diff options
Diffstat (limited to 'nixos/lib/make-disk-image.nix')
| -rw-r--r-- | nixos/lib/make-disk-image.nix | 149 |
1 files changed, 134 insertions, 15 deletions
diff --git a/nixos/lib/make-disk-image.nix b/nixos/lib/make-disk-image.nix index 8aa606a56af..55643facea0 100644 --- a/nixos/lib/make-disk-image.nix +++ b/nixos/lib/make-disk-image.nix @@ -15,12 +15,18 @@ , # size of the boot partition, is only used if partitionTableType is # either "efi" or "hybrid" + # This will be undersized slightly, as this is actually the offset of + # the end of the partition. Generally it will be 1MiB smaller. bootSize ? "256M" , # The files and directories to be placed in the target file system. - # This is a list of attribute sets {source, target} where `source' - # is the file system object (regular file or directory) to be - # grafted in the file system at path `target'. + # This is a list of attribute sets {source, target, mode, user, group} where + # `source' is the file system object (regular file or directory) to be + # grafted in the file system at path `target', `mode' is a string containing + # the permissions that will be set (ex. "755"), `user' and `group' are the + # user and group name that will be set as owner of the files. + # `mode', `user', and `group' are optional. + # When setting one of `user' or `group', the other needs to be set too. contents ? [] , # Type of partition table to use; either "legacy", "efi", or "none". @@ -28,6 +34,9 @@ # partition of reasonable size is created in addition to the root partition. # For "legacy", the msdos partition table is used and a single large root # partition is created. + # For "legacy+gpt", the GPT partition table is used, a 1MiB no-fs partition for + # use by the bootloader is created, and a single large root partition is + # created. # For "hybrid", the GPT partition table is used and a mandatory ESP # partition of reasonable size is created in addition to the root partition. # Also a legacy MBR will be present. @@ -54,9 +63,14 @@ format ? "raw" }: -assert partitionTableType == "legacy" || partitionTableType == "efi" || partitionTableType == "hybrid" || partitionTableType == "none"; +assert partitionTableType == "legacy" || partitionTableType == "legacy+gpt" || partitionTableType == "efi" || partitionTableType == "hybrid" || partitionTableType == "none"; # We use -E offset=X below, which is only supported by e2fsprogs assert partitionTableType != "none" -> fsType == "ext4"; +# Either both or none of {user,group} need to be set +assert lib.all + (attrs: ((attrs.user or null) == null) + == ((attrs.group or null) == null)) + contents; with lib; @@ -75,6 +89,7 @@ let format' = format; in let rootPartition = { # switch-case legacy = "1"; + "legacy+gpt" = "2"; efi = "2"; hybrid = "3"; }.${partitionTableType}; @@ -85,6 +100,16 @@ let format' = format; in let mklabel msdos \ mkpart primary ext4 1MiB -1 ''; + "legacy+gpt" = '' + parted --script $diskImage -- \ + mklabel gpt \ + mkpart no-fs 1MB 2MB \ + set 1 bios_grub on \ + align-check optimal 1 \ + mkpart primary ext4 2MB -1 \ + align-check optimal 2 \ + print + ''; efi = '' parted --script $diskImage -- \ mklabel gpt \ @@ -120,7 +145,7 @@ let format' = format; in let binPath = with pkgs; makeBinPath ( [ rsync - utillinux + util-linux parted e2fsprogs lkl @@ -134,9 +159,14 @@ let format' = format; in let # !!! should use XML. sources = map (x: x.source) contents; targets = map (x: x.target) contents; + modes = map (x: x.mode or "''") contents; + users = map (x: x.user or "''") contents; + groups = map (x: x.group or "''") contents; closureInfo = pkgs.closureInfo { rootPaths = [ config.system.build.toplevel channelSources ]; }; + blockSize = toString (4 * 1024); # ext4fs block size (not block device sector size) + prepareImage = '' export PATH=${binPath} @@ -149,6 +179,24 @@ let format' = format; in let echo $(( "$1" * 512 )) } + # Given lines of numbers, adds them together + sum_lines() { + local acc=0 + while read -r number; do + acc=$((acc+number)) + done + echo "$acc" + } + + mebibyte=$(( 1024 * 1024 )) + + # Approximative percentage of reserved space in an ext4 fs over 512MiB. + # 0.05208587646484375 + # × 1000, integer part: 52 + compute_fudge() { + echo $(( $1 * 52 / 1000 )) + } + mkdir $out root="$PWD/root" @@ -160,22 +208,33 @@ let format' = format; in let set -f sources_=(${concatStringsSep " " sources}) targets_=(${concatStringsSep " " targets}) + modes_=(${concatStringsSep " " modes}) set +f for ((i = 0; i < ''${#targets_[@]}; i++)); do source="''${sources_[$i]}" target="''${targets_[$i]}" + mode="''${modes_[$i]}" + if [ -n "$mode" ]; then + rsync_chmod_flags="--chmod=$mode" + else + rsync_chmod_flags="" + fi + # Unfortunately cptofs only supports modes, not ownership, so we can't use + # rsync's --chown option. Instead, we change the ownerships in the + # VM script with chown. + rsync_flags="-a --no-o --no-g $rsync_chmod_flags" if [[ "$source" =~ '*' ]]; then # If the source name contains '*', perform globbing. mkdir -p $root/$target for fn in $source; do - rsync -a --no-o --no-g "$fn" $root/$target/ + rsync $rsync_flags "$fn" $root/$target/ done else mkdir -p $root/$(dirname $target) if ! [ -e $root/$target ]; then - rsync -a --no-o --no-g $source $root/$target + rsync $rsync_flags $source $root/$target else echo "duplicate entry $target -> $source" exit 1 @@ -198,12 +257,53 @@ let format' = format; in let ${if diskSize == "auto" then '' ${if partitionTableType == "efi" || partitionTableType == "hybrid" then '' - additionalSpace=$(( ($(numfmt --from=iec '${additionalSpace}') + $(numfmt --from=iec '${bootSize}')) / 1000 )) + # Add the GPT at the end + gptSpace=$(( 512 * 34 * 1 )) + # Normally we'd need to account for alignment and things, if bootSize + # represented the actual size of the boot partition. But it instead + # represents the offset at which it ends. + # So we know bootSize is the reserved space in front of the partition. + reservedSpace=$(( gptSpace + $(numfmt --from=iec '${bootSize}') )) + '' else if partitionTableType == "legacy+gpt" then '' + # Add the GPT at the end + gptSpace=$(( 512 * 34 * 1 )) + # And include the bios_grub partition; the ext4 partition starts at 2MB exactly. + reservedSpace=$(( gptSpace + 2 * mebibyte )) + '' else if partitionTableType == "legacy" then '' + # Add the 1MiB aligned reserved space (includes MBR) + reservedSpace=$(( mebibyte )) '' else '' - additionalSpace=$(( $(numfmt --from=iec '${additionalSpace}') / 1000 )) + reservedSpace=0 ''} - diskSize=$(( $(set -- $(du -d0 $root); echo "$1") + $additionalSpace )) - truncate -s "$diskSize"K $diskImage + additionalSpace=$(( $(numfmt --from=iec '${additionalSpace}') + reservedSpace )) + + # Compute required space in filesystem blocks + diskUsage=$(find . ! -type d -print0 | du --files0-from=- --apparent-size --block-size "${blockSize}" | cut -f1 | sum_lines) + # Each inode takes space! + numInodes=$(find . | wc -l) + # Convert to bytes, inodes take two blocks each! + diskUsage=$(( (diskUsage + 2 * numInodes) * ${blockSize} )) + # Then increase the required space to account for the reserved blocks. + fudge=$(compute_fudge $diskUsage) + requiredFilesystemSpace=$(( diskUsage + fudge )) + + diskSize=$(( requiredFilesystemSpace + additionalSpace )) + + # Round up to the nearest mebibyte. + # This ensures whole 512 bytes sector sizes in the disk image + # and helps towards aligning partitions optimally. + if (( diskSize % mebibyte )); then + diskSize=$(( ( diskSize / mebibyte + 1) * mebibyte )) + fi + + truncate -s "$diskSize" $diskImage + + printf "Automatic disk size...\n" + printf " Closure space use: %d bytes\n" $diskUsage + printf " fudge: %d bytes\n" $fudge + printf " Filesystem size needed: %d bytes\n" $requiredFilesystemSpace + printf " Additional space: %d bytes\n" $additionalSpace + printf " Disk image size: %d bytes\n" $diskSize '' else '' truncate -s ${toString diskSize}M $diskImage ''} @@ -214,18 +314,19 @@ let format' = format; in let # Get start & length of the root partition in sectors to $START and $SECTORS. eval $(partx $diskImage -o START,SECTORS --nr ${rootPartition} --pairs) - mkfs.${fsType} -F -L ${label} $diskImage -E offset=$(sectorsToBytes $START) $(sectorsToKilobytes $SECTORS)K + mkfs.${fsType} -b ${blockSize} -F -L ${label} $diskImage -E offset=$(sectorsToBytes $START) $(sectorsToKilobytes $SECTORS)K '' else '' - mkfs.${fsType} -F -L ${label} $diskImage + mkfs.${fsType} -b ${blockSize} -F -L ${label} $diskImage ''} echo "copying staging root to image..." - cptofs -p ${optionalString (partitionTableType != "none") "-P ${rootPartition}"} -t ${fsType} -i $diskImage $root/* / + cptofs -p ${optionalString (partitionTableType != "none") "-P ${rootPartition}"} -t ${fsType} -i $diskImage $root/* / || + (echo >&2 "ERROR: cptofs failed. diskSize might be too small for closure."; exit 1) ''; in pkgs.vmTools.runInLinuxVM ( pkgs.runCommand name { preVM = prepareImage; - buildInputs = with pkgs; [ utillinux e2fsprogs dosfstools ]; + buildInputs = with pkgs; [ util-linux e2fsprogs dosfstools ]; postVM = '' ${if format == "raw" then '' mv $diskImage $out/${filename} @@ -245,6 +346,9 @@ in pkgs.vmTools.runInLinuxVM ( # Some tools assume these exist ln -s vda /dev/xvda ln -s vda /dev/sda + # make systemd-boot find ESP without udev + mkdir /dev/block + ln -s /dev/vda1 /dev/block/254:1 mountPoint=/mnt mkdir $mountPoint @@ -270,6 +374,21 @@ in pkgs.vmTools.runInLinuxVM ( # The above scripts will generate a random machine-id and we don't want to bake a single ID into all our images rm -f $mountPoint/etc/machine-id + # Set the ownerships of the contents. The modes are set in preVM. + # No globbing on targets, so no need to set -f + targets_=(${concatStringsSep " " targets}) + users_=(${concatStringsSep " " users}) + groups_=(${concatStringsSep " " groups}) + for ((i = 0; i < ''${#targets_[@]}; i++)); do + target="''${targets_[$i]}" + user="''${users_[$i]}" + group="''${groups_[$i]}" + if [ -n "$user$group" ]; then + # We have to nixos-enter since we need to use the user and group of the VM + nixos-enter --root $mountPoint -- chown -R "$user:$group" "$target" + fi + done + umount -R /mnt # Make sure resize2fs works. Note that resize2fs has stricter criteria for resizing than a normal |