bitbake: event.py, knotty.py, ncurses.py, runningbuild.py: Add support for LogExecTTY event

The LogExecTTY even is intended to provide the ability to spawn a task
on a the controlling tty, if a tty is availble.  When a controlling
tty is not availble the previous behavior is preserved where a warning
is issued about the action an end user must execute.

All the available UI's were tested against the new event type.

This feature is primarily intended for hooking up a screen client
session automatically on the controlling tty to allow for a more
streamlined end user experience when using a pure command line driven
environment.  The changes that send the LogExecTTY event are in the
oe-core side.

(Bitbake rev: cffe80d82a46aaf52ff4a7b6409435754043553f)

Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/lib/bb/ui/knotty.py

@@ -27,6 +27,7 @@ import logging
 import progressbar
 import signal
 import bb.msg
+import time
 import fcntl
 import struct
 import copy
@@ -216,6 +217,10 @@ def main(server, eventHandler, tf = TerminalFilter):
     includelogs = server.runCommand(["getVariable", "BBINCLUDELOGS"])
     loglines = server.runCommand(["getVariable", "BBINCLUDELOGS_LINES"])
     consolelogfile = server.runCommand(["getVariable", "BB_CONSOLELOG"])
+    if sys.stdin.isatty() and sys.stdout.isatty():
+        log_exec_tty = True
+    else:
+        log_exec_tty = False
 
     helper = uihelper.BBUIHelper()
 
@@ -271,6 +276,20 @@ def main(server, eventHandler, tf = TerminalFilter):
                 if not main.shutdown:
                     main.shutdown = 1
 
+            if isinstance(event, bb.event.LogExecTTY):
+                if log_exec_tty:
+                    tries = event.retries
+                    while tries:
+                        print "Trying to run: %s" % event.prog
+                        if os.system(event.prog) == 0:
+                            break
+                        time.sleep(event.sleep_delay)
+                        tries -= 1
+                    if tries:
+                        continue
+                logger.warn(event.msg)
+                continue
+
             if isinstance(event, logging.LogRecord):
                 if event.levelno >= format.ERROR:
                     errors = errors + 1