bufferhubd: Implement more DetachedBuffer logic

1/ Separate DetachedBuffer related logic into a dedicated subclass of
   BufferHubRPC. This actually is the right thing to do as it utilizes
   the PDX's client/service programming pattern better.
2/ Add IsValid() check for the DetachedBufferChannel object.
3/ Add BufferHubClient to handle general PDX operations.
4/ Add DetachedBuffer which composites a BufferHubClient.
5/ Fully functional logic of allocating a DetachedBuffer, converting it
   to a BufferHub-backed GraphicBuffer, then converting it back to a
   DetachedBuffer.

Bug: 38137191
Bug: 70046255
Bug: 70912269
Test: buffer_hub-test
Change-Id: I81bf9259cbbaeb29a6df2769363b5a03464e7864
diff --git a/services/vr/bufferhubd/buffer_hub.cpp b/services/vr/bufferhubd/buffer_hub.cpp
index e4e19c7..72bf6f2 100644
--- a/services/vr/bufferhubd/buffer_hub.cpp
+++ b/services/vr/bufferhubd/buffer_hub.cpp
@@ -6,6 +6,7 @@
 #include <utils/Trace.h>
 
 #include <iomanip>
+#include <memory>
 #include <sstream>
 #include <string>
 #include <thread>
@@ -13,6 +14,7 @@
 #include <pdx/default_transport/service_endpoint.h>
 #include <private/dvr/bufferhub_rpc.h>
 #include "consumer_channel.h"
+#include "detached_buffer_channel.h"
 #include "producer_channel.h"
 #include "producer_queue_channel.h"
 
@@ -245,6 +247,11 @@
           *this, &BufferHubService::OnCreateBuffer, message);
       return {};
 
+    case DetachedBufferRPC::Create::Opcode:
+      DispatchRemoteMethod<DetachedBufferRPC::Create>(
+          *this, &BufferHubService::OnCreateDetachedBuffer, message);
+      return {};
+
     case BufferHubRPC::CreateProducerQueue::Opcode:
       DispatchRemoteMethod<BufferHubRPC::CreateProducerQueue>(
           *this, &BufferHubService::OnCreateProducerQueue, message);
@@ -295,6 +302,43 @@
   }
 }
 
+pdx::Status<void> BufferHubService::OnCreateDetachedBuffer(
+    pdx::Message& message, uint32_t width, uint32_t height,
+    uint32_t layer_count, uint32_t format, uint64_t usage,
+    size_t user_metadata_size) {
+  // Use the producer channel id as the global buffer id.
+  const int buffer_id = message.GetChannelId();
+  ALOGD_IF(TRACE,
+           "BufferHubService::OnCreateDetachedBuffer: buffer_id=%d width=%u "
+           "height=%u layer_count=%u format=%u usage=%" PRIx64
+           " user_metadata_size=%zu",
+           buffer_id, width, height, layer_count, format, usage,
+           user_metadata_size);
+
+  // See if this channel is already attached to a buffer.
+  if (const auto channel = message.GetChannel<BufferHubChannel>()) {
+    ALOGE(
+        "BufferHubService::OnCreateDetachedBuffer: Buffer already created: "
+        "buffer=%d",
+        buffer_id);
+    return ErrorStatus(EALREADY);
+  }
+
+  std::unique_ptr<DetachedBufferChannel> channel =
+      DetachedBufferChannel::Create(this, buffer_id, width, height, layer_count,
+                                    format, usage, user_metadata_size);
+  if (!channel) {
+    ALOGE(
+        "BufferHubService::OnCreateDetachedBuffer: Failed to allocate buffer, "
+        "buffer=%d.",
+        buffer_id);
+    return ErrorStatus(ENOMEM);
+  }
+
+  message.SetChannel(std::move(channel));
+  return {};
+}
+
 Status<QueueInfo> BufferHubService::OnCreateProducerQueue(
     pdx::Message& message, const ProducerQueueConfig& producer_config,
     const UsagePolicy& usage_policy) {
diff --git a/services/vr/bufferhubd/buffer_hub.h b/services/vr/bufferhubd/buffer_hub.h
index e04967a..e47ffa3 100644
--- a/services/vr/bufferhubd/buffer_hub.h
+++ b/services/vr/bufferhubd/buffer_hub.h
@@ -147,6 +147,11 @@
   pdx::Status<void> OnCreateBuffer(pdx::Message& message, uint32_t width,
                                    uint32_t height, uint32_t format,
                                    uint64_t usage, size_t meta_size_bytes);
+  pdx::Status<void> OnCreateDetachedBuffer(pdx::Message& message,
+                                           uint32_t width, uint32_t height,
+                                           uint32_t layer_count,
+                                           uint32_t format, uint64_t usage,
+                                           size_t user_metadata_size);
   pdx::Status<QueueInfo> OnCreateProducerQueue(
       pdx::Message& message, const ProducerQueueConfig& producer_config,
       const UsagePolicy& usage_policy);
diff --git a/services/vr/bufferhubd/detached_buffer_channel.cpp b/services/vr/bufferhubd/detached_buffer_channel.cpp
index edb2111..4f4160a 100644
--- a/services/vr/bufferhubd/detached_buffer_channel.cpp
+++ b/services/vr/bufferhubd/detached_buffer_channel.cpp
@@ -1,5 +1,6 @@
 #include "detached_buffer_channel.h"
 
