generate an esp image using dosfs tools

README.md

Creating an esp image is a pain. The gen-esp here tries to make it less painful.

Would like to use diskfs, but some things broke #132

gen-esp

#!/bin/sh
# shellcheck disable=SC2015,SC2039,SC2046,SC2086,SC2166

CR='
'
Usage(){
    cat <<EOF
${0##*/} create [--size=128MB] output path[:targetpath] ...

   if targetpath is not provided for a path, then
   default of 'efi/boot/bootx64.efi' is used.

   if there are no '/' in targetpath, then efi/boot/
   is assumed.

Also support 'update' with:

    ${0##*/} update existing.img path:targetpath ...
EOF
}

fail() { echo "$@" 1>&2; exit 1; }
stderr() { echo "$@" 1>&2; }
cleanup() {
    [ -n "$TMPD" ] || return 0
    rm -Rf "${TMPD}"
}

create() {
    local size="128MB" staged=""
    case "$1" in
        --size=*) size="${1#--size=}"; shift;;
    esac
    rm -f "$img" || return 1
    stderr "creating image ${size} in $img"
    fallocate "--length=$size" "$img" || return 1
    out=$(mkfs.fat "$img" 2>&1) || {
        stderr "failed mkfs.fat $img: $out"
        return 1
    }
    return 0
}


# update([--size=128MB,] output, file[:file] ...)
#   create file 'output' of size 'size'.
#   copy files provided to target.  files are 'src:dest'
#   if no dest is given, default is efi/boot/bootx64.efi
#   all filenames in image are converted to upper case.
update() {
    local img="$1" f="" src="" dest="" destd="" out=""
    shift
    staged="${TMPD}/genesp"
    rm -Rf "$staged" || return 1

    # create a staging directory with renamed files.
    for f in "$@"; do
        src="${f%%:*}"
        dest="${f#*:}"
        case "$dest" in
            */*) :;;
            *) dest="efi/boot/$dest";;
        esac
        out=$(echo "$dest" | tr '[:lower:]' '[:upper:]') && dest="$out" || {
            stderr "failed to convert '$dest' to upper case"
            return 1
        }
        destd=$(dirname "$dest")
        mkdir -p "$staged/$destd" || {
            stderr "failed to stage dir '$dest'"
            return 1
        }
        cp "$src" "$staged/$dest" || {
            stderr "failed to stage cp $src -> $dest"
            return 1
        }
    done

    # shellcheck disable=SC2035
    ( cd "$staged" && find * -type f ) > "${TMPD}/list" || {
        stderr "failed t find stage files";
        return 1;
    }

    # shellcheck disable=SC2035
    dirs=$( cd "$staged" && find * -type d ) > "${TMPD}/dirs" || {
        stderr "failed to find dirs"
        return 1;
    }

    local oifs="$IFS"
    IFS="${CR}"; set -- $dirs; IFS="$oifs"

    mmd -D s -i "$img" "$@" >/dev/null 2>&1 || {
        # if a dir exists, it will fail. just ignore this.
        # assuming things will fail later.
        :
    }

    # shellcheck disable=SC2162
    while read f; do
        echo "$f -> $f" 1>&2
        mcopy -D o -Q -i "$img" "${staged}/$f" "::$f" || {
            stderr "mcopy failed $f -> $f";
            return 1;
        }
    done < "${TMPD}/list"


    rm -Rf "$staged" || {
        stderr "failed to remove $staged"
        return 1
    }
}

[ $# -eq 0 ] && { Usage 1>&2; exit 1; }
[ "$1" = "-h" -o "$1" = "--help" ] && { Usage; exit 0; }

missing=""
for dep in mcopy mkfs.vfat; do
    command -v "$dep" >/dev/null 2>&1 || missing="$missing $dep"
done
[ -z "$missing" ] ||
    fail "missing deps: ${missing# }"

TMPD=$(mktemp -d "${TMPDIR:-/tmp}/${0##*/}.XXXXXX") ||
    fail "failed mktemp"
trap cleanup EXIT

case "$1" in
    create)
        shift
        sizef=""
        case "$1" in
            size=*) sizef="$1"; shift;;
        esac
        img="$1"
        shift
        create ${sizef:+"$sizef"} "$img" || fail "failed create $sizef $1"
        if [ $# -ne 0 ]; then
            update "$img" "$@"
        fi
        ;;
    update)
        shift;
        update "$@";;
    *) fail "Unknown cmd '$1'";;
esac