Replace pscomp() with a cleaner version, mostly written by bde (*).

This corrects a problem of lost-precision for `-r' (sort-by-CPU).  Also,
for sort-by-CPU and sort-by-memory, any processes which have the same
value CPU or MEMORY are now sorted by TTY and then (if needed) by pid.

(* - I just added the NODEV checks, after doing some testing of my own)

Submitted by:	bde
MFC after:	1 week

1 files changed, 43 insertions, 14 deletions

diff --git a/bin/ps/ps.c b/bin/ps/ps.c
index 183c0febdda1..7db9dce4c2dc 100644
--- a/bin/ps/ps.c
+++ b/bin/ps/ps.c
@@ -1024,20 +1024,49 @@ saveuser(KINFO *ki)
 static int
 pscomp(const void *a, const void *b)
 {
-	int i;
-#define VSIZE(k) ((k)->ki_p->ki_dsize + (k)->ki_p->ki_ssize + \
-		  (k)->ki_p->ki_tsize)
-
-	if (sortby == SORTCPU)
-		return (getpcpu((const KINFO *)b) - getpcpu((const KINFO *)a));
-	if (sortby == SORTMEM)
-		return (VSIZE((const KINFO *)b) - VSIZE((const KINFO *)a));
-	i =  (int)((const KINFO *)a)->ki_p->ki_tdev -
-	    (int)((const KINFO *)b)->ki_p->ki_tdev;
-	if (i == 0)
-		i = ((const KINFO *)a)->ki_p->ki_pid -
-		    ((const KINFO *)b)->ki_p->ki_pid;
-	return (i);
+	const KINFO *ka, *kb;
+	double cpua, cpub;
+	segsz_t sizea, sizeb;
+
+	ka = a;
+	kb = b;
+	/* SORTCPU and SORTMEM are sorted in descending order. */
+	if (sortby == SORTCPU) {
+		cpua = getpcpu(ka);
+		cpub = getpcpu(kb);
+		if (cpua < cpub)
+			return (1);
+		if (cpua > cpub)
+			return (-1);
+	}
+	if (sortby == SORTMEM) {
+		sizea = ka->ki_p->ki_tsize + ka->ki_p->ki_dsize +
+		    ka->ki_p->ki_ssize;
+		sizeb = kb->ki_p->ki_tsize + kb->ki_p->ki_dsize +
+		    kb->ki_p->ki_ssize;
+		if (sizea < sizeb)
+			return (1);
+		if (sizea > sizeb)
+			return (-1);
+	}
+	/*
+	 * TTY's are sorted in ascending order, except that all NODEV
+	 * processes come before all processes with a device.
+	 */
+	if (ka->ki_p->ki_tdev == NODEV && kb->ki_p->ki_tdev != NODEV)
+		return (-1);
+	if (ka->ki_p->ki_tdev != NODEV && kb->ki_p->ki_tdev == NODEV)
+		return (1);
+	if (ka->ki_p->ki_tdev < kb->ki_p->ki_tdev)
+		return (-1);
+	if (ka->ki_p->ki_tdev > kb->ki_p->ki_tdev)
+		return (1);
+	/* PID's are sorted in ascending order. */
+	if (ka->ki_p->ki_pid < kb->ki_p->ki_pid)
+		return (-1);
+	if (ka->ki_p->ki_pid > kb->ki_p->ki_pid)
+		return (1);
+	return (0);
 }
 
 /*