and possibly EFI bootloader cp -rL $v "${staged_boot_partition_contents[@]}" "$boot_partition_root" >&2 || Error "Could not populate boot partition" ### Install syslinux stuff as required # Note: This may add files to the boot file system *and* modify the boot sector directly within the raw disk image. # After installing a Legacy BIOS bootloader, files on the boot partition should not change: The bootloader file is # patched during installation with a list of its exact on-disk block locations. if is_true "$RAWDISK_BOOT_USING_SYSLINUX" || is_true $use_syslinux_legacy; then # Install syslinux configuration, which may be shared between syslinux/EFI and syslinux/Legacy bootloaders. local syslinux_installation_dir="$boot_partition_root/syslinux" mkdir -p "$syslinux_installation_dir" || Error "Could not create syslinux bootloader directory" cat > "$syslinux_installation_dir/syslinux.cfg" << EOF DEFAULT rescue LABEL rescue SAY SAY ${RAWDISK_BOOT_SYSLINUX_START_INFORMATION:-Starting the rescue system...} KERNEL ../$(basename "$KERNEL_FILE") APPEND $KERNEL_CMDLINE INITRD ../$REAR_INITRD_FILENAME EOF StopIfError "Could not write syslinux bootloader configuration" if is_true $use_syslinux_legacy; then LogPrint "Using syslinux to install a Legacy BIOS bootloader" # Install syslinux as Legacy BIOS bootloader syslinux --directory "/syslinux" --install "$boot_partition" StopIfError "Could not install Legacy BIOS bootloader (syslinux)" # Install the BIOS boot sector dd if="$(find_syslinux_file gptmbr.bin)" of="$disk_device" bs=440 count=1 oflag=sync StopIfError "Could not install Legacy BIOS boot sector (syslinux)" fi fi Log "Raw disk boot partition capacity after copying:" df -h "$boot_partition_root" >&2 ### Allow examining the boot file system and loop device for debugging if is_true ${RAWDISK_DEBUG:-no}; then LogUserOutput "Entering shell to examine the raw disk's boot file system, exit to continue:" (cd "$boot_partition_root"; bash) <&6 >&7 2>&8 fi ### Unmount the boot partition, release the loop device umount "$boot_partition_root" || Error "Could not unmount boot file system" RemoveExitTask "umount $boot_partition_root >&2" if is_true $use_kpartx; then kpartx -d "$disk_device" || Error "Could not delete partition device nodes from loop device $disk_device" RemoveExitTask "kpartx -d $disk_device >&2" fi losetup -d "$disk_device" || Error "Could not delete loop device" RemoveExitTask "losetup -d $disk_device >&2" ### Compress the disk image on request if [[ -n "$RAWDISK_IMAGE_COMPRESSION_COMMAND" ]]; then $RAWDISK_IMAGE_COMPRESSION_COMMAND "$disk_image" StopIfError "Could not compress disk image using <<$RAWDISK_IMAGE_COMPRESSION_COMMAND \"$disk_image\">>" disk_image="$(echo "$disk_image"*)" [[ -f "$disk_image" ]] || Error "Could not find compressed disk image ${disk_image}*" fi ### Add disk the image to the result files RESULT_FILES+=( "$disk_image" )