/* GStreamer video dmabuf pool

 *

 * Copyright (C) 2025 Collabora Ltd.

 * Author: Robert Mader <robert.mader@collabora.com>

 *

 * This library is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Library General Public

 * License as published by the Free Software Foundation; either

 * version 2 of the License, or (at your option) any later version.

 *

 * This library is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * Library General Public License for more details.

 *

 * You should have received a copy of the GNU Library General Public

 * License along with this library; if not, write to the

 * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,

 * Boston, MA 02110-1301, USA.

 */

/**

 * SECTION:gstvideodmabufpool

 * @title: GstVideoDmabufPool

 * @short_description: Pool for virtual memory backed dmabufs

 * @see_also: #GstUdmabufAllocator

 *

 * Using #GstUdmabufAllocator, setting defaults and implementing implicit sync.

 *

 * Since: 1.28

 */

#ifdef HAVE_CONFIG_H

#include "config.h"

#endif

#include "gstvideodmabufpool.h"

#include <gst/allocators/gstudmabufallocator.h>

#ifdef HAVE_LINUX_DMA_BUF_H

#include <linux/dma-buf.h>

#include <sys/ioctl.h>

#include <unistd.h>

#endif

/* This alignment is needed on many AMD GPUs and is known to work well across

 * many vendors/GPUs, see e.g. GstGLDMABufBufferPool. */

#define UDMABUF_ALIGNMENT_MASK (256 - 1)

struct _GstVideoDmabufPool

{

  GstVideoBufferPool parent;

  GMainContext *context;

  GMainLoop *loop;

  GThread *thread;

};

GST_DEBUG_CATEGORY_STATIC (gst_video_dmabuf_pool_debug);

G_DEFINE_TYPE_WITH_CODE (GstVideoDmabufPool, gst_video_dmabuf_pool,

    GST_TYPE_VIDEO_BUFFER_POOL,

    GST_DEBUG_CATEGORY_INIT (gst_video_dmabuf_pool_debug, "video-dmabuf-pool",

        0, "video dmabuf pool");

    );

#ifdef HAVE_LINUX_DMA_BUF_H

#ifdef DMA_BUF_IOCTL_EXPORT_SYNC_FILE

typedef struct _DmaBufSource

{

  GSource base;

  GstVideoDmabufPool *pool;

  GstBuffer *buffer;

  gint mem_fds[GST_VIDEO_MAX_PLANES];

  gpointer fd_tags[GST_VIDEO_MAX_PLANES];

} DmaBufSource;

static gboolean

dma_buf_fd_readable (gint fd)

{

  GPollFD poll_fd;

  poll_fd.fd = fd;

  poll_fd.events = G_IO_IN;

  poll_fd.revents = 0;

  if (!g_poll (&poll_fd, 1, 0))

    return FALSE;

  return (poll_fd.revents & (G_IO_IN | G_IO_NVAL)) != 0;

}

static int

get_sync_file (gint fd)

{

  struct dma_buf_export_sync_file sync_file_in_out = {

    .flags = DMA_BUF_SYNC_WRITE,

    .fd = -1

  };

  gint ret;

  do {

    ret = ioctl (fd, DMA_BUF_IOCTL_EXPORT_SYNC_FILE, &sync_file_in_out);

  } while (ret == -1 && errno == EINTR);

  if (ret == 0)

    return sync_file_in_out.fd;

  return -1;

}

static gboolean

dma_buf_source_dispatch (GSource * base,

    GSourceFunc callback, gpointer user_data)

{

  DmaBufSource *source = (DmaBufSource *) base;

  GstVideoDmabufPool *self = GST_VIDEO_DMABUF_POOL (source->pool);

  gboolean ready;

  GST_DEBUG_OBJECT (self, "Dispatch source for buffer %p", source->buffer);

  ready = TRUE;

  for (gint i = 0; i < GST_VIDEO_MAX_PLANES; i++) {

    if (!source->fd_tags[i])

      continue;

    if (!dma_buf_fd_readable (source->mem_fds[i])) {

      GST_DEBUG_OBJECT (self, "Buffer %p not ready, sync file: %d",

          source->buffer, source->mem_fds[i]);

      ready = FALSE;

      continue;

    }

    close (source->mem_fds[i]);

    g_source_remove_unix_fd (base, source->fd_tags[i]);

    source->fd_tags[i] = NULL;

  }

  if (!ready)

    return G_SOURCE_CONTINUE;

  GST_DEBUG_OBJECT (self, "Releasing buffer %p from source, pool %p",

      source->buffer, self);

  GST_BUFFER_POOL_CLASS (gst_video_dmabuf_pool_parent_class)->release_buffer

      (GST_BUFFER_POOL_CAST (self), source->buffer);

  g_source_unref (base);

  return G_SOURCE_REMOVE;

}

static void

dma_buf_source_finalize (GSource * base)

{

  DmaBufSource *source = (DmaBufSource *) base;

