- Implement a first cut for const String.env in the VM to allow

runtime/bin/main.cc

Index: runtime/bin/main.cc
===================================================================
--- runtime/bin/main.cc	(revision 28427)
+++ runtime/bin/main.cc	(working copy)
@@ -414,6 +414,32 @@
   }                                                                            \
 
 
+static Dart_Handle ConfigCallback(Dart_ConfigType type, Dart_Handle name) {
+  uint8_t* utf8_array;
+  intptr_t utf8_len;
+  Dart_Handle result = Dart_Null();
+  Dart_Handle handle = Dart_StringToUTF8(name, &utf8_array, &utf8_len);
+  if (Dart_IsError(handle)) {
+    handle = Dart_ThrowException(
+        DartUtils::NewDartArgumentError(Dart_GetError(handle)));
+  } else {
+    char* name_chars = reinterpret_cast<char*>(malloc(utf8_len + 1));
+    memmove(name_chars, utf8_array, utf8_len);
+    name_chars[utf8_len] = '\0';
+    const char* value = getenv(name_chars);
+    if (value != NULL) {
+      if ((type == kStringConfig) || (type == kIntegerConfig)) {
+        result = Dart_NewStringFromUTF8(reinterpret_cast<const uint8_t*>(value),
+                                      strlen(value));
+      } else if (type == kBoolConfig) {
+        UNIMPLEMENTED();
+      }
+    }
+  }
+  return result;
+}
+
+
 // Returns true on success, false on failure.
 static Dart_Isolate CreateIsolateAndSetupHelper(const char* script_uri,
                                                 const char* main,
@@ -438,6 +464,9 @@
   Dart_Handle result = Dart_SetLibraryTagHandler(DartUtils::LibraryTagHandler);
   CHECK_RESULT(result);
 
+  result = Dart_SetConfigCallback(ConfigCallback);
+  CHECK_RESULT(result);
+
   // Load the specified application script into the newly created isolate.
 
   // Prepare builtin and its dependent libraries for use to resolve URIs.