We are currently migrating Bugzilla to GitHub issues.
Any changes made to the bug tracker now will be lost, so please do not post new bugs or make changes to them.
When we're done, all bug URLs will redirect to their equivalent location on the new bug tracker.

Bug 4218 - SDL crashes when accessing IBUS (with workaround)
Summary: SDL crashes when accessing IBUS (with workaround)
Status: ASSIGNED
Alias: None
Product: SDL
Classification: Unclassified
Component: *don't know* (show other bugs)
Version: 2.0.8
Hardware: x86 Linux
: P2 normal
Assignee: Ryan C. Gordon
QA Contact: Sam Lantinga
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2018-07-15 01:46 UTC by post
Modified: 2018-11-05 12:12 UTC (History)
2 users (show)

See Also:

Attachments
Add an attachment (proposed patch, testcase, etc.)

Note You need to log in before you can comment on or make changes to this bug.
Description post 2018-07-15 01:46:51 UTC 
When starting simutrans game I get an error from dbus which seems to complain about some ibus message. (I don’t know what ibus is for, but this isn’t important here). Error message and backtrace follow:

dbus[8517]: arguments to dbus_message_new_method_call() were incorrect, assertion "path != NULL" failed in file dbus-message.c line 1362.
This is normally a bug in some application using the D-Bus library.

  D-Bus not built with -rdynamic so unable to print a backtrace

Program received signal SIGABRT, Aborted.
0xb7fd5d41 in __kernel_vsyscall ()
(gdb) bt
#0  0xb7fd5d41 in __kernel_vsyscall ()
#1  0xb79d7132 in raise () from /lib/libc.so.6
#2  0xb79bf7e8 in abort () from /lib/libc.so.6
#3  0xb74ab34a in _dbus_abort () at dbus-sysdeps.c:93
#4  0xb74cf0ac in _dbus_warn_check_failed (
    format=0xb74df6b8 "arguments to %s() were incorrect, assertion \"%s\" failed in file %s line %d.\nThis is normally a bug in some application using the D-Bus library.\n") at dbus-internals.c:281
#5  0xb74cf87b in _dbus_warn_return_if_fail (function=0xb74de5c0 <__func__.4821> "dbus_message_new_method_call", 
    assertion=0xb74dab26 "path != NULL", file=0xb74ddbc1 "dbus-message.c", line=1362) at dbus-internals.c:936
#6  0xb74be1a7 in dbus_message_new_method_call (destination=0xb7f20bb4 <IBUS_SERVICE> "org.freedesktop.IBus", path=0x0, 
    iface=0xb7f20b60 <IBUS_INPUT_INTERFACE> "org.freedesktop.IBus.InputContext", method=0xb7f20ac3 "FocusOut") at dbus-message.c:1367
#7  0xb7efc3f4 in SDL_DBus_CallVoidMethodInternal () from /usr/lib/libSDL2-2.0.so.0
#8  0xb7efcc64 in SDL_DBus_CallVoidMethodOnConnection () from /usr/lib/libSDL2-2.0.so.0
#9  0xb7efdeb5 in IBus_SimpleMessage () from /usr/lib/libSDL2-2.0.so.0
#10 0xb7efda6b in IBus_SetupConnection () from /usr/lib/libSDL2-2.0.so.0
#11 0xb7efdbd9 in SDL_IBus_Init () from /usr/lib/libSDL2-2.0.so.0
#12 0xb7efcffe in SDL_IME_Init () from /usr/lib/libSDL2-2.0.so.0
#13 0xb7ee7b75 in X11_InitKeyboard () from /usr/lib/libSDL2-2.0.so.0
#14 0xb7eeec34 in X11_VideoInit () from /usr/lib/libSDL2-2.0.so.0
#15 0xb7ed45d6 in SDL_VideoInit_REAL () from /usr/lib/libSDL2-2.0.so.0
#16 0xb7e42be2 in SDL_InitSubSystem_REAL () from /usr/lib/libSDL2-2.0.so.0
#17 0x0079cc9b in dr_os_init(int const*) ()
#18 0x00711e68 in simu_main(int, char**) ()
---Type <return> to continue, or q <return> to quit---
#19 0x0072b07b in sysmain(int, char**) ()
#20 0x0041e127 in main ()
(gdb) 



So workaround is to start program with some misleading ibus setting, such as:

IBUS_ADDRESS=bääää /usr/bin/simutrans

This will let return SDL_IBus_Init with SDL_FALSE and game’s working.

