From ef12e42bdb04dcc564ab7c957e47341570a14a0c Mon Sep 17 00:00:00 2001
From: Stephan <glaubinix@users.noreply.github.com>
Date: Fri, 1 Apr 2022 16:13:22 +0100
Subject: [PATCH] GitDriver: try to fetch default branch from remote (#10687)

The initial clone determined what the default branch of the cache git repository was. Changing it on the remote didn't have any impact on the local data. However, cloning it on a different machine would then store a different default branch on that machine. This could lead to different results for the same command on different machines.
---
 src/Composer/Repository/Vcs/GitDriver.php     | 12 +++
 .../Test/Repository/Vcs/GitDriverTest.php     | 95 +++++++++++++++++++
 2 files changed, 107 insertions(+)
 create mode 100644 tests/Composer/Test/Repository/Vcs/GitDriverTest.php

diff --git a/src/Composer/Repository/Vcs/GitDriver.php b/src/Composer/Repository/Vcs/GitDriver.php
index 182d2816b..6397d3abe 100644
--- a/src/Composer/Repository/Vcs/GitDriver.php
+++ b/src/Composer/Repository/Vcs/GitDriver.php
@@ -13,6 +13,7 @@
 namespace Composer\Repository\Vcs;
 
 use Composer\Pcre\Preg;
+use Composer\Util\Platform;
 use Composer\Util\ProcessExecutor;
 use Composer\Util\Filesystem;
 use Composer\Util\Url;
@@ -93,6 +94,17 @@ class GitDriver extends VcsDriver
         if (null === $this->rootIdentifier) {
             $this->rootIdentifier = 'master';
 
+            if (!(bool) Platform::getEnv('COMPOSER_DISABLE_NETWORK')) {
+                try {
+                    $this->process->execute('git remote show origin', $output, $this->repoDir);
+                    if (Preg::isMatch('{^\s*HEAD branch:\s(.+)\s*$}m', $output, $matches)) {
+                        return $this->rootIdentifier = $matches[1];
+                    }
+                } catch (\Exception $e) {
+                    $this->io->writeError('<error>Failed to fetch root identifier from remote: ' . $e->getMessage() . '</error>', true, IOInterface::DEBUG);
+                }
+            }
+
             // select currently checked out branch if master is not available
             $this->process->execute('git branch --no-color', $output, $this->repoDir);
             $branches = $this->process->splitLines($output);
diff --git a/tests/Composer/Test/Repository/Vcs/GitDriverTest.php b/tests/Composer/Test/Repository/Vcs/GitDriverTest.php
new file mode 100644
index 000000000..e4e3c86b7
--- /dev/null
+++ b/tests/Composer/Test/Repository/Vcs/GitDriverTest.php
@@ -0,0 +1,95 @@
+<?php declare(strict_types=1);
+
+namespace Composer\Test\Repository\Vcs;
+
+use Composer\Config;
+use Composer\IO\IOInterface;
+use Composer\Repository\Vcs\GitDriver;
+use Composer\Test\TestCase;
+use Composer\Util\Filesystem;
+use Composer\Util\Platform;
+
+class GitDriverTest extends TestCase
+{
+    /** @var Config */
+    private $config;
+    /** @var string */
+    private $home;
+    /** @var false|string */
+    private $networkEnv;
+
+    public function setUp(): void
+    {
+        $this->home = self::getUniqueTmpDirectory();
+        $this->config = new Config();
+        $this->config->merge([
+            'config' => [
+                'home' => $this->home,
+            ],
+        ]);
+        $this->networkEnv = Platform::getEnv('COMPOSER_DISABLE_NETWORK');
+    }
+
+    protected function tearDown(): void
+    {
+        parent::tearDown();
+        $fs = new Filesystem;
+        $fs->removeDirectory($this->home);
+        if ($this->networkEnv === false) {
+            Platform::clearEnv('COMPOSER_DISABLE_NETWORK');
+        } else {
+            Platform::putEnv('COMPOSER_DISABLE_NETWORK', $this->networkEnv);
+        }
+    }
+
+    public function testGetRootIdentifierFromRemote(): void
+    {
+        $process = $this->getProcessExecutorMock();
+        $io = $this->getMockBuilder(IOInterface::class)->getMock();
+
+        $driver = new GitDriver(['url' => 'https://example.org/acme.git'], $io, $this->config, $this->getHttpDownloaderMock(), $process);
+
+        $stdout = <<<GIT
+* remote origin
+  Fetch URL: https://example.org/acme.git
+  Push  URL: https://example.org/acme.git
+  HEAD branch: main
+  Remote branches:
+    1.10                       tracked
+    2.2                        tracked
+    main                       tracked
+GIT;
+
+        $process
+            ->expects([[
+                'cmd' => 'git remote show origin',
+                'stdout' => $stdout,
+            ]]);
+
+        $this->assertSame('main', $driver->getRootIdentifier());
+    }
+
+    public function testGetRootIdentifierFromLocalWithNetworkDisabled(): void
+    {
+        Platform::putEnv('COMPOSER_DISABLE_NETWORK', '1');
+
+        $process = $this->getProcessExecutorMock();
+        $io = $this->getMockBuilder(IOInterface::class)->getMock();
+
+        $driver = new GitDriver(['url' => 'https://example.org/acme.git'], $io, $this->config, $this->getHttpDownloaderMock(), $process);
+
+        $stdout = <<<GIT
+* main
+  2.2
+  1.10
+GIT;
+
+        $process
+            ->expects([[
+                'cmd' => 'git branch --no-color',
+                'stdout' => $stdout,
+            ]]);
+
+        $this->assertSame('main', $driver->getRootIdentifier());
+    }
+}