bruh

modules/nixos/hardware/raspberry-pi/generational/nixos-generations-builder.sh

@@ -0,0 +1,146 @@
+#! @bash@/bin/sh -e
+
+# shellcheck disable=SC3043,SC3044,SC3054
+
+shopt -s nullglob
+
+export PATH=/empty:@path@
+
+# used to track copied generations to decide which are obsolete
+# and need to be removed
+declare -A activeGenerations
+
+moveWBackup() {
+    local src="$1"
+    local dst="$2"
+
+    # Backup $dst if already exists
+    local dstBkp="$dst.bkp.$$"
+    if [ -e "$dst" ]; then
+        mv "$dst" "$dstBkp"
+    fi
+
+    # Move $src as "new" $dst
+    mv "$src" "$dst"
+
+    # Remove backup directory of the previous $dst
+    rm -rf "$dstBkp"
+}
+
+# Copy generation's kernel, initrd, cmdline to `gensDir/generationName`.
+addEntry() {
+    local generationPath="$1"
+    local generationName="$2"
+    local gensDir="$3"
+
+    local dst="$gensDir/$generationName"
+
+    echo "* nixos generation '$generationName' -> $dst"
+    # Don't copy the files if $dst already exists, unless it's the default
+    # configuration.
+    # This means that we have to create $dst atomically to prevent partially
+    # copied generations if this script is ever interrupted.
+    #
+    # For "default" generation: make backup and then replace with the new
+    # "default", minimizing the time when where isn't any "default" generation
+    # directory
+    if ! [ -e $dst ] || [ "$generationName" = "default" ]; then
+        local dstTmp="$dst.tmp.$$"
+        mkdir -p "$dstTmp" || true
+
+        @nixosGenBuilder@ -c "$generationPath" -n "$generationName" -d "$dstTmp"
+
+        # Move new generation on its place, backing up the previous version
+        # if it exists
+        # This may only happen when "$generationName" = "default"
+        moveWBackup "$dstTmp" "$dst"
+    fi
+
+    activeGenerations["$generationName"]=1
+}
+
+removeObsoleteGenerations() {
+    local path="$1"
+
+    echo "removing obsolete generations in $path..."
+    for gen in $path/*; do
+        if ! [ "${activeGenerations["$(basename "$gen")"]}" = 1 ]; then
+            echo "* $gen is obsolete"
+            rm -vrf "$gen"
+        fi
+    done
+}
+
+addAllEntries() {
+    local defaultGenerationPath="$1"
+    local outdir="$2"
+    local numGenerations="$3"
+
+    local gensDir="$outdir/@nixosGenerationsDir@"
+    mkdir -p "$gensDir" || true
+
+    # Add default generation
+    addEntry "$defaultGenerationPath" default "$gensDir"
+
+    if [ "$numGenerations" -gt 0 ]; then
+        # Add up to $numGenerations generations of the system profile, in reverse
+        # (most recent to least recent) order.
+        for generation in $(
+            (cd /nix/var/nix/profiles && ls -d system-*-link) \
+            | sed 's/system-\([0-9]\+\)-link/\1/' \
+            | sort -n -r \
+            | head -n "$numGenerations"); do
+            link=/nix/var/nix/profiles/system-$generation-link
+            addEntry "$link" "${generation}-default" "$gensDir"
+            for specialisation in $(
+                ls /nix/var/nix/profiles/system-$generation-link/specialisation \
+                | sort -n -r); do
+                link=/nix/var/nix/profiles/system-$generation-link/specialisation/$specialisation
+                addEntry "$link" "${generation}-${specialisation}" "$gensDir"
+            done
+        done
+    fi
+
+    removeObsoleteGenerations "$gensDir"
+}
+
+usage() {
+    echo "usage: $0 -c <path-to-default-configuration> [-b <boot-dir>] [-g <num-generations>]" >&2
+    exit 1
+}
+
+
+default=                # Default configuration
+numGenerations=0        # Number of other generations to keep (kernel, initrd, DTBs, overlays)
+
+echo "$0: $@"
+while getopts "c:b:g:f:" opt; do
+    case "$opt" in
+        c) default="$OPTARG" ;;
+        b) boottarget="$OPTARG" ;;
+        g) numGenerations="$OPTARG" ;;
+        f) fwtarget="$OPTARG" ;;
+        \?) usage ;;
+    esac
+done
+
+if [ -z "$boottarget" ] && [ -z "$fwtarget" ]; then
+    echo "Error: at least one of \`-b <boot-dir>\` and \`-f <firmware-dir>\` must be set"
+    usage
+fi
+
+if [ -n "$fwtarget" ]; then
+    echo "installing nixos-generation-independent firmware..."
+    @installFirmwareBuilder@ -c "$default" -d "$fwtarget"
+
+    echo "installing nixos generations..."
+    addAllEntries "$default" "$fwtarget" "$numGenerations"
+fi
+
+if [ -n "$boottarget" ]; then
+    echo "'-b $boottarget' isn't used when loading the kernel directly with \`kernel\`: "\
+         "kernels are copied directly to <firmware-dir>"
+    exit 0
+fi
+
+echo "generational bootloader installed"