From 00aaffb8f955a4ddca8d7ebb74882637b5e22887 Mon Sep 17 00:00:00 2001
From: Jordi Boggiano <j.boggiano@seld.be>
Date: Thu, 26 Nov 2020 14:28:58 +0100
Subject: [PATCH] Make cache writes atomic

---
 src/Composer/Cache.php | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/Composer/Cache.php b/src/Composer/Cache.php
index d92cb4ac4..c4bb4b2eb 100644
--- a/src/Composer/Cache.php
+++ b/src/Composer/Cache.php
@@ -115,7 +115,7 @@ class Cache
             $this->io->writeError('Writing '.$this->root . $file.' into cache', true, IOInterface::DEBUG);
 
             try {
-                return file_put_contents($this->root . $file, $contents);
+                return file_put_contents($this->root . $file.'.tmp', $contents) !== false && rename($this->root . $file . '.tmp', $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)) {