Make Linux enrollment resilient to package update locks

scripts/Install-SguLinuxRustDeskClient.sh

@@ -44,6 +44,23 @@ need_command() {
     command -v "$1" >/dev/null 2>&1 || fail "Required command is unavailable: $1"
 }
 
+apt_get_with_retry() {
+    local attempt
+    for attempt in $(seq 1 60); do
+        if apt-get "$@"; then
+            return 0
+        fi
+        if fuser /var/lib/dpkg/lock-frontend /var/lib/dpkg/lock /var/lib/apt/lists/lock \
+            >/dev/null 2>&1; then
+            printf 'Waiting for another package operation before retrying apt-get %s.\n' "$1" >&2
+            sleep 5
+            continue
+        fi
+        fail "apt-get $1 failed for a reason other than a temporary package lock."
+    done
+    fail 'Timed out waiting for another package operation to finish.'
+}
+
 while (($#)); do
     case "$1" in
         --domain-name) DOMAIN_NAME=${2:?Missing value for --domain-name}; shift 2 ;;
@@ -60,8 +77,8 @@ done
 install_prerequisites() {
     if command -v apt-get >/dev/null 2>&1; then
         export DEBIAN_FRONTEND=noninteractive
-        apt-get update
-        apt-get install -y curl openssl smbclient dnsutils
+        apt_get_with_retry update
+        apt_get_with_retry install -y curl openssl smbclient dnsutils
         return
     fi
     if command -v dnf >/dev/null 2>&1; then
@@ -131,7 +148,7 @@ install_rustdesk() {
         [[ $actual_hash == "$EXPECTED_SHA256" ]] || fail 'RustDesk package SHA-256 verification failed.'
 
         if command -v apt-get >/dev/null 2>&1; then
-            dpkg -i "$installer_path" || apt-get install -f -y
+            dpkg -i "$installer_path" || apt_get_with_retry install -f -y
         else
             fail 'The pinned RustDesk package is currently provided as a Debian package only.'
         fi