gen_graph.py

Description

Python command line tool to visualize function-call-flow for a C/C++ program using graphviz dot object and matplotlib.

Directory structure:

├── gallery
│   ├── graph_GNU_MAKE_.png
│   ├── graph_QEMU.png
│   ├── graph_VIM.png
│   ├── some_library_graph.png
│   ├── test.png
│   └── test.svg
├── gen_graph.py
├── LICENSE
├── README.md
├── requiments.txt
└── test
    ├── test.c
    └── test.log

Motivation

I wanted to view call-graph for OS source (written in C, C++) that connected APIs within one layer and APIs across layers. This helps in getting a bigger picture of the source code and makes understanding large code bases QUICK.

Input

Requires data from gdb to get nodes (functions) and edges (function 1 calling function 2).

Output

Di-graph showing relationship between functions across software layers, the "bigger picture".

Usage

There are two parts to the whole process:

1. get data by runnning process under gdb
2. process this data with gen_graph.py

Part I: Get data from GDB

Test code

$ cat test.c
#include<stdio.h>


static void func9(void) { printf("leaf\n");; }
void func8(void) { func9(); }
void func7(void) { func8(); }
void func6(void) { func7(); }
void func5(void) { func6(); }
void func4(void) { func5(); }
void func3(void) { func4(); }
void func2(void) { func3(); }
void func1(void) { func2(); }
int main()
{
        func1();
        return 0;
}

Enable debugging symbols

$ test -g test.c

Now, the GDB part

start binary under GDB

$ gdb a.out
. . .
Reading symbols from a.out...done.

Insert breakpoints on functions of interest, or to put in every funtion in a file:

(gdb) rbreak test.c:.
Breakpoint 1 at 0x40058f: file he.c, line 12.
void func1(void);
Breakpoint 2 at 0x400583: file he.c, line 11.
void func2(void);
Breakpoint 3 at 0x400577: file he.c, line 10.
void func3(void);
Breakpoint 4 at 0x40056b: file he.c, line 9.
void func4(void);
Breakpoint 5 at 0x40055f: file he.c, line 8.
void func5(void);
Breakpoint 6 at 0x400553: file he.c, line 7.
void func6(void);
Breakpoint 7 at 0x400547: file he.c, line 6.
void func7(void);
Breakpoint 8 at 0x40053b: file he.c, line 5.
void func8(void);
Breakpoint 9 at 0x40052a: file he.c, line 4.
void func9(void);
Breakpoint 10 at 0x40059b: file he.c, line 15.
int main();

Enable logging

(gdb) set pagination off
(gdb) set print pretty
(gdb) set logging file ./test.log
(gdb) set logging on
Copying output to ./test.log.

Tell gdb to print backtrace and continue without asking when it hits a breakpoint

(gdb) command
Type commands for breakpoint(s) 1-10, one per line.
End with a line saying just "end".
>bt
>c
>end

Start the program

(gdb) r
Starting program: /home/vagrant/c_code/a.out

Once the program finishes, it would have dumped the logs to the disk in test.log

$ cat test.log
Type commands for breakpoint(s) 1-10, one per line.
End with a line saying just "end".
Starting program: /home/vagrant/c_code/a.out

Breakpoint 9, main () at he.c:15
15              func1();
#0  main () at he.c:15

Breakpoint 1, func1 () at he.c:12
12      void func1(void) { func2(); }
#0  func1 () at he.c:12
#1  0x00000000004005a0 in main () at he.c:15

Breakpoint 2, func2 () at he.c:11
11      void func2(void) { func3(); }
#0  func2 () at he.c:11
#1  0x0000000000400594 in func1 () at he.c:12
#2  0x00000000004005a0 in main () at he.c:15

Breakpoint 3, func3 () at he.c:10
10      void func3(void) { func4(); }
#0  func3 () at he.c:10
#1  0x0000000000400588 in func2 () at he.c:11
#2  0x0000000000400594 in func1 () at he.c:12
#3  0x00000000004005a0 in main () at he.c:15

