Message-Id: <200303022227.h22MRjYU061341@thor.piqnet.org>
Date: Sun, 2 Mar 2003 14:27:45 -0800 (PST)
From: Joel Ray Holveck <joelh@piqnet.org>
Reply-To: Joel Ray Holveck <joelh@piqnet.org>
To: FreeBSD-gnats-submit@FreeBSD.org
Subject: ports/48852: sysutils/pstree can go into infinite loop for zombies [PATCH]
Sender: owner-freebsd-ports-bugs@FreeBSD.ORG
Precedence: bulk


>Number:         48852
>Category:       ports
>Synopsis:       sysutils/pstree can go into infinite loop for zombies [PATCH]
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    freebsd-ports-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Sun Mar 02 14:30:04 PST 2003
>Closed-Date:
>Last-Modified:
>Originator:     Joel Ray Holveck
>Release:        FreeBSD 5.0-RELEASE i386
>Organization:
>Environment:
System: FreeBSD thor.piqnet.org 5.0-RELEASE FreeBSD 5.0-RELEASE #13: Sun Feb 9 17:11:33 PST 2003 root@thor.piqnet.org:/usr/local/src/freebsd/src/sys/i386/compile/THOR i386
pstree v2.17
>Description:
Under FreeBSD 5.0, zombie processes are reported by ps with pid 0.
Also, init and swapper have ppid 0.  This leads to a cycle, and pstree
is only designed to handle trees.
>How-To-Repeat:
    thor$ perl -e 'fork() && sleep 100;'
    ^Z
    [1]+  Stopped                 perl -e 'fork() && sleep 100;'
    thor$ bg
    [1]+ perl -e 'fork() && sleep 100;' &
    thor$ ps ax | grep perl
        0  p9  ZW     0:00.00  (perl)
    33322  p9  S      0:00.02 perl -e fork() && sleep 100;
    33374  p9  S+     0:00.01 grep perl
Note the zombie perl with pid 0.
Now:
    thor$ pstree|more
Watch the output for cycles.  You can search for '00000' to find them easily.
>Fix:
I know that there's a patch mechanism in ports, but I'm not sure what
the proper way to submit a patch for that is.  So here's a patch to
the pstree source.

--- pstree.c.~1~        Mon Dec 17 04:18:02 2001
+++ pstree.c    Sun Mar  2 14:15:11 2003
@@ -655,8 +655,9 @@
   sprintf(nhead, "%s%s ", head,
          head[0] == '\0' ? "" : EXIST(P[idx].sister) ? C->bar : " ");

-  for (child = P[idx].child; EXIST(child); child = P[child].sister)
-    PrintTree(child, nhead);
+  if (P[idx].pid)
+    for (child = P[idx].child; EXIST(child); child = P[child].sister)
+      PrintTree(child, nhead);
 }

 void Usage(void) {
>Release-Note:
>Audit-Trail:
>Unformatted:

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