[elinks-dev] [patch] don't resume terminal-stopped slave sessions

[Scott]

I have made this patch to avoid having to fg-suspend-fg to get a slave
session back if I have initially suspended it for longer than one
second.  I also find this behavior unpleasant because elinks loses its place in
my shell's job control queue as being the default process to foreground
without specifying a job number (because it is running in the background,
even though I did not tell it to do that).

It seems to me that automatically continuing suspended elinks sessions
unrequested behind the back of the user is a bit mysterious and initially
inexplicable for the naive user (like me ;)  The following patch allows this
behavior to affect the master only, and be configurable even in that
case.  Please let me know what you think.  Thanks.

diff -ur elinks-0.12-20071028/src/config/options.inc
elinks-nosusp/src/config/options.inc
--- elinks-0.12-20071028/src/config/options.inc	2007-10-27
15:40:03.000000000 -0700
+++ elinks-nosusp/src/config/options.inc	2007-11-02 22:33:29.000000000 -0700
@@ -1280,6 +1280,17 @@
 		"sessions", OPT_SORT,
 		N_("Sessions settings.")),

+#if defined (SIGCONT) && defined(SIGTTOU)
+	/* XXX see comment in signals.c to understand this */
+	INIT_OPT_BOOL("ui.sessions", N_("Keep session master running"),
+		"keep_master_running", 0, 0,
+		N_("Cause a master suspended instance to revive itself\n"
+		"after 1s.  Be aware that unsetting this option will\n"
+		"put the onus on the user to either keep the master\n"
+		"session running or start it in the background\n"
+		"and hangup the terminal.\n")),
+#endif
+
 	INIT_OPT_BOOL("ui.sessions", N_("Keep session active"),
 		"keep_session_active", 0, 0,
 		N_("Keep the session active even if the last terminal exits.")),
diff -ur elinks-0.12-20071028/src/osdep/signals.c
elinks-nosusp/src/osdep/signals.c
--- elinks-0.12-20071028/src/osdep/signals.c	2007-10-27 15:40:03.000000000 -0700
+++ elinks-nosusp/src/osdep/signals.c	2007-11-02 22:27:07.000000000 -0700
@@ -74,16 +74,40 @@
 	pid_t pid = getpid();

 	block_itrm();
+
 #if defined (SIGCONT) && defined(SIGTTOU)
-	if (!fork()) {
-		sleep(1);
-		kill(pid, SIGCONT);
-		/* Use _exit() rather than exit(), so that atexit
-		 * functions are not called, and stdio output buffers
-		 * are not flushed.  Any such things must have been
-		 * inherited from the parent process, which will take
-		 * care of them when appropriate.  */
-		_exit(0);
+	/*
+	 * If the master session is suspended, all slave
+	 * instances will block waiting for it to resume.
+	 * The following code is intended to prevent this by
+	 * causing any terminal-stopped instance to be
+	 * resumed after one second by a short-lived child
+	 * that continues its parent.  This is really only
+	 * needed by the session master, but we do it
+	 * unconditionally based on the setting of the
+	 * config option.
+	 *
+	 * This works out fine because load_config() is
+	 * never called from slave instances, so they will
+	 * only use the compiled-in default for the option;
+	 * slaves can be suspended happily without blocking
+	 * any other instances, so it shouldn't ever be
+	 * needed to enable this behavior in slave
+	 * instances.
+	 */
+	if (get_opt_bool("ui.sessions.keep_master_running")) {
+		if (!fork()) {
+			sleep(1);
+			kill(pid, SIGCONT);
+			/* Use _exit() rather than exit(),
+			 * so that atexit functions are not
+			 * called, and stdio output buffers
+			 * are not flushed.  Any such things
+			 * must have been inherited from the
+			 * parent process, which will take
+			 * care of them when appropriate.  */
+			_exit(0);
+		}
 	}
 #endif
 	raise(SIGSTOP);