So I recently ran into a problem trying to build a program using under chromeos (chronos).
I cloned the repository and as instructed ran ./autogen.sh. No problems this far.
However, when I ran ./configure I got the following message:
checking arpa/inet.h usability... no
This told me that the configure script wasn't able to find the arpa/inet.h header file, however it didn't tell me where it was looking for.
Given that a regular chrome installation is pretty unusual, I wasn't surprised with getting some kind of error, but the message wasn't helpful at all as to how to fix it.
So my questions where:
./configure looking for the headers?For the first question I looked into the configure file itself. It was a shell script so I could just replace append -x to #! /bin/sh at the very top to make shell echo every command it ran.
That turned out to be unmaneagable since configure was huge and there was a lot of jumping between functions. So I wondered what was that magical configure script and what was that ./autogen.sh script that I ran earlier and how could I make it run in a more verbose manner. Turns out that autogen is a description that's read by autoconf and the result is written as a configure file. Turn's out there's a documentation page explaining how to debug the resulting script.
As instructed I have wrapped the call that checked for arpa/inet.h in the configure script with set -x and set +x.
I couldn't find any find or anything similar in it but I saw some gcc -E test.c here and there. I guessed that autoconf was creating a simple C file that contained an #include directive and then autoconf parsed the output of gcc to tell if the header could be found at all.
So my next test was to create a simple test file that did exactly that:
#include <arpa/inet.h>
I saved the above content as a C file and tried compiling it with gcc -E test.c > /dev/null. The output was this:
In file included from /usr/local/include/sys/socket.h:33,
from /usr/local/include/netinet/in.h:23,
from /usr/local/include/arpa/inet.h:22,
from test.c:1:
/usr/local/include/bits/socket.h:390:10: fatal error: asm/socket.h: No such file or directory
390 | #include <asm/socket.h>
| ^~~~~~~~~~~~~~
compilation terminated.
That told me that one of the dependencies of arpa/inet.h was importing asm/socket.h and failing to find it.
After reaching this far I wanted to make sure that gcc was looking in the right places for the headers before proceeding any further. Fortunately there's a page in the documentation that explains that.
Running,
cpp -v /dev/null -o /dev/null
I obtained the follwing in the output:
...
#include <...> search starts here:
/usr/local/include
/usr/include
End of search list.
...
/usr/local/include was indeed where my header files were. And answering the second question, no I didn't have asm/socket.h somewhere else. Googling I found that it was supposed to be included in the linux source header files, normally found in a distribution package.
As I was using chromebrew I needed to run crew install linuxheaders to get them.
And that was how I answered the third question. By installing the packages configure was able to run and generate the make files and I was able to build and install openfortivpn.
Hopefully this will be useful to someone (probably myself) in the future.