In the pvwatchfd_s structure, use booleans "displayable" and "unused" instead of having values of watch_pid=0 for unused and watch_fd=-1 for not displayable, so that each item only means one thing.

src/include/pv-internal.h

@@ -514,7 +514,9 @@ struct pvwatchfd_s {
 	off_t position;			 /* position last seen at */
 	struct timespec start_time;	 /* time we started watching the fd */
 	pid_t watch_pid;		 /* PID to watch */
-	int watch_fd;			 /* fd to watch, -1 = not displayed */
+	int watch_fd;			 /* fd to watch */
+	bool displayable;		 /* false if not displayable */
+	bool unused;			 /* true if free for re-use */
 };
 typedef struct pvwatchfd_s *pvwatchfd_t;
 

src/pv/loop.c

@@ -618,6 +618,8 @@ int pv_watchfd_loop(pvstate_t state)
 	memset(&info, 0, sizeof(info));
 	info.watch_pid = state->watchfd.pid[0];
 	info.watch_fd = state->watchfd.fd[0];
+	info.displayable = true;
+	info.unused = false;
 	pv_reset_watchfd(&info);
 	rc = pv_watchfd_info(state, &info, false);
 	if (0 != rc) {
@@ -900,7 +902,7 @@ int pv_watchpid_loop(pvstate_t state)
 			state->control.height = new_height;
 
 			for (idx = 0; NULL != info_array && idx < array_length; idx++) {
-				if (info_array[idx].watch_fd < 0)
+				if (!info_array[idx].displayable)
 					continue;
 				pv_watchpid_setname(state, &(info_array[idx]));
 				info_array[idx].flags.reparse_display = 1;
@@ -934,15 +936,20 @@ int pv_watchpid_loop(pvstate_t state)
 			if (idx < 0)
 				continue;
 
-			if (info_array[idx].watch_fd < 0) {
+			if (info_array[idx].unused) {
+				debug("%s %d: %s", "fd", fd, "unused array entry - skipping");
+				continue;
+			}
+
+			if (!info_array[idx].displayable) {
 				/*
 				 * Non-displayable fd - just remove if
 				 * changed
 				 */
 				if (pv_watchfd_changed(&(info_array[idx]))) {
 					fd_to_idx[fd] = -1;
-					info_array[idx].watch_pid = 0;
-					info_array[idx].watch_fd = -1;
+					info_array[idx].unused = true;
+					info_array[idx].displayable = false;
 					pv_freecontents_watchfd(&(info_array[idx]));
 					debug("%s %d: %s", "fd", fd, "removing");
 				}
@@ -962,8 +969,8 @@ int pv_watchpid_loop(pvstate_t state)
 
 			if (position_now < 0) {
 				fd_to_idx[fd] = -1;
-				info_array[idx].watch_pid = 0;
-				info_array[idx].watch_fd = -1;
+				info_array[idx].unused = true;
+				info_array[idx].displayable = false;
 				pv_freecontents_watchfd(&(info_array[idx]));
 				debug("%s %d: %s", "fd", fd, "removing");
 				continue;
@@ -1069,7 +1076,8 @@ int pv_watchpid_loop(pvstate_t state)
 	 */
 	for (idx = 0; NULL != info_array && idx < array_length; idx++) {
 		pv_freecontents_watchfd(&(info_array[idx]));
-		info_array[idx].watch_fd = -1;
+		info_array[idx].unused = true;
+		info_array[idx].displayable = false;
 	}
 
 	if (NULL != info_array)

src/pv/watchpid.c

@@ -353,6 +353,8 @@ static bool extend_info_array(int *array_length_ptr, pvwatchfd_t * info_array_pt
 		return false;
 	}
 
+	new_info_array[array_length - 1].unused = true;
+
 	debug("%s", "extended info array");
 
 	*info_array_ptr = new_info_array;
@@ -466,12 +468,11 @@ int pv_watchpid_scanfds(pvstate_t state,
 		}
 
 		/*
-		 * See if there's an empty slot we can re-use. An empty slot
-		 * has a watch_pid of 0.
+		 * See if there's an empty slot we can re-use.
 		 */
 		use_idx = -1;
 		for (check_idx = 0; check_idx < array_length; check_idx++) {
-			if (info_array[check_idx].watch_pid == 0) {
+			if (info_array[check_idx].unused) {
 				use_idx = check_idx;
 				break;
 			}
@@ -498,6 +499,8 @@ int pv_watchpid_scanfds(pvstate_t state,
 		pv_reset_watchfd(&(info_array[use_idx]));
 		info_array[use_idx].watch_pid = watch_pid;
 		info_array[use_idx].watch_fd = fd;
+		info_array[use_idx].unused = false;
+		info_array[use_idx].displayable = true;
 
 		/*
 		 * Set the average rate window so that a new history buffer
@@ -520,20 +523,20 @@ int pv_watchpid_scanfds(pvstate_t state,
 		if ((rc != 0) && (rc != 4)) {
 			debug("%s %d: %s: %d", "fd", fd, "lookup failed - marking slot for re-use", use_idx);
 			pv_freecontents_watchfd(&(info_array[use_idx]));
-			info_array[use_idx].watch_pid = 0;
-			info_array[use_idx].watch_fd = -1;
+			info_array[use_idx].unused = true;
+			info_array[use_idx].displayable = false;
 			continue;
 		}
 
 		fd_to_idx[fd] = use_idx;
 
 		/*
-		 * Not displayable - set fd to -1 so the main loop doesn't
-		 * show it.
+		 * Not displayable - mark it as such so the main loop
+		 * doesn't show it.
 		 */
 		if (rc != 0) {
 			debug("%s %d: %s", "fd", fd, "marking as not displayable");
-			info_array[use_idx].watch_fd = -1;
+			info_array[use_idx].displayable = false;
 		}
 
 		/* Set the info display_name appropriately. */