Added traces are cleared if elf file is passed later on command line

[couchand]

Passing the input elf file on the command line after --add-trace parameters causes the added traces to be silently dropped. This is pretty surprising, and caused me much headache.

It looks like the argument processing for --add-trace directly modifies the same elf_firmware_t that is passed to elf_read_firmware. Two possible mitigations would be to accumulate the trace structs separately and later merge, or update elf_read_firmware to not clobber traces already added. I couldn't immediately find where the latter was happening.

If you'd like to suggest the right strategy to take and point me in the right direction, I'd be happy to submit a patch. Thanks!

[gatk555]

It sounds similar to the cause in Pull Request #438: elf_read_firmware() starts with memset(), destroying all initialiasations. Removing memset() crashes, so a fix may not be so simple ...

[buserror]

We might need a split functionality for the firmware loading approach then, with an _init that prepares the structure, leave user code a way to add their own things, and then do an read_firmware() to finish it up.