+using android::pdx::BorrowedHandle;
 using android::pdx::ErrorStatus;
 using android::pdx::Message;
 using android::pdx::RemoteChannelHandle;
@@ -17,7 +18,49 @@
     : BufferHubChannel(service, buffer_id, channel_id, kDetachedBufferType),
       buffer_(std::move(buffer)),
       metadata_buffer_(std::move(metadata_buffer)),
-      user_metadata_size_(user_metadata_size) {}
+      user_metadata_size_(user_metadata_size) {
+}
+
+DetachedBufferChannel::DetachedBufferChannel(BufferHubService* service,
+                                             int buffer_id, uint32_t width,
+                                             uint32_t height,
+                                             uint32_t layer_count,
+                                             uint32_t format, uint64_t usage,
+                                             size_t user_metadata_size)
+    : BufferHubChannel(service, buffer_id, buffer_id, kDetachedBufferType),
+      user_metadata_size_(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() -
+                              BufferHubDefs::kMetadataHeaderSize)) {
+    ALOGE(
+        "DetachedBufferChannel::DetachedBufferChannel: metadata size too big.");
+    return;
+  }
+
+  if (int ret = buffer_.Alloc(width, height, layer_count, format, usage)) {
+    ALOGE(
+        "DetachedBufferChannel::DetachedBufferChannel: Failed to allocate "
+        "buffer: %s",
+        strerror(-ret));
+    return;
+  }
+
+  // Buffer metadata has two parts: 1) a fixed sized metadata header; and 2)
+  // user requested metadata.
+  const size_t size = BufferHubDefs::kMetadataHeaderSize + user_metadata_size_;
+  if (int ret = metadata_buffer_.Alloc(size,
+                                       /*height=*/1,
+                                       /*layer_count=*/1,
+                                       BufferHubDefs::kMetadataFormat,
+                                       BufferHubDefs::kMetadataUsage)) {
+    ALOGE(
+        "DetachedBufferChannel::DetachedBufferChannel: Failed to allocate "
+        "metadata: %s",
+        strerror(-ret));
+    return;
+  }
+}
 
 BufferHubChannel::BufferInfo DetachedBufferChannel::GetBufferInfo() const {
   return BufferInfo(buffer_id(), /*consumer_count=*/0, buffer_.width(),
@@ -33,8 +76,13 @@
 bool DetachedBufferChannel::HandleMessage(Message& message) {
   ATRACE_NAME("DetachedBufferChannel::HandleMessage");
   switch (message.GetOp()) {
-    case BufferHubRPC::DetachedBufferPromote::Opcode:
-      DispatchRemoteMethod<BufferHubRPC::DetachedBufferPromote>(
+    case DetachedBufferRPC::Import::Opcode:
+      DispatchRemoteMethod<DetachedBufferRPC::Import>(
+          *this, &DetachedBufferChannel::OnImport, message);
+      return true;
+
+    case DetachedBufferRPC::Promote::Opcode:
+      DispatchRemoteMethod<DetachedBufferRPC::Promote>(
           *this, &DetachedBufferChannel::OnPromote, message);
       return true;
 
