/* GStreamer

 * Copyright (C) 1999,2000 Erik Walthinsen <omega@cse.ogi.edu>

 * Copyright (C) 2000,2005 Wim Taymans <wim@fluendo.com>

 * Copyright (C) 2006      Tim-Philipp Müller <tim centricular net>

 *

 * gsttypefindhelper.c:

 *

 * 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:gsttypefindhelper

 * @title: GstTypeFindHelper

 * @short_description: Utility functions for typefinding

 *

 * Utility functions for elements doing typefinding:

 * gst_type_find_helper() does typefinding in pull mode, while

 * gst_type_find_helper_for_buffer() is useful for elements needing to do

 * typefinding in push mode from a chain function.

 */

#ifdef HAVE_CONFIG_H

#  include "config.h"

#endif

#include <stdlib.h>

#include <string.h>

#include "gsttypefindhelper.h"

/* ********************** typefinding in pull mode ************************ */

static void

helper_find_suggest (gpointer data, guint probability, GstCaps * caps);

typedef struct

{

  GstBuffer *buffer;

  GstMapInfo map;

} GstMappedBuffer;

typedef struct

{

  GSList *buffers;              /* buffer cache */

  guint64 size;

  guint64 last_offset;

  GstTypeFindHelperGetRangeFunction func;

  GstTypeFindProbability best_probability;

  GstCaps *caps;

  GstTypeFindFactory *factory;  /* for logging */

  GstObject *obj;               /* for logging */

  GstObject *parent;

} GstTypeFindHelper;

/*

 * helper_find_peek:

 * @data: helper data struct

 * @off: stream offset

 * @size: block size

 *

 * Get data pointer within a stream. Keeps a cache of read buffers (partly

 * for performance reasons, but mostly because pointers returned by us need

 * to stay valid until typefinding has finished)

 *

 * Returns: (nullable): address of the data or %NULL if buffer does not cover

 * the requested range.

 */

static const guint8 *

helper_find_peek (gpointer data, gint64 offset, guint size)

{

  GstTypeFindHelper *helper;

  GstBuffer *buffer;

  GstFlowReturn ret;

  GSList *insert_pos = NULL;

  gsize buf_size;

  guint64 buf_offset;

  GstMappedBuffer *bmap;

#if 0

  GstCaps *caps;

#endif

  helper = (GstTypeFindHelper *) data;

  GST_LOG_OBJECT (helper->obj, "'%s' called peek (%" G_GINT64_FORMAT

      ", %u)", GST_OBJECT_NAME (helper->factory), offset, size);

  if (size == 0)

    return NULL;

  if (offset < 0) {

    if (helper->size == -1 || helper->size < -offset)

      return NULL;

    offset += helper->size;

  }

  /* see if we have a matching buffer already in our list */

  if (size > 0 && offset <= helper->last_offset) {

    GSList *walk;

    for (walk = helper->buffers; walk; walk = walk->next) {

      GstMappedBuffer *bmp = (GstMappedBuffer *) walk->data;

      GstBuffer *buf = GST_BUFFER_CAST (bmp->buffer);

      buf_offset = GST_BUFFER_OFFSET (buf);

      buf_size = bmp->map.size;

      /* buffers are kept sorted by end offset (highest first) in the list, so

       * at this point we save the current position and stop searching if

       * we're after the searched end offset */

      if (buf_offset <= offset) {

        if ((offset + size) < (buf_offset + buf_size)) {

          /* must already have been mapped before */

          return (guint8 *) bmp->map.data + (offset - buf_offset);

        }

      } else if (offset + size >= buf_offset + buf_size) {

        insert_pos = walk;

        break;

      }

    }

  }

  buffer = NULL;

  /* some typefinders go in 1 byte steps over 1k of data and request

   * small buffers. It is really inefficient to pull each time, and pulling

   * a larger chunk is almost free. Trying to pull a larger chunk at the end

   * of the file is also not a problem here, we'll just get a truncated buffer

   * in that case (and we'll have to double-check the size we actually get

   * anyway, see below) */

  ret =

      helper->func (helper->obj, helper->parent, offset, MAX (size, 4096),

      &buffer);

  if (ret != GST_FLOW_OK)

    goto error;

