1 files changed, 12 insertions, 1 deletions
diff --git a/ztest.cc b/ztest.cc
index 86a8518..cb78eb1 100644
--- a/ztest.cc
+++ b/ztest.cc
@@ -152,13 +152,24 @@ int ztest_file( const int infd, int format_index,
                 const std::string & input_filename,
                 const std::vector< const char * > & ztest_args )
   {
+  static int disable_xz = -1;				// tri-state bool
   const uint8_t * magic_data = 0;
   int magic_size = 0;
   if( format_index < 0 )
     format_index = test_format( infd, &magic_data, &magic_size );
   const char * const compressor_name = get_compressor_name( format_index );
   if( !compressor_name )
-    return 0;				// skip this file
+    return 0;				// ignore this file
+  if( format_index == fmt_xz )
+    {
+    if( disable_xz < 0 )
+      {
+      std::string command( compressor_name ); command += " -V > /dev/null";
+      disable_xz = ( std::system( command.c_str() ) != 0 );
+      }
+    if( disable_xz ) return 0;		// ignore this file if no xz installed
+    }
+
   const pid_t pid = fork();
 
   if( pid == 0 )			// child (compressor)