gstreamer/gst/gstdeviceprovider.c
Daniel Drake e0c9b04538 deviceprovider: fix counting number of times started
GstDeviceProvider has a started_count private variable counter,
and the gst_device_provider_start() documentation emphasizes the
importance of balancing the start and stop calls.

However, when starting a provider that is already started, the
current code will never increment the counter more than once.

So you start it twice, but it will have start_count 1, which is the
maximum value it will ever see.

Then when you stop it twice, on the 2nd stop, after decrementing the
counter in gst_device_provider_stop():

  else if (provider->priv->started_count < 1) {
    g_critical
        ("Trying to stop a GstDeviceProvider %s which is already stopped",
        GST_OBJECT_NAME (provider));

and the program is killed.

Fix this by incrementing the counter when starting a device provider that
was already started.
2019-01-14 16:26:44 +08:00

774 lines
22 KiB
C

/* GStreamer
* Copyright (C) 2012 Olivier Crete <olivier.crete@collabora.com>
*
* gstdeviceprovider.c: Device probing and monitoring
*
* 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., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
/**
* SECTION:gstdeviceprovider
* @title: GstDeviceProvider
* @short_description: A device provider
* @see_also: #GstDevice, #GstDeviceMonitor
*
* A #GstDeviceProvider subclass is provided by a plugin that handles devices
* if there is a way to programmatically list connected devices. It can also
* optionally provide updates to the list of connected devices.
*
* Each #GstDeviceProvider subclass is a singleton, a plugin should
* normally provide a single subclass for all devices.
*
* Applications would normally use a #GstDeviceMonitor to monitor devices
* from all relevant providers.
*
* Since: 1.4
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include "gst_private.h"
#include "gstdeviceprovider.h"
#include "gstelementmetadata.h"
#include "gstquark.h"
struct _GstDeviceProviderPrivate
{
GstBus *bus;
GMutex start_lock;
gboolean started_count;
GList *hidden_providers;
};
enum
{
PROVIDER_HIDDEN,
PROVIDER_UNHIDDEN,
LAST_SIGNAL
};
static guint gst_device_provider_signals[LAST_SIGNAL] = { 0 };
/* this is used in gstelementfactory.c:gst_element_register() */
GQuark __gst_deviceproviderclass_factory = 0;
static void gst_device_provider_class_init (GstDeviceProviderClass * klass);
static void gst_device_provider_init (GstDeviceProvider * element);
static void gst_device_provider_base_class_init (gpointer g_class);
static void gst_device_provider_dispose (GObject * object);
static void gst_device_provider_finalize (GObject * object);
static gpointer gst_device_provider_parent_class = NULL;
static gint private_offset = 0;
GType
gst_device_provider_get_type (void)
{
static volatile gsize gst_device_provider_type = 0;
if (g_once_init_enter (&gst_device_provider_type)) {
GType _type;
static const GTypeInfo element_info = {
sizeof (GstDeviceProviderClass),
gst_device_provider_base_class_init,
NULL, /* base_class_finalize */
(GClassInitFunc) gst_device_provider_class_init,
NULL,
NULL,
sizeof (GstDeviceProvider),
0,
(GInstanceInitFunc) gst_device_provider_init,
NULL
};
_type = g_type_register_static (GST_TYPE_OBJECT, "GstDeviceProvider",
&element_info, G_TYPE_FLAG_ABSTRACT);
private_offset =
g_type_add_instance_private (_type, sizeof (GstDeviceProviderPrivate));
__gst_deviceproviderclass_factory =
g_quark_from_static_string ("GST_DEVICEPROVIDERCLASS_FACTORY");
g_once_init_leave (&gst_device_provider_type, _type);
}
return gst_device_provider_type;
}
static inline gpointer
gst_device_provider_get_instance_private (GstDeviceProvider * self)
{
return (G_STRUCT_MEMBER_P (self, private_offset));
}
static void
gst_device_provider_base_class_init (gpointer g_class)
{
GstDeviceProviderClass *klass = GST_DEVICE_PROVIDER_CLASS (g_class);
/* Copy the element details here so elements can inherit the
* details from their base class and classes only need to set
* the details in class_init instead of base_init */
klass->metadata =
klass->metadata ? gst_structure_copy (klass->metadata) :
gst_structure_new_empty ("metadata");
klass->factory = g_type_get_qdata (G_TYPE_FROM_CLASS (klass),
__gst_deviceproviderclass_factory);
}
static void
gst_device_provider_class_init (GstDeviceProviderClass * klass)
{
GObjectClass *gobject_class = (GObjectClass *) klass;
gst_device_provider_parent_class = g_type_class_peek_parent (klass);
if (private_offset != 0)
g_type_class_adjust_private_offset (klass, &private_offset);
gobject_class->dispose = gst_device_provider_dispose;