  GstVideoDmabufPool *self = GST_VIDEO_DMABUF_POOL (source->pool);

  gboolean need_buffer_release = FALSE;

  for (gint i = 0; i < GST_VIDEO_MAX_PLANES; i++) {

    if (!source->fd_tags[i])

      continue;

    close (source->mem_fds[i]);

    g_source_remove_unix_fd (base, source->fd_tags[i]);

    source->fd_tags[i] = NULL;

    need_buffer_release = TRUE;

  }

  if (need_buffer_release) {

    GST_DEBUG_OBJECT (self, "Releasing buffer %p from source, pool %p",

        source->buffer, self);

    GST_BUFFER_POOL_CLASS (gst_video_dmabuf_pool_parent_class)->release_buffer

        (GST_BUFFER_POOL_CAST (self), source->buffer);

  }

}

static GSourceFuncs dma_buf_source_funcs = {

  .dispatch = dma_buf_source_dispatch,

  .finalize = dma_buf_source_finalize,

};

static gpointer

dmabuf_source_thread (gpointer data)

{

  GstVideoDmabufPool *self = data;

  GMainContext *context = NULL;

  GMainLoop *loop = NULL;

  GST_OBJECT_LOCK (self);

  if (self->context)

    context = g_main_context_ref (self->context);

  if (self->loop)

    loop = g_main_loop_ref (self->loop);

  if (context == NULL || loop == NULL) {

    g_clear_pointer (&loop, g_main_loop_unref);

    g_clear_pointer (&context, g_main_context_unref);

    GST_OBJECT_UNLOCK (self);

    return NULL;

  }

  GST_OBJECT_UNLOCK (self);

  g_main_context_push_thread_default (context);

  GST_DEBUG_OBJECT (self, "Running main loop");

  g_main_loop_run (loop);

  g_main_loop_unref (loop);

  g_main_context_unref (context);

  gst_object_unref (self);

  return NULL;

}

static gboolean

gst_video_dmabuf_pool_start (GstBufferPool * pool)

{

  GstVideoDmabufPool *self = GST_VIDEO_DMABUF_POOL (pool);

  GST_OBJECT_LOCK (self);

  GST_DEBUG_OBJECT (self, "Starting main loop");

  g_assert (self->context == NULL);

  self->context = g_main_context_new ();

  self->loop = g_main_loop_new (self->context, FALSE);

  self->thread =

      g_thread_new ("video-dmabuf-pool-source-loop", dmabuf_source_thread,

      g_object_ref (self));

  GST_OBJECT_UNLOCK (self);

  return

      GST_BUFFER_POOL_CLASS (gst_video_dmabuf_pool_parent_class)->start (pool);

}

static gboolean

gst_video_dmabuf_pool_stop (GstBufferPool * pool)

{

  GstVideoDmabufPool *self = GST_VIDEO_DMABUF_POOL (pool);

  GMainContext *context;

  GMainLoop *loop;

  GSource *idle_stop_source;

  GST_OBJECT_LOCK (self);

  GST_DEBUG_OBJECT (self, "Stopping main loop");

  context = self->context;

  loop = self->loop;

  self->context = NULL;

  self->loop = NULL;

  GST_OBJECT_UNLOCK (self);

  if (!context || !loop) {

    g_clear_pointer (&loop, g_main_loop_unref);

    g_clear_pointer (&context, g_main_context_unref);

    goto out;

  }

  idle_stop_source = g_idle_source_new ();

  g_source_set_callback (idle_stop_source, (GSourceFunc) g_main_loop_quit, loop,

      NULL);

  g_source_attach (idle_stop_source, context);

  g_source_unref (idle_stop_source);

  g_thread_join (self->thread);

  self->thread = NULL;

  g_main_loop_unref (loop);

  g_main_context_unref (context);

out:

  return

      GST_BUFFER_POOL_CLASS (gst_video_dmabuf_pool_parent_class)->stop (pool);

}

static void

gst_video_dmabuf_pool_release_buffer (GstBufferPool * pool, GstBuffer * buffer)

{

  GstVideoDmabufPool *self = GST_VIDEO_DMABUF_POOL (pool);

  DmaBufSource *source = NULL;

  guint n_mem;

  GST_DEBUG_OBJECT (self, "Buffer: %p", buffer);

  n_mem = gst_buffer_n_memory (buffer);

  for (gint i = 0; i < n_mem; i++) {

    GstMemory *mem;

    gint mem_fd, sync_file;

    mem = gst_buffer_peek_memory (buffer, i);

    if (!gst_is_dmabuf_memory (mem))

      continue;

    mem_fd = gst_dmabuf_memory_get_fd (mem);

    sync_file = get_sync_file (mem_fd);

    if (sync_file == -1) {

      GST_ERROR_OBJECT (self, "Exporting sync file failed");

      continue;

    }

    if (dma_buf_fd_readable (sync_file)) {

      GST_DEBUG_OBJECT (self, "Sync file readable");

      close (sync_file);

      continue;

    }

    if (!source) {

      GST_DEBUG_OBJECT (self, "Creating source for buffer %p, pool %p", buffer,

          self);

      source =

          (DmaBufSource *) g_source_new (&dma_buf_source_funcs,

          sizeof (*source));

      source->pool = self;

      source->buffer = buffer;

