From 18221ff472e95df5d36d1422868c7263b5495be7 Mon Sep 17 00:00:00 2001
From: Stephen Gallagher <sgallagh@redhat.com>
Date: Mar 17 2016 14:19:54 +0000
Subject: Fork to execute systemctl calls


Calling os.execute() to apply presets was a mistake for two reasons:
1) os.execute() calls out to a shell, which defeated the purpose of
   rewriting the scriptlet in Lua to avoid a /bin/sh dependency.
2) os.execute() only took a single argument, so it wasn't actually
   applying the presets at all.

Rewriting this to explicitly fork()/exec() results in properly-
applied presets without the /bin/sh dependency.

Signed-off-by: Stephen Gallagher <sgallagh@redhat.com>

---

diff --git a/convert-to-edition.lua b/convert-to-edition.lua
index d52a471..2a5b9d9 100644
--- a/convert-to-edition.lua
+++ b/convert-to-edition.lua
@@ -125,8 +125,17 @@ local function set_presets(edition, apply_presets)
       local presets = read_presets(target)
       local systemctl = "/usr/bin/systemctl"
       if posix.access(systemctl, "x") then
-        os.execute(systemctl, "preset", "-q",
-                   table.unpack(presets))
+        --fork off a systemctl call
+        local pid = assert(posix.fork())
+        if pid == 0 then
+          -- Child
+          posix.exec(systemctl, "preset", "-q", table.unpack(presets))
+          -- In case exec() fails
+          os.exit(17)
+        else
+          -- RPM
+          assert(posix.wait(pid))
+        end
       end
     end
   end