fixup! Deprecate GSC_PAL and use instead GRAMINE_MODE

Signed-off-by: Dmitrii Kuvaiskii <dmitrii.kuvaiskii@intel.com>

templates/apploader.common.template

@@ -9,6 +9,37 @@ set -e
 {% block path %}{% endblock %}
 
 # Note: default to SGX if Gramine mode (`direct`, `sgx`) wasn't specified
-exec gramine-${GRAMINE_MODE:-sgx} /gramine/app_files/entrypoint \
+GRAMINE_EXEC=gramine-sgx
+
+# TODO: remove GSC_PAL in GSC v1.9
+if [ -n "$GSC_PAL" ] && [ -n "$GRAMINE_MODE" ]; then
+    echo "ERROR: GSC_PAL and GRAMINE_MODE environment variables cannot be set together."
+    exit 1
+fi
+
+if [ -n "$GSC_PAL" ]; then
+    echo "WARNING: GSC_PAL environment variable is deprecated in v1.8 and will be removed in v1.9."
+    echo "         Use instead the GRAMINE_MODE={direct|sgx} environment variable."
+
+    # legacy logic was peculiar: if GSC_PAL != Linux-SGX then we set Gramine to `gramine-direct`
+    if [ "$GSC_PAL" == "Linux-SGX" ]; then
+        GRAMINE_EXEC=gramine-sgx
+    else
+        GRAMINE_EXEC=gramine-direct
+    fi
+fi
+
+if [ -n "$GRAMINE_MODE" ]; then
+    if [ "$GRAMINE_MODE" == "sgx" ]; then
+        GRAMINE_EXEC=gramine-sgx
+    elif [ "$GRAMINE_MODE" == "direct" ]; then
+        GRAMINE_EXEC=gramine-direct
+    else
+        echo "ERROR: unrecognized GRAMINE_MODE; can only be 'direct' or 'sgx'."
+        exit 1
+    fi
+fi
+
+exec ${GRAMINE_EXEC} /gramine/app_files/entrypoint \
     {% if insecure_args %}{{ binary_arguments | map('shlex_quote') | join(' ') }} \
     "${@}"{% endif %}