[Mammoth/Teton] Add an OpenFile interface and use it to load a font.

lib/mammoth/file/file.cpp

@@ -0,0 +1,45 @@
+#include "file/file.h"
+
+#include <victoriafalls/victoriafalls.yunq.client.h>
+#include <yellowstone/yellowstone.yunq.client.h>
+#include <zglobal.h>
+
+#include "util/debug.h"
+
+namespace mmth {
+namespace {
+
+VFSClient* gVfsClient = nullptr;
+
+}  // namespace
+
+File File::Open(glcr::StringView path) {
+  if (gVfsClient == 0) {
+    YellowstoneClient client(gInitEndpointCap);
+
+    GetEndpointRequest yreq;
+    yreq.set_endpoint_name("victoriafalls");
+    Endpoint yresp;
+    check(client.GetEndpoint(yreq, yresp));
+
+    gVfsClient = new VFSClient(yresp.endpoint());
+  }
+
+  OpenFileRequest req;
+  req.set_path(path);
+  OpenFileResponse resp;
+  check(gVfsClient->OpenFile(req, resp));
+
+  return File(OwnedMemoryRegion::FromCapability(resp.memory()));
+}
+
+glcr::StringView File::as_str() {
+  return glcr::StringView((char*)raw_ptr(), file_data_.size());
+}
+
+void* File::raw_ptr() { return reinterpret_cast<void*>(file_data_.vaddr()); }
+uint8_t* File::byte_ptr() {
+  return reinterpret_cast<uint8_t*>(file_data_.vaddr());
+}
+
+}  // namespace mmth

lib/mammoth/file/file.h

@@ -0,0 +1,25 @@
+#pragma once
+
+#include <glacier/memory/move.h>
+#include <glacier/string/string_view.h>
+
+#include "mammoth/util/memory_region.h"
+
+namespace mmth {
+
+class File {
+ public:
+  static File Open(glcr::StringView path);
+
+  glcr::StringView as_str();
+
+  void* raw_ptr();
+  uint8_t* byte_ptr();
+
+ private:
+  OwnedMemoryRegion file_data_;
+
+  File(OwnedMemoryRegion&& file) : file_data_(glcr::Move(file)) {}
+};
+
+}  // namespace mmth