How to get list of all header files included in C source file?

Question

I have tried parsing files using #include by Python. I have tried to match pattern using sed command. Both these ways I get garbage data. For example, if in some comment I have /* #include "header.h" */ I get those lines as well. How to avoid this?

can you post code what ever you tried? – Jayesh Bhoi Sep 10 '14 at 05:54 — Jayesh Bhoi, Sep 10 '14 at 05:54
do you have any code that u have tried out so far !! – DOOM Sep 10 '14 at 05:54 — DOOM, Sep 10 '14 at 05:54
I tried : sed -nr \'/#include/p\' file.c – Aabha Geed Sep 10 '14 at 06:02 — Aabha Geed, Sep 10 '14 at 06:02

score 7 · Answer 1 · answered Sep 10 '14 at 06:19

GCC supports the -H option. Consider the source file hw.c:

#include <stdio.h>
int main(void) { puts("Hello world"); return 0; }

On Mac OS X 10.9.4 with GCC 4.8.1:

$ gcc -H -c hw.c
. /usr/include/stdio.h
.. /usr/include/sys/cdefs.h
... /usr/include/sys/_symbol_aliasing.h
... /usr/include/sys/_posix_availability.h
.. /usr/include/Availability.h
... /usr/include/AvailabilityInternal.h
.. /usr/include/_types.h
... /usr/include/sys/_types.h
.... /usr/include/machine/_types.h
..... /usr/include/i386/_types.h
.. /usr/include/sys/_types/_va_list.h
.. /usr/include/sys/_types/_size_t.h
.. /usr/include/sys/_types/_null.h
.. /usr/include/sys/_types/_off_t.h
.. /usr/include/sys/_types/_ssize_t.h
.. /usr/include/secure/_stdio.h
... /usr/include/secure/_common.h
Multiple include guards may be useful for:
/usr/include/secure/_stdio.h
/usr/include/sys/_posix_availability.h
/usr/include/sys/_symbol_aliasing.h
$

+1 That's the easy way. something new to know. – Jayesh Bhoi Sep 10 '14 at 06:20 — Jayesh Bhoi, Sep 10 '14 at 06:20

5gon12eder · Answer 2 · 2014-09-11T13:50:46.213

Once you start thinking about non-trivial cases like

/* #include <header.h> */

you'll soon reach the point where it is no longer really practical to write your own dependency extractor.

Consider for example these:

#define PLUGIN "my_extension.h"
#include PLUGIN

#ifdef WITH_CURSES
#  include <curses.h>
#endif

You can continue the list indefinitely. If you want to handle all these correctly, you'll end up implementing a full preprocessor.

I don't know what you want to do with the generated list of flies but a common situation is to determine on which files a compilation unit depends, for example to generate makefiles. Most compilers have included special support for this. In GCC, it is the -M option.

main.c

#include <alpha.h>

/* #include <beta.h> */

#ifdef PLUGIN
#include PLUGIN
#endif

#if WITH_DELTA
#include <delta.h>
#endif

alpha.h

#include <epsilon.h>

Let beta.h, gamma.h, delta.h and epsilon.h be empty (or, at least, not #include anything).

$ gcc -I. -M main.c
main.o: main.c /usr/include/stdc-predef.h alpha.h epsilon.h

$ gcc -I. -DPLUGIN='<gamma.h>' -M main.c
main.o: main.c /usr/include/stdc-predef.h alpha.h epsilon.h gamma.h

$ gcc -I. -DWITH_DELTA=1 -M main.c
main.o: main.c /usr/include/stdc-predef.h alpha.h epsilon.h delta.h

Even if you are not ultimately trying to generate a makefile, parsing the preprocessor's output will be a lot easier than walking your own way through the source files.

I tried using -M option of GCC. if the headers are not in same directory as the one with source file the i get error: No such file or directory — Aabha Geed, Sep 10 '14 at 06:32
You must add the respective directories to the include path via the `-I` option, just as if you were actually compiling. — 5gon12eder, Sep 10 '14 at 06:33

score 0 · Answer 3 · answered Sep 10 '14 at 05:57

0

If your compiler supports the -E (or similar) option, something like this may be useful:

cc -E myprogram.c | grep '^# 1 '

The -E option says just run the preprocessing stage and show the results.

An advantage of this method is that you can include any important -I and -D command line options as you would for a normal compile, thus capturing any behavior change those might engender.

answered Sep 10 '14 at 05:57

John Hascall

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This will work on gcc and clang, but you could use `-MD` or `-H` to better effect. – rici Sep 10 '14 at 14:59

score 0 · Accepted Answer · answered Sep 10 '14 at 05:59

0

Have you considered using something like pycparser that parses C files? It may be overkill for your question, but it does allow much more advanced parsing options.

answered Sep 10 '14 at 05:59

Michael Petch

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The re module serches for all the matches of #includes. The problem is when a comment is multi line I am not able to filter the multi line comments if I get garbage value for ex. /*-------------- – Aabha Geed Sep 10 '14 at 06:09
Can you tell me how do i use pycparser? – Aabha Geed Sep 10 '14 at 12:00

score -1 · Answer 5 · answered Sep 10 '14 at 06:01

-1

You could use the grep utility (Linux, MacOS X):

grep '/^\s*#/' my_file.c

or (for a multi-file search)

grep '/^\s*#/' *.c

answered Sep 10 '14 at 06:01

Miguel Prz

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This doesn't seem to work at all... – John Hascall Sep 10 '14 at 06:04
Grep doesn't understand `\s` (unless you're using gnu grep, and even then you need to specify `-P` to enable Perl-style regexen). Use `[[:space:]]` instead. But anyway, this could still fail if the supposed `#include` is inside of a `/*` comment. – rici Sep 10 '14 at 14:55

score -1 · Answer 6 · answered Sep 10 '14 at 06:03

-1

I use re module with Match and Search functions. Search will find the text anywere in the string while match starts from the beginning of the string

answered Sep 10 '14 at 06:03

aivision2020

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The re module serches for all the matches of #includes. The problem is when a comment is multi line I am not able to filter the multi line comments if I get garbage value for ex. /*-------------- #include stuff ---------*/ – Aabha Geed Sep 10 '14 at 06:10
you are right, I was thinking of matching per line. without parsing the entire file how do you think to do it? – aivision2020 Sep 10 '14 at 11:34
Ill need to use some tool of compiler or any open source parser – Aabha Geed Sep 10 '14 at 11:48

How to get list of all header files included in C source file?

6 Answers6