[RFC] Add SymbolLocator for Windows PDB Symbol Servers in LLDB

[compnerd]

@weliveindetail

Ok, I agree on your thought about Server in the name. I’d see the SymStore proposal as an option, but the whole protocol is really very specific to Windows, PE and PDB, which is all Microsoft land. I’d like to be pragmatic and keep this term. (IMHO SymbolLocatorApple would have been a less confusing name for the DebugSymbols one as well.)

Can you share why you believe this to be Microsoft-centric? The protocol is:

• extract build ID from executable
• walk symbol stores (explicitly specified or loaded from environment via _NT_SYMBOL_PATH)
  • for each store, attempt to copy the debug info (continue if failed, break if succeeded)

There is nothing Microsoft centric in this model. The build ID is stored as a RSDS record in PE/COFF, but you can store it as a .gnu.build-id note in ELF, or a LC_UUID load command in MachO.

You can generate the path to a PDB, dSYM, or DWP relative to the store base location.

In fact, you technically also use the symbol store to download the executable. This is helpful if you are doing a post-mortem diagnosis, and wish to retrieve the DLLs associated with the minidump (which amusingly enough I believe breakpad also uses on all platforms).