    }

    GST_DEBUG_OBJECT (self, "Adding sync file to source");

    source->mem_fds[i] = sync_file;

    source->fd_tags[i] =

        g_source_add_unix_fd (&source->base, sync_file, G_IO_IN);

  }

  if (source) {

    g_assert (self->context);

    g_source_attach ((GSource *) source, self->context);

    return;

  }

  GST_BUFFER_POOL_CLASS (gst_video_dmabuf_pool_parent_class)->release_buffer

      (pool, buffer);

}

#endif /* DMA_BUF_IOCTL_EXPORT_SYNC_FILE */

static gboolean

gst_video_dmabuf_pool_set_config (GstBufferPool * pool, GstStructure * config)

{

  GstVideoDmabufPool *self = GST_VIDEO_DMABUF_POOL (pool);

  GstAllocator *allocator;

  GstAllocationParams params;

  GstVideoAlignment video_align = { 0 };

  gboolean config_updated = FALSE;

  gboolean alignment_updated = FALSE;

  gboolean res;

  gst_buffer_pool_config_get_allocator (config, &allocator, &params);

  if (!GST_IS_DMABUF_ALLOCATOR (allocator) ||

      GST_OBJECT_FLAG_IS_SET (allocator, GST_ALLOCATOR_FLAG_CUSTOM_ALLOC)) {

    GST_DEBUG_OBJECT (self,

        "Allocator not a dmabuf allocator or having the CUSTOM_ALLOC flag set, trying to update to udmabuf");

    allocator = gst_udmabuf_allocator_get ();

    if (allocator) {

      params.align |= UDMABUF_ALIGNMENT_MASK;

      gst_buffer_pool_config_set_allocator (config, allocator, &params);

      gst_object_unref (allocator);

      config_updated = TRUE;

    } else {

      GST_ERROR_OBJECT (self, "udmabuf allocator not available");

      return FALSE;

    }

  } else if (params.align < UDMABUF_ALIGNMENT_MASK) {

    GST_DEBUG_OBJECT (self, "updating allocator params");

    params.align |= UDMABUF_ALIGNMENT_MASK;

    gst_buffer_pool_config_set_allocator (config, allocator, &params);

    config_updated = TRUE;

  }

  if (!gst_buffer_pool_config_has_option (config,

          GST_BUFFER_POOL_OPTION_VIDEO_META)) {

    GST_DEBUG_OBJECT (self, "missing video meta option");

    return FALSE;

  }

  if (!gst_buffer_pool_config_has_option (config,

          GST_BUFFER_POOL_OPTION_VIDEO_ALIGNMENT)) {

    GST_DEBUG_OBJECT (self, "missing video alignment option");

    return FALSE;

  }

  gst_buffer_pool_config_get_video_alignment (config, &video_align);

  for (int i = 0; i != GST_VIDEO_MAX_PLANES; ++i) {

    if (video_align.stride_align[i] < UDMABUF_ALIGNMENT_MASK) {

      video_align.stride_align[i] |= UDMABUF_ALIGNMENT_MASK;

      alignment_updated = TRUE;

    }

  }

  if (alignment_updated) {

    GST_DEBUG_OBJECT (self, "updating video alignment");

    gst_buffer_pool_config_set_video_alignment (config, &video_align);

    config_updated = TRUE;

  }

  res =

      GST_BUFFER_POOL_CLASS (gst_video_dmabuf_pool_parent_class)->set_config

      (pool, config);

  if (config_updated)

    return FALSE;

  return res;

}

#endif /* HAVE_LINUX_DMA_BUF_H */

static void

gst_video_dmabuf_pool_init (GstVideoDmabufPool * self)

{

}

static void

gst_video_dmabuf_pool_class_init (GstVideoDmabufPoolClass * klass)

{

#ifdef HAVE_LINUX_DMA_BUF_H

  GstBufferPoolClass *pool_class = GST_BUFFER_POOL_CLASS (klass);

#ifdef DMA_BUF_IOCTL_EXPORT_SYNC_FILE

  pool_class->start = gst_video_dmabuf_pool_start;

  pool_class->stop = gst_video_dmabuf_pool_stop;

  pool_class->release_buffer = gst_video_dmabuf_pool_release_buffer;

#endif /* DMA_BUF_IOCTL_EXPORT_SYNC_FILE */

  pool_class->set_config = gst_video_dmabuf_pool_set_config;

#endif

}

/**

 * gst_video_dmabuf_pool_new:

 *

 * Create a new #GstVideoDmabufPool instance.

 *

 * Returns: (transfer full) (nullable): a #GstVideoDmabufPool or %NULL

 *     if dmabufs are not supported.

 *

 * Since: 1.28

 */

GstBufferPool *

gst_video_dmabuf_pool_new (void)

{

#ifdef HAVE_LINUX_DMA_BUF_H

  return g_object_new (GST_TYPE_VIDEO_DMABUF_POOL, NULL);

#else

  return NULL;

#endif

}