Remove the state from the pv_error arguments, by adding a new function pv_set_error_prefix to call on startup, eliminating the need for a state program_name string; and add a private boolean to track whether there has been any output which means errors need preceding by a newline, which is updated by pv_display directly (#165).

src/include/pv-internal.h

@@ -142,7 +142,6 @@ struct pvstate_s {
 	 * Program status *
 	 ******************/
 	struct pvprogramstatus_s {
-		/*@only@*/ char *program_name;	 /* program name for error reporting */
 		char cwd[PV_SIZEOF_CWD];	 /* current working directory for relative path */
 		int current_input_file;		 /* index of current file being read */
 		int exit_status; 		 /* exit status to give (0=OK) */
@@ -505,7 +504,7 @@ struct pvwatchfd_s {
 };
 typedef struct pvwatchfd_s *pvwatchfd_t;
 
-void pv_error(pvstate_t, char *, ...);
+void pv_error(char *, ...);
 
 int pv_main_loop(pvstate_t);
 void pv_calculate_transfer_rate(pvtransfercalc_t, readonly_pvtransferstate_t, readonly_pvcontrol_t, readonly_pvdisplay_t, bool);

src/include/pv.h

@@ -175,10 +175,15 @@ void pv_nanosleep(long long);
  * Main PV functions.
  */
 
+/*
+ * Set the prefix (program name) for any PV error messages.
+ */
+extern void pv_set_error_prefix(/*@unique@ */ const char *);
+
 /*
  * Create a new state structure, and return it, or 0 (NULL) on error.
  */
-extern /*@null@*/ /*@only@*/ pvstate_t pv_state_alloc(const char *);
+extern /*@null@*/ /*@only@*/ pvstate_t pv_state_alloc(void);
 
 /*
  * Clear the calculated parts of a state structure.