- Implement .packages specification.

runtime/bin/vmservice/loader.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.
 
 part of vmservice_io;
 
+_log(msg) {
+  print("% $msg");
+}
+
 var _httpClient;
 
 // Send a response to the requesting isolate.
-void _sendResponse(SendPort sp, int id, dynamic data) {
+void _sendResourceResponse(SendPort sp, int id, dynamic data) {
   assert((data is List<int>) || (data is String));
   var msg = new List(2);
   msg[0] = id;
   msg[1] = data;
   sp.send(msg);
 }
 
 void _loadHttp(SendPort sp, int id, Uri uri) {
   if (_httpClient == null) {
     _httpClient = new HttpClient()..maxConnectionsPerHost = 6;
   }
   _httpClient.getUrl(uri)
     .then((HttpClientRequest request) => request.close())
     .then((HttpClientResponse response) {
       var builder = new BytesBuilder(copy: false);
       response.listen(
           builder.add,
           onDone: () {
             if (response.statusCode != 200) {
               var msg = "Failure getting $uri:\n"
                         "  ${response.statusCode} ${response.reasonPhrase}";
-              _sendResponse(sp, id, msg);
+              _sendResourceResponse(sp, id, msg);
             } else {
-              _sendResponse(sp, id, builder.takeBytes());
+              _sendResourceResponse(sp, id, builder.takeBytes());
             }
           },
           onError: (e) {
-            _sendResponse(sp, d, e.toString());
+            _sendResourceResponse(sp, id, e.toString());
           });
     })
     .catchError((e) {
-      _sendResponse(sp, id, e.toString());
+      _sendResourceResponse(sp, id, e.toString());
     });
   // It's just here to push an event on the event loop so that we invoke the
   // scheduled microtasks.
   Timer.run(() {});
 }
 
 void _loadFile(SendPort sp, int id, Uri uri) {
   var path = uri.toFilePath();
   var sourceFile = new File(path);
   sourceFile.readAsBytes().then((data) {
-    _sendResponse(sp, id, data);
+    _sendResourceResponse(sp, id, data);
   },
   onError: (e) {
     var err = "Error loading $uri:\n  $e";
-    _sendResponse(sp, id, err);
+    _sendResourceResponse(sp, id, err);
   });
 }
 
 var dataUriRegex = new RegExp(
     r"data:([\w-]+/[\w-]+)?(;charset=([\w-]+))?(;base64)?,(.*)");
 
 void _loadDataUri(SendPort sp, int id, Uri uri) {
   try {
     var match = dataUriRegex.firstMatch(uri.toString());
     if (match == null) throw "Malformed data uri";
 
     var mimeType = match.group(1);
     var encoding = match.group(3);
     var maybeBase64 = match.group(4);
     var encodedData = match.group(5);
 
     if (mimeType != "application/dart") {
       throw "MIME-type must be application/dart";
     }
     if (encoding != "utf-8") {
       // Default is ASCII. The C++ portion of the embedder assumes UTF-8.
       throw "Only utf-8 encoding is supported";
     }
     if (maybeBase64 != null) {
       throw "Only percent encoding is supported";
     }
 
