util.subp: do not attach stdin cloud-init's stdin to subprocesses (LP: 831505)

Fix issue where 'isatty' would return true for apt-add-repository.
It would get stdin which was attached to a terminal (/dev/console) and would
thus hang when running during boot.

This was done by changing all users of util.subp to have None input unless
input was given.  In that case, the input will be the string passed in.

LP: #831505

2 files changed, 3 insertions, 5 deletions

diff --git a/cloudinit/CloudConfig/cc_apt_update_upgrade.py b/cloudinit/CloudConfig/cc_apt_update_upgrade.py
index 41c34bc3..495b8522 100644
--- a/cloudinit/CloudConfig/cc_apt_update_upgrade.py
+++ b/cloudinit/CloudConfig/cc_apt_update_upgrade.py
@@ -127,7 +127,7 @@ def add_sources(srclist, searchList={ }):
 
         source=ent['source']
         if source.startswith("ppa:"):
-            try: util.subp(["add-apt-repository",source], "/dev/null")
+            try: util.subp(["add-apt-repository",source])
             except:
                 elst.append([source, "add-apt-repository failed"])
             continue
diff --git a/cloudinit/util.py b/cloudinit/util.py
index 5058e1d4..bdc1fce2 100644
--- a/cloudinit/util.py
+++ b/cloudinit/util.py
@@ -141,10 +141,8 @@ def runparts(dirp, skip_no_exist=True):
     return
 
 def subp(args, input=None):
-    s_in = None
-    if input is not None:
-        s_in = subprocess.PIPE
-    sp = subprocess.Popen(args, stdout=subprocess.PIPE, stderr=subprocess.PIPE, stdin=s_in)
+    sp = subprocess.Popen(args, stdout=subprocess.PIPE,
+        stderr=subprocess.PIPE, stdin=subprocess.PIPE)
     out,err = sp.communicate(input)
     if sp.returncode is not 0:
         raise subprocess.CalledProcessError(sp.returncode,args, (out,err))