#if 0

  caps = GST_BUFFER_CAPS (buffer);

  if (caps && !gst_caps_is_empty (caps) && !gst_caps_is_any (caps)) {

    GST_DEBUG ("buffer has caps %" GST_PTR_FORMAT ", suggest max probability",

        caps);

    gst_caps_replace (&helper->caps, caps);

    helper->best_probability = GST_TYPE_FIND_MAXIMUM;

    gst_buffer_unref (buffer);

    return NULL;

  }

#endif

  /* getrange might silently return shortened buffers at the end of a file,

   * we must, however, always return either the full requested data or %NULL */

  buf_offset = GST_BUFFER_OFFSET (buffer);

  buf_size = gst_buffer_get_size (buffer);

  if (buf_size < size) {

    GST_DEBUG ("dropping short buffer of size %" G_GSIZE_FORMAT ","

        "requested size was %u", buf_size, size);

    gst_buffer_unref (buffer);

    return NULL;

  }

  if (buf_offset != -1 && buf_offset != offset) {

    GST_DEBUG ("dropping buffer with unexpected offset %" G_GUINT64_FORMAT ", "

        "expected offset was %" G_GUINT64_FORMAT, buf_offset, offset);

    gst_buffer_unref (buffer);

    return NULL;

  }

  bmap = g_slice_new0 (GstMappedBuffer);

  if (!gst_buffer_map (buffer, &bmap->map, GST_MAP_READ))

    goto map_failed;

  bmap->buffer = buffer;

  if (insert_pos) {

    helper->buffers = g_slist_insert_before (helper->buffers, insert_pos, bmap);

  } else {

    /* if insert_pos is not set, our offset is bigger than the largest offset

     * we have so far; since we keep the list sorted with highest offsets

     * first, we need to prepend the buffer to the list */

    helper->last_offset = GST_BUFFER_OFFSET (buffer) + buf_size;

    helper->buffers = g_slist_prepend (helper->buffers, bmap);

  }

  return bmap->map.data;

error:

  {

    GST_INFO ("typefind function returned: %s", gst_flow_get_name (ret));

    return NULL;

  }

map_failed:

  {

    GST_ERROR ("map failed");

    gst_buffer_unref (buffer);

    g_slice_free (GstMappedBuffer, bmap);

    return NULL;

  }

}

/*

 * helper_find_suggest:

 * @data: helper data struct

 * @probability: probability of the match

 * @caps: caps of the type

 *

 * If given @probability is higher, replace previously store caps.

 */

static void

helper_find_suggest (gpointer data, guint probability, GstCaps * caps)

{

  GstTypeFindHelper *helper = (GstTypeFindHelper *) data;

  GST_LOG_OBJECT (helper->obj,

      "'%s' called suggest (%u, %" GST_PTR_FORMAT ")",

      GST_OBJECT_NAME (helper->factory), probability, caps);

  if (probability > helper->best_probability) {

    gst_caps_replace (&helper->caps, caps);

    helper->best_probability = probability;

  }

}

static guint64

helper_find_get_length (gpointer data)

{

  GstTypeFindHelper *helper = (GstTypeFindHelper *) data;

  GST_LOG_OBJECT (helper->obj, "'%s' called get_length, returning %"

      G_GUINT64_FORMAT, GST_OBJECT_NAME (helper->factory), helper->size);

  return helper->size;

}

/**

 * gst_type_find_helper_get_range:

 * @obj: A #GstObject that will be passed as first argument to @func

 * @parent: (allow-none): the parent of @obj or %NULL

 * @func: (scope call): A generic #GstTypeFindHelperGetRangeFunction that will

 *        be used to access data at random offsets when doing the typefinding

 * @size: The length in bytes

 * @extension: extension of the media

 * @prob: (out) (allow-none): location to store the probability of the found

 *     caps, or %NULL

 *

 * Utility function to do pull-based typefinding. Unlike gst_type_find_helper()

 * however, this function will use the specified function @func to obtain the

 * data needed by the typefind functions, rather than operating on a given

 * source pad. This is useful mostly for elements like tag demuxers which

 * strip off data at the beginning and/or end of a file and want to typefind

 * the stripped data stream before adding their own source pad (the specified

 * callback can then call the upstream peer pad with offsets adjusted for the

 * tag size, for example).

 *

 * When @extension is not %NULL, this function will first try the typefind

 * functions for the given extension, which might speed up the typefinding

 * in many cases.

 *

 * Free-function: gst_caps_unref

 *

 * Returns: (transfer full) (nullable): the #GstCaps corresponding to the data

 *     stream.  Returns %NULL if no #GstCaps matches the data stream.

