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authorРоман Донченко <dpb corrigendum ru>2014-04-30 19:11:56 +0100
committerSimon McVittie <simon.mcvittie@collabora.co.uk>2014-04-30 19:11:56 +0100
commit3be6063729017060fbca41970fa1ab7768be37e4 (patch)
tree4e36c2dfb9ada111d4efa25eaa9b3c4cdd4fd57b /tools
parent370ba31171f83dcd74e3b369338308f7cbb11a7f (diff)
downloaddbus-3be6063729017060fbca41970fa1ab7768be37e4.tar.gz
Avoid killing all available processes if an X error arrives early on
The timeline of events in dbus-launch's main process goes something like this: * do initial X calls [1] * do some other stuff * fork (child process starts doing some other stuff) * return "intermediate parent" pid from fork() * obtain bus daemon pid from bus_pid_to_launcher_pipe [2] * do things that might include X11 calls or killing the dbus-daemon Meanwhile, the "babysitter" child goes like this: * return 0 from fork() [3] * obtain bus daemon pid from parent process via bus_pid_to_babysitter_pipe [4] * do things that might include X11 calls or killing the bus daemon Before [1] or [3], the right thing to do about an X error is to just exit. The current implementation called kill(-1) first, which is undesirable: it kills unrelated processes. With this change, we just exit. After [2] or [4], the right thing to do is to kill the dbus-daemon, and that's what the existing code did. Between [1] and [2], or between [3] and [4], there is no correct thing that we can do immediately: we would have to wait for the end of the "critical section", *then* kill the dbus-daemon. This has not yet been implemented, so this patch relies for its correctness on the fact that there are no libX11 calls between those points, so we cannot receive an X error between them. dbus-launch deserves more comments, or a reimplementation that is easier to understand, but this change is certainly better than nothing. [Commit message added, summarizing reviewers' comments -smcv] Bug: https://bugs.freedesktop.org/show_bug.cgi?id=74698 Reviewed-by: Simon McVittie Reviewed-by: Thiago Macieira
Diffstat (limited to 'tools')
-rw-r--r--tools/dbus-launch.c8
1 files changed, 7 insertions, 1 deletions
diff --git a/tools/dbus-launch.c b/tools/dbus-launch.c
index 7ecee63e..58a0322e 100644
--- a/tools/dbus-launch.c
+++ b/tools/dbus-launch.c
@@ -406,6 +406,9 @@ static pid_t bus_pid_to_kill = -1;
static void
kill_bus(void)
{
+ if (bus_pid_to_kill <= 0)
+ return;
+
verbose ("Killing message bus and exiting babysitter\n");
kill (bus_pid_to_kill, SIGTERM);
sleep (3);
@@ -1275,6 +1278,10 @@ main (int argc, char **argv)
bus_pid = val;
+ /* Have to initialize bus_pid_to_kill ASAP, so that the
+ X error callback can kill it if an error happens. */
+ bus_pid_to_kill = bus_pid;
+
close (bus_pid_to_launcher_pipe[READ_END]);
#ifdef DBUS_ENABLE_X11_AUTOLAUNCH
@@ -1291,7 +1298,6 @@ main (int argc, char **argv)
{
char *address = NULL;
/* another window got added. Return its address */
- bus_pid_to_kill = bus_pid;
if (x11_get_address (&address, &bus_pid, &wid)
&& address != NULL)
{