1 files changed, 111 insertions, 0 deletions
diff --git a/libs/ui/BufferHubMetadata.cpp b/libs/ui/BufferHubMetadata.cpp
new file mode 100644
index 0000000000..0e5fce0c46
--- /dev/null
+++ b/libs/ui/BufferHubMetadata.cpp
@@ -0,0 +1,111 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <errno.h>
+#include <sys/mman.h>
+
+#include <cutils/ashmem.h>
+#include <log/log.h>
+#include <ui/BufferHubMetadata.h>
+
+namespace android {
+namespace dvr {
+
+namespace {
+
+static const int kAshmemProt = PROT_READ | PROT_WRITE;
+
+}  // namespace
+
+using BufferHubDefs::kMetadataHeaderSize;
+using BufferHubDefs::MetadataHeader;
+
+/* static */
+BufferHubMetadata BufferHubMetadata::Create(size_t user_metadata_size) {
+  // The size the of metadata buffer is used as the "width" parameter during
+  // allocation. Thus it cannot overflow uint32_t.
+  if (user_metadata_size >=
+      (std::numeric_limits<uint32_t>::max() - kMetadataHeaderSize)) {
+    ALOGE("BufferHubMetadata::Create: metadata size too big: %zu.",
+          user_metadata_size);
+    return {};
+  }
+
+  const size_t metadata_size = user_metadata_size + kMetadataHeaderSize;
+  int fd = ashmem_create_region(/*name=*/"BufferHubMetadata", metadata_size);
+  if (fd < 0) {
+    ALOGE("BufferHubMetadata::Create: failed to create ashmem region.");
+    return {};
+  }
+
+  // Hand over the ownership of the fd to a pdx::LocalHandle immediately after
+  // the successful return of ashmem_create_region. The ashmem_handle is going
+  // to own the fd and to prevent fd leaks during error handling.
+  pdx::LocalHandle ashmem_handle{fd};
+
+  if (ashmem_set_prot_region(ashmem_handle.Get(), kAshmemProt) != 0) {
+    ALOGE("BufferHubMetadata::Create: failed to set protect region.");
+    return {};
+  }
+
+  return BufferHubMetadata::Import(std::move(ashmem_handle));
+}
+
+/* static */
+BufferHubMetadata BufferHubMetadata::Import(pdx::LocalHandle ashmem_handle) {
+  if (!ashmem_valid(ashmem_handle.Get())) {
+    ALOGE("BufferHubMetadata::Import: invalid ashmem fd.");
+    return {};
+  }
+
+  size_t metadata_size = static_cast<size_t>(ashmem_get_size_region(ashmem_handle.Get()));
+  size_t user_metadata_size = metadata_size - kMetadataHeaderSize;
+
+  // Note that here the buffer state is mapped from shared memory as an atomic
+  // object. The std::atomic's constructor will not be called so that the
+  // original value stored in the memory region can be preserved.
+  auto metadata_header = static_cast<MetadataHeader*>(
+      mmap(nullptr, metadata_size, kAshmemProt, MAP_SHARED, ashmem_handle.Get(),
+           /*offset=*/0));
+  if (metadata_header == nullptr) {
+    ALOGE("BufferHubMetadata::Import: failed to map region.");
+    return {};
+  }
+
+  return BufferHubMetadata(user_metadata_size, std::move(ashmem_handle),
+                           metadata_header);
+}
+
+BufferHubMetadata::BufferHubMetadata(size_t user_metadata_size,
+                                     pdx::LocalHandle ashmem_handle,
+                                     MetadataHeader* metadata_header)
+    : user_metadata_size_(user_metadata_size),
+      ashmem_handle_(std::move(ashmem_handle)),
+      metadata_header_(metadata_header) {}
+
+BufferHubMetadata::~BufferHubMetadata() {
+  if (metadata_header_ != nullptr) {
+    int ret = munmap(metadata_header_, metadata_size());
+    ALOGE_IF(ret != 0,
+             "BufferHubMetadata::~BufferHubMetadata: failed to unmap ashmem, "
+             "error=%d.",
+             errno);
+    metadata_header_ = nullptr;
+  }
+}
+
+}  // namespace dvr
+}  // namespace android