 */

GstCaps *

gst_type_find_helper_get_range (GstObject * obj, GstObject * parent,

    GstTypeFindHelperGetRangeFunction func, guint64 size,

    const gchar * extension, GstTypeFindProbability * prob)

{

  GstTypeFindHelper helper;

  GstTypeFind find;

  GSList *walk;

  GList *l, *type_list;

  GstCaps *result = NULL;

  gint pos = 0;

  g_return_val_if_fail (GST_IS_OBJECT (obj), NULL);

  g_return_val_if_fail (func != NULL, NULL);

  helper.buffers = NULL;

  helper.size = size;

  helper.last_offset = 0;

  helper.func = func;

  helper.best_probability = GST_TYPE_FIND_NONE;

  helper.caps = NULL;

  helper.obj = obj;

  helper.parent = parent;

  find.data = &helper;

  find.peek = helper_find_peek;

  find.suggest = helper_find_suggest;

  if (size == 0 || size == (guint64) - 1) {

    find.get_length = NULL;

  } else {

    find.get_length = helper_find_get_length;

  }

  type_list = gst_type_find_factory_get_list ();

  /* move the typefinders for the extension first in the list. The idea is that

   * when one of them returns MAX we don't need to search further as there is a

   * very high chance we got the right type. */

  if (extension) {

    GList *next;

    GST_LOG_OBJECT (obj, "sorting typefind for extension %s to head",

        extension);

    for (l = type_list; l; l = next) {

      const gchar *const *ext;

      GstTypeFindFactory *factory;

      next = l->next;

      factory = GST_TYPE_FIND_FACTORY (l->data);

      ext = gst_type_find_factory_get_extensions (factory);

      if (ext == NULL)

        continue;

      GST_LOG_OBJECT (obj, "testing factory %s for extension %s",

          GST_OBJECT_NAME (factory), extension);

      while (*ext != NULL) {

        if (strcmp (*ext, extension) == 0) {

          /* found extension, move in front */

          GST_LOG_OBJECT (obj, "moving typefind for extension %s to head",

              extension);

          /* remove entry from list */

          type_list = g_list_delete_link (type_list, l);

          /* insert at the position */

          type_list = g_list_insert (type_list, factory, pos);

          /* next element will be inserted after this one */

          pos++;

          break;

        }

        ++ext;

      }

    }

  }

  for (l = type_list; l; l = l->next) {

    helper.factory = GST_TYPE_FIND_FACTORY (l->data);

    gst_type_find_factory_call_function (helper.factory, &find);

    if (helper.best_probability >= GST_TYPE_FIND_MAXIMUM)

      break;

  }

  gst_plugin_feature_list_free (type_list);

  for (walk = helper.buffers; walk; walk = walk->next) {

    GstMappedBuffer *bmap = (GstMappedBuffer *) walk->data;

    gst_buffer_unmap (bmap->buffer, &bmap->map);

    gst_buffer_unref (bmap->buffer);

    g_slice_free (GstMappedBuffer, bmap);

  }

  g_slist_free (helper.buffers);

  if (helper.best_probability > 0)

    result = helper.caps;

  if (prob)

    *prob = helper.best_probability;

  GST_LOG_OBJECT (obj, "Returning %" GST_PTR_FORMAT " (probability = %u)",

      result, (guint) helper.best_probability);

  return result;

}

/**

 * gst_type_find_helper:

 * @src: A source #GstPad

 * @size: The length in bytes

 *

 * Tries to find what type of data is flowing from the given source #GstPad.

 *

 * Free-function: gst_caps_unref

 *

 * Returns: (transfer full) (nullable): the #GstCaps corresponding to the data

 *     stream.  Returns %NULL if no #GstCaps matches the data stream.

 */

GstCaps *

gst_type_find_helper (GstPad * src, guint64 size)

{

  GstTypeFindHelperGetRangeFunction func;

  g_return_val_if_fail (GST_IS_OBJECT (src), NULL);

  g_return_val_if_fail (GST_PAD_GETRANGEFUNC (src) != NULL, NULL);

  func = (GstTypeFindHelperGetRangeFunction) (GST_PAD_GETRANGEFUNC (src));

  return gst_type_find_helper_get_range (GST_OBJECT (src),

      GST_OBJECT_PARENT (src), func, size, NULL, NULL);

}

/* ********************** typefinding for buffers ************************* */

typedef struct

{

  const guint8 *data;           /* buffer data */

  gsize size;

  GstTypeFindProbability best_probability;

  GstCaps *caps;

  GstTypeFindFactory *factory;  /* for logging */

  GstObject *obj;               /* for logging */

} GstTypeFindBufHelper;

/*

 * buf_helper_find_peek:

 * @data: helper data struct

 * @off: stream offset

 * @size: block size

 *

 * Get data pointer within a buffer.