Breakpoint 4, func4 () at he.c:9
9       void func4(void) { func5(); }
#0  func4 () at he.c:9
#1  0x000000000040057c in func3 () at he.c:10
#2  0x0000000000400588 in func2 () at he.c:11
#3  0x0000000000400594 in func1 () at he.c:12
#4  0x00000000004005a0 in main () at he.c:15

Breakpoint 5, func5 () at he.c:8
8       void func5(void) { func6(); }
#0  func5 () at he.c:8
#1  0x0000000000400570 in func4 () at he.c:9
#2  0x000000000040057c in func3 () at he.c:10
#3  0x0000000000400588 in func2 () at he.c:11
#4  0x0000000000400594 in func1 () at he.c:12
#5  0x00000000004005a0 in main () at he.c:15

Breakpoint 6, func6 () at he.c:7
7       void func6(void) { func7(); }
#0  func6 () at he.c:7
#1  0x0000000000400564 in func5 () at he.c:8
#2  0x0000000000400570 in func4 () at he.c:9
#3  0x000000000040057c in func3 () at he.c:10
#4  0x0000000000400588 in func2 () at he.c:11
#5  0x0000000000400594 in func1 () at he.c:12
#6  0x00000000004005a0 in main () at he.c:15

Breakpoint 7, func7 () at he.c:6
6       void func7(void) { func8(); }
#0  func7 () at he.c:6
#1  0x0000000000400558 in func6 () at he.c:7
#2  0x0000000000400564 in func5 () at he.c:8
#3  0x0000000000400570 in func4 () at he.c:9
#4  0x000000000040057c in func3 () at he.c:10
#5  0x0000000000400588 in func2 () at he.c:11
#6  0x0000000000400594 in func1 () at he.c:12
#7  0x00000000004005a0 in main () at he.c:15

Breakpoint 8, func8 () at he.c:5
5       void func8(void) { func9(); }
#0  func8 () at he.c:5
#1  0x000000000040054c in func7 () at he.c:6
#2  0x0000000000400558 in func6 () at he.c:7
#3  0x0000000000400564 in func5 () at he.c:8
#4  0x0000000000400570 in func4 () at he.c:9
#5  0x000000000040057c in func3 () at he.c:10
#6  0x0000000000400588 in func2 () at he.c:11
#7  0x0000000000400594 in func1 () at he.c:12
#8  0x00000000004005a0 in main () at he.c:15

Breakpoint 10, func9 () at he.c:4
4       static void func9(void) { printf("leaf\n");; }
#0  func9 () at he.c:4
#1  0x0000000000400540 in func8 () at he.c:5
#2  0x000000000040054c in func7 () at he.c:6
#3  0x0000000000400558 in func6 () at he.c:7
#4  0x0000000000400564 in func5 () at he.c:8
#5  0x0000000000400570 in func4 () at he.c:9
#6  0x000000000040057c in func3 () at he.c:10
#7  0x0000000000400588 in func2 () at he.c:11
#8  0x0000000000400594 in func1 () at he.c:12
#9  0x00000000004005a0 in main () at he.c:15
[Inferior 1 (process 3363) exited normally]
$

Part II: run gen_graph.py on collected data

Dependencies

sudo apt-get install graphviz
sudo python3 -m pip install -r requiments.txt

Now run gen_graph.py

$ python gen_graphs.py
Usage:
python3 ./gen_graphs.py  <gdb_backtrace_logs>


$ python3 gen_graphs.py test.log
[1] parsing gdb logs..
[2] adding nodes..
        # of nodes: 10
[3] adding edges..
        # of edges: 9
[4] saving graph to:
        /home/vagrant/gdb_graphs/test.svg

Open the svg file in a browser

New

• Interactive graphs: Click on a node and entire parent and child chain is highlighted (to reset - reload page - untill I find a better way to do from JS)
• C++ Support