Merge pull request #1744 from howardlopez/stream_wrapper_fixes

S3 stream wrapper write empty files

.changes/nextrelease/stream_wrapper_fixes.json

@@ -0,0 +1,7 @@
+[
+    {
+        "type": "feature",
+        "category": "S3",
+        "description": "Updates the S3 stream wrapper to be able to write empty files for PHP 7+."
+    }
+]

src/S3/StreamWrapper.php

@@ -94,6 +94,9 @@ class StreamWrapper
     /** @var string The opened protocol (e.g., "s3") */
     private $protocol = 's3';
 
+    /** @var bool Keeps track of whether stream has been flushed since opening */
+    private $isFlushed = false;
+
     /**
      * Register the 's3://' stream wrapper
      *
@@ -127,12 +130,16 @@ public static function register(
 
     public function stream_close()
     {
+        if ($this->body->getSize() === 0 && !($this->isFlushed)) {
+            $this->stream_flush();
+        }
         $this->body = $this->cache = null;
     }
 
     public function stream_open($path, $mode, $options, &$opened_path)
     {
         $this->initProtocol($path);
+        $this->isFlushed = false;
         $this->params = $this->getBucketKey($path);
         $this->mode = rtrim($mode, 'bt');
 
@@ -156,6 +163,7 @@ public function stream_eof()
 
     public function stream_flush()
     {
+        $this->isFlushed = true;
         if ($this->mode == 'r') {
             return false;
         }

tests/S3/StreamWrapperTest.php

@@ -170,6 +170,25 @@ public function testCanOpenWriteOnlyStreams()
         $this->assertEquals('test', (string) $cmd['Body']);
     }
 
+    public function testCanWriteEmptyFileToStream()
+    {
+        $history = new History();
+        $this->client->getHandlerList()->appendSign(Middleware::history($history));
+        $this->addMockResults($this->client, [new Result()]);
+        $s = fopen('s3://bucket/key', 'w');
+        $this->assertEquals(0, fwrite($s, ''));
+        $this->assertTrue(fclose($s));
+
+        // Ensure that the stream was flushed even with zero characters, and
+        // that it only executed PutObject once.
+        $this->assertCount(1, $history);
+        $cmd = $history->getLastCommand();
+        $this->assertEquals('PutObject', $cmd->getName());
+        $this->assertEquals('bucket', $cmd['Bucket']);
+        $this->assertEquals('key', $cmd['Key']);
+        $this->assertEquals('', (string) $cmd['Body']);
+    }
+
     /**
      * @expectedException \PHPUnit\Framework\Error\Warning
      * @expectedExceptionMessage 403 Forbidden