Adds JNI symbol check to ensure we don't miss any definitions (#160)

java/java.gradle

@@ -93,6 +93,27 @@ task jniHeadersNetworkTables {
     }
 }
 
+ext.getNativeJNISymbols = {
+    def symbolsList = []
+
+    jniHeadersNetworkTables.outputs.files.each {
+        FileTree tree = fileTree(dir: it)
+        tree.each { File file ->
+            file.eachLine { line ->
+                if (line.trim()) {
+                    if (line.startsWith("JNIEXPORT ") && line.contains('JNICALL')) {
+                        def (p1, p2) = line.split('JNICALL').collect { it.trim() }
+                        // p2 is our JNI call
+                        symbolsList << p2
+                    }
+                }
+            }
+        }
+    }
+
+    return symbolsList
+}
+
 clean {
     delete generatedJNIHeaderLoc
 }

ntcore.gradle

@@ -12,6 +12,7 @@ def ntcoreSetupModel = { project ->
 
                 if (includeJava) {
                     project.setupJniIncludes(binaries)
+                    project.checkNativeSymbols(project.getNativeJNISymbols)
                     binaries.all {
                         project.setupDef(linker, "${rootDir}/ntcore-jni.def")
                     }

toolchains/arm.gradle

@@ -92,3 +92,29 @@ ext.debugStripSetup = {
         }
     }
 }
+
+ext.checkNativeSymbols = { getSymbolFunc ->
+    project.tasks.whenObjectAdded { task ->
+        if (task.name.contains('link') && task.name.contains('SharedLibrary')) {
+            def library = task.outputFile.absolutePath
+            task.doLast {
+                def nmOutput = new ByteArrayOutputStream()
+                exec { 
+                    commandLine "${compilerPrefix}nm", library
+                    standardOutput nmOutput
+                }
+                // Remove '\r' so we can check for full string contents
+                String nmSymbols = nmOutput.toString().replace('\r', '')
+
+                def symbolList = getSymbolFunc()
+                symbolList.each {
+                    //Add \n so we can check for the exact symbol
+                    def found = nmSymbols.contains(it + '\n')
+                    if (!found) {
+                        throw new GradleException("Found a definition that does not have a matching symbol ${it}")
+                    }
+                }
+            }
+        }
+    }
+}

toolchains/linux.gradle

@@ -59,3 +59,29 @@ ext.debugStripSetup = {
         }
     }
 }
+
+ext.checkNativeSymbols = { getSymbolFunc ->
+    project.tasks.whenObjectAdded { task ->
+        if (task.name.contains('link') && task.name.contains('SharedLibrary')) {
+            def library = task.outputFile.absolutePath
+            task.doLast {
+                def nmOutput = new ByteArrayOutputStream()
+                exec { 
+                    commandLine "nm", library
+                    standardOutput nmOutput
+                }
+                // Remove '\r' so we can check for full string contents
+                String nmSymbols = nmOutput.toString().replace('\r', '')
+
+                def symbolList = getSymbolFunc()
+                symbolList.each {
+                    //Add \n so we can check for the exact symbol
+                    def found = nmSymbols.contains(it + '\n')
+                    if (!found) {
+                        throw new GradleException("Found a definition that does not have a matching symbol ${it}")
+                    }
+                }
+            }
+        }
+    }
+}

toolchains/mac.gradle

@@ -46,3 +46,29 @@ ext.debugStripSetup = {
         }
     }
 }
+
+ext.checkNativeSymbols = { getSymbolFunc ->
+    project.tasks.whenObjectAdded { task ->
+        if (task.name.contains('link') && task.name.contains('SharedLibrary')) {
+            def library = task.outputFile.absolutePath
+            task.doLast {
+                def nmOutput = new ByteArrayOutputStream()
+                exec { 
+                    commandLine "nm", library
+                    standardOutput nmOutput
+                }
+                // Remove '\r' so we can check for full string contents
+                String nmSymbols = nmOutput.toString().replace('\r', '')
+
+                def symbolList = getSymbolFunc()
+                symbolList.each {
+                    //Add \n so we can check for the exact symbol
+                    def found = nmSymbols.contains(it + '\n')
+                    if (!found) {
+                        throw new GradleException("Found a definition that does not have a matching symbol ${it}")
+                    }
+                }
+            }
+        }
+    }
+}

toolchains/windows.gradle

@@ -50,3 +50,7 @@ ext.setupDef = { linker, deffile ->
 // This is a noop on Windows. On gcc platforms, we strip the release binary and create a separate
 // debug library, but Windows already separates debug symbols into a .pdb file.
 ext.debugStripSetup = { }
+
+// This is a noop on Windows. The def file already implicilty checks for the symbols
+ext.checkNativeSymbols = { getSymbolFunc ->
+}