How to print call sequence of functions in c?

Question

I'm reading Apache httpd source code, I would like to know when a request come, which function get called first, followed by which function, and so on, is there some easy way to do so?

Something like

Waiting client connection...  # a client send a HTTP request
client.c:accept_request() is called
client.c:handle_request() is called
asdf.c:func1() is called
fdsa.c:func2() is called
response.c:send_response() is called
Waiting client connection...

ehh? Isn't is C code? (you tagged so), and AFAIK, C is process oriented... — Sourav Ghosh, Aug 01 '17 at 08:14
Please clarify: Do you want to print the call stack at runtime? This isn't possible in standard C. — , Aug 01 '17 at 08:15
For Linux, there is [`backtrace()`](http://man7.org/linux/man-pages/man3/backtrace.3.html) .. compile with debugging symbols for meaningful output. — , Aug 01 '17 at 08:22
Possible duplicate of [How can one grab a stack trace in C?](https://stackoverflow.com/questions/105659/how-can-one-grab-a-stack-trace-in-c) — , Aug 01 '17 at 08:22
Can you give an example of the output you want to see? This can probably be done using `systemtap`. — Mark Plotnick, Aug 01 '17 at 15:00

haccks · Accepted Answer · 2017-08-01T08:21:46.890

1

Put a printf statement at the beginning of each function

printf("Called function: %s\n", __func__);

This will print the name of the function when that function is called and this way you will able to know the function call sequence.

edited Aug 01 '17 at 08:21

answered Aug 01 '17 at 08:15

haccks

104,019
25
176
264

This is the only hard way. – haccks Aug 01 '17 at 08:18

score 1 · Answer 2 · answered Aug 01 '17 at 08:16

Not an easy way no, but there are multiple possibilities:

if you can run the code then going through it with a debugger or a profiler can help you see what is going on
again if you can run the code you can add traces to understand the flow of functions

printf(">>> entering %s\n", __func__);
printf("<<< leaving %s\n", __func__);

if you cannot run the code then maybe tools like ctags or cscope can help your see which functions are called when (or an IDE like eclipse or intellij)

How to print call sequence of functions in c?

2 Answers2