From ed035f85e38f7c9efe6ac84c8f13c9a455f7014c Mon Sep 17 00:00:00 2001
From: Oleg Zhurakousky <oleg@suitcase.io>
Date: Wed, 26 Oct 2016 12:57:37 -0400
Subject: [PATCH] NIFI-2928 added support to validate accessibility of the file
 system

NIFI-2928 polishing

This closes #1160
---
 .../apache/nifi/processors/standard/FetchFile.java  |  9 +++++++--
 .../nifi/processors/standard/TestFetchFile.java     | 13 +++++++++++++
 2 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/nifi-nar-bundles/nifi-standard-bundle/nifi-standard-processors/src/main/java/org/apache/nifi/processors/standard/FetchFile.java b/nifi-nar-bundles/nifi-standard-bundle/nifi-standard-processors/src/main/java/org/apache/nifi/processors/standard/FetchFile.java
index 04675c9e0e..afdd6cfbb0 100644
--- a/nifi-nar-bundles/nifi-standard-bundle/nifi-standard-processors/src/main/java/org/apache/nifi/processors/standard/FetchFile.java
+++ b/nifi-nar-bundles/nifi-standard-bundle/nifi-standard-processors/src/main/java/org/apache/nifi/processors/standard/FetchFile.java
@@ -183,8 +183,13 @@ public class FetchFile extends AbstractProcessor {
         final LogLevel levelPermDenied = LogLevel.valueOf(context.getProperty(PERM_DENIED_LOG_LEVEL).getValue());
         final File file = new File(filename);
 
-        // Verify that file exists
-        if (!file.exists()) {
+        // Verify that file system is reachable and file exists
+        Path filePath = file.toPath();
+        if (!Files.exists(filePath) && !Files.notExists(filePath)){ // see https://docs.oracle.com/javase/tutorial/essential/io/check.html for more details
+            getLogger().log(levelFileNotFound, "Could not fetch file {} from file system for {} because the existence of the file cannot be verified; routing to failure", new Object[] {file, flowFile});
+            session.transfer(session.penalize(flowFile), REL_FAILURE);
+            return;
+        } else if (!Files.exists(filePath)) {
             getLogger().log(levelFileNotFound, "Could not fetch file {} from file system for {} because the file does not exist; routing to not.found", new Object[] {file, flowFile});
             session.getProvenanceReporter().route(flowFile, REL_NOT_FOUND);
             session.transfer(session.penalize(flowFile), REL_NOT_FOUND);
diff --git a/nifi-nar-bundles/nifi-standard-bundle/nifi-standard-processors/src/test/java/org/apache/nifi/processors/standard/TestFetchFile.java b/nifi-nar-bundles/nifi-standard-bundle/nifi-standard-processors/src/test/java/org/apache/nifi/processors/standard/TestFetchFile.java
index 0e69216dd3..cfced0a551 100644
--- a/nifi-nar-bundles/nifi-standard-bundle/nifi-standard-processors/src/test/java/org/apache/nifi/processors/standard/TestFetchFile.java
+++ b/nifi-nar-bundles/nifi-standard-bundle/nifi-standard-processors/src/test/java/org/apache/nifi/processors/standard/TestFetchFile.java
@@ -47,6 +47,19 @@ public class TestFetchFile {
         }
     }
 
+    @Test
+    public void notFound() throws IOException {
+        final File sourceFile = new File("notFound");
+
+        final TestRunner runner = TestRunners.newTestRunner(new FetchFile());
+        runner.setProperty(FetchFile.FILENAME, sourceFile.getAbsolutePath());
+        runner.setProperty(FetchFile.COMPLETION_STRATEGY, FetchFile.COMPLETION_NONE.getValue());
+
+        runner.enqueue(new byte[0]);
+        runner.run();
+        runner.assertAllFlowFilesTransferred(FetchFile.REL_NOT_FOUND, 1);
+    }
+
     @Test
     public void testSimpleSuccess() throws IOException {
         final File sourceFile = new File("target/1.txt");