     var data = UTF8.encode(Uri.decodeComponent(encodedData));
-    _sendResponse(sp, id, data);
+    _sendResourceResponse(sp, id, data);
   } catch (e) {
-    _sendResponse(sp, id, "Invalid data uri ($uri):\n  $e");
-  }
-}
-
+    _sendResourceResponse(sp, id, "Invalid data uri ($uri):\n  $e");
+  }
+}
+
+_handleResourceRequest(SendPort sp, bool traceLoading, int id, Uri resource) {
+  if (resource.scheme == 'file') {
+    _loadFile(sp, id, resource);
+  } else if ((resource.scheme == 'http') || (resource.scheme == 'https')) {
+    _loadHttp(sp, id, resource);
+  } else if ((resource.scheme == 'data')) {
+    _loadDataUri(sp, id, resource);
+  } else {
+    _sendResourceResponse(sp, id,
+                          'Unknown scheme (${resource.scheme}) for $resource');
+  }
+}
+
+
+// Handling of packages requests. Finding and parsing of .packages file or
+// packages/ directories.
+const _LF    = 0x0A;
+const _CR    = 0x0D;
+const _SPACE = 0x20;
+const _HASH  = 0x23;
+const _DOT   = 0x2E;
+const _COLON = 0x3A;
+const _DEL   = 0x7F;
+
+const _invalidPackageNameChars = const [
+  // space  !      "      #      $      %      &      '
+     true , false, true , true , false, true , false, false,
+  // (      )      *      +      ,      -      .      /
+     false, false, false, false, false, false, false, true ,
+  // 0      1      2      3      4      5      6      7
+     false, false, false, false, false, false, false, false,
+  // 8      9      :      ;      <      =      >      ?
+     false, false, true , false, true , false, true , true ,
+  // @      A      B      C      D      E      F      G
+     false, false, false, false, false, false, false, false,
+  // H      I      J      K      L      M      N      O
+     false, false, false, false, false, false, false, false,
+  // P      Q      R      S      T      U      V      W
+     false, false, false, false, false, false, false, false,
+  // X      Y      Z      [      \      ]      ^      _
+     false, false, false, true , true , true , true , false,
+  // `      a      b      c      d      e      f      g
+     true , false, false, false, false, false, false, false,
+  // h      i      j      k      l      m      n      o
+     false, false, false, false, false, false, false, false,
+  // p      q      r      s      t      u      v      w
+     false, false, false, false, false, false, false, false,
+  // x      y      z      {      |      }      ~      DEL
+     false, false, false, true , true , true , false, true
+];
+
+_parsePackagesFile(SendPort sp,
+                   bool traceLoading,
+                   Uri packagesFile,
+                   List<int> data) {
+  var result = [];
+  var index = 0;
+  var len = data.length;
+  while (index < len) {
+    var start = index;
+    var char = data[index];
+    if ((char == _CR) || (char == _LF)) {
+      // Skipping empty lines.
+      index++;
+      continue;
+    }
+
+    // Identify split within the line and end of the line.
+    var separator = -1;
+    var end = len;
+    // Verifying validity of package name while scanning the line.
+    var nonDot = false;
+    var invalidPackageName = false;
+
+    // Scan to the end of the line or data.
+    while (index < len) {
+      char = data[index++];
+      if (separator == -1) {
+        if ((char == _COLON)) {
+          // The first colon on a line is the separator between package name and
+          // related URI.
+          separator = index - 1;
+        } else {
+          // Still scanning the package name part. Check for the validity of
+          // the characters.
+          nonDot = nonDot || (char != _DOT);
+          invalidPackageName = invalidPackageName ||
+                               (char < _SPACE) || (char > _DEL) ||
+                               _invalidPackageNameChars[char - _SPACE];
+        }
+      } else if ((char == _CR) || (char == _LF)) {
+        // Identify end of line.
+        end = index - 1;
+        break;
+      }
+    }
+
+    // No further handling needed for comment lines.
+    if (data[start] == _HASH) {
+      if (traceLoading) {
+        _log("Skipping comment in $packagesFile:\n"
+             "${new String.fromCharCodes(data, start, end)}");
+      }
+      continue;
+    }
+
+    // Check for a badly formatted line, starting with a ':'.
+    if (separator == start) {
+      var line = new String.fromCharCodes(data, start, end);
+      if (traceLoading) {
+        _log("Line starts with ':' in $packagesFile:\n"
+             "$line");
+      }
+      sp.send("Missing package name in $packagesFile:\n"
+              "$line");
+      return;
+    }
+
+    // Ensure there is a separator on the line.
+    if (separator == -1) {
+      var line = new String.fromCharCodes(data, start, end);
+      if (traceLoading) {
+        _log("Line has no ':' in $packagesFile:\n"
+              "$line");
+      }
+      sp.send("Missing ':' separator in $packagesFile:\n"
+              "$line");
+      return;
+    }
+
+    var packageName = new String.fromCharCodes(data, start, separator);

[siva, 2015/07/28 23:50:09]

packageName duplicate check (needs to be a warning or a hard error according to
the spec). If it is a warning it needs to be a hard error when the package name
is used.

[Ivan Posva, 2015/07/29 18:22:18]

Added TODO in builtin.dart where we are adding the entries into the map.
Separate CL.

