From c0aaeb1c79510cbee15a3942c46a7494b4c401eb Mon Sep 17 00:00:00 2001
From: Jason den Dulk <jasondendulk@catalyst-au.net>
Date: Mon, 15 May 2023 15:53:34 +1000
Subject: [PATCH] Issue 722: Throw exception when cannot open input.

---
 classes/local/step/reader_csv.php        | 40 +++++++++++++-----------
 tests/tool_dataflows_reader_csv_test.php | 29 +++++++++++++++++
 2 files changed, 50 insertions(+), 19 deletions(-)

diff --git a/classes/local/step/reader_csv.php b/classes/local/step/reader_csv.php
index a156015c..fcb85fca 100644
--- a/classes/local/step/reader_csv.php
+++ b/classes/local/step/reader_csv.php
@@ -64,28 +64,30 @@ public function csv_contents_generator() {
         $strheaders = $config->headers;
         $path = $this->enginestep->engine->resolve_path($config->path);
 
-        if (($handle = fopen($path, 'r')) !== false) {
-            try {
-                // Prepare and resolve headers.
-                if (empty($strheaders)) {
-                    $strheaders = fgets($handle);
-                }
+        if (($handle = @fopen($path, 'r')) === false) {
+            throw new \moodle_exception('writer_stream:failed_to_open_stream', 'tool_dataflows', '', $path);
+        }
+
+        try {
+            // Prepare and resolve headers.
+            if (empty($strheaders)) {
+                $strheaders = fgets($handle);
+            }
 
-                // At this point, if headers is false, then the file is empty, and
-                // so it should continue as if the file finished.
-                if ($strheaders === false) {
-                    return;
-                }
+            // At this point, if headers is false, then the file is empty, and
+            // so it should continue as if the file finished.
+            if ($strheaders === false) {
+                return;
+            }
 
-                // Convert header string to an actual headers array.
-                $headers = str_getcsv($strheaders, $config->delimiter);
-                while (($data = fgetcsv($handle, $maxlinelength, $config->delimiter)) !== false) {
-                    $record = array_combine($headers, $data);
-                    yield (object) $record;
-                }
-            } finally {
-                fclose($handle);
+            // Convert header string to an actual headers array.
+            $headers = str_getcsv($strheaders, $config->delimiter);
+            while (($data = fgetcsv($handle, $maxlinelength, $config->delimiter)) !== false) {
+                $record = array_combine($headers, $data);
+                yield (object) $record;
             }
+        } finally {
+            fclose($handle);
         }
     }
 
diff --git a/tests/tool_dataflows_reader_csv_test.php b/tests/tool_dataflows_reader_csv_test.php
index cfd42574..30b7ef1c 100644
--- a/tests/tool_dataflows_reader_csv_test.php
+++ b/tests/tool_dataflows_reader_csv_test.php
@@ -36,6 +36,9 @@
  */
 class tool_dataflows_reader_csv_test extends \advanced_testcase {
 
+    /** @var string|null Input path for reader to read from. */
+    protected $inputpath = null;
+
     /**
      * Set up before each test
      */
@@ -43,6 +46,7 @@ protected function setUp(): void {
         parent::setUp();
         $this->resetAfterTest();
 
+        $this->inputpath = null;
         set_config('permitted_dirs', '/tmp', 'tool_dataflows');
     }
 
@@ -127,6 +131,31 @@ public function test_csv_with_custom_headers_configured() {
         $this->assertEquals($expected, $output);
     }
 
+    /**
+     * Tests for an invalid input stream.
+     */
+    public function test_bad_input_stream() {
+        [$dataflow, $steps] = $this->create_dataflow();
+        $path = 'path/to/nowhere';
+
+        $reader = $steps[$dataflow->steps->reader->id];
+        $reader->config = Yaml::dump([
+            'path' => $path,
+            'headers' => '',
+            'delimiter' => ',',
+        ]);
+
+        $this->expectException('\moodle_exception');
+
+        // Execute.
+        ob_start();
+        $engine = new engine($dataflow);
+        $this->expectExceptionMessage(get_string('writer_stream:failed_to_open_stream',
+            'tool_dataflows', $engine->resolve_path($path)));
+        $engine->execute();
+        ob_get_clean();
+    }
+
     /**
      * Dataflow creation helper function
      *