+/* If true, transfer output data to the output file's storage device
+ when supported. Otherwise, if the system crashes around the time
+ gzip is run, the user might lose both input and output data. See:
+ Pillai TS et al. All file systems are not created equal: on the
+ complexity of crafting crash-consistent applications. OSDI'14. 2014:433-48.
+ https://www.usenix.org/conference/osdi14/technical-sessions/presentation/pillai */
+static bool synchronous;
+