[PATCH] os: added the -upstart option for Upstart's signaling method.

[Oliver McFadden]

This is very similar to the RunFromSmartParent option, except we do not
send the signal to our parent process, but our own process instead; also
the signal is SIGSTOP, not SIGUSR1.

Upstart will detect that our process has stopped, and interprets this as
"process ready" (to accept clients), send us SIGCONT, and move our job
from the SPAWNED to RUNNING status.

Signed-off-by: Oliver McFadden <oliver.mcfadden at nokia.com>
---
Unfortunately we're stuck with using Upstart, and in the tradition of trying to
keep as close to upstream as possible, I'm sending this for review...

According to http://upstart.ubuntu.com/ Upstart is used by a number of
distributions (Ubuntu, Fedora, Debian, and of course Maemo) so this is probably
a worthwhile patch.

 include/opaque.h |    1 +
 os/connection.c  |    5 +++++
 os/utils.c       |    5 +++++
 3 files changed, 11 insertions(+), 0 deletions(-)

diff --git a/include/opaque.h b/include/opaque.h
index b3c7c70..f8c0000 100644
--- a/include/opaque.h
+++ b/include/opaque.h
@@ -55,6 +55,7 @@ extern _X_EXPORT int defaultBackingStore;
 extern _X_EXPORT Bool disableBackingStore;
 extern _X_EXPORT Bool enableBackingStore;
 extern _X_EXPORT Bool PartialNetwork;
+extern _X_EXPORT Bool RunFromUpstart;
 #ifndef NOLOGOHACK
 extern _X_EXPORT int logoScreenSaver;
 #endif
diff --git a/os/connection.c b/os/connection.c
index 3ff93bb..92aec38 100644
--- a/os/connection.c
+++ b/os/connection.c
@@ -146,6 +146,8 @@ Bool NewOutputPending;		/* not yet attempted to write some new output */
 Bool AnyClientsWriteBlocked;	/* true if some client blocked on write */
 
 static Bool RunFromSmartParent;	/* send SIGUSR1 to parent process */
+Bool RunFromUpstart;		/* send SIGSTOP to our own process;
+				   Upstart will send SIGCONT back. */
 Bool PartialNetwork;	/* continue even if unable to bind all addrs */
 static Pid_t ParentProcess;
 
@@ -357,6 +359,9 @@ NotifyParentProcess(void)
 	    kill (ParentProcess, SIGUSR1);
 	}
     }
+    if (RunFromUpstart) {
+	kill (getpid (), SIGSTOP);
+    }
 #endif
 }
 
diff --git a/os/utils.c b/os/utils.c
index 21e25e0..d19ffb0 100644
--- a/os/utils.c
+++ b/os/utils.c
@@ -538,6 +538,7 @@ void UseMsg(void)
 #endif
     ErrorF("-dumbSched             Disable smart scheduling, enable old behavior\n");
     ErrorF("-schedInterval int     Set scheduler interval in msec\n");
+    ErrorF("-upstart               Enable support for Upstart's signaling method\n");
     ErrorF("+extension name        Enable extension\n");
     ErrorF("-extension name        Disable extension\n");
 #ifdef XDMCP
@@ -936,6 +937,10 @@ ProcessCommandLine(int argc, char *argv[])
 		UseMsg ();
 	}
 #endif
+	else if ( strcmp( argv[i], "-upstart") == 0)
+	{
+	    RunFromUpstart = TRUE;
+	}
 	else if ( strcmp( argv[i], "+extension") == 0)
 	{
 	    if (++i < argc)
-- 
1.6.1