I'm not surprised. I was recently tasked with a very simple change in a bootloader in an industrial product used in the nuclear industry. Part of the task was also to find the latest sourcecode that was actually compiled into the product. The last known changes was some 20+ years ago!
I, as a contractor, and an employee (who was the one who actually coded the last change!) spent more than a week trying to hunt down any leads to anyone who could know where the source could be found. In the end we gave up, we had no leads at all it turned out. The code was not developed in the same company, and not even those working peripherally with these things were still working in the company.
In the end, the 15 lines of assembly that was supposed to be reverted/removed was done, but the uncertainty of the C-code part of the bootloader and some evidence that the known code was in fact no the latest and greatest, the change was abandoned altogether and a workaround in another part used instead.
I reverted to binary comparisons of machine code, and I also suggested editing the actual machine code to avoid recompiling other parts of the code, but it wasn't a very popular option and I advised against it if there were a possible workaround.
I, as a contractor, and an employee (who was the one who actually coded the last change!) spent more than a week trying to hunt down any leads to anyone who could know where the source could be found. In the end we gave up, we had no leads at all it turned out. The code was not developed in the same company, and not even those working peripherally with these things were still working in the company.
In the end, the 15 lines of assembly that was supposed to be reverted/removed was done, but the uncertainty of the C-code part of the bootloader and some evidence that the known code was in fact no the latest and greatest, the change was abandoned altogether and a workaround in another part used instead.
I reverted to binary comparisons of machine code, and I also suggested editing the actual machine code to avoid recompiling other parts of the code, but it wasn't a very popular option and I advised against it if there were a possible workaround.