From 9915ae30baea58608c15ce277c66172f12288ce0 Mon Sep 17 00:00:00 2001
From: Matthias Schmidt <matthias@dragonflybsd.org>
Date: Thu, 10 Jan 2008 14:18:39 +0000
Subject: [PATCH] Warn the user if he uses -e and procfs(5) is not mounted.

Obtained-from: FreeBSD
---
 bin/ps/ps.c | 25 ++++++++++++++++++++++++-
 1 file changed, 24 insertions(+), 1 deletion(-)

diff --git a/bin/ps/ps.c b/bin/ps/ps.c
index 5024b795f5..337b00e57e 100644
--- a/bin/ps/ps.c
+++ b/bin/ps/ps.c
@@ -33,7 +33,7 @@
  * @(#) Copyright (c) 1990, 1993, 1994 The Regents of the University of California.  All rights reserved.
  * @(#)ps.c	8.4 (Berkeley) 4/2/94
  * $FreeBSD: src/bin/ps/ps.c,v 1.30.2.6 2002/07/04 08:30:37 sobomax Exp $
- * $DragonFly: src/bin/ps/ps.c,v 1.24 2007/12/27 13:31:42 matthias Exp $
+ * $DragonFly: src/bin/ps/ps.c,v 1.25 2008/01/10 14:18:39 matthias Exp $
  */
 
 #include <sys/param.h>
@@ -44,6 +44,7 @@
 #include <sys/stat.h>
 #include <sys/ioctl.h>
 #include <sys/sysctl.h>
+#include <sys/mount.h>
 
 #include <ctype.h>
 #include <err.h>
@@ -95,6 +96,7 @@ static void	 saveuser (KINFO *);
 static void	 scanvars (void);
 static void	 dynsizevars (KINFO *);
 static void	 sizevars (void);
+static int	 check_procfs(void);
 static void	 usage (void);
 static uid_t	*getuids(const char *, int *);
 
@@ -293,6 +295,15 @@ main(int argc, char **argv)
 	argc -= optind;
 	argv += optind;
 
+	/*
+	 * If the user specified ps -e then they want a copy of the process
+	 * environment kvm_getenvv(3) attempts to open /proc/<pid>/mem.
+	 * Check to make sure that procfs is mounted on /proc, otherwise
+	 * print a warning informing the user that output will be incomplete.
+	 */
+	if (needenv == 1 && check_procfs() == 0)
+		warnx("Process environment requires procfs(5)");
+
 #define	BACKWARD_COMPATIBILITY
 #ifdef	BACKWARD_COMPATIBILITY
 	if (*argv) {
@@ -643,6 +654,18 @@ kludge_oldps_options(char *s)
 	return (newopts);
 }
 
+static int
+check_procfs(void)
+{
+	struct statfs mnt;
+
+	if (statfs("/proc", &mnt) < 0)
+		return (0);
+	if (strcmp(mnt.f_fstypename, "procfs") != 0)
+		return (0);
+	return (1);
+}
+
 static void
 usage(void)
 {
-- 
2.41.0