From e829ff80bc7312d7fa70fbd7be441863eb6dcc61 Mon Sep 17 00:00:00 2001
From: Ilya Urvachev <rtm@ctrlz.ru>
Date: Tue, 29 Dec 2020 23:57:29 +0300
Subject: [PATCH] feat(Cache): make cache writes more atomic

Fixes #9568
---
 src/Composer/Cache.php | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/Composer/Cache.php b/src/Composer/Cache.php
index c4bb4b2eb..df45e66ed 100644
--- a/src/Composer/Cache.php
+++ b/src/Composer/Cache.php
@@ -115,7 +115,8 @@ class Cache
             $this->io->writeError('Writing '.$this->root . $file.' into cache', true, IOInterface::DEBUG);
 
             try {
-                return file_put_contents($this->root . $file.'.tmp', $contents) !== false && rename($this->root . $file . '.tmp', $this->root . $file);
+                $tempFileName = $this->root . $file . uniqid('.tmp.', true);
+                return file_put_contents($tempFileName, $contents) !== false && rename($tempFileName, $this->root . $file);
             } catch (\ErrorException $e) {
                 $this->io->writeError('<warning>Failed to write into cache: '.$e->getMessage().'</warning>', true, IOInterface::DEBUG);
                 if (preg_match('{^file_put_contents\(\): Only ([0-9]+) of ([0-9]+) bytes written}', $e->getMessage(), $m)) {