Fix runWithPreprocessorAndOutput (#219)

Author: fabsx00

src/main/scala/io/shiftleft/fuzzyc2cpg/FuzzyC2Cpg.scala

@@ -23,7 +23,8 @@ class FuzzyC2Cpg() {
                                    includePaths: Set[String],
                                    defines: Set[String],
                                    undefines: Set[String],
-                                   preprocessorExecutable: String): Unit = {
+                                   preprocessorExecutable: String,
+                                   optionalOutputPath: Option[String] = None): Unit = {
     // Create temp dir to store preprocessed source.
     val preprocessedPath = Files.createTempDirectory("fuzzyc2cpg_preprocessed_")
     logger.info(s"Writing preprocessed files to [$preprocessedPath]")
@@ -54,7 +55,7 @@ class FuzzyC2Cpg() {
 
     if (exitCode == 0) {
       logger.info(s"Preprocessing complete, files written to [$preprocessedPath], starting CPG generation...")
-      val cpg = runAndOutput(Set(preprocessedPath.toString), sourceFileExtensions)
+      val cpg = runAndOutput(Set(preprocessedPath.toString), sourceFileExtensions, optionalOutputPath)
       cpg.close()
     } else {
       logger.error(
@@ -81,6 +82,10 @@ class FuzzyC2Cpg() {
     cpg
   }
 
+  /**
+    * Create an empty CPG, backed by the file at `optionalOutputPath` or
+    * in-memory if `optionalOutputPath` is empty.
+    * */
   private def initCpg(optionalOutputPath: Option[String]): Cpg = {
     val odbConfig = optionalOutputPath
       .map { outputPath =>
@@ -113,13 +118,16 @@ object FuzzyC2Cpg {
         val fuzzyc = new FuzzyC2Cpg()
 
         if (config.usePreprocessor) {
-          fuzzyc.runWithPreprocessorAndOutput(config.inputPaths,
-                                              config.sourceFileExtensions,
-                                              config.includeFiles,
-                                              config.includePaths,
-                                              config.defines,
-                                              config.undefines,
-                                              config.preprocessorExecutable)
+          fuzzyc.runWithPreprocessorAndOutput(
+            config.inputPaths,
+            config.sourceFileExtensions,
+            config.includeFiles,
+            config.includePaths,
+            config.defines,
+            config.undefines,
+            config.preprocessorExecutable,
+            Some(config.outputPath)
+          )
         } else {
           val cpg = fuzzyc.runAndOutput(config.inputPaths, config.sourceFileExtensions, Some(config.outputPath))
           cpg.close()