How to setup custom breakpoints in the C++ program? - c++

Question

I'm working on a project, where I cannot disclose the details of the code. So, the application is all written in C and C++. Since, a particular file which wanted to debug has a lot of dependencies and exports, I need to debug the whole project. How do I set breakpoints in the code itself so that the debugging would stop at that particular point? I'm using Ubuntu 14.04 (since the project is compatible with this environment) and gdb debugger.
I've tried using
#include <csignal>
// Generate an interrupt
std::raise(SIGINT);
But I keep getting error
error: ‘raise’ is not a member of ‘std’
Even this also didn't work
#include <signal.h>
raise(SIGINT);
Plus the debugging wont stop at that point, so that I could foresee the function at that point. I only want to debug it from console, rather using any IDE.
Since the programfile I want to debug has lot many header files which it imports, I'm unable to make a executable to use gdb. So, while make clean build of my MakeFile I want to debug the particular program file at a particular function. So, for that I want to add breakpoints in the program. I cannot use any GUI for debugging since I should not use.

Answer 1

Have you tried to use GDB Commands?
b lineno - set a break point at line 'lineno'
b srcfile:lineno - set a break point in source file 'srcfile' at line 'lineno'

Answer 2

Read more about debugging with gdb. Be sure to compile all your code with DWARF debug information (so use g++ -Wall -Wextra -g to compile it with GCC).
GDB is extensible and you can define your own gdb commands at startup in your init file, probably .gdbinit and put some initial commands there.
BTW, on Linux, debugging (so the gdb debugger) is using ptrace(2) facilities. And you can use gdb non-interactively on the command line, using scripts.
How do I set breakpoints in the code itself
I don't recommend adding specific C code for breakpoints. So don't do that in your C code. But see also this.
Perhaps you want some backtrace library, like Ian Taylor's libbacktrace ?
I cannot use any GUI for debugging
You don't need to. You'll use gdb on the command line. With an appropriate gdb script, you can even use it non-interactively (e.g. in a Makefile)
I only want to debug it from console, rather using any IDE.
Please realize that IDEs are only glorified source code editors capable of running other external tools (including the GCC compiler and the gdb debugger). You certainly don't need -on Linux- any IDE to run a compiler or a debugger (but IDEs could be convenient, but not necessary, for that), because you can (and should) run your compiler, your debugger, your build automation tool, on the command line.
Since the program file I want to debug has lot many header files which it imports, I'm unable to make a executable
You should fix that first. You need to make an executable. BTW, there is no "import" involved at run time, since header files are relevant only at compile time. Read more about the cpp preprocessor. You probably should invoke GCC (e.g. the g++ compiler, since you have C++ code) with appropriate preprocessor options (sometimes, tools like pkg-config are useful for that). You probably should use some build automation tool such as GNU make (with your Makefile; see this for inspiration) or ninja. You could add ad hoc gdb commands to your build procedure (e.g. with some additional and specific rules and/or recipes in your Makefile).

Answer 3

First, make sure you have compiled with -g. There are other gdb specific flags in gcc. You could add them in too.
Try using ddd, the graphical version of gdb. Great tool if you don't know the gdb command line. Just open up the relevant source file, select the line then click on breakpoint on the toolbar. It will tell you on the console section, what command was actually executed (good way to learn). There is a floating button list with run, next etc. for stepping through your code.
ddd will work on most of the gcc toolchain.
EDIT:
Say your code is made up of 2 files main.cpp and child.cpp. main.cpp contains main(). The executable is called a.out.
To start
ddd a.out &
It will open in main.cpp. To put a breakpoint in child.cpp, click on File/Open Source... and select child.cpp. Then scroll to where you want a breakpoint. Put your cursor on the line, then click on break in the toolbar.
To run, either type run in the gdb window below or click on Run in the floating button dialog.