 *

 * Returns: (nullable): address inside the buffer or %NULL if buffer does not

 * cover the requested range.

 */

static const guint8 *

buf_helper_find_peek (gpointer data, gint64 off, guint size)

{

  GstTypeFindBufHelper *helper;

  helper = (GstTypeFindBufHelper *) data;

  GST_LOG_OBJECT (helper->obj, "'%s' called peek (%" G_GINT64_FORMAT ", %u)",

      GST_OBJECT_NAME (helper->factory), off, size);

  if (size == 0)

    return NULL;

  if (off < 0) {

    GST_LOG_OBJECT (helper->obj, "'%s' wanted to peek at end; not supported",

        GST_OBJECT_NAME (helper->factory));

    return NULL;

  }

  /* If we request beyond the available size, we're sure we can't return

   * anything regardless of the requested offset */

  if (size > helper->size)

    return NULL;

  /* Only return data if there's enough room left for the given offset.

   * This is the same as "if (off + size <= helper->size)" except that

   * it doesn't exceed type limits */

  if (off <= helper->size - size)

    return helper->data + off;

  return NULL;

}

/*

 * buf_helper_find_suggest:

 * @data: helper data struct

 * @probability: probability of the match

 * @caps: caps of the type

 *

 * If given @probability is higher, replace previously store caps.

 */

static void

buf_helper_find_suggest (gpointer data, guint probability, GstCaps * caps)

{

  GstTypeFindBufHelper *helper = (GstTypeFindBufHelper *) data;

  GST_LOG_OBJECT (helper->obj,

      "'%s' called suggest (%u, %" GST_PTR_FORMAT ")",

      GST_OBJECT_NAME (helper->factory), probability, caps);

  /* Note: not >= as we call typefinders in order of rank, highest first */

  if (probability > helper->best_probability) {

    gst_caps_replace (&helper->caps, caps);

    helper->best_probability = probability;

  }

}

/**

 * gst_type_find_helper_for_data:

 * @obj: (allow-none): object doing the typefinding, or %NULL (used for logging)

 * @data: (transfer none) (array length=size): * a pointer with data to typefind

 * @size: the size of @data

 * @prob: (out) (allow-none): location to store the probability of the found

 *     caps, or %NULL

 *

 * Tries to find what type of data is contained in the given @data, the

 * assumption being that the data represents the beginning of the stream or

 * file.

 *

 * All available typefinders will be called on the data in order of rank. If

 * a typefinding function returns a probability of %GST_TYPE_FIND_MAXIMUM,

 * typefinding is stopped immediately and the found caps will be returned

 * right away. Otherwise, all available typefind functions will the tried,

 * and the caps with the highest probability will be returned, or %NULL if

 * the content of @data could not be identified.

 *

 * Free-function: gst_caps_unref

 *

 * Returns: (transfer full) (nullable): the #GstCaps corresponding to the data,

 *     or %NULL if no type could be found. The caller should free the caps

 *     returned with gst_caps_unref().

 */

GstCaps *

gst_type_find_helper_for_data (GstObject * obj, const guint8 * data, gsize size,

    GstTypeFindProbability * prob)

{

  GstTypeFindBufHelper helper;

  GstTypeFind find;

  GList *l, *type_list;

  GstCaps *result = NULL;

  g_return_val_if_fail (data != NULL, NULL);

  helper.data = data;

  helper.size = size;

  helper.best_probability = GST_TYPE_FIND_NONE;

  helper.caps = NULL;

  helper.obj = obj;

  if (helper.data == NULL || helper.size == 0)

    return NULL;

  find.data = &helper;

  find.peek = buf_helper_find_peek;

  find.suggest = buf_helper_find_suggest;

  find.get_length = NULL;

  type_list = gst_type_find_factory_get_list ();

  for (l = type_list; l; l = l->next) {

    helper.factory = GST_TYPE_FIND_FACTORY (l->data);

    gst_type_find_factory_call_function (helper.factory, &find);

    if (helper.best_probability >= GST_TYPE_FIND_MAXIMUM)

      break;

