sed -n -e 's/^VLC_EXPORT\s*([^,]*,\s*\([a-zA-Z0-9_]*\)\s*,.*$/\1/p' | \
sort -du > libvlc-headers.sym
-exec diff -u ${srcdir}/libvlc.sym libvlc-headers.sym
+if grep -e "^_" libvlc-headers.sym; then
+ echo "Illegal symbol name (starting with underscore) found!";
+ exit 1
+fi
+
+if ! diff -u ${srcdir}/libvlc.sym libvlc-headers.sym; then
+ echo "Mismatching symbols found!"
+ exit 1
+fi