Basic (26) GDB Debugging so tutorial

When you develop a so file, how to debug it?

For a and how to write a so, please refer to the article: http://blog.csdn.net/zz7zz7zz/article/details/41448987

For GDB debugging, please refer to the article: http://blog.csdn.net/zz7zz7zz/article/details/41654457

Let's say our source files are:

Filea.c

#include <stdio.h>void fun1 () {printf ("I am from Filea fun1 \ n");p rintf ("I am from Filea fun11 \ n");p rintf ("I am from Filea fun12 \ n ");}

Fileb.c

#include <stdio.h>void fun2 () {printf ("I am from Fileb fun2 \ n");p rintf ("I am from Fileb fun21 \ n");p rintf ("I am from Fileb fun22 \ n ");}

CLoadSo.h

#ifndef _cloadso_h#define _cloadso_h#ifdef _cplusplusextern "C" {#endifvoid fun1 (); void Fun2 (); #ifdef _cplusplus}# Endif#endif

Cloadso.c

#include <stdio.h> #include <dlfcn.h> #include "CLoadSo.h" int main (int argc,char **argv) {void *sohandle;int (*fun) (); Char *errormsg;sohandle=dlopen ("first.so", Rtld_lazy), Errormsg=dlerror ();p rintf ("A1---------Loadso is%s \ n", Sohandle? "Success": "Failed"), if (errormsg) {printf ("A2--------loadso Error, MSG is:%s \ n", errormsg); return-1;} Fun=dlsym (Sohandle, "fun1"); Errormsg=dlerror ();p rintf ("B1---------fun1, fun1 is%s \ n", fun? "Success": "Null"), if (fun) {fun ();} if (errormsg) {printf ("B2---------fun1 Error, MSG is:%s \ n", errormsg);} Fun=dlsym (Sohandle, "fun2"); Errormsg=dlerror ();p rintf ("B3---------fun2, fun2 is%s \ n", fun? "Success": "Null"), if (fun) {fun ();} if (errormsg) {printf ("B4---------fun2 Error, MSG is:%s \ n", errormsg);} Fun=dlsym (Sohandle, "fun3"); Errormsg=dlerror ();p rintf ("B5---------Fun3, Fun3 is%s \ n", fun? "Success": "Null"), if (fun) {fun ();} if (!errormsg) {printf ("B6---------fun3 Error, MSG is:%s \ n", errormsg);} Dlclose (Sohandle);p rintf ("C---------close LOADSO \ n"); return 0;} 

With the command gcc-wall-fpic-g-shared filea.c fileb.c-o first.soGenerate First.so File

Generate the executable file with the command gcc-g-wall cloadso.c-o cloadso-ldl cloadso

The GDB steps are as follows (please observe the Red Comment statement):

[email protected] gdbso]$ gdb CLOADSO ----------(1). Start GdB Debugging

GNU gdb (GDB) CentOS (7.0.1-45.el5.centos) Copyright (C) software Foundation, Inc.license gplv3+: GNU GPL version 3 or later 
The result: successful entry into the fun1 of so
Approximate steps:
1. Start GdB debugging: GdB CLOADSO
2. Breaking point gdb): Break 28
3. Execute gdb): Run
4. read the symbol for the dynamic library into GDB for you to find the variable and function name gdb) sharedlibrary first.so
5.s Enter function, l list source code, n step to end.








Basic (26) GDB Debugging so tutorial