[lxc-devel] Possible bug in lxc-netstat w/ patch; feature patch

[Andrew Gilbert]

Hi,
I think I've discovered a bug in lxc-netstat when trying to have it run 
netstat with the '-n' option. I've attached a patch for this below 
(patch 1). I've also attached a patch that tries to Do The Right Thing 
if someone uses '-n' without the '--' before it (patch 2). I'd be happy 
to resend the patches as separate emails if that would be better.
--Andrew G

S T E P S   T O   R E P R O D U C E:
1. Start a container.
2. Use lxc-netstat -n <container-name> -- -n -a to try to get numeric 
IPs in netstat output.
3. Get error "./lxc-netstat: 75: shift: can't shift that many."

It appears that after the execution of lxc-unshare, the call to 
lxc-netstat does not include the '--' separator to prevent the netstat 
arguments being interpreted as lxc-netstat arguments. This only would 
manifest as a bug if the option is one that is valid for lxc-netstat as 
well as netstat, as the lone -n option is.

P A T C H   1:
 From 78ea721f2a6b0cc01cffba93109bd8d8202eeb98 Mon Sep 17 00:00:00 2001
From: Andrew Gilbert <andrewg800 at gmail.com>
Date: Fri, 21 Jun 2013 11:24:37 -0700
Subject: [PATCH] Add double-dash to lxc-netstat re-call arguments

When lxc-netstat was called by lxc-unshare, it would be given the
arguments intended for netstat from the first invocation, but without
anything to separate them from the arguments intended for lxc-netstat.
This meant that netstat arguments like -n would result in lxc-netstat
trying to process them
---
  src/lxc/lxc-netstat.in | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/lxc/lxc-netstat.in b/src/lxc/lxc-netstat.in
index 2fa2d23..229c214 100644
--- a/src/lxc/lxc-netstat.in
+++ b/src/lxc/lxc-netstat.in
@@ -93,7 +93,7 @@ if [ -z "$name" ]; then
  fi

  if [ -z "$exec" ]; then
-    exec @BINDIR@/lxc-unshare -s MOUNT -- $0 -n $name --exec "$@"
+    exec @BINDIR@/lxc-unshare -s MOUNT -- $0 -n $name --exec -- "$@"
  fi

  if lxc-info -n $name --state-is 'STOPPED'; then
-- 
1.8.1.2

P A T C H   2:
 From e45138027e08d291f4fad1357bcf5cb1b610c402 Mon Sep 17 00:00:00 2001
From: Andrew Gilbert <andrewg800 at gmail.com>
Date: Fri, 21 Jun 2013 14:36:28 -0700
Subject: [PATCH 2/2] Add -n differentiation to lxc-netstat

lxc-netstat now only processes an -n argument if it has not previously
received a value for $name from --name or -n. If it _has_ received such
a value, it stops processing arguments and leaves the -n for netstat.
This does not apply to the use of --name after a name has been provided
by --name or -n; the current behaviour continues.
---
  src/lxc/lxc-netstat.in | 13 ++++++++++++-
  1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/src/lxc/lxc-netstat.in b/src/lxc/lxc-netstat.in
index 229c214..4a239d9 100644
--- a/src/lxc/lxc-netstat.in
+++ b/src/lxc/lxc-netstat.in
@@ -66,12 +66,23 @@ get_parent_cgroup()
  }

  exec=""
+name=""

  while true; do
      case $1 in
          -h|--help)
              help; exit 1;;
-        -n|--name)
+        -n)
+            # If we already have a value for $name, treat -n as being an
+            # argument for netstat
+            if [ -n "$name" ]
+            then
+                break
+            else
+                name="$2"; shift 2;
+            fi
+            ;;
+        --name)
              name=$2; shift 2;;
          --exec)
              exec="exec"; shift;;
-- 
1.8.1.2