Attempt working around Vagrant filesystem issues, added COMPOSER_RUNTIME_ENV env var (set to vagrant), fixes #9627

src/Composer/Installer/InstallationManager.php

@@ -26,6 +26,7 @@ use Composer\DependencyResolver\Operation\MarkAliasInstalledOperation;
 use Composer\DependencyResolver\Operation\MarkAliasUninstalledOperation;
 use Composer\EventDispatcher\EventDispatcher;
 use Composer\Util\Loop;
+use Composer\Util\Platform;
 use React\Promise\PromiseInterface;
 
 /**
@@ -440,6 +441,8 @@ class InstallationManager
             $this->waitOnPromises($promises);
         }
 
+        Platform::workaroundFilesystemIssues();
+
         foreach ($postExecCallbacks as $cb) {
             $cb();
         }

src/Composer/Installer/PluginInstaller.php

@@ -18,6 +18,7 @@ use Composer\Repository\InstalledRepositoryInterface;
 use Composer\Package\PackageInterface;
 use Composer\Util\Filesystem;
 use Composer\Installer\InstallationManager;
+use Composer\Util\Platform;
 use React\Promise\PromiseInterface;
 
 /**
@@ -97,6 +98,7 @@ class PluginInstaller extends LibraryInstaller
 
         return $promise->then(function () use ($self, $pluginManager, $initial, $target, $repo) {
             try {
+                Platform::workaroundFilesystemIssues();
                 $pluginManager->deactivatePackage($initial, true);
                 $pluginManager->registerPackage($target, true);
             } catch (\Exception $e) {

src/Composer/Util/Platform.php

@@ -19,6 +19,9 @@ namespace Composer\Util;
  */
 class Platform
 {
+    /** @var ?bool */
+    private static $isVagrantGuest = null;
+
     /**
      * Parses tildes and environment variables in paths.
      *
@@ -117,4 +120,37 @@ class Platform
         // Check if formatted mode is S_IFCHR
         return $stat ? 0020000 === ($stat['mode'] & 0170000) : false;
     }
+
+    public static function workaroundFilesystemIssues()
+    {
+        if (self::isVagrantGuest()) {
+            usleep(200000);
+        }
+    }
+
+    /**
+     * Attempts detection of vagrant guest VMs
+     *
+     * This works based on the process' user being "vagrant", or the COMPOSER_RUNTIME_ENV env var being set to "vagrant"
+     *
+     * @return bool
+     */
+    private static function isVagrantGuest()
+    {
+        if (null === self::$isVagrantGuest) {
+            self::$isVagrantGuest = false;
+            if (!self::isWindows() && function_exists('posix_getpwuid') && function_exists('posix_geteuid')) {
+                $processUser = posix_getpwuid(posix_geteuid());
+                if ($processUser && $processUser['name'] === 'vagrant') {
+                    return self::$isVagrantGuest = true;
+                }
+            }
+
+            if (getenv('COMPOSER_RUNTIME_ENV') === 'vagrant') {
+                return self::$isVagrantGuest = true;
+            }
+        }
+
+        return self::$isVagrantGuest;
+    }
 }