minor #35933 [Mime] strengthen is_resource() checks (nicolas-grekas)

This PR was merged into the 5.1-dev branch.

Discussion
----------

[Mime] strengthen is_resource() checks

| Q             | A
| ------------- | ---
| Branch?       | master
| Bug fix?      | no
| New feature?  | no
| Deprecations? | no
| Tickets       | -
| License       | MIT
| Doc PR        | -

Improves seekable checks by using
`stream_get_meta_data($h)['seekable'] && 0 === fseek($h, 0, SEEK_CUR)`
instead of just
`stream_get_meta_data($h)['seekable']`

which is better when using userland stream wrappers.

Commits
-------

be9c675 [Mime] strengthen is_resource() checks

src/Symfony/Component/Mime/CharacterStream.php

@@ -97,10 +97,7 @@ public function __construct($input, ?string $charset = 'utf-8')
             }
         }
         if (\is_resource($input)) {
-            $blocks = 512;
-            if (stream_get_meta_data($input)['seekable'] ?? false) {
-                rewind($input);
-            }
+            $blocks = 16372;
             while (false !== $read = fread($input, $blocks)) {
                 $this->write($read);
             }

src/Symfony/Component/Mime/Email.php

@@ -464,14 +464,8 @@ private function prepareParts(): ?array
         $htmlPart = null;
         $html = $this->html;
         if (null !== $this->html) {
-            if (\is_resource($html)) {
-                if (stream_get_meta_data($html)['seekable'] ?? false) {
-                    rewind($html);
-                }
-
-                $html = stream_get_contents($html);
-            }
             $htmlPart = new TextPart($html, $this->htmlCharset, 'html');
+            $html = $htmlPart->getBody();
             preg_match_all('(<img\s+[^>]*src\s*=\s*(?:([\'"])cid:([^"]+)\\1|cid:([^>\s]+)))i', $html, $names);
             $names = array_filter(array_unique(array_merge($names[2], $names[3])));
         }
@@ -559,28 +553,16 @@ private function setListAddressHeaderBody(string $name, array $addresses)
     public function __serialize(): array
     {
         if (\is_resource($this->text)) {
-            if (stream_get_meta_data($this->text)['seekable'] ?? false) {
-                rewind($this->text);
-            }
-
-            $this->text = stream_get_contents($this->text);
+            $this->text = (new TextPart($this->text))->getBody();
         }
 
         if (\is_resource($this->html)) {
-            if (stream_get_meta_data($this->html)['seekable'] ?? false) {
-                rewind($this->html);
-            }
-
-            $this->html = stream_get_contents($this->html);
+            $this->html = (new TextPart($this->html))->getBody();
         }
 
         foreach ($this->attachments as $i => $attachment) {
             if (isset($attachment['body']) && \is_resource($attachment['body'])) {
-                if (stream_get_meta_data($attachment['body'])['seekable'] ?? false) {
-                    rewind($attachment['body']);
-                }
-
-                $this->attachments[$i]['body'] = stream_get_contents($attachment['body']);
+                $this->attachments[$i]['body'] = (new TextPart($attachment['body']))->getBody();
             }
         }
 

src/Symfony/Component/Mime/Encoder/Base64ContentEncoder.php

@@ -32,11 +32,8 @@ public function encodeByteStream($stream, int $maxLineLength = 0): iterable
             throw new RuntimeException('Unable to set the base64 content encoder to the filter.');
         }
 
-        if (stream_get_meta_data($stream)['seekable'] ?? false) {
-            rewind($stream);
-        }
         while (!feof($stream)) {
-            yield fread($stream, 8192);
+            yield fread($stream, 16372);
         }
         stream_filter_remove($filter);
     }

src/Symfony/Component/Mime/Encoder/QpContentEncoder.php

@@ -23,10 +23,6 @@ public function encodeByteStream($stream, int $maxLineLength = 0): iterable
         }
 
         // we don't use PHP stream filters here as the content should be small enough
-        if (stream_get_meta_data($stream)['seekable'] ?? false) {
-            rewind($stream);
-        }
-
         yield $this->encodeString(stream_get_contents($stream), 'utf-8', 0, $maxLineLength);
     }
 

src/Symfony/Component/Mime/Part/TextPart.php

@@ -31,6 +31,7 @@ class TextPart extends AbstractPart
     private $disposition;
     private $name;
     private $encoding;
+    private $seekable;
 
     /**
      * @param resource|string $body
@@ -46,6 +47,7 @@ public function __construct($body, ?string $charset = 'utf-8', $subtype = 'plain
         $this->body = $body;
         $this->charset = $charset;
         $this->subtype = $subtype;
+        $this->seekable = \is_resource($body) ? stream_get_meta_data($body)['seekable'] && 0 === fseek($body, 0, SEEK_CUR) : null;
 
         if (null === $encoding) {
             $this->encoding = $this->chooseEncoding();
@@ -93,11 +95,11 @@ public function setName($name)
 
     public function getBody(): string
     {
-        if (!\is_resource($this->body)) {
+        if (null === $this->seekable) {
             return $this->body;
         }
 
-        if (stream_get_meta_data($this->body)['seekable'] ?? false) {
+        if ($this->seekable) {
             rewind($this->body);
         }
 
@@ -111,8 +113,8 @@ public function bodyToString(): string
 
     public function bodyToIterable(): iterable
     {
-        if (\is_resource($this->body)) {
-            if (stream_get_meta_data($this->body)['seekable'] ?? false) {
+        if (null !== $this->seekable) {
+            if ($this->seekable) {
                 rewind($this->body);
             }
             yield from $this->getEncoder()->encodeByteStream($this->body);
@@ -185,7 +187,7 @@ private function chooseEncoding(): string
     public function __sleep()
     {
         // convert resources to strings for serialization
-        if (\is_resource($this->body)) {
+        if (null !== $this->seekable) {
             $this->body = $this->getBody();
         }