Use more semantic exit codes so we can detect HTTP errors.

utils/pub/pub.dart

 // Copyright (c) 2012, 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.
 
 /**
  * The main entrypoint for the pub command line application.
  */
 #library('pub');
 
 #import('../../pkg/args/lib/args.dart');
 #import('dart:io');
 #import('dart:math');
 #import('io.dart');
 #import('command_help.dart');
 #import('command_install.dart');
 #import('command_list.dart');
 #import('command_update.dart');
 #import('command_version.dart');
 #import('entrypoint.dart');
+#import('exit_codes.dart', prefix: 'exit_codes');
 #import('git_source.dart');
 #import('hosted_source.dart');
 #import('package.dart');
 #import('pubspec.dart');
 #import('sdk_source.dart');
 #import('source.dart');
 #import('source_registry.dart');
 #import('system_cache.dart');
 #import('utils.dart');
 #import('version.dart');
@@ skipping 59 matching lines @@
   cache.register(new SdkSource(sdkDir));
   cache.register(new GitSource());
   cache.register(new HostedSource());
   cache.sources.setDefault('hosted');
 
   // Select the command.
   var command = pubCommands[globalOptions.rest[0]];
   if (command == null) {
     printError('Unknown command "${globalOptions.rest[0]}".');
     printError('Run "pub help" to see available commands.');
-    exit(64); // See http://www.freebsd.org/cgi/man.cgi?query=sysexits.
+    exit(exit_codes.USAGE);
     return;
   }
 
   var commandArgs =
     globalOptions.rest.getRange(1, globalOptions.rest.length - 1);
   command.run(cache, globalOptions, commandArgs);
 }
 
 /** Displays usage information for the app. */
 void printUsage([String description = 'Pub is a package manager for Dart.']) {
@@ skipping 59 matching lines @@
 
   void run(SystemCache cache_, ArgResults globalOptions_,
       List<String> commandArgs) {
     cache = cache_;
     globalOptions = globalOptions_;
 
     try {
      commandOptions = commandParser.parse(commandArgs);
     } on FormatException catch (e) {
       this.printUsage(description: e.message);
-      return;
+      exit(exit_codes.USAGE);
     }
 
     handleError(error, trace) {
       // This is basically the top-level exception handler so that we don't
       // spew a stack trace on our users.
       var message = error.toString();
 
       // TODO(rnystrom): The default exception implementation class puts
       // "Exception:" in the output, so strip that off.
       if (message.startsWith("Exception: ")) {
         message = message.substring("Exception: ".length);
       }
 
       printError(message);
       if (globalOptions['trace'] && trace != null) {
         printError(trace);
       }
 
-      // TODO(nweiz): Use the more semantic error codes in
-      // http://www.freebsd.org/cgi/man.cgi?query=sysexits
-      exit(1);
+      exit(_exitCode(error));
     }
 
     var future = new Future.immediate(null);
     if (requiresEntrypoint) {
       // TODO(rnystrom): Will eventually need better logic to walk up
       // subdirectories until we hit one that looks package-like. For now, just
       // assume the cwd is it.
       future = Package.load(null, workingDir, cache.sources)
           .transform((package) => new Entrypoint(package, cache));
     }
@@ skipping 40 matching lines @@
     print(description);
     print('');
     print('Usage: $usage');
 
     var commandUsage = commandParser.getUsage();
     if (!commandUsage.isEmpty()) {
       print('');
       print(commandUsage);
     }
   }
+
+  /// Returns the appropriate exit code for [exception], falling back on 1 if no
+  /// appropriate exit code could be found.
+  int _exitCode(exception) {

[Bob Nystrom, 2012/09/19 18:27:42]

How about a nice verby name like _chooseExitCode?

[nweiz, 2012/09/19 18:33:56]

Done.

+    if (exception is HttpException || exception is HttpParserException ||
+        exception is SocketIOException || exception is PubHttpException) {
+      return exit_codes.UNAVAILABLE;
+    } else if (exception is FormatException) {
+      return exit_codes.DATA;
+    } else {
+      return 1;
+    }
+  }
 }