  }

  gst_plugin_feature_list_free (type_list);

  if (helper.best_probability > 0)

    result = helper.caps;

  if (prob)

    *prob = helper.best_probability;

  GST_LOG_OBJECT (obj, "Returning %" GST_PTR_FORMAT " (probability = %u)",

      result, (guint) helper.best_probability);

  return result;

}

/**

 * gst_type_find_helper_for_buffer:

 * @obj: (allow-none): object doing the typefinding, or %NULL (used for logging)

 * @buf: (in) (transfer none): a #GstBuffer with data to typefind

 * @prob: (out) (allow-none): location to store the probability of the found

 *     caps, or %NULL

 *

 * Tries to find what type of data is contained in the given #GstBuffer, the

 * assumption being that the buffer represents the beginning of the stream or

 * file.

 *

 * All available typefinders will be called on the data in order of rank. If

 * a typefinding function returns a probability of %GST_TYPE_FIND_MAXIMUM,

 * typefinding is stopped immediately and the found caps will be returned

 * right away. Otherwise, all available typefind functions will the tried,

 * and the caps with the highest probability will be returned, or %NULL if

 * the content of the buffer could not be identified.

 *

 * Free-function: gst_caps_unref

 *

 * Returns: (transfer full) (nullable): the #GstCaps corresponding to the data,

 *     or %NULL if no type could be found. The caller should free the caps

 *     returned with gst_caps_unref().

 */

GstCaps *

gst_type_find_helper_for_buffer (GstObject * obj, GstBuffer * buf,

    GstTypeFindProbability * prob)

{

  GstCaps *result;

  GstMapInfo info;

  g_return_val_if_fail (buf != NULL, NULL);

  g_return_val_if_fail (GST_IS_BUFFER (buf), NULL);

  g_return_val_if_fail (GST_BUFFER_OFFSET (buf) == 0 ||

      GST_BUFFER_OFFSET (buf) == GST_BUFFER_OFFSET_NONE, NULL);

  if (!gst_buffer_map (buf, &info, GST_MAP_READ))

    return NULL;

  result = gst_type_find_helper_for_data (obj, info.data, info.size, prob);

  gst_buffer_unmap (buf, &info;;

  return result;

}

/**

 * gst_type_find_helper_for_extension:

 * @obj: (allow-none): object doing the typefinding, or %NULL (used for logging)

 * @extension: an extension

 *

 * Tries to find the best #GstCaps associated with @extension.

 *

 * All available typefinders will be checked against the extension in order

 * of rank. The caps of the first typefinder that can handle @extension will be

 * returned.

 *

 * Free-function: gst_caps_unref

 *

 * Returns: (transfer full) (nullable): the #GstCaps corresponding to

 *     @extension, or %NULL if no type could be found. The caller should free

 *     the caps returned with gst_caps_unref().

 */

GstCaps *

gst_type_find_helper_for_extension (GstObject * obj, const gchar * extension)

{

  GList *l, *type_list;

  GstCaps *result = NULL;

  g_return_val_if_fail (extension != NULL, NULL);

  GST_LOG_OBJECT (obj, "finding caps for extension %s", extension);

  type_list = gst_type_find_factory_get_list ();

  for (l = type_list; l; l = g_list_next (l)) {

    GstTypeFindFactory *factory;

    const gchar *const *ext;

    factory = GST_TYPE_FIND_FACTORY (l->data);

    /* we only want to check those factories without a function */

    if (gst_type_find_factory_has_function (factory))

      continue;

    /* get the extension that this typefind factory can handle */

    ext = gst_type_find_factory_get_extensions (factory);

    if (ext == NULL)

      continue;

    /* there are extension, see if one of them matches the requested

     * extension */

    while (*ext != NULL) {

      if (strcmp (*ext, extension) == 0) {

        /* we found a matching extension, take the caps */

        if ((result = gst_type_find_factory_get_caps (factory))) {

          gst_caps_ref (result);

          goto done;

        }

      }

      ++ext;

    }

  }

done:

  gst_plugin_feature_list_free (type_list);

  GST_LOG_OBJECT (obj, "Returning %" GST_PTR_FORMAT, result);

  return result;

}