gdb and shared libraries

[Patrick Alken <patrick dot alken at colorado dot edu>]

Hello,

  I am the developer of ald (http://ald.sourceforge.net), which
is a GNU licensed debugger designed specifically for assembly
level debugging.  Right now I am trying to solve the problem of
loading in the symbol tables of shared libraries for a target
program so that breakpoints can be set at addresses in these
libraries.

  Unfortunately it has not been easy to find information on
how to best do this, and after studying the gdb source code
for a while I decided it was best to ask this list for help.

  I am looking for a big picture with perhaps some useful
details for the more complicated steps. As an example,

1. fork + ptrace(TRACE_ME) + exec (child)
2. catch SIGTRAP (parent)
3. user types "run"
4. (start singlestepping/continuing/whatever until shared libraries
    have been loaded and ?somehow? get names of all libraries
    loaded by dynamic linker)
5. mmap() that list of libraries and then load their symbol tables
   into memory so breakpoints can be set there

So it is step #4 that I am hoping someone on the list can give me
details for. How do you know when all the libraries have been loaded
so that you can stop execution of the program while you load
the libs symbol tables? How do you get the pathnames of the libraries
after they have been loaded so you can mmap them?

Thank you in advance,
Patrick Alken