Use HEADERS variable to set public header property of libjapi. PUBLIC…

[Michael-M-Baron]

…_HEADERS as a variable was not set and thus leading to no installed headers

[vornkat-iis]

Can you please add the usage of make install in the README? Cause while you explained to me why this is necessary, I was confused as well and there is no documentation. make help also just gives you a list of possible targets without explanation

[Michael-M-Baron]

Added a new section to README.md explaining how libjapi can be installed.

[Michael-M-Baron]

I also had a look add the linux conventions of where to install the library (See https://www.pathname.com/fhs/ and https://ubuntuforums.org/showthread.php?t=1528661 for reference).

• /usr/include: This is where all of the system’s general-use include files for the C programming language should be placed. Libraries in this folder are usually managed by the systems package manager and libraries like json-c will be installed in here.
• /usr/local/include: This hierarchy is for use by the system administrator when compiling and installing software locally. It needs to
  be safe from being overwritten when the system software is updated.
  The same explanation can be used for /usr/lib and /usr/local/lib.

In our case libjapi will be installed in /usr/local/lib and /usr/local/include/japi which makes sense since we do not have an officially managed package and install the library locally.

The header files of libjapi will be installed in /usr/local/include/japi (into a subfolder japi) to follow the conventions used in json-c which header files are installed in /usr/include/json-c

[Michael-M-Baron]

When testing on my machine, /usr/local/lib was already present in the linker searchs path:

root@72a51fea23f0:/# ld --verbose | grep SEARCH_DIR | tr -s ' ;' \\012
SEARCH_DIR("=/usr/local/lib/arm-linux-gnueabihf")
SEARCH_DIR("=/lib/arm-linux-gnueabihf")
SEARCH_DIR("=/usr/lib/arm-linux-gnueabihf")
SEARCH_DIR("=/usr/local/lib")
SEARCH_DIR("=/lib")
SEARCH_DIR("=/usr/lib")
SEARCH_DIR("=/usr/arm-linux-gnueabihf/lib")

The include files of japi however I had to manually add to the system environemnt with:

export C_INCLUDE_PATH=/usr/local/include

I then could use the installed version of libjapi to link against my application. Libjapi header files can be included like

#include <japi/japi.h>
#include <japi/japi_pushsrv.h>

This of course depends on how you set the C_INCLUDE_PATH environment variable. When set to /usr/local/include/japi

#include <japi.h>
#include <japi_pushsrv.h>

will be enough when including