Merge branch '4.4' into 5.4

* 4.4:
  [HttpClient] Fix seeking in not-yet-initialized requests
  [Serializer] Allow getting discriminated type by class name

Author: nicolas-grekas

Response/StreamWrapper.php

@@ -22,7 +22,7 @@
  */
 class StreamWrapper
 {
-    /** @var resource|string|null */
+    /** @var resource|null */
     public $context;
 
     /** @var HttpClientInterface */
@@ -31,7 +31,7 @@ class StreamWrapper
     /** @var ResponseInterface */
     private $response;
 
-    /** @var resource|null */
+    /** @var resource|string|null */
     private $content;
 
     /** @var resource|null */
@@ -89,6 +89,7 @@ public function bindHandles(&$handle, &$content): void
     {
         $this->handle = &$handle;
         $this->content = &$content;
+        $this->offset = null;
     }
 
     public function stream_open(string $path, string $mode, int $options): bool
@@ -133,7 +134,7 @@ public function stream_read(int $count)
                 }
             }
 
-            if (0 !== fseek($this->content, $this->offset)) {
+            if (0 !== fseek($this->content, $this->offset ?? 0)) {
                 return false;
             }
 
@@ -162,6 +163,11 @@ public function stream_read(int $count)
             try {
                 $this->eof = true;
                 $this->eof = !$chunk->isTimeout();
+
+                if (!$this->eof && !$this->blocking) {
+                    return '';
+                }
+
                 $this->eof = $chunk->isLast();
 
                 if ($chunk->isFirst()) {
@@ -204,7 +210,7 @@ public function stream_set_option(int $option, int $arg1, ?int $arg2): bool
 
     public function stream_tell(): int
     {
-        return $this->offset;
+        return $this->offset ?? 0;
     }
 
     public function stream_eof(): bool
@@ -214,14 +220,19 @@ public function stream_eof(): bool
 
     public function stream_seek(int $offset, int $whence = \SEEK_SET): bool
     {
+        if (null === $this->content && null === $this->offset) {
+            $this->response->getStatusCode();
+            $this->offset = 0;
+        }
+
         if (!\is_resource($this->content) || 0 !== fseek($this->content, 0, \SEEK_END)) {
             return false;
         }
 
         $size = ftell($this->content);
 
         if (\SEEK_CUR === $whence) {
-            $offset += $this->offset;
+            $offset += $this->offset ?? 0;
         }
 
         if (\SEEK_END === $whence || $size < $offset) {

Tests/HttpClientTestCase.php

@@ -131,6 +131,18 @@ public function testNonBlockingStream()
         $this->assertTrue(feof($stream));
     }
 
+    public function testSeekAsyncStream()
+    {
+        $client = $this->getHttpClient(__FUNCTION__);
+        $response = $client->request('GET', 'http://localhost:8057/timeout-body');
+        $stream = $response->toStream(false);
+
+        $this->assertSame(0, fseek($stream, 0, \SEEK_CUR));
+        $this->assertSame('<1>', fread($stream, 8192));
+        $this->assertFalse(feof($stream));
+        $this->assertSame('<2>', stream_get_contents($stream));
+    }
+
     public function testResponseStreamRewind()
     {
         $client = $this->getHttpClient(__FUNCTION__);

Tests/MockHttpClientTest.php

@@ -443,6 +443,7 @@ protected function getHttpClient(string $testCase): HttpClientInterface
                 return $client;
 
             case 'testNonBlockingStream':
+            case 'testSeekAsyncStream':
                 $responses[] = new MockResponse((function () { yield '<1>'; yield ''; yield '<2>'; })(), ['response_headers' => $headers]);
                 break;