runtime/dart_runner/mapped_resource.cc

// Copyright 2018 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "topaz/runtime/dart_runner/mapped_resource.h"

#include <fcntl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <trace/event.h>
#include <zircon/status.h>

#include "topaz/runtime/dart/utils/inlines.h"
#include "topaz/runtime/dart/utils/vmo.h"

#include "topaz/runtime/dart_runner/logging.h"

namespace dart_runner {

bool MappedResource::LoadFromNamespace(fdio_ns_t* namespc,
                                       const std::string& path,
                                       MappedResource& resource,
                                       bool executable) {
  TRACE_DURATION("dart", "LoadFromNamespace", "path", path);

  // openat of a path with a leading '/' ignores the namespace fd.
  dart_utils::Check(path[0] != '/', LOG_TAG);

  fuchsia::mem::Buffer resource_vmo;
  if (namespc == nullptr) {
    if (!dart_utils::VmoFromFilename(path, &resource_vmo)) {
      return false;
    }
  } else {
    auto root_dir = fdio_ns_opendir(namespc);
    if (root_dir < 0) {
      return false;
    }

    if (!dart_utils::VmoFromFilenameAt(root_dir, path, &resource_vmo)) {
      return false;
    }
  }

  if (executable) {
    // VmoFromFilenameAt will return VMOs without ZX_RIGHT_EXECUTE,
    // so we need replace_as_executable to be able to map them as
    // ZX_VM_PERM_EXECUTE.
    // TODO(mdempsky): Update comment once SEC-42 is fixed.
    zx_status_t status =
        resource_vmo.vmo.replace_as_executable(zx::handle(), &resource_vmo.vmo);
    if (status != ZX_OK) {
      FX_LOGF(ERROR, LOG_TAG, "Failed to make VMO executable: %s",
              zx_status_get_string(status));
      return false;
    }
  }

  return LoadFromVmo(path, std::move(resource_vmo), resource, executable);
}

bool MappedResource::LoadFromVmo(const std::string& path,
                                 fuchsia::mem::Buffer resource_vmo,
                                 MappedResource& resource, bool executable) {
  if (resource_vmo.size == 0) {
    return true;
  }

  uint32_t flags = ZX_VM_PERM_READ;
  if (executable) {
    flags |= ZX_VM_PERM_EXECUTE;
  }
  uintptr_t addr;
  zx_status_t status = zx::vmar::root_self()->map(
      0, resource_vmo.vmo, 0, resource_vmo.size, flags, &addr);
  if (status != ZX_OK) {
    FX_LOGF(ERROR, LOG_TAG, "Failed to map %s: %s", path.c_str(),
            zx_status_get_string(status));
    return false;
  }

  resource.address_ = reinterpret_cast<void*>(addr);
  resource.size_ = resource_vmo.size;
  return true;
}

MappedResource::~MappedResource() {
  if (address_ != nullptr) {
    zx::vmar::root_self()->unmap(reinterpret_cast<uintptr_t>(address_), size_);
    address_ = nullptr;
    size_ = 0;
  }
}

}  // namespace dart_runner