fix: master and main

lib/git_service.php

@@ -40,6 +40,38 @@ function git_service_write_repository_file($path, $contents) {
     return @file_put_contents($path, $contents, LOCK_EX) === strlen($contents);
 }
 
+/* A newly-created repository starts with an unborn main branch. If the first
+   push creates a differently named branch, make that branch the default. */
+function git_service_update_unborn_head($git_path, $updated_refs) {
+    $head = resolve_ref($git_path, 'HEAD');
+    if ($head[1] !== NULL) {
+        return TRUE;
+    }
+
+    $head_path = get_safe_file_path($git_path, '/HEAD');
+    $contents = $head_path === FALSE ? FALSE : @file_get_contents($head_path);
+    if ($contents === FALSE
+        || !preg_match('~^ref:\s*(refs/heads/[^\r\n]+)\s*$~', $contents)) {
+        return TRUE;
+    }
+
+    $branch = NULL;
+    foreach ($updated_refs as $ref) {
+        $resolved = resolve_ref($git_path, $ref);
+        if (strpos($ref, 'refs/heads/') === 0 && $resolved[1] !== NULL) {
+            $branch = $ref;
+            break;
+        }
+    }
+    if ($branch === NULL) {
+        return TRUE;
+    }
+
+    $new_contents = "ref: ".$branch."\n";
+    return @file_put_contents($git_path.'/HEAD', $new_contents, LOCK_EX)
+        === strlen($new_contents);
+}
+
 function git_service_init_bare_repository_with_php($path) {
     $directories = array(
         '',
@@ -482,9 +514,10 @@ function git_service_rpc($application, $repository, $request, $service, $input)
         && $service === 'git-receive-pack') {
         if (!git_receive_pack_rpc_native($repository, $input)) {
             error_log('Native Git receive-pack failed for '.$repository['url'].'.');
+            return 1;
         }
-        return;
+        return 0;
     }
 
-    git_service_run($application, $repository, $request, $service, FALSE, $input);
+    return git_service_run($application, $repository, $request, $service, FALSE, $input);
 }

operations/push.php

@@ -231,6 +231,11 @@ function push_run_receive_pack($repository, $request, $application) {
         send_error(403, 'Forbidden', $validation);
     }
 
-    git_service_rpc($application, $repository, $request, 'git-receive-pack', $input);
+    $exit_code = git_service_rpc(
+        $application, $repository, $request, 'git-receive-pack', $input);
+    if ($exit_code === 0
+        && !git_service_update_unborn_head($repository['path'], $updates)) {
+        error_log('Unable to update unborn HEAD for '.$repository['url'].'.');
+    }
     fclose($input);
 }

tests/regression_unborn_head.php

@@ -0,0 +1,49 @@
+<?php
+
+require_once dirname(__DIR__).'/lib/repository.php';
+require_once dirname(__DIR__).'/lib/git_service.php';
+
+function test_remove_directory($path) {
+    if (!is_dir($path)) {
+        return;
+    }
+    foreach (scandir($path) as $entry) {
+        if ($entry === '.' || $entry === '..') {
+            continue;
+        }
+        $entry_path = $path.'/'.$entry;
+        if (is_dir($entry_path)) {
+            test_remove_directory($entry_path);
+        } else {
+            unlink($entry_path);
+        }
+    }
+    rmdir($path);
+}
+
+$path = sys_get_temp_dir().'/php-git-server-head-'.bin2hex(random_bytes(8)).'.git';
+mkdir($path.'/refs/heads', 0777, TRUE);
+mkdir($path.'/objects', 0777, TRUE);
+file_put_contents($path.'/HEAD', "ref: refs/heads/main\n");
+file_put_contents($path.'/refs/heads/master', str_repeat('1', 40)."\n");
+
+try {
+    git_service_update_unborn_head($path, array('refs/heads/master'));
+    $head = file_get_contents($path.'/HEAD');
+    if ($head !== "ref: refs/heads/master\n") {
+        fwrite(STDERR, 'Expected HEAD to follow the first pushed branch, got: '.$head);
+        exit(1);
+    }
+
+    file_put_contents($path.'/refs/heads/main', str_repeat('2', 40)."\n");
+    git_service_update_unborn_head($path, array('refs/heads/master'));
+    $head = file_get_contents($path.'/HEAD');
+    if ($head !== "ref: refs/heads/master\n") {
+        fwrite(STDERR, "Expected an existing HEAD target to remain unchanged.\n");
+        exit(1);
+    }
+} finally {
+    test_remove_directory($path);
+}
+
+fwrite(STDOUT, "unborn HEAD regression test passed\n");