CMake Build Error

[chairmanfaust]

When attempting to build this project on my raspberry pi running debian bookworm i'm hitting this problem at the end of the build instructions:

`mqtt@mqtt:/serial2mqtt $ cd build/
mqtt@mqtt:/serial2mqtt/build $ cmake ..
CMake Error at CMakeLists.txt:12 (find_package):
By not providing "Findeclipse-paho-mqtt-c.cmake" in CMAKE_MODULE_PATH this
project has asked CMake to find a package configuration file provided by
"eclipse-paho-mqtt-c", but CMake did not find one.

Could not find a package configuration file provided by
"eclipse-paho-mqtt-c" with any of the following names:

eclipse-paho-mqtt-cConfig.cmake
eclipse-paho-mqtt-c-config.cmake

Add the installation prefix of "eclipse-paho-mqtt-c" to CMAKE_PREFIX_PATH
or set "eclipse-paho-mqtt-c_DIR" to a directory containing one of the above
files. If "eclipse-paho-mqtt-c" provides a separate development package or
SDK, be sure it has been installed.

-- Configuring incomplete, errors occurred!
See also "/home/mqtt/serial2mqtt/build/CMakeFiles/CMakeOutput.log".
`

[oven-lab]

Same issue here.

[vortex314]

As I'm not a CMAKE expert, any suggestion is welcome, I'm spending most of my time in Rust these days.

[Gagns4395]

I could progress a bit on that. Seems the paho lib must be built and installed:

christophe@serveur-u:~/serial2mqtt$ cd paho.mqtt.c/
christophe@serveur-u:~/serial2mqtt/paho.mqtt.c$ sudo cmake --build . --target install
christophe@serveur-u:~/serial2mqtt/paho.mqtt.c$ make

but this not sufficient, because there's a next error as the paho lib is not build static, therefore paho-mqtt3as-static is missing

That can be fixed by adding -DPAHO_WITH_SSL=true to the paho command:

cd paho.mqtt.c && cmake -DPAHO_BUILD_STATIC=true -DPAHO_WITH_SSL=true && make && cd ..

I found that potentially -DPAHO_WITH_MQTT_C=ON in both paho and serial2mqtt was about, however my tries weren't successful.

If you put the -DPAHO_BUILD_STATIC=true, the last error that is raised is:

CMake Error at CMakeLists.txt:14 (add_executable):
  Target "serial2mqtt" links to target
  "eclipse-paho-mqtt-c::paho-mqtt3as-static" but the target was not found.
  Perhaps a find_package() call is missing for an IMPORTED target, or an
  ALIAS target is missing?

and indeed,

Consolidate compiler generated dependencies of target paho-mqtt3a-static
[ 30%] Building C object src/CMakeFiles/paho-mqtt3a-static.dir/MQTTAsync.c.o
[ 30%] Linking C static library libpaho-mqtt3a.a
[ 31%] Built target paho-mqtt3a-static

as only the non-SSL one is generated, but not the paho-mqtt3as-static

I don't know what to change in order to ask the paho build to install also the -DPAHO_BUILD_STATIC=true

[Gagns4395]

I will correct myself.

eclipse-paho-mqtt-c::paho-mqtt3as-static in CMakeList.txt requires to use the SSL version, and therefore find_package(OpenSSL REQUIRED) must be added.

...
if(PAHO_BUILD_STATIC)
    set(_PAHO_MQTT_C_LIB_NAME ${_PAHO_MQTT_C_LIB_NAME}-static)
endif()
find_package(eclipse-paho-mqtt-c REQUIRED)
find_package(OpenSSL REQUIRED)
add_definitions(-DLINUX -std=c++11)
add_executable(serial2mqtt)
...

Then the correct way to build paho-mqtt-c with the expected flavor is

cd paho.mqtt.c && cmake -DPAHO_BUILD_STATIC=true -DPAHO_WITH_SSL=true && make && cd ..

I mae some additional tests such as installing the lib paho-mqtt-c, so I hope it does not have fixed some issues without me knowing exactly what changed.

[vortex314]

Thanks a lot for your help.
Will you do a pull request ?

[Gagns4395]

This is the first time I involve myself in such open source project. Although I know enough GIT to be able to clone/commit, I'm not yet familiar with pull-request.
So please give me time to learn.
In addition, I must verify that what I recommend is sufficient, by testing it live with my Arduino Mega.

I was looking for such a solution on google, and was surprised that there is not a lot people interrested in that use-case.

[Gagns4395]

@vortex314 as I thought, the fix is not sufficient. I tested on a fresh computer, and there are many actions that can be done to fix the build.
Some are really shortcuts to pure Linux binary format.
However I think that you wanted to have something portable to other platforms. And that becomes a bit more tricky.

Let me investigate and come back to you.

[vortex314]

@Gagns4395 thanks already for your effort !

[Gagns4395]

@vortex314 please find my pull-request #62

[chairmanfaust]

Hey its been a long time since i've had a chance to look at this project, my goal is to connect my meshtastic station g2 esp32 device to my raspberry pi mosquitto mqtt server via usb/serial instead of wifi which is unreliable. I was able to progress further in the build but failed on the final 'make' step, see below:

mqtt@mqtt:~/serial2mqtt/build $ make
[  8%] Building CXX object CMakeFiles/serial2mqtt.dir/src/Serial2Mqtt.cpp.o
[ 16%] Building CXX object CMakeFiles/serial2mqtt.dir/src/LogFile.cpp.o
[ 25%] Building CXX object CMakeFiles/serial2mqtt.dir/src/Sys.cpp.o
[ 33%] Building CXX object CMakeFiles/serial2mqtt.dir/src/Timer.cpp.o
[ 41%] Building CXX object CMakeFiles/serial2mqtt.dir/src/main.cpp.o
[ 50%] Building CXX object CMakeFiles/serial2mqtt.dir/src/Config.cpp.o
[ 58%] Building CXX object CMakeFiles/serial2mqtt.dir/src/Bytes.cpp.o
[ 66%] Building CXX object CMakeFiles/serial2mqtt.dir/src/Log.cpp.o
/home/mqtt/serial2mqtt/src/Log.cpp: In member function ‘void Log::log(char, const char*, uint32_t, const char*, const char*, ...)’:
/home/mqtt/serial2mqtt/src/Log.cpp:157:24: error: ‘pthread_self’ was not declared in this scope; did you mean ‘pthread_t’?
  157 |     pthread_getname_np(pthread_self(), _application, sizeof(_application));
      |                        ^~~~~~~~~~~~
      |                        pthread_t
/home/mqtt/serial2mqtt/src/Log.cpp:157:5: error: ‘pthread_getname_np’ was not declared in this scope
  157 |     pthread_getname_np(pthread_self(), _application, sizeof(_application));
      |     ^~~~~~~~~~~~~~~~~~
make[2]: *** [CMakeFiles/serial2mqtt.dir/build.make:174: CMakeFiles/serial2mqtt.dir/src/Log.cpp.o] Error 1
make[1]: *** [CMakeFiles/Makefile2:83: CMakeFiles/serial2mqtt.dir/all] Error 2
make: *** [Makefile:91: all] Error 2