Re: How to have gdb step into a function from the application's shared library?

[lee <lee@yun.yagibdah.de>]

On Fri, Jul 17, 2009 at 11:34:40PM +0000, sobtwmxt wrote:
> Consider the following pseudo code:
> 
>     ::::::::
>     appLib.h
>     ::::::::
>     int funcInAppLib(void);
> 
> 
>     ::::::
>     main.c
>     ::::::
>     #include "appLib.h"
> 
>     int main(void) {
>         if (funcInAppLib() < 0)  printf("funcInAppLib() < 0\n"); 
>     }
> 
> 
>   Where the application is debianized, and appLib is installed as a 
> shared library.  It has an associated -dev library, which is not 
> normally installed.
> 
>   I want to have gdb step into funcInAppLib().  What should I do so 
> that single step in main will actually step into funcInAppLib()?  What 
> I did so far is:
> 1) Make the deb without stripping debugging symbols.
> 2) Single step main() with gdb, by gdb s command.  But that process 
>    skipped stepping into funcInAppLib(). 

You might want to install ddd (just to make it easier) and use it to
set a breakpoint at the start of the function before running the
program.

That still doesn't guarantee that the function is called. There can be
circumstances under which a function somehow gets "optimized away",
like getting inlined. In such a case, you might need to turn off all
optimization when compiling and/or put in some extra code for
debugging to the function being called.

I would change the code like that:


int main(void) {
  int ret;

  ret = funcInAppLib();
  if(ret < 0) {
    puts("funcInAppLib() < 0\n");
    fflush(stdout);
  }
}


Doing it step by step in the source like that can make it easier to
trace. Do the like in the function, and set a breakpoint in the
function.