@@ -43,6 +91,20 @@
   }
 }
 
+Status<BufferDescription<BorrowedHandle>> DetachedBufferChannel::OnImport(
+    Message& /*message*/) {
+  ATRACE_NAME("DetachedBufferChannel::OnGetBuffer");
+  ALOGD_IF(TRACE, "DetachedBufferChannel::OnGetBuffer: buffer=%d.",
+           buffer_id());
+
+  return BufferDescription<BorrowedHandle>{buffer_,
+                                           metadata_buffer_,
+                                           buffer_id(),
+                                           /*buffer_state_bit=*/0,
+                                           BorrowedHandle{},
+                                           BorrowedHandle{}};
+}
+
 Status<RemoteChannelHandle> DetachedBufferChannel::OnPromote(
     Message& /*message*/) {
   ATRACE_NAME("DetachedBufferChannel::OnPromote");
diff --git a/services/vr/bufferhubd/detached_buffer_channel.h b/services/vr/bufferhubd/detached_buffer_channel.h
index 7ce4aed..079ba72 100644
--- a/services/vr/bufferhubd/detached_buffer_channel.h
+++ b/services/vr/bufferhubd/detached_buffer_channel.h
@@ -3,20 +3,25 @@
 
 #include "buffer_hub.h"
 
-// #include <pdx/channel_handle.h>
-// #include <pdx/file_handle.h>
-// #include <pdx/rpc/buffer_wrapper.h>
-// #include <private/dvr/ion_buffer.h>
+#include <pdx/channel_handle.h>
+#include <pdx/file_handle.h>
 
 namespace android {
 namespace dvr {
 
 class DetachedBufferChannel : public BufferHubChannel {
  public:
-  // Creates a detached buffer.
-  DetachedBufferChannel(BufferHubService* service, int buffer_id,
-                        int channel_id, IonBuffer buffer,
-                        IonBuffer metadata_buffer, size_t user_metadata_size);
+  template <typename... Args>
+  static std::unique_ptr<DetachedBufferChannel> Create(Args&&... args) {
+    auto buffer = std::unique_ptr<DetachedBufferChannel>(
+        new DetachedBufferChannel(std::forward<Args>(args)...));
+    return buffer->IsValid() ? std::move(buffer) : nullptr;
+  }
+
+  // Returns whether the object holds a valid graphic buffer.
+  bool IsValid() const {
+    return buffer_.IsValid() && metadata_buffer_.IsValid();
+  }
 
   size_t user_metadata_size() const { return user_metadata_size_; }
 
@@ -27,6 +32,19 @@
   void HandleImpulse(pdx::Message& message) override;
 
  private:
+  // Creates a detached buffer from existing IonBuffers.
+  DetachedBufferChannel(BufferHubService* service, int buffer_id,
+                        int channel_id, IonBuffer buffer,
+                        IonBuffer metadata_buffer, size_t user_metadata_size);
+
+  // Allocates a new detached buffer.
+  DetachedBufferChannel(BufferHubService* service, int buffer_id,
+                        uint32_t width, uint32_t height, uint32_t layer_count,
+                        uint32_t format, uint64_t usage,
+                        size_t user_metadata_size);
+
+  pdx::Status<BufferDescription<pdx::BorrowedHandle>> OnImport(
+      pdx::Message& message);
   pdx::Status<pdx::RemoteChannelHandle> OnPromote(pdx::Message& message);
 
   // Gralloc buffer handles.
diff --git a/services/vr/bufferhubd/producer_channel.cpp b/services/vr/bufferhubd/producer_channel.cpp
index c38c12b..a753168 100644
--- a/services/vr/bufferhubd/producer_channel.cpp
+++ b/services/vr/bufferhubd/producer_channel.cpp
@@ -377,11 +377,17 @@
     return ErrorStatus(-ret);
   };
 
-  auto channel = std::make_shared<DetachedBufferChannel>(
-      service(), buffer_id(), channel_id, std::move(buffer_),
-      std::move(metadata_buffer_), user_metadata_size_);
+  std::unique_ptr<DetachedBufferChannel> channel =
+      DetachedBufferChannel::Create(
+          service(), buffer_id(), channel_id, std::move(buffer_),
+          std::move(metadata_buffer_), user_metadata_size_);
+  if (!channel) {
+    ALOGE("ProducerChannel::OnProducerDetach: Invalid buffer.");
+    return ErrorStatus(EINVAL);
+  }
 
-  const auto channel_status = service()->SetChannel(channel_id, channel);
+  const auto channel_status =
+      service()->SetChannel(channel_id, std::move(channel));
   if (!channel_status) {
     // Technically, this should never fail, as we just pushed the channel. Note
     // that LOG_FATAL will be stripped out in non-debug build.