+
+    // Check for valid package name.
+    if (invalidPackageName || !nonDot) {
+      var line = new String.fromCharCodes(data, start, end);
+      if (traceLoading) {
+        _log("Invalid package name $packageName in $packagesFile");
+      }
+      sp.send("Invalid package name '$packageName' in $packagesFile:\n"
+              "$line");
+      return;
+    }
+
+    if (traceLoading) {
+      _log("packageName: $packageName");
+    }
+    var packageUri = new String.fromCharCodes(data, separator + 1, end);
+    if (traceLoading) {
+      _log("original packageUri: $packageUri");
+    }
+    // Ensure the package uri ends with a /.
+    if (!packageUri.endsWith("/")) {
+      packageUri = "$packageUri/";
+    }
+    packageUri = packagesFile.resolve(packageUri).toString();
+    if (traceLoading) {
+      _log("mapping: $packageName -> $packageUri");
+    }
+    result.add(packageName);
+    result.add(packageUri);
+  }
+
+  if (traceLoading) {
+    _log("Parsed packages file at $packagesFile. Sending:\n$result");
+  }
+  sp.send(result);
+}
+
+_loadPackagesFile(SendPort sp, bool traceLoading, Uri packagesFile) async {
+  try {
+    var data = await new File.fromUri(packagesFile).readAsBytes();
+    if (traceLoading) {
+      _log("Loaded packages file from $packagesFile:\n"
+           "${new String.fromCharCodes(data)}");
+    }
+    _parsePackagesFile(sp, traceLoading, packagesFile, data);
+  } catch (e, s) {
+    if (traceLoading) {
+      _log("Error loading packages: $e\n$s");
+    }
+    sp.send("Uncaught error ($e) loading packags file.");
+  }
+}
+
+_findPackagesFile(SendPort sp, bool traceLoading, Uri base) async {
+  try {
+    // Check for the existence of a .packages file and if it exists try to load
+    // and parse it.
+    var packagesFile = base.resolve(".packages");
+    if (traceLoading) {
+      _log("Checking for $packagesFile file.");
+    }
+    var exists = await new File.fromUri(packagesFile).exists();
+    if (traceLoading) {
+      _log("$packagesFile exists: $exists");
+    }
+    if (exists) {
+      _loadPackagesFile(sp, traceLoading, packagesFile);
+      return;
+    }
+
+    // Try whether there is a packages/ directory instead.
+    var packageRoot = base.resolve("packages/");
+    if (traceLoading) {
+      _log("Checking for $packageRoot directory.");
+    }
+    exists = await new Directory.fromUri(packageRoot).exists();
+    if (traceLoading) {
+      _log("$packageRoot exists: $exists");
+    }
+    if (exists) {
+      if (traceLoading) {
+        _log("Found a package root at: $packageRoot");
+      }
+      sp.send([packageRoot.toString()]);
+      return;
+    }
+
+    // Walk up the directory hierarchy to check for the existence of
+    // .packages files in parent directories.
+    var dir = new File.fromUri(base).parent;
+    var parent = dir.parent;
+    // Keep searching until we reach the root.
+    while (parent.path != dir.path) {
+      // Already looked in dir: Move up one level.
+      dir = parent;
+      parent = dir.parent;
+      packagesFile = dir.uri.resolve(".packages");
+      if (traceLoading) {
+        _log("Checking for $packagesFile file.");
+      }
+      exists = await new File.fromUri(packagesFile).exists();
+      if (traceLoading) {
+        _log("$packagesFile exists: $exists");
+      }
+      if (exists) {
+        _loadPackagesFile(sp, traceLoading, packagesFile);
+        return;
+      }

[siva, 2015/07/28 23:50:09]

This chunk of code for finiding ".packages" file could be factored into a helper
function as it is repeated twice.

[Ivan Posva, 2015/07/29 18:22:18]

Refactored into a single loop. It probably now makes it easier to understand.

+    }
+
+    // No .packages file was found.
+    if (traceLoading) {
+      _log("Could not resolve a package location from $base");
+    }
+    sp.send("Could not resolve a package location for base at $base");
+  } catch (e, s) {
+    if (traceLoading) {
+      _log("Error loading packages: $e\n$s");
+    }
+    sp.send("Uncaught error ($e) loading packages file.");
+  }
+}
+
+_handlePackagesRequest(SendPort sp, bool traceLoading, int id, Uri resource) {
+  if (id == -1) {

[siva, 2015/07/28 23:50:09]

-1 and -2 seem like magic numbers maybe we can have a common import file for the
two files with these defined as named constants.

+    if (resource.scheme == 'file') {
+      _findPackagesFile(sp, traceLoading, resource);
+    } else if ((resource.scheme == 'http') || (resource.scheme == 'https')) {
+      // TODO(iposva): Check for the existence of a .packages file when loading
+      // from http or https.
+      var packageRoot = resource.resolve('packages/');
+      sp.send([packageRoot.toString()]);
+    } else {
+      sp.send("Unsupported base URI to identify .packages file: '$resource'.");
+    }
+  } else if (id == -2) {
+    if (traceLoading) {
+      _log("Handling load of packages map: '$resource'.");
+    }
+    _loadPackagesFile(sp, traceLoading, resource);
+  } else {
+    sp.send("Unknown packages request id: $id for '$resource'.");
+  }
+}
+
+
+// External entry point for loader requests.
 _processLoadRequest(request) {
   SendPort sp = request[0];
-  int id = request[1];
-  String resource = request[2];
-  var uri = Uri.parse(request[2]);
-  if (uri.scheme == 'file') {
-    _loadFile(sp, id, uri);
-  } else if ((uri.scheme == 'http') || (uri.scheme == 'https')) {
-    _loadHttp(sp, id, uri);
-  } else if ((uri.scheme == 'data')) {
-    _loadDataUri(sp, id, uri);
+  assert(sp != null);
+  bool traceLoading = request[1];
+  assert(traceLoading != null);
+  int id = request[2];
+  assert(id != null);
+  String resource = request[3];
+  assert(resource != null);
+  var uri = Uri.parse(resource);
+  if (id >= 0) {
+    _handleResourceRequest(sp, traceLoading, id, uri);
   } else {
-    sp.send([id, 'Unknown scheme (${uri.scheme}) for $uri']);
-  }
-}
+    _handlePackagesRequest(sp, traceLoading, id, uri);
+  }
+}