Add an alias for the name for %N to the display sub-structure, so that the name can be varied between displays without having to alter the control value (#165).

src/include/pv-internal.h

@@ -245,6 +245,14 @@ struct pvstate_s {
 	/*****************
 	 * Display state *
 	 *****************/
+	/*
+	 * Note that the "name" pointer is an alias - it should point to
+	 * some other string that's allocated and freed separately, such as
+	 * control.name.  It is used here so that the name can be changed
+	 * for different display structures without having to also change
+	 * the control structure, for example when watching multiple file
+	 * descriptors with --watchfd.
+	 */
 	struct pvdisplay_s {
 
 		struct pvdisplay_segment_s {	/* format string broken into segments */
@@ -273,6 +281,8 @@ struct pvstate_s {
 		off_t initial_offset;			 /* offset when first opened (when watching fds) */
 		size_t next_line_len;				 /* length of currently receiving line so far */
 
+		/*@dependent@*/ /*@null@*/ const char *name; /* copy of pointer to string for %N */
+
 		size_t format_segment_count;	 /* number of format string segments */
 
 		pvtransfercount_t count_type;	 /* type of count for transfer, rate, etc */