greeter crashes at launch on fedora, segfaults in gsettings code

[decathorpe]

I tried finding the root cause of this issue, but I can't figure out why the greeter crashes on fedora but works on ubuntu.

This is the traceback that I can gather from the SIGSEGV crash (I think only the first thread is interesting):

Process 949 (io.elementary.g) of user 977 dumped core.

Stack trace of thread 949:
#0  0x00007fc039bad855 _g_log_abort (libglib-2.0.so.0)
#1  0x00007fc039bae921 g_log_default_handler (libglib-2.0.so.0)
#2  0x00007fc039baeb6f g_logv (libglib-2.0.so.0)
#3  0x00007fc039baed63 g_log (libglib-2.0.so.0)
#4  0x00007fc038432b1e g_settings_schema_get_value (libgio-2.0.so.0)
#5  0x00007fc038433180 g_settings_schema_key_init (libgio-2.0.so.0)
#6  0x00007fc03843760f g_settings_set_value (libgio-2.0.so.0)
#7  0x00005567b5c86080 settings_daemon_set_plugin_enabled (io.elementary.greeter)
#8  0x00005567b5c86c8d settings_daemon_start (io.elementary.greeter)
#9  0x00005567b5c84d82 pantheon_greeter_construct (io.elementary.greeter)
#10 0x00005567b5c85efa pantheon_greeter_new (io.elementary.greeter)
#11 0x00007fc03710f11b __libc_start_main (libc.so.6)
#12 0x00005567b5c8314a _start (io.elementary.greeter)

Stack trace of thread 955:
#0  0x00007fc0371db3e9 __poll (libc.so.6)
#1  0x00007fc039ba7bc6 g_main_context_iterate.isra.21 (libglib-2.0.so.0)
#2  0x00007fc039ba7cf0 g_main_context_iteration (libglib-2.0.so.0)
#3  0x00007fc039ba7d41 glib_worker_main (libglib-2.0.so.0)
#4  0x00007fc039bcff8a g_thread_proxy (libglib-2.0.so.0)
#5  0x00007fc0374b2594 start_thread (libpthread.so.0)
#6  0x00007fc0371e5e6f __clone (libc.so.6)

Stack trace of thread 985:
#0  0x00007fc0374b851c pthread_cond_wait@@GLIBC_2.3.2 (libpthread.so.0)
#1  0x00007fc0287d80c3 thread_function (swrast_dri.so)
#2  0x00007fc0287d800b impl_thrd_routine (swrast_dri.so)
#3  0x00007fc0374b2594 start_thread (libpthread.so.0)
#4  0x00007fc0371e5e6f __clone (libc.so.6)

Stack trace of thread 988:
#0  0x00007fc0374b851c pthread_cond_wait@@GLIBC_2.3.2 (libpthread.so.0)
#1  0x00007fc0287d80c3 thread_function (swrast_dri.so)
#2  0x00007fc0287d800b impl_thrd_routine (swrast_dri.so)
#3  0x00007fc0374b2594 start_thread (libpthread.so.0)
#4  0x00007fc0371e5e6f __clone (libc.so.6)

Stack trace of thread 987:
#0  0x00007fc0374b851c pthread_cond_wait@@GLIBC_2.3.2 (libpthread.so.0)
#1  0x00007fc0287d80c3 thread_function (swrast_dri.so)
#2  0x00007fc0287d800b impl_thrd_routine (swrast_dri.so)
#3  0x00007fc0374b2594 start_thread (libpthread.so.0)
#4  0x00007fc0371e5e6f __clone (libc.so.6)

Stack trace of thread 986:
#0  0x00007fc0374b851c pthread_cond_wait@@GLIBC_2.3.2 (libpthread.so.0)
#1  0x00007fc0287d80c3 thread_function (swrast_dri.so)
#2  0x00007fc0287d800b impl_thrd_routine (swrast_dri.so)
#3  0x00007fc0374b2594 start_thread (libpthread.so.0)
#4  0x00007fc0371e5e6f __clone (libc.so.6)

Stack trace of thread 970:
#0  0x00007fc0371e0879 syscall (libc.so.6)
#1  0x00007fc039bee76e g_cond_wait_until (libglib-2.0.so.0)
#2  0x00007fc039b7a0f1 g_async_queue_pop_intern_unlocked (libglib-2.0.so.0)
#3  0x00007fc039bd0ad2 g_thread_pool_thread_proxy (libglib-2.0.so.0)
#4  0x00007fc039bcff8a g_thread_proxy (libglib-2.0.so.0)
#5  0x00007fc0374b2594 start_thread (libpthread.so.0)
#6  0x00007fc0371e5e6f __clone (libc.so.6)

Stack trace of thread 967:
#0  0x00007fc0371db3e9 __poll (libc.so.6)
#1  0x00007fc039ba7bc6 g_main_context_iterate.isra.21 (libglib-2.0.so.0)
#2  0x00007fc039ba7f82 g_main_loop_run (libglib-2.0.so.0)
#3  0x00007fc0383f27aa gdbus_shared_thread_func (libgio-2.0.so.0)
#4  0x00007fc039bcff8a g_thread_proxy (libglib-2.0.so.0)
#5  0x00007fc0374b2594 start_thread (libpthread.so.0)
#6  0x00007fc0371e5e6f __clone (libc.so.6)

Stack trace of thread 971:
#0  0x00007fc0371e0879 syscall (libc.so.6)
#1  0x00007fc039bee76e g_cond_wait_until (libglib-2.0.so.0)
#2  0x00007fc039b7a0f1 g_async_queue_pop_intern_unlocked (libglib-2.0.so.0)
#3  0x00007fc039bd0ad2 g_thread_pool_thread_proxy (libglib-2.0.so.0)
#4  0x00007fc039bcff8a g_thread_proxy (libglib-2.0.so.0)
#5  0x00007fc0374b2594 start_thread (libpthread.so.0)
#6  0x00007fc0371e5e6f __clone (libc.so.6)

Stack trace of thread 1058:
#0  0x00007fc018753e34 dconf_gdbus_worker_thread (libdconfsettings.so)
#1  0x00007fc039bcff8a g_thread_proxy (libglib-2.0.so.0)
#2  0x00007fc0374b2594 start_thread (libpthread.so.0)
#3  0x00007fc0371e5e6f __clone (libc.so.6)

If I comment out the code handling gnome-settings-daemon in the src/SettingsDaemon.vala file, the greeter launches fine, but GTK and icon theme are messed up (probably because it's falling back to adwaita / hicolor).

[decathorpe]

After spending some more time investigating this, I found that the elementary greeter code relies on ubuntu-specific downstream patches to gnome-settings-daemon here. The active GSettings keys aren't present in upstream gnome-settings-daemon anymore (which is why they're not present in fedora).

With this patch I'm able to get it working - mostly:
https://github.com/decathorpe/elementary-nightly-rpms/blob/master/sources/elementary-greeter/00-remove-broken-gsettings.patch