[gnome-chess/gnome-3-10] Do not unconditionally call prctl in distributed C

[Michael Catanzaro <mcatanzaro src gnome org>]

commit a3de4249eebde1fc3714ef464c278d6b0cf09677
Author: Michael Catanzaro <mcatanzaro gnome org>
Date:   Thu Mar 20 22:41:17 2014 -0500

    Do not unconditionally call prctl in distributed C
    
    The existing check for linux/prctl.h works great if you are compiling
    the Vala code, but it's expected that users and distributions may start
    with the distributed C files instead. If the tarball is generated on
    Linux, then the call to prctl() will unconditionally appear in the
    distributed C, and if the tarball isn't generated on Linux, then it will
    be unconditionally absent.
    
    There are only two ways to fix this: (a) not distribute any C code, or
    (b) move the conditional compilation out of the Vala code. Though it
    looks like the Autotools Vala world may be starting to lean towards (a),
    let's be conservative and pick (b) for now.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=726614

 src/Makefile.am       |    8 +++-----
 src/chess-engine.vala |    6 +-----
 src/portability.c     |   30 ++++++++++++++++++++++++++++++
 src/portability.h     |   17 +++++++++++++++++
 src/portability.vapi  |    5 +++++
 src/prctl.vapi        |    9 ---------
 6 files changed, 56 insertions(+), 19 deletions(-)
---
diff --git a/src/Makefile.am b/src/Makefile.am
index 18edb60..0124689 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -9,7 +9,9 @@ gnome_chess_SOURCES = \
        gl.vapi \
        glu.vapi \
        glx.vapi \
-       prctl.vapi \
+       portability.vapi \
+       portability.c \
+       portability.h \
        3ds.vala \
        gnome-chess.vala \
        ai-profile.vala \
@@ -67,10 +69,6 @@ gnome_chess_VALAFLAGS = \
     --pkg posix \
     --pkg sqlite3
 
-if WITH_PRCTL
-    gnome_chess_VALAFLAGS += -D HAVE_LINUX_PRCTL_H
-endif
-
 CLEANFILES = \
        $(patsubst %.vala,%.c,$(filter %.vala, $(SOURCES))) \
        *_vala.stamp \
diff --git a/src/chess-engine.vala b/src/chess-engine.vala
index d5d98c0..d85d7a3 100644
--- a/src/chess-engine.vala
+++ b/src/chess-engine.vala
@@ -63,11 +63,7 @@ public abstract class ChessEngine : Object
         {
             Process.spawn_async_with_pipes (null, argv, null,
                                             SpawnFlags.SEARCH_PATH | SpawnFlags.DO_NOT_REAP_CHILD,
-#if HAVE_LINUX_PRCTL_H
-                                            () => Prctl.prctl (Prctl.SET_PDEATHSIG, Posix.SIGTERM),
-#else
-                                            null,
-#endif
+                                            () => Portability.maybe_kill_orphan_engine (),
                                             out pid, out stdin_fd, out stdout_fd, out stderr_fd);
         }
         catch (SpawnError e)
diff --git a/src/portability.c b/src/portability.c
new file mode 100644
index 0000000..00c098f
--- /dev/null
+++ b/src/portability.c
@@ -0,0 +1,30 @@
+/* -*- Mode: C; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ *
+ * Copyright © 2014 Michael Catanzaro
+ *
+ * This program is free software: you can redistribute it and/or modify it under
+ * the terms of the GNU General Public License as published by the Free Software
+ * Foundation, either version 2 of the License, or (at your option) any later
+ * version. See http://www.gnu.org/copyleft/gpl.html the full text of the
+ * license.
+ */
+
+#include "portability.h"
+
+#if HAVE_LINUX_PRCTL_H
+#include <signal.h>
+
+#include <linux/prctl.h>
+#include <sys/prctl.h>
+#endif
+
+/*
+ * When called in the engine process before exec, this ensures
+ * the engine is terminated in the event that we crash.
+ */
+void maybe_kill_orphan_engine ()
+{
+#if HAVE_LINUX_PRCTL_H
+    prctl (PR_SET_PDEATHSIG, SIGTERM);
+#endif
+}
diff --git a/src/portability.h b/src/portability.h
new file mode 100644
index 0000000..634a066
--- /dev/null
+++ b/src/portability.h
@@ -0,0 +1,17 @@
+/* -*- Mode: C; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ *
+ * Copyright © 2014 Michael Catanzaro
+ *
+ * This program is free software: you can redistribute it and/or modify it under
+ * the terms of the GNU General Public License as published by the Free Software
+ * Foundation, either version 2 of the License, or (at your option) any later
+ * version. See http://www.gnu.org/copyleft/gpl.html the full text of the
+ * license.
+ */
+
+#ifndef GNOME_CHESS_PORTABILITY_H
+#define GNOME_CHESS_PORTABILITY_H
+
+void maybe_kill_orphan_engine ();
+
+#endif GNOME_CHESS_PORTABILITY_H
diff --git a/src/portability.vapi b/src/portability.vapi
new file mode 100644
index 0000000..a620c3c
--- /dev/null
+++ b/src/portability.vapi
@@ -0,0 +1,5 @@
+[CCode (cheader_filename = "portability.h", lower_case_cprefix = "")]
+namespace Portability
+{
+    public void maybe_kill_orphan_engine ();
+}