I suggest to either make SDL more robust against such errors or to publicly document IBUS_ADDRESS parameter (e.g. like this: https://www.libsdl.org/release/SDL-1.2.15/docs/html/sdlenvvars.html).


Remark: I posted this on mailing list and on https://discourse.libsdl.org/t/sdl-crashes-when-accessing-ibus-with-workaround/24713 but then discovered you wanted an entry in bugzilla. So this is kind-of duplicate.
Comment 1 Sam Lantinga 2018-07-17 16:00:35 UTC 
Ryan, is this fixed with your recent change?
Comment 2 Stas Sergeev 2018-11-03 22:17:03 UTC 
I have the same problem.
The bug is that when "CreateInputContext" method
fails, SDL continues with IBus, hitting an assert.
Something like this should fix the problem (untested):

--- SDL_ibus.c.old	2018-11-04 01:12:50.074897655 +0300
+++ SDL_ibus.c	2018-11-04 01:14:58.376753098 +0300
@@ -342,6 +342,8 @@
         dbus->connection_try_register_object_path(ibus_conn, input_ctx_path, &ibus_vtable, dbus, NULL);
         dbus->connection_flush(ibus_conn);
         result = SDL_TRUE;
+    } else {
+        return SDL_FALSE;
     }
 
     SDL_IBus_SetFocus(SDL_GetKeyboardFocus() != NULL);
Comment 3 Ozkan Sezer 2018-11-05 11:11:03 UTC 
(In reply to Stas Sergeev from comment #2)
> I have the same problem.
> The bug is that when "CreateInputContext" method
> fails, SDL continues with IBus, hitting an assert.
> Something like this should fix the problem (untested):
> 
> --- SDL_ibus.c.old	2018-11-04 01:12:50.074897655 +0300
> +++ SDL_ibus.c	2018-11-04 01:14:58.376753098 +0300
> @@ -342,6 +342,8 @@
>          dbus->connection_try_register_object_path(ibus_conn, input_ctx_path, &ibus_vtable, dbus, NULL);
>          dbus->connection_flush(ibus_conn);
>          result = SDL_TRUE;
> +    } else {
> +        return SDL_FALSE;
>      }
>  
>      SDL_IBus_SetFocus(SDL_GetKeyboardFocus() != NULL);

Do we not need to do  dbus->connection_close(ibus_conn)  and
dbus->connection_unref(ibus_conn)  before returning SDL_FALSE
in there?
Comment 4 Stas Sergeev 2018-11-05 11:33:04 UTC 
(In reply to Ozkan Sezer from comment #3)
> Do we not need to do  dbus->connection_close(ibus_conn)  and
> dbus->connection_unref(ibus_conn)  before returning SDL_FALSE
> in there?
Likely so, ideed.
For me the problem happens only on a multilib
setup, the native one works properly. So I have
not built the multilib version of SDL with the
patch. It would be better if you attach the patch
with your amendments, and hope someone will test. :)
Comment 5 Ozkan Sezer 2018-11-05 11:44:37 UTC 
Well I only looked at the code briefly and made that comment:
I do not have the issue myself so I cannot reproduce or test.
(If only we had a foolproof reproducer for this.)
Comment 6 Stas Sergeev 2018-11-05 12:12:14 UTC 
(In reply to Ozkan Sezer from comment #5)
> (If only we had a foolproof reproducer for this.)
Easily: just modify the IBus_SetupConnection() the
way to not call SDL_DBus_CallMethodOnConnection(),
pretending it returned FALSE. Then you go further
but with "input_ctx_path == NULL", which will quickly
lead to an assert (right on SDL_IBus_SetFocus(), which
is even called in the same function).