Convert a gcc command to CMake for android ndk

Question

I need to add a c project which can be compiled with gcc as follows

gcc  -I/usr/include/epic5.1 -I/usr/include/i386-linux-gnu/epic5.1 -I./smproject/ -o code code.c ./smproject/smlib.so -lepic5.1

I have moved the code.c files content to my Android NDK .cpp file (src/main/cpp/native-lib.cpp) and also moved all files inside smproject directory to src/main/cpp/smproject/ directory

Here is my CMakeList.txt content

# For more information about using CMake with Android Studio, read the
# documentation: https://d.android.com/studio/projects/add-native-code.html

# Sets the minimum version of CMake required to build the native library.

cmake_minimum_required(VERSION 3.4.1)

# Creates and names a library, sets it as either STATIC
# or SHARED, and provides the relative paths to its source code.
# You can define multiple libraries, and CMake builds them for you.
# Gradle automatically packages shared libraries with your APK.
include_directories( /usr/include/epic5.1 )
include_directories( /usr/include/i386-linux-gnu/epic5.1 )
include_directories( src/main/cpp )

set_target_properties( delorean PROPERTIES IMPORTED_LOCATION
                       src/main/cpp/smlib.so
                        )
add_library( smlib STATIC IMPORTED )

add_library( # Sets the name of the library.
             native-lib

             # Sets the library as a shared library.
             SHARED

             # Provides a relative path to your source file(s).
             src/main/cpp/native-lib.cpp
             )

# Searches for a specified prebuilt library and stores the path as a
# variable. Because CMake includes system libraries in the search path by
# default, you only need to specify the name of the public NDK library
# you want to add. CMake verifies that the library exists before
# completing its build.

find_library( # Sets the name of the path variable.
              log-lib

              # Specifies the name of the NDK library that
              # you want CMake to locate.
              log)

# Specifies libraries CMake should link to your target library. You
# can link multiple libraries, such as libraries you define in this
# build script, pre-built third-party libraries, or system libraries.

target_link_libraries( # Specifies the target library.
                       native-lib

                       # Links the target library to the log library
                       # included in the NDK.
                       ${log-lib}
                       smlib
                       )

I tried to follow Android NDK, CMake with other libraries but that didn't work for me it started throwing gradle error

tried following in build.gradle file

apply plugin: 'com.android.application'

android {
    compileSdkVersion 25
    buildToolsVersion "25.0.2"
    defaultConfig {
        applicationId "in.etpg.sampleapp"
        minSdkVersion 15
        targetSdkVersion 25
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
        externalNativeBuild {
            cmake {
                cppFlags "-I/usr/include/epic5.1 -I/usr/include/i386-linux-gnu/epic5.1 -lepic5.1 -frtti -fexceptions"
            }
        }
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
    externalNativeBuild {
        cmake {
            path "CMakeLists.txt"
        }
    }
}

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
        exclude group: 'com.android.support', module: 'support-annotations'
    })
    compile 'com.android.support:appcompat-v7:25.3.1'
    compile 'com.android.support.constraint:constraint-layout:1.0.2'
    testCompile 'junit:junit:4.12'
}

Errors

Error:cannot find -lepic5.1
Error:error: linker command failed with exit code 1 (use -v to see
Warning:warning: -lepic5.1: 'linker' input unused
Error:A problem occurred configuring project ':app'.
> executing external native build for cmake /Users/laptop.user/AndroidStudioProjects/SampleApp/app/CMakeLists.txt

Answer 1

You simply need to add something to your module build.gradle, like this

ndk {
    moduleName "code"
    cFlags "-I/usr/include/epic5.1 -I/usr/include/i386-linux-gnu/epic5.1 -lepic5.1 -frtti -fexceptions"
    ldLibs "log"
}

and place the source files in main/jni.

Perhaps, you need to change cFlags to cppFlags, but I recommend that you search for more information about this, the suggestion is based on the fact that you have -fnoexceptions flag, which is for c++.

You need of course libepic5.1.so binary to use it for compilation, if you can add it's source code it will work.