ureport: allow empty file_name/build_id for topmost frame

[mmilata]

Related to abrt/satyr#127.

One of the reasons file_name is missing in a frame is that the address in the topmost (i.e. most recent) frame does not belong to the address space of the program and therefore has no corresponding file_name or build_id. This is usually because the program jumped to invalid address, which caused the crash.

Usually this happens for the thread marked as crash thread, but not always:

• the crash thread detection we use is not very good
• in theory, it is possible for this to happen to multiple threads simultaneously when running on multi-core CPU

[mbrysa]

Closed via https://github.com/abrt/faf/commit/d73551138c82d4c00cca9d5a704b452c8dc373b2

[ernestask]

Well, the mentioned commit does something quite different than what the issue is about…

See https://bugzilla.redhat.com/show_bug.cgi?id=1747110

Aug 29 23:27:30 dhcp70-199 systemd-coredump[10123]: Process 9001 (gnome-shell) of user 0 dumped core.#012#012Stack trace of thread 9073:#012#0  0x00007fff958f0020 n/a (n/a)#012#1  0x00007fff870bb774 lp_rast_shade_tile (kms_swrast_dri.so)#012#2  0x00007fff870bbcb4 rasterize_scene (kms_swrast_dri.so)#012#3  0x00007fff870bc680 thread_function (kms_swrast_dri.so)#012#4  0x00007fff870bc3d0 impl_thrd_routine (kms_swrast_dri.so)#012#5  0x00007fff9b7b8ba0 start_thread (libpthread.so.0)#012#6  0x00007fff9cb71398 __clone (libc.so.6)

(Formatting retained from the bug)

The most recent frame has no file_name field and sending micro-reports fails:

pyfaf.checker.CheckError: Element 'stacktrace' is invalid: List element is invalid: Element 'frames' is invalid: List element is invalid: Element 'file_name' is missing