bin/142911: [patch] vmstat(8) -w should produce error message if fed a negative value

[Efstratios Karatzas <gpf.kira at gmail.com>]

>Number:         142911
>Category:       bin
>Synopsis:       [patch] vmstat(8) -w should produce error message if fed a negative value
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Sun Jan 17 17:20:01 UTC 2010
>Closed-Date:
>Last-Modified:
>Originator:     Efstratios Karatzas <gpf.kira at gmail.com>
>Release:        FreeBSD 8.0-STABLE i386
>Organization:
>Environment:
FreeBSD Eternal_Crusader 8.0-STABLE FreeBSD 8.0-STABLE #0: Thu Jan 7 04:08:09 EET 2010     root at bt:/usr/obj/usr/src/sys/GENERIC i386
>Description:
vmstat(8) -w should produce an error message and exit when fed a negative numerical value or a non numerical value at all, in which case atoi simply returns 0. This is the way iostat(8) handles this situation.

If we do not check for a negative value, then the negative value we are fed becomes an extremely large unsigned int and the thread will sleep(3) for a long time indeed.

>How-To-Repeat:
> vmstat -w -1
> vmstat -w -32409
> vmstat -w abc
>Fix:
apply my patch, all we need is a simple check if the value is less than 1. This way an error message also occurs if we could not parse a number, since the return value in that case is 0.

version of the file i've used:

FBSDID("$FreeBSD: src/usr.bin/vmstat/vmstat.c,v 1.98.2.4 2009/11/06 20:33:53 jhb Exp $");

Patch attached with submission follows:

--- vmstat.c	2010-01-17 18:01:12.000000000 +0200
+++ vmstat.orig.c	2010-01-17 17:59:02.000000000 +0200
@@ -244,8 +244,6 @@
 			break;
 		case 'w':
 			interval = atoi(optarg);
-			if ((int)interval < 1)
-				errx(1, "wait time < 1");
 			break;
 		case 'z':
 			todo |= ZMEMSTAT;


>Release-Note:
>Audit-Trail:
>Unformatted: