core: make detach non-destructive

scripts/daemon/lesavka-core.sh

@@ -13,21 +13,36 @@ find_udc() {
     ls /sys/class/udc 2>/dev/null | head -n1 || true
 }
 
+udc_state() {
+    local udc="$1"
+    if [[ -z $udc ]]; then
+        echo "unknown"
+        return 0
+    fi
+    cat "/sys/class/udc/$udc/state" 2>/dev/null || echo "unknown"
+}
+
 detach_gadget() {
     local udc=""
     udc="$(find_udc)"
+    local state
+    state="$(udc_state "$udc")"
+    case "$state" in
+        configured|addressed|default|suspended)
+            log "detach skipped (state=$state)"
+            return 0
+            ;;
+    esac
     if [[ -n $udc && -w /sys/class/udc/$udc/soft_connect ]]; then
         echo 0 >"/sys/class/udc/$udc/soft_connect" 2>/dev/null || true
     fi
-    if [[ -e $G/UDC ]]; then
+    if [[ -n ${LESAVKA_DETACH_CLEAR_UDC:-} && -e $G/UDC ]]; then
         echo "" >"$G/UDC" 2>/dev/null || true
     fi
-    if [[ -n $udc && -f /sys/class/udc/$udc/state ]]; then
+    if [[ -n $udc ]]; then
-        local state
-        state="$(cat "/sys/class/udc/$udc/state" 2>/dev/null || true)"
         log "detached (state=${state:-unknown})"
     else
-        log "detached (no UDC state)"
+        log "detached (no UDC)"
     fi
 }
 
@@ -42,7 +57,10 @@ attach_gadget() {
         log "UDC not found; need full setup"
         return 1
     fi
-    if [[ -e $G/UDC ]]; then
+    if [[ -n $udc && -w /sys/class/udc/$udc/soft_connect ]]; then
+        echo 1 >"/sys/class/udc/$udc/soft_connect" 2>/dev/null || true
+    fi
+    if [[ -n ${LESAVKA_ATTACH_WRITE_UDC:-} && -e $G/UDC ]]; then
         echo "$udc" >"$G/UDC" 2>/dev/null || true
     fi
     log "attached to $udc"
@@ -54,13 +72,17 @@ case "${1:-}" in
         detach_gadget
         exit 0
         ;;
+    --detach-hard)
+        LESAVKA_DETACH_CLEAR_UDC=1 detach_gadget
+        exit 0
+        ;;
     --attach)
         if attach_gadget; then
             exit 0
         fi
         ;;
     --help|-h)
-        echo "Usage: $0 [--attach|--detach]"
+        echo "Usage: $0 [--attach|--detach|--detach-hard]"
         exit 0
         ;;
 esac