ipc: Work on Android using AHardwareBuffer instead of FDs for graphics

src/xrt/include/xrt/xrt_handles.h

@@ -9,6 +9,8 @@
 
 #pragma once
 
+#include "xrt_config_os.h"
+
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -20,6 +22,12 @@ extern "C" {
  */
 typedef int xrt_shmem_handle_t;
 
+#if defined(XRT_OS_ANDROID)
+typedef struct AHardwareBuffer AHardwareBuffer;
+
+typedef AHardwareBuffer *xrt_graphics_buffer_handle_t;
+#else
+
 /*!
  * The type underlying buffers shared between compositor clients and the main
  * compositor.
@@ -27,6 +35,7 @@ typedef int xrt_shmem_handle_t;
  * On Linux, this is a file descriptor.
  */
 typedef int xrt_graphics_buffer_handle_t;
+#endif
 
 #ifdef __cplusplus
 }

src/xrt/ipc/ipc_utils.c

@@ -237,6 +237,60 @@ ipc_send_handles_shmem(struct ipc_message_channel *imc,
 	return ipc_send_fds(imc, data, size, handles, num_handles);
 }
 
+#if defined(XRT_OS_ANDROID)
+
+#include <android/hardware_buffer.h>
+
+#if __ANDROID_API__ < 26
+#error "Android API level 26 or higher needed for AHardwareBuffer"
+#endif
+
+xrt_result_t
+ipc_receive_handles_graphics_buffer(struct ipc_message_channel *imc,
+                                    void *out_data,
+                                    size_t size,
+                                    xrt_graphics_buffer_handle_t *out_handles,
+                                    uint32_t num_handles)
+{
+	xrt_result_t result = ipc_receive(imc, out_data, size);
+	if (result != XRT_SUCCESS) {
+		return result;
+	}
+	bool failed = false;
+	for (uint32_t i = 0; i < num_handles; ++i) {
+		int err = AHardwareBuffer_recvHandleFromUnixSocket(
+		    imc->socket_fd, &(out_handles[i]));
+		if (err != 0) {
+			failed = true;
+		}
+	}
+	return failed ? XRT_ERROR_IPC_FAILURE : XRT_SUCCESS;
+}
+
+
+xrt_result_t
+ipc_send_handles_graphics_buffer(struct ipc_message_channel *imc,
+                                 const void *data,
+                                 size_t size,
+                                 const xrt_graphics_buffer_handle_t *handles,
+                                 uint32_t num_handles)
+{
+	xrt_result_t result = ipc_send(imc, data, size);
+	if (result != XRT_SUCCESS) {
+		return result;
+	}
+	bool failed = false;
+	for (uint32_t i = 0; i < num_handles; ++i) {
+		int err = AHardwareBuffer_sendHandleToUnixSocket(
+		    handles[i], imc->socket_fd);
+		if (err != 0) {
+			failed = true;
+		}
+	}
+	return failed ? XRT_ERROR_IPC_FAILURE : XRT_SUCCESS;
+}
+
+#else
 
 xrt_result_t
 ipc_receive_handles_graphics_buffer(struct ipc_message_channel *imc,
@@ -258,3 +312,5 @@ ipc_send_handles_graphics_buffer(struct ipc_message_channel *imc,
 {
 	return ipc_send_fds(imc, data, size, handles, num_handles);
 }
+
+#endif