Add the beginnings of a Dart wrapper for libarchive.

utils/archive/dart_archive.c

+// 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.
+
+#include <assert.h>
+#include <errno.h>
+#include <stdlib.h>
+
+#include "dart_archive.h"
+#include "messaging.h"
+
+/** The enumeration of request types for communicating with Dart. */
+enum RequestType {
+  kArchiveReadNew = 0,
+  kArchiveReadSupportFilterAll,
+  kArchiveReadSupportFilterBzip2,
+  kArchiveReadSupportFilterCompress,
+  kArchiveReadSupportFilterGzip,
+  kArchiveReadSupportFilterLzma,
+  kArchiveReadSupportFilterXz,
+  kArchiveReadSupportFilterProgram,
+  kArchiveReadSupportFilterProgramSignature,
+  kArchiveReadSupportFormatAll,
+  kArchiveReadSupportFormatAr,
+  kArchiveReadSupportFormatCpio,
+  kArchiveReadSupportFormatEmpty,
+  kArchiveReadSupportFormatIso9660,
+  kArchiveReadSupportFormatMtree,
+  kArchiveReadSupportFormatRaw,
+  kArchiveReadSupportFormatTar,
+  kArchiveReadSupportFormatZip,
+  kArchiveReadSetFilterOptions,
+  kArchiveReadSetFormatOptions,
+  kArchiveReadSetOptions,
+  kArchiveReadOpenFilename,
+  kArchiveReadOpenMemory,
+  kArchiveReadNextHeader,
+  kArchiveReadDataBlock,
+  kArchiveReadDataSkip,
+  kArchiveReadClose,
+  kArchiveReadFree,
+  kNumberOfRequestTypes
+};
+
+/**
+ * Dispatches a message from Dart to its native function equivalent.
+ *
+ * In addition to matching up a message with its respective function, this
+ * parses out the standard archive struct argument from the message and resolves
+ * it to an actual pointer to an archive struct.
+ */
+static void archiveDispatch(Dart_Port dest_port_id,
+                            Dart_Port reply_port_id,
+                            Dart_CObject* message) {
+  if (message->type != kArray) {
+    postInvalidArgument(reply_port_id, "Message was not an array.");
+    return;
+  } else if (message->value.as_array.length < 2) {
+    char buffer[100];
+    snprintf(buffer, 100, "Message array had %d elements, expected at least 2.",
+             message->value.as_array.length);
+    postInvalidArgument(reply_port_id, buffer);
+    return;
+  }
+
+  Dart_CObject* wrapped_request_type = message->value.as_array.values[0];
+  if (wrapped_request_type->type != kInt32) {
+    char buffer[100];
+    snprintf(buffer, 100, "Invalid request type %d.",
+             wrapped_request_type->type);
+    postInvalidArgument(reply_port_id, buffer);

[Bob Nystrom, 2012/07/31 21:56:48]

The above three lines are repeated frequently. I know arglists are a chore to
deal with, but can you break this out into a separate function, like:

postArgumentError(Dart_Port reply_port_id, const char* format, ...) { ... }

[nweiz, 2012/07/31 23:38:25]

Done.

+    return;
+  }
+  enum RequestType request_type = wrapped_request_type->value.as_int32;
+  if (request_type < kArchiveReadNew || request_type >= kNumberOfRequestTypes) {
+    char buffer[100];

[Bob Nystrom, 2012/07/31 21:56:48]

Instead of checking this here, how about making it the default for the switch()
below?

[nweiz, 2012/07/31 23:38:25]

Done.

