PDB file vs SDB file?

Question

Radare has a format called a sdb. I asked a question here,

• What is an SDB file?

The answer I got was,

These sdbfiles contain function names (DLL's exports) and their equivalent ordinals for each dll in ./libr/bin/d/dll/.

One of the pages linked tells you how to make a sdb file, given a dll as input. I've done that. Now I see there are pdb files too.

|Usage: id Debug information
| Output mode:     
| '*'              Output in radare commands
| id               Source lines
| idp [file.pdb]   Load pdb file information
| idpi [file.pdb]  Show pdb file information
| idpd             Download pdb file on remote server

The specific sdb I've created is of a Microsoft dll. Moreover, I see Microsoft offers official pdb files.

• Is there any advantage to using a pdb over an sdb?
• Do these both convey the same information to the extent that adding a pdb when you already have a loaded sdb does nothing?

Looking at a function in question nothing changed when I loaded the pdb.

Answer 1

While sdb files was created to translate imports that are referenced by ordinal instead of by name (see "Exporting Functions from a DLL by Ordinal Rather Than by Name"), pdb files are something entirely different.

Program Database

Program Database (PDB) file or DBG file are produced by the compiler. PDB files are used by developers to debug their program and is commonly removed from the binary before it distributed to the client. Most chances is that you won't find debug symbols inside most of the real-world binaries.

Symbol files hold a variety of data which are not actually needed when running the binaries, but which could be very useful in the debugging process.

PDB files typically contain:

• Public symbols (typically all functions, static and global variables)
• A list of object files that are responsible for sections of code in the executable
• Frame pointer optimization information (FPO)
• Name and type information for local variables and data structures
• Source file and line number information

Microsoft publishes all the PDB files for all operating systems and other redistributed components on its symbol server. This makes it easy to debug an application that uses these DLL or executable files. You can use the Microsoft symbol server to resolve symbols, together with any local symbols for components that were built on your computer.

You can find more information about how radare2 interpret PDB files in the following links:

• Symbols information | radare2book
• PDB Usage | radare2 docs

PDB vs SDB

As you probably figured out by now, SDB and PDB are two different things and for debugging purposes, PDB is much more helpful.

Further reading:

• Linking by ordinal
• Import Symbols by Ordinals in Link-Time
• Debugging with Symbols
• Symbols and symbol files
• Information from Microsoft about the PDB format