bug symfony#17195 bug symfony#14246 [Filesystem] dumpFile() non atomic (Hidde Boomsma)

This PR was merged into the 2.3 branch.

Discussion
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bug symfony#14246 [Filesystem] dumpFile() non atomic

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | symfony#14246
| License       | MIT
| Doc PR        | none

Remove race condition where `dumpFile` has written the resulting file but has not given access yet.

Commits
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e4015d5 bug symfony#14246 [Filesystem] dumpFile() non atomic

Author: nicolas-grekas

src/Symfony/Component/Filesystem/Filesystem.php

@@ -477,9 +477,9 @@ public function dumpFile($filename, $content, $mode = 0666)
             throw new IOException(sprintf('Failed to write file "%s".', $filename));
         }
 
-        $this->rename($tmpFile, $filename, true);
         if (null !== $mode) {
-            $this->chmod($filename, $mode);
+            $this->chmod($tmpFile, $mode);
         }
+        $this->rename($tmpFile, $filename, true);
     }
 }