Handle SIGTERM/SIGINT for clean shutdown, add device wrapper script

sdlamp2 now catches SIGTERM and SIGINT via a sig_atomic_t flag checked
in the main loop, ensuring position and volume are saved before exit.
Previously, a kill signal would terminate instantly without saving.

New tools/rg35xx-wrapper.sh replaces sdlamp2 as the dmenu_ln CMD on
the RG35XX Plus. Skeleton includes placeholders for WiFi hotspot and
power button monitoring (TBD after on-device investigation).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

docs/rg35xx-plus.md

@@ -87,21 +87,22 @@ The `dmenu_ln` script already supports switching the startup binary via config f
 
 ### Setup
 
-1. **Copy the binary** to the device:
+1. **Copy the binary and wrapper** to the device:
 
    ```sh
    scp build/sdlamp2 root@<device>:/mnt/vendor/bin/sdlamp2
+   scp tools/rg35xx-wrapper.sh root@<device>:/mnt/vendor/bin/rg35xx-wrapper.sh
    ```
 
 2. **Add the config check** to `/mnt/vendor/ctrl/dmenu_ln`. In the section where `CMD` overrides are checked (after the existing `muos.ini` / `vpRun.ini` checks, before the `app_scheduling` call), add:
 
    ```bash
    if [ -f "/mnt/vendor/sdlamp2.ini" ];then
-       CMD="/mnt/vendor/bin/sdlamp2 /mnt/sdcard/Music"
+       CMD="/mnt/vendor/bin/rg35xx-wrapper.sh"
    fi
    ```
 
-   The unquoted `$CMD` in `app_scheduling` undergoes word splitting, so the path argument is passed correctly.
+   The wrapper script handles device-specific concerns (WiFi hotspot, power button monitoring) and launches sdlamp2 as its main foreground process. See `tools/rg35xx-wrapper.sh` for details.
 
 3. **Enable sdlamp2 on boot:**
 
@@ -121,7 +122,7 @@ Everything else in the boot chain continues to work:
 
 - **Charging mode** — handled in `loadapp.sh` before the restart loop
 - **LED/backlight control** — `brightCtrl.bin` started by `launcher.sh`
-- **Clean shutdown** — system shutdown scripts unaffected
+- **Clean shutdown** — sdlamp2 handles SIGTERM/SIGINT, saving position and volume before exit. The wrapper script can trigger `poweroff` after sdlamp2 exits
 - **Restart on exit** — if sdlamp2 exits cleanly (status 0), the restart loop in `loadapp.sh` re-launches it immediately
 - **Crash recovery** — if sdlamp2 crashes (non-zero exit), `app_scheduling` sleeps 30s then the loop retries
 - **Easy revert** — removing `sdlamp2.ini` restores the stock menu on next boot

docs/sdlamp2-fsd.md

@@ -43,6 +43,10 @@ This document specifies the functional requirements for an SDL2 based media play
 
 ## 6. Changelog
 
+### 2026-02-13 — Clean shutdown on SIGTERM/SIGINT
+
+- **Signal handling**: sdlamp2 now catches SIGTERM and SIGINT via a `sig_atomic_t` flag checked in the main loop. On signal, the existing cleanup path runs (save position, save volume, close decoder, SDL_Quit) instead of being killed instantly. This ensures position is saved when the system shuts down or the process is terminated by a wrapper script.
+
 ### 2026-02-13 — Combine Play/Stop, add Previous Cassette button
 
 - **Play/Stop combined**: The separate Stop and Play buttons are merged into a single toggle button that shows the play icon (▶) when paused and the stop icon (■) when playing.

src/sdlamp2.c

@@ -5,6 +5,7 @@
 #include <libswresample/swresample.h>
 
 #include <dirent.h>
+#include <signal.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -38,6 +39,15 @@ typedef struct {
   int art_height;
 } Decoder;
 
+/* --- Signal handling --- */
+
+static volatile sig_atomic_t got_signal = 0;
+
+static void signal_handler(int sig) {
+  (void)sig;
+  got_signal = 1;
+}
+
 /* --- Globals --- */
 
 static SDL_Window* window = NULL;
@@ -656,6 +666,10 @@ int main(int argc, char** argv) {
     panic_and_abort("Could not create controls texture!", SDL_GetError());
   }
 
+  /* Handle SIGTERM/SIGINT for clean shutdown (save position before exit) */
+  signal(SIGTERM, signal_handler);
+  signal(SIGINT, signal_handler);
+
   /* Scan directory and open first file */
   scan_audio_files(audio_dir);
   volume = load_volume();
@@ -669,6 +683,8 @@ int main(int argc, char** argv) {
   SDL_Event e;
 
   while (running) {
+    if (got_signal) running = SDL_FALSE;
+
     /* --- Event handling --- */
     while (SDL_PollEvent(&e)) {
       /* Debug: log all input-related events */

tools/rg35xx-wrapper.sh

@@ -0,0 +1,63 @@
+#!/bin/sh
+#
+# RG35XX Plus wrapper for sdlamp2
+#
+# Launched by dmenu_ln instead of sdlamp2 directly. Handles device-specific
+# concerns that don't belong in the player binary:
+#   1. Start WiFi hotspot (AP mode for SSH access)
+#   2. Launch sdlamp2 as the foreground process
+#   3. Monitor power button and trigger clean shutdown
+#
+# Install: copy to /mnt/vendor/bin/rg35xx-wrapper.sh
+# Config:  set CMD in dmenu_ln to point here instead of sdlamp2 directly
+
+SDLAMP2="/mnt/vendor/bin/sdlamp2"
+AUDIO_DIR="/mnt/sdcard/Music"
+
+# --- WiFi hotspot ---
+# TODO: Investigate how the stock menu starts AP mode.
+# Likely candidates: hostapd, nmcli, or a vendor script in /mnt/vendor/ctrl/.
+# Run these on the device to find out:
+#   grep -r 'hostapd\|hotspot\|ap_mode\|wifi' /mnt/vendor/ctrl/
+#   systemctl list-units | grep -i net
+#   nmcli general status && nmcli connection show
+#
+# Placeholder — uncomment/replace once the mechanism is known:
+# nmcli connection up hotspot 2>/dev/null || true
+
+# --- Power button monitor ---
+# TODO: Investigate power button input device.
+# Run on device:
+#   cat /proc/bus/input/devices   (find the power button event device)
+#   evtest /dev/input/eventN      (confirm KEY_POWER event code)
+#   cat /etc/systemd/logind.conf  (check HandlePowerKey setting)
+#
+# Strategy: read key events from the power button input device in background.
+# When KEY_POWER (code 116) is detected, send SIGTERM to sdlamp2 and poweroff.
+#
+# POWER_EVENT_DEV="/dev/input/eventN"  # TBD: set after investigation
+#
+# monitor_power_button() {
+#   # evtest writes one line per event; filter for KEY_POWER press (value 1)
+#   evtest "$POWER_EVENT_DEV" 2>/dev/null | while read -r line; do
+#     case "$line" in
+#       *"code 116"*"value 1"*)
+#         kill -TERM "$SDLAMP2_PID" 2>/dev/null
+#         sleep 1
+#         poweroff
+#         ;;
+#     esac
+#   done
+# }
+# monitor_power_button &
+# MONITOR_PID=$!
+
+# --- Launch sdlamp2 ---
+"$SDLAMP2" "$AUDIO_DIR"
+SDLAMP2_EXIT=$?
+
+# --- Cleanup ---
+# Kill the power button monitor if it's still running
+# kill "$MONITOR_PID" 2>/dev/null
+
+exit "$SDLAMP2_EXIT"