+    snprintf(buffer, 100, "Invalid request id %d.", request_type);
+    postInvalidArgument(reply_port_id, buffer);
+    return;
+  }
+
+  Dart_CObject* archive_id = message->value.as_array.values[1];
+  struct archive* archive;
+  if (archive_id->type == kNull) {
+    archive = NULL;
+  } else if (archive_id->type == kInt64 || archive_id->type == kInt32) {
+    archive = (struct archive*) (intptr_t) getInteger(archive_id);
+  } else {
+    char buffer[100];
+    snprintf(buffer, 100, "Invalid archive id type %d.", archive_id->type);
+    postInvalidArgument(reply_port_id, buffer);
+    return;
+  }
+
+  switch (request_type) {
+  case kArchiveReadNew:
+    archiveReadNew(reply_port_id);
+    break;
+  case kArchiveReadSupportFilterAll:
+    archiveReadSupportFilterAll(reply_port_id, archive);
+    break;
+  case kArchiveReadSupportFilterBzip2:
+    archiveReadSupportFilterBzip2(reply_port_id, archive);
+    break;
+  case kArchiveReadSupportFilterCompress:
+    archiveReadSupportFilterCompress(reply_port_id, archive);
+    break;
+  case kArchiveReadSupportFilterGzip:
+    archiveReadSupportFilterGzip(reply_port_id, archive);
+    break;
+  case kArchiveReadSupportFilterLzma:
+    archiveReadSupportFilterLzma(reply_port_id, archive);
+    break;
+  case kArchiveReadSupportFilterXz:
+    archiveReadSupportFilterXz(reply_port_id, archive);
+    break;
+  case kArchiveReadSupportFilterProgram:
+    archiveReadSupportFilterProgram(reply_port_id, archive, message);
+    break;
+  case kArchiveReadSupportFilterProgramSignature:
+    archiveReadSupportFilterProgramSignature(
+        reply_port_id, archive, message);
+    break;
+  case kArchiveReadSupportFormatAll:
+    archiveReadSupportFormatAll(reply_port_id, archive);
+    break;
+  case kArchiveReadSupportFormatAr:
+    archiveReadSupportFormatAr(reply_port_id, archive);
+    break;
+  case kArchiveReadSupportFormatCpio:
+    archiveReadSupportFormatCpio(reply_port_id, archive);
+    break;
+  case kArchiveReadSupportFormatEmpty:
+    archiveReadSupportFormatEmpty(reply_port_id, archive);
+    break;
+  case kArchiveReadSupportFormatIso9660:
+    archiveReadSupportFormatIso9660(reply_port_id, archive);
+    break;
+  case kArchiveReadSupportFormatMtree:
+    archiveReadSupportFormatMtree(reply_port_id, archive);
+    break;
+  case kArchiveReadSupportFormatRaw:
+    archiveReadSupportFormatRaw(reply_port_id, archive);
+    break;
+  case kArchiveReadSupportFormatTar:
+    archiveReadSupportFormatTar(reply_port_id, archive);
+    break;
+  case kArchiveReadSupportFormatZip:
+    archiveReadSupportFormatZip(reply_port_id, archive);
+    break;
+  case kArchiveReadSetFilterOptions:
+    archiveReadSetFilterOptions(reply_port_id, archive, message);
+    break;
+  case kArchiveReadSetFormatOptions:
+    archiveReadSetFormatOptions(reply_port_id, archive, message);
+    break;
+  case kArchiveReadSetOptions:
+    archiveReadSetOptions(reply_port_id, archive, message);
+    break;
+  case kArchiveReadOpenFilename:
+    archiveReadOpenFilename(reply_port_id, archive, message);
+    break;
+  case kArchiveReadOpenMemory:
+    archiveReadOpenMemory(reply_port_id, archive, message);
+    break;
+  case kArchiveReadNextHeader:
+    archiveReadNextHeader(reply_port_id, archive);
+    break;
+  case kArchiveReadDataBlock:
+    archiveReadDataBlock(reply_port_id, archive);
+    break;
+  case kArchiveReadDataSkip:
+    archiveReadDataSkip(reply_port_id, archive);
+    break;
+  case kArchiveReadClose:
+    archiveReadClose(reply_port_id, archive);
+    break;
+  case kArchiveReadFree:
+    archiveReadFree(reply_port_id, archive);
+    break;
+  }
+}
+
+/**
+ * Checks if [handle] represents an error and, if so, propagates it to Dart.
+ * Otherwise, returns [handle].
+ */
+static Dart_Handle HandleError(Dart_Handle handle) {
+  if (Dart_IsError(handle)) Dart_PropagateError(handle);
+  return handle;
+}
+
+/**
+ * A function exposed to Dart that creates a [ServicePort] for two-way
+ * communication between Dart and C.
+ *
+ * Takes no arguments and returns a [ServicePort].
+ */
+static void archiveServicePort(Dart_NativeArguments arguments) {
+  Dart_EnterScope();
+  Dart_SetReturnValue(arguments, Dart_Null());
+  Dart_Port service_port =
+      Dart_NewNativePort("ArchiveService", archiveDispatch, false);
+  if (service_port != ILLEGAL_PORT) {
+    Dart_Handle send_port = HandleError(Dart_NewSendPort(service_port));
+    Dart_SetReturnValue(arguments, send_port);
+  }
+  Dart_ExitScope();
+}
+
+// Standard name resolution code

[Bob Nystrom, 2012/07/31 21:56:48]

Can probably remove this.

[nweiz, 2012/07/31 23:38:25]

Done.

+
+/**
+ * A struct representing a function exposed to Dart and the name under which it
+ * can be looked up.
+ */
+struct FunctionLookup {
+  const char* name;
+  Dart_NativeFunction function;
+};
+
+/** The list of functions exposed to Dart. */
+struct FunctionLookup function_list[] = {
+  {"Archive_ServicePort", archiveServicePort},
+  {NULL, NULL}};

[Bob Nystrom, 2012/07/31 21:56:48]

I would put the last } on the next line:

struct FunctionLookup function_list[] = {
  {"Archive_ServicePort", archiveServicePort},
  {NULL, NULL}
};

[nweiz, 2012/07/31 23:38:25]

This style was copied from the sample_extension example, but as per our
discussion I agree that we should follow a more Dart-like style instead.

[nweiz, 2012/07/31 23:38:25]

Done.

+
+/**
+ * Resolves a Dart name as provided in a `native` declaration and returns the
+ * C function that should be invoked for that name.
+ */
+static Dart_NativeFunction ResolveName(Dart_Handle name, int argc) {
+  if (!Dart_IsString8(name)) return NULL;
+  Dart_NativeFunction result = NULL;
+  Dart_EnterScope();
+  const char* cname;
+  HandleError(Dart_StringToCString(name, &cname));
+
+  int i;

[Bob Nystrom, 2012/07/31 21:56:48]

I would move the declaration of result to just above this.

[nweiz, 2012/07/31 23:38:25]

Done. This is all copied from sample_extension, but I suppose it can't hurt to
clean it up.

+  for (i=0; function_list[i].name != NULL; ++i) {

[Bob Nystrom, 2012/07/31 21:56:48]

Spaces around =

[nweiz, 2012/07/31 23:38:25]

Done.

+    if (strcmp(function_list[i].name, cname) == 0) {
+      result = function_list[i].function;
+      break;
+    }
+  }
+  Dart_ExitScope();
+  return result;
+}
+
+/** Initializes the C extension. */
+DART_EXPORT Dart_Handle dart_archive_Init(Dart_Handle parent_library) {
+  if (Dart_IsError(parent_library)) return parent_library;
+
+  Dart_Handle result_code = Dart_SetNativeResolver(parent_library, ResolveName);
+  if (Dart_IsError(result_code)) return result_code;
+
+  return Dart_Null();
+}