Add a method to run protoc with parameters given in a file.

Author: thesamet

bridge/src/main/scala/protocbridge/ProtocRunner.scala

@@ -1,5 +1,6 @@
 package protocbridge
 
+import java.nio.file.Files
 import scala.io.Source
 import scala.sys.process.Process
 import scala.sys.process.ProcessLogger
@@ -74,4 +75,31 @@ object ProtocRunner {
         extraEnv: _*
       ).!
   }
+
+  // Transforms the given protoc runner to a new runner that writes the
+  // options into a temporary file and passes the file to `protoc` as an `@`
+  // parameter.
+  def withParametersAsFile[T](underlying: ProtocRunner[T]): ProtocRunner[T] =
+    fromFunction { (args, extraEnv) =>
+      {
+        val argumentFile = Files.createTempFile("protoc-args-", ".txt")
+        try {
+          val writer = Files.newBufferedWriter(argumentFile)
+
+          try {
+            args.foreach { arg =>
+              writer.write(arg)
+              writer.write('\n')
+            }
+          } finally {
+            writer.close()
+          }
+
+          val fileArgument = s"@${argumentFile.toString}"
+          underlying.run(Seq(fileArgument), extraEnv)
+        } finally {
+          Files.delete(argumentFile)
+        }
+      }
+    }
 }

bridge/src/test/scala/protocbridge/ProtocIntegrationSpec.scala

@@ -67,7 +67,7 @@ object TestUtils {
 }
 
 class ProtocIntegrationSpec extends AnyFlatSpec with Matchers {
-  "ProtocBridge.run" should "invoke JVM and Java plugin properly" in {
+  def invokeProtocProperly(runner: ProtocRunner[Int]) = {
     val protoFile =
       new File(getClass.getResource("/test.proto").getFile).getAbsolutePath
     val protoDir = new File(getClass.getResource("/").getFile).getAbsolutePath
@@ -77,7 +77,7 @@ class ProtocIntegrationSpec extends AnyFlatSpec with Matchers {
       (0 to 4).map(i => Files.createTempDirectory(s"testout$i").toFile())
 
     ProtocBridge.execute(
-      RunProtoc,
+      runner,
       Seq(
         protocbridge.gens.java("3.8.0") -> javaOutDir,
         TestJvmPlugin -> testOutDirs(0),
@@ -111,6 +111,14 @@ class ProtocIntegrationSpec extends AnyFlatSpec with Matchers {
     readLines(new File(testOutDirs(0), "parameters.txt")) must be(Seq("Empty"))
   }
 
+  "ProtocBridge.run" should "invoke JVM and Java plugin properly" in {
+    invokeProtocProperly(RunProtoc)
+  }
+
+  "ProtocBridge.run" should "invoke JVM and Java plugin properly with options file" in {
+    invokeProtocProperly(ProtocRunner.withParametersAsFile(RunProtoc))
+  }
+
   it should "not deadlock for highly concurrent invocations" in {
     val availableProcessors = Runtime.getRuntime.availableProcessors
     assert(