gstreamer/gst/gstprotection.c
Matthew Waters fdf6a793dc gst: don't use volatile to mean atomic
volatile is not sufficient to provide atomic guarantees and real atomics
should be used instead.  GCC 11 has started warning about using volatile
with atomic operations.

https://gitlab.gnome.org/GNOME/glib/-/merge_requests/1719

Discovered in https://gitlab.freedesktop.org/gstreamer/gst-plugins-good/-/issues/868

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/793>
2021-04-13 01:58:54 +01:00

296 lines
8.9 KiB
C

/* GStreamer
* Copyright (C) <2013> YouView TV Ltd.
*
* 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:gstprotection
* @title: GstProtection
* @short_description: Functions and classes to support encrypted streams.
*
* The GstProtectionMeta class enables the information needed to decrypt a
* #GstBuffer to be attached to that buffer.
*
* Typically, a demuxer element would attach GstProtectionMeta objects
* to the buffers that it pushes downstream. The demuxer would parse the
* protection information for a video/audio frame from its input data and use
* this information to populate the #GstStructure @info field,
* which is then encapsulated in a GstProtectionMeta object and attached to
* the corresponding output buffer using the gst_buffer_add_protection_meta()
* function. The information in this attached GstProtectionMeta would be
* used by a downstream decrypter element to recover the original unencrypted
* frame.
*
* Since: 1.6
*/
#include "gst_private.h"
#include "glib-compat-private.h"
#include "gstprotection.h"
#define GST_CAT_DEFAULT GST_CAT_PROTECTION
static gboolean gst_protection_meta_init (GstMeta * meta, gpointer params,
GstBuffer * buffer);
static void gst_protection_meta_free (GstMeta * meta, GstBuffer * buffer);
static const gchar *gst_protection_factory_check (GstElementFactory * fact,
const gchar ** system_identifiers);
GType
gst_protection_meta_api_get_type (void)
{
static GType type;
static const gchar *tags[] = { NULL };
if (g_once_init_enter (&type)) {
GType _type = gst_meta_api_type_register ("GstProtectionMetaAPI", tags);
g_once_init_leave (&type, _type);
}
return type;
}
static gboolean
gst_protection_meta_init (GstMeta * meta, gpointer params, GstBuffer * buffer)
{
GstProtectionMeta *protection_meta = (GstProtectionMeta *) meta;
protection_meta->info = NULL;
return TRUE;
}
static void
gst_protection_meta_free (GstMeta * meta, GstBuffer * buffer)
{
GstProtectionMeta *protection_meta = (GstProtectionMeta *) meta;
if (protection_meta->info)
gst_structure_free (protection_meta->info);
}
static gboolean
gst_protection_meta_transform (GstBuffer * transbuf, GstMeta * meta,
GstBuffer * buffer, GQuark type, gpointer data)
{
GstProtectionMeta *protection_meta = (GstProtectionMeta *) meta;
if (GST_META_TRANSFORM_IS_COPY (type)) {
GstMetaTransformCopy *copy = data;
if (!copy->region) {
/* only copy if the complete data is copied as well */
gst_buffer_add_protection_meta (transbuf,
gst_structure_copy (protection_meta->info));
} else {
return FALSE;
}
} else {
/* transform type not supported */
return FALSE;
}
return TRUE;
}
const GstMetaInfo *
gst_protection_meta_get_info (void)
{
static const GstMetaInfo *protection_meta_info = NULL;
if (g_once_init_enter ((GstMetaInfo **) & protection_meta_info)) {
const GstMetaInfo *meta =
gst_meta_register (GST_PROTECTION_META_API_TYPE, "GstProtectionMeta",
sizeof (GstProtectionMeta), gst_protection_meta_init,
gst_protection_meta_free, gst_protection_meta_transform);
g_once_init_leave ((GstMetaInfo **) & protection_meta_info,
(GstMetaInfo *) meta);
}
return protection_meta_info;
}
/**
* gst_buffer_add_protection_meta:
* @buffer: #GstBuffer holding an encrypted sample, to which protection
* metadata should be added.
* @info: (transfer full): a #GstStructure holding cryptographic
* information relating to the sample contained in @buffer. This
* function takes ownership of @info.
*
* Attaches protection metadata to a #GstBuffer.
*
* Returns: (transfer none): a pointer to the added #GstProtectionMeta if successful; %NULL if
* unsuccessful.
*
* Since: 1.6
*/
GstProtectionMeta *
gst_buffer_add_protection_meta (GstBuffer * buffer, GstStructure * info)
