From 86cfcb0da5a13e7044d7e6938f3e6f76f73f410d Mon Sep 17 00:00:00 2001
From: funman300 <funman300@gmail.com>
Date: Sun, 10 May 2026 17:08:28 -0700
Subject: [PATCH] scripts: add enable-hibernation.sh (one-time bootstrap)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
---
 scripts/enable-hibernation.sh | 78 +++++++++++++++++++++++++++++++++++
 1 file changed, 78 insertions(+)
 create mode 100755 scripts/enable-hibernation.sh

diff --git a/scripts/enable-hibernation.sh b/scripts/enable-hibernation.sh
new file mode 100755
index 0000000..a1fe9a0
--- /dev/null
+++ b/scripts/enable-hibernation.sh
@@ -0,0 +1,78 @@
+#!/bin/bash
+# enable-hibernation.sh — one-time setup for laptop hibernation on btrfs.
+# Idempotent: re-runs are no-ops once everything is in place. Run with sudo.
+# After successful run, reboot before testing `systemctl hibernate`.
+
+set -euo pipefail
+
+if [ "$EUID" -ne 0 ]; then
+    echo "Run as root: sudo bash $0" >&2
+    exit 1
+fi
+
+SWAPFILE=/swapfile
+SWAPSIZE=16g
+ROOT_PARTUUID=$(findmnt -no PARTUUID /)
+
+echo "==> Step 1/6: ensure swap file exists at $SWAPFILE (size $SWAPSIZE)"
+if [ ! -f "$SWAPFILE" ]; then
+    btrfs filesystem mkswapfile --size "$SWAPSIZE" "$SWAPFILE"
+    echo "    created $SWAPFILE"
+else
+    actual_bytes=$(stat -c %s "$SWAPFILE")
+    min_bytes=$((14 * 1024 * 1024 * 1024))
+    if [ "$actual_bytes" -lt "$min_bytes" ]; then
+        echo "ERROR: $SWAPFILE exists but is smaller than 14 GiB (got $actual_bytes bytes)." >&2
+        echo "       Remove it manually and re-run." >&2
+        exit 1
+    fi
+    echo "    already exists ($((actual_bytes / 1024 / 1024 / 1024)) GiB) — skipping creation"
+fi
+
+echo "==> Step 2/6: activate swap and persist in fstab"
+if ! swapon --show | grep -q "^$SWAPFILE "; then
+    swapon "$SWAPFILE"
+    echo "    swapon $SWAPFILE"
+else
+    echo "    already active — skipping swapon"
+fi
+if ! grep -qE "^$SWAPFILE\s" /etc/fstab; then
+    printf '%s\tnone\tswap\tdefaults\t0 0\n' "$SWAPFILE" >> /etc/fstab
+    echo "    appended to /etc/fstab"
+else
+    echo "    /etc/fstab already references $SWAPFILE — skipping"
+fi
+
+echo "==> Step 3/6: compute resume params"
+RESUME_OFFSET=$(btrfs inspect-internal map-swapfile -r "$SWAPFILE")
+echo "    resume=PARTUUID=$ROOT_PARTUUID"
+echo "    resume_offset=$RESUME_OFFSET"
+
+echo "==> Step 4/6: ensure 'resume' hook in /etc/mkinitcpio.conf"
+if grep -qE "^HOOKS=\(.*\bresume\b.*\)" /etc/mkinitcpio.conf; then
+    echo "    resume hook already present — skipping"
+else
+    sed -i -E 's/(^HOOKS=\(.*\bblock\b)/\1 resume/' /etc/mkinitcpio.conf
+    if ! grep -qE "^HOOKS=\(.*\bresume\b.*\)" /etc/mkinitcpio.conf; then
+        echo "ERROR: failed to insert 'resume' hook. Check /etc/mkinitcpio.conf manually." >&2
+        exit 1
+    fi
+    echo "    inserted 'resume' after 'block'"
+fi
+
+echo "==> Step 5/6: append resume params to /etc/kernel/cmdline"
+if grep -q "resume=" /etc/kernel/cmdline; then
+    echo "    cmdline already contains resume= — skipping"
+else
+    sed -i "1 s|\$| resume=PARTUUID=$ROOT_PARTUUID resume_offset=$RESUME_OFFSET|" /etc/kernel/cmdline
+    echo "    appended to /etc/kernel/cmdline"
+fi
+
+echo "==> Step 6/6: regenerate UKI"
+mkinitcpio -P
+
+echo
+echo "Done. Reboot to activate hibernation:"
+echo "    sudo reboot"
+echo
+echo "After reboot, test with: systemctl hibernate"