bug symfony#42033 [HttpFoundation] Fix deleteFileAfterSend on client abortion (nerg4l)

This PR was squashed before being merged into the 4.4 branch.

Discussion
----------

[HttpFoundation] Fix deleteFileAfterSend on client abortion

| Q             | A
| ------------- | ---
| Branch?       | 4.4
| Bug fix?      | yes
| New feature?  | no <!-- please update src/**/CHANGELOG.md files -->
| Deprecations? | no <!-- please update UPGRADE-*.md and src/**/CHANGELOG.md files -->
| Tickets       | Fix symfony#27538 <!-- prefix each issue number with "Fix #", no need to create an issue if none exist, explain below instead -->
| License       | MIT
| Doc PR        | <!-- required for new features -->

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**Description**

If someone sets `deleteFileAfterSend` to `true` for a `BinaryFileResponse` instance they expect the file to be deleted when the response finished. This is not the case when the response is cancelled because PHP won't continue running the code. `ignore_user_abort` can be used to allow it to finish but this means `stream_copy_to_stream` will also continue to run regardless of the abort. To fix this later problem it can be a solution to run the copy in a loop and detect the connect abort manually with `connection_aborted`.

**Tests**

I don't know how can I simulate connection abort in PHPUnit. I would appreciate if I could get some guidance if it is possible.

**Todo**

- [ ] add tests if connection abort can be simulated
- [ ] gather feedback for my changes

Commits
-------

f097bef [HttpFoundation] Fix deleteFileAfterSend on client abortion

Author: fabpot

src/Symfony/Component/HttpFoundation/BinaryFileResponse.php

@@ -34,6 +34,7 @@ class BinaryFileResponse extends Response
     protected $offset = 0;
     protected $maxlen = -1;
     protected $deleteFileAfterSend = false;
+    protected $chunkSize = 8 * 1024;
 
     /**
      * @param \SplFileInfo|string $file               The file to stream
@@ -124,6 +125,22 @@ public function getFile()
         return $this->file;
     }
 
+    /**
+     * Sets the response stream chunk size.
+     *
+     * @return $this
+     */
+    public function setChunkSize(int $chunkSize): self
+    {
+        if ($chunkSize < 1 || $chunkSize > \PHP_INT_MAX) {
+            throw new \LogicException('The chunk size of a BinaryFileResponse cannot be less than 1 or greater than PHP_INT_MAX.');
+        }
+
+        $this->chunkSize = $chunkSize;
+
+        return $this;
+    }
+
     /**
      * Automatically sets the Last-Modified header according the file modification date.
      */
@@ -303,7 +320,23 @@ public function sendContent()
         $out = fopen('php://output', 'w');
         $file = fopen($this->file->getPathname(), 'r');
 
-        stream_copy_to_stream($file, $out, $this->maxlen, $this->offset);
+        ignore_user_abort(true);
+
+        if (0 !== $this->offset) {
+            fseek($file, $this->offset);
+        }
+
+        $length = $this->maxlen;
+        while ($length && !feof($file)) {
+            $read = ($length > $this->chunkSize) ? $this->chunkSize : $length;
+            $length -= $read;
+
+            stream_copy_to_stream($file, $out, $read);
+
+            if (connection_aborted()) {
+                break;
+            }
+        }
 
         fclose($out);
         fclose($file);