{
GstProtectionMeta *meta;
g_return_val_if_fail (GST_IS_BUFFER (buffer), NULL);
g_return_val_if_fail (info != NULL, NULL);
meta =
(GstProtectionMeta *) gst_buffer_add_meta (buffer,
GST_PROTECTION_META_INFO, NULL);
meta->info = info;
return meta;
}
/**
* gst_protection_select_system:
* @system_identifiers: (transfer none) (array zero-terminated=1): A null terminated array of strings
* that contains the UUID values of each protection system that is to be
* checked.
*
* Iterates the supplied list of UUIDs and checks the GstRegistry for
* an element that supports one of the supplied UUIDs. If more than one
* element matches, the system ID of the highest ranked element is selected.
*
* Returns: (transfer none) (nullable): One of the strings from
* @system_identifiers that indicates the highest ranked element that
* implements the protection system indicated by that system ID, or %NULL if no
* element has been found.
*
* Since: 1.6
*/
const gchar *
gst_protection_select_system (const gchar ** system_identifiers)
{
GList *decryptors, *walk;
const gchar *retval = NULL;
decryptors =
gst_element_factory_list_get_elements (GST_ELEMENT_FACTORY_TYPE_DECRYPTOR,
GST_RANK_MARGINAL);
for (walk = decryptors; !retval && walk; walk = g_list_next (walk)) {
GstElementFactory *fact = (GstElementFactory *) walk->data;
retval = gst_protection_factory_check (fact, system_identifiers);
}
gst_plugin_feature_list_free (decryptors);
return retval;
}
/**
* gst_protection_filter_systems_by_available_decryptors:
* @system_identifiers: (transfer none) (array zero-terminated=1):
* A null terminated array of strings that contains the UUID values of each
* protection system that is to be checked.
*
* Iterates the supplied list of UUIDs and checks the GstRegistry for
* all the decryptors supporting one of the supplied UUIDs.
*
* Returns: (transfer full) (array zero-terminated=1) (nullable):
* A null terminated array containing all
* the @system_identifiers supported by the set of available decryptors, or
* %NULL if no matches were found.
*
* Since: 1.14
*/
gchar **
gst_protection_filter_systems_by_available_decryptors (const gchar **
system_identifiers)
{
GList *decryptors, *walk;
gchar **retval = NULL;
guint i = 0, decryptors_number;
decryptors =
gst_element_factory_list_get_elements (GST_ELEMENT_FACTORY_TYPE_DECRYPTOR,
GST_RANK_MARGINAL);
decryptors_number = g_list_length (decryptors);
GST_TRACE ("found %u decrytors", decryptors_number);
if (decryptors_number == 0)
goto beach;
retval = g_new (gchar *, decryptors_number + 1);
for (walk = decryptors; walk; walk = g_list_next (walk)) {
GstElementFactory *fact = (GstElementFactory *) walk->data;
const char *found_sys_id =
gst_protection_factory_check (fact, system_identifiers);
GST_DEBUG ("factory %s is valid for %s", GST_OBJECT_NAME (fact),
found_sys_id);
if (found_sys_id) {
retval[i++] = g_strdup (found_sys_id);
}
}
retval[i] = NULL;
if (retval[0] == NULL) {
g_free (retval);
retval = NULL;
}
beach:
gst_plugin_feature_list_free (decryptors);
return retval;
}
static const gchar *
gst_protection_factory_check (GstElementFactory * fact,
const gchar ** system_identifiers)
{
const GList *template, *walk;
const gchar *retval = NULL;
template = gst_element_factory_get_static_pad_templates (fact);
for (walk = template; walk && !retval; walk = g_list_next (walk)) {
GstStaticPadTemplate *templ = walk->data;
GstCaps *caps = gst_static_pad_template_get_caps (templ);
guint leng = gst_caps_get_size (caps);
guint i, j;
for (i = 0; !retval && i < leng; ++i) {
GstStructure *st;
st = gst_caps_get_structure (caps, i);
if (gst_structure_has_field_typed (st,
GST_PROTECTION_SYSTEM_ID_CAPS_FIELD, G_TYPE_STRING)) {
const gchar *sys_id =
gst_structure_get_string (st, GST_PROTECTION_SYSTEM_ID_CAPS_FIELD);
GST_DEBUG ("Found decryptor that supports protection system %s",
sys_id);
for (j = 0; !retval && system_identifiers[j]; ++j) {
GST_TRACE (" compare with %s", system_identifiers[j]);
if (g_ascii_strcasecmp (system_identifiers[j], sys_id) == 0) {
GST_DEBUG (" Selecting %s", system_identifiers[j]);
retval = system_identifiers[j];
}
}
}
}
gst_caps_unref (caps);
}
return retval;
}