Limit the length of file paths used in many_files_test.

sdk/lib/_internal/pub/test/lish/many_files_test.dart

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 import 'dart:convert';
 import 'dart:io';
 import 'dart:math' as math;
 
 import 'package:path/path.dart' as p;
 import 'package:scheduled_test/scheduled_test.dart';
 import 'package:scheduled_test/scheduled_server.dart';
 import 'package:shelf/shelf.dart' as shelf;
 
 import '../../lib/src/exit_codes.dart' as exit_codes;
 import '../descriptor.dart' as d;
 import '../test_pub.dart';
 import 'utils.dart';
 
-/// The depth of directories to use when creating files to tickle
-/// argument-length limits.
-final _depth = 10;
-
-/// The maximum number of characters in a path component.
+/// The maximum number of bytes in an entire path.
 ///
-/// Only Windows has this tight of a constraint, but we abide by it on all
-/// operating systems to avoid specializing the test too much.
-final _componentMax = 255;
+/// This is [Windows's number][MAX_PATH], which is a much tighter constraint
+/// than OS X or Linux. We use it everywhere for consistency.
+///
+/// [MAX_PATH]: https://msdn.microsoft.com/en-us/library/windows/desktop/aa383130(v=vs.85).aspx
+const _pathMax = 260;
 
 main() {
   initConfig();
 
-  integration('archives and uploads a package', () {
+  integration('archives and uploads a package with more files than can fit on '
+      'the command line', () {
     d.validPackage.create();
 
     var argMax;
     if (Platform.isWindows) {
       // On Windows, the maximum argument list length is 8^5 bytes.
       argMax = math.pow(8, 5);
     } else {
       // On POSIX, the maximum argument list length can be retrieved
       // automatically.
       var result = Process.runSync("getconf", ["ARG_MAX"]);
       if (result.exitCode != 0) {
         fail("getconf failed with exit code ${result.exitCode}:\n"
             "${result.stderr}");
       }
 
       argMax = int.parse(result.stdout);
     }
 
     schedule(() {
-      var dir = p.join(sandboxDir, appPath);
-      for (var i = 0; i < _depth; i++) {
-        dir = p.join(dir, "x" * _componentMax);
-        new Directory(dir).createSync();
-      }
+      var appRoot = p.join(sandboxDir, appPath);
 
-      var pathLength = (_componentMax + 1) * _depth;
-      var filesToCreate = (argMax / pathLength).ceil();
+      // We'll make the filenames as long as possible to reduce the number of
+      // files we have to create to hit the maximum. However, the tar process
+      // uses relative paths, which means we can't count the root as part of the
+      // length.
+      var lengthPerFile = _pathMax - appRoot.length;
+
+      // Create enough files to hit [argMax]. This may be a slight overestimate,
+      // since other options are passed to the tar command line, but we don't
+      // know how long those will be.
+      var filesToCreate = (argMax / lengthPerFile).ceil();
+
       for (var i = 0; i < filesToCreate; i++) {
-        var filePath = p.join(dir, "x" * _componentMax);
         var iString = i.toString();
-        filePath = filePath.substring(0, filePath.length - iString.length) +
-            iString;
 
-        new File(filePath).writeAsStringSync("");
+        // The file name contains "x"s to make the path hit [_pathMax],
+        // followed by a number to distinguish different files.
+        var fileName =
+          "x" * (_pathMax - appRoot.length - iString.length - 1) + iString;
+
+        new File(p.join(appRoot, fileName)).writeAsStringSync("");
       }
     });
 
     var server = new ScheduledServer();
     d.credentialsFile(server, 'access token').create();
     var pub = startPublish(server);
 
     confirmPublish(pub);
     handleUploadForm(server);
     handleUpload(server);
 
     server.handle('GET', '/create', (request) {
       return new shelf.Response.ok(JSON.encode({
         'success': {'message': 'Package test_pkg 1.0.0 uploaded!'}
       }));
     });
 
     pub.stdout.expect(startsWith('Uploading...'));
     pub.stdout.expect('Package test_pkg 1.0.0 uploaded!');
     pub.shouldExit(exit_codes.SUCCESS);
   });
 }