Fix invalid files being listed in "log" command

Ignores output from other processes during the SSH connection

Copies a method from the RemoteEnvVars class

src/Command/Environment/EnvironmentLogCommand.php

@@ -73,7 +73,10 @@ protected function execute(InputInterface $input, OutputInterface $output)
             /** @var \Doctrine\Common\Cache\CacheProvider $cache */
             $cache = $this->getService('cache');
             if (!$result = $cache->fetch($cacheKey)) {
-                $result = $host->runCommand('ls -1 ' . $logDir . '/*.log');
+                $result = $host->runCommand('echo -n _BEGIN_FILE_LIST_; ls -1 ' . $logDir . '/*.log; echo -n _END_FILE_LIST_');
+                if (is_string($result)) {
+                    $result = $this->extractResult($result, '_BEGIN_FILE_LIST_', '_END_FILE_LIST_');
+                }
 
                 // Cache the list for 1 day.
                 $cache->save($cacheKey, $result, 86400);
@@ -84,7 +87,7 @@ protected function execute(InputInterface $input, OutputInterface $output)
                 $logDir . '/access.log',
                 $logDir . '/error.log',
             ];
-            $files = $result ? explode("\n", $result) : $defaultFiles;
+            $files = $result && is_string($result) ? explode("\n", trim($result)) : $defaultFiles;
 
             // Ask the user to choose a file.
             $files = array_combine($files, array_map(function ($file) {
@@ -129,4 +132,25 @@ public function completeArgumentValues($argumentName, CompletionContext $context
 
         return $values;
     }
+
+    /**
+     * Extracts a result from 'echo' output between beginning and ending delimiters.
+     *
+     * @param string $output
+     * @param string $begin
+     * @param string $end
+     *
+     * @return string
+     */
+    private function extractResult($output, $begin, $end)
+    {
+        $first = \strpos($output, $begin);
+        $last = \strrpos($output, $end, $first);
+        if ($first === false || $last === false) {
+            return $output;
+        }
+        $offset = $first + \strlen($begin);
+        $length = $last - $first - \strlen($begin);
+        return \substr($output, $offset, $length);
+    }
 }