gobject_class->finalize = gst_device_provider_finalize;
gst_device_provider_signals[PROVIDER_HIDDEN] =
g_signal_new ("provider-hidden", G_TYPE_FROM_CLASS (klass),
G_SIGNAL_RUN_FIRST, 0, NULL,
NULL, g_cclosure_marshal_generic, G_TYPE_NONE, 1, G_TYPE_STRING);
gst_device_provider_signals[PROVIDER_UNHIDDEN] =
g_signal_new ("provider-unhidden", G_TYPE_FROM_CLASS (klass),
G_SIGNAL_RUN_FIRST, 0, NULL,
NULL, g_cclosure_marshal_generic, G_TYPE_NONE, 1, G_TYPE_STRING);
}
static void
gst_device_provider_init (GstDeviceProvider * provider)
{
provider->priv = gst_device_provider_get_instance_private (provider);
g_mutex_init (&provider->priv->start_lock);
provider->priv->bus = gst_bus_new ();
gst_bus_set_flushing (provider->priv->bus, TRUE);
}
static void
gst_device_provider_dispose (GObject * object)
{
GstDeviceProvider *provider = GST_DEVICE_PROVIDER (object);
gst_object_replace ((GstObject **) & provider->priv->bus, NULL);
GST_OBJECT_LOCK (provider);
g_list_free_full (provider->devices, (GDestroyNotify) gst_object_unparent);
provider->devices = NULL;
GST_OBJECT_UNLOCK (provider);
G_OBJECT_CLASS (gst_device_provider_parent_class)->dispose (object);
}
static void
gst_device_provider_finalize (GObject * object)
{
GstDeviceProvider *provider = GST_DEVICE_PROVIDER (object);
g_mutex_clear (&provider->priv->start_lock);
G_OBJECT_CLASS (gst_device_provider_parent_class)->finalize (object);
}
/**
* gst_device_provider_class_add_metadata:
* @klass: class to set metadata for
* @key: the key to set
* @value: the value to set
*
* Set @key with @value as metadata in @klass.
*
* Since: 1.4
*/
void
gst_device_provider_class_add_metadata (GstDeviceProviderClass * klass,
const gchar * key, const gchar * value)
{
g_return_if_fail (GST_IS_DEVICE_PROVIDER_CLASS (klass));
g_return_if_fail (key != NULL);
g_return_if_fail (value != NULL);
gst_structure_set ((GstStructure *) klass->metadata,
key, G_TYPE_STRING, value, NULL);
}
/**
* gst_device_provider_class_add_static_metadata:
* @klass: class to set metadata for
* @key: the key to set
* @value: (transfer full): the value to set
*
* Set @key with @value as metadata in @klass.
*
* Same as gst_device_provider_class_add_metadata(), but @value must be a static string
* or an inlined string, as it will not be copied. (GStreamer plugins will
* be made resident once loaded, so this function can be used even from
* dynamically loaded plugins.)
*
* Since: 1.4
*/
void
gst_device_provider_class_add_static_metadata (GstDeviceProviderClass * klass,
const gchar * key, const gchar * value)
{
GValue val = G_VALUE_INIT;
g_return_if_fail (GST_IS_DEVICE_PROVIDER_CLASS (klass));
g_return_if_fail (key != NULL);
g_return_if_fail (value != NULL);
g_value_init (&val, G_TYPE_STRING);
g_value_set_static_string (&val, value);
gst_structure_take_value ((GstStructure *) klass->metadata, key, &val);
}
/**
* gst_device_provider_class_set_metadata:
* @klass: class to set metadata for
* @longname: The long English name of the device provider. E.g. "File Sink"
* @classification: String describing the type of device provider, as an
* unordered list separated with slashes ('/'). See draft-klass.txt of the
* design docs
* for more details and common types. E.g: "Sink/File"
* @description: Sentence describing the purpose of the device provider.
* E.g: "Write stream to a file"
* @author: Name and contact details of the author(s). Use \n to separate
* multiple author metadata. E.g: "Joe Bloggs &lt;joe.blogs at foo.com&gt;"
*
* Sets the detailed information for a #GstDeviceProviderClass.
*
* > This function is for use in _class_init functions only.
*
* Since: 1.4
*/
void
gst_device_provider_class_set_metadata (GstDeviceProviderClass * klass,
const gchar * longname, const gchar * classification,
const gchar * description, const gchar * author)
{
g_return_if_fail (GST_IS_DEVICE_PROVIDER_CLASS (klass));
g_return_if_fail (longname != NULL && *longname != '\0');
g_return_if_fail (classification != NULL && *classification != '\0');
g_return_if_fail (description != NULL && *description != '\0');
g_return_if_fail (author != NULL && *author != '\0');
gst_structure_id_set ((GstStructure *) klass->metadata,
GST_QUARK (ELEMENT_METADATA_LONGNAME), G_TYPE_STRING, longname,
GST_QUARK (ELEMENT_METADATA_KLASS), G_TYPE_STRING, classification,
GST_QUARK (ELEMENT_METADATA_DESCRIPTION), G_TYPE_STRING, description,
GST_QUARK (ELEMENT_METADATA_AUTHOR), G_TYPE_STRING, author, NULL);
}
/**
* gst_device_provider_class_set_static_metadata:
* @klass: class to set metadata for
* @longname: (transfer full): The long English name of the element. E.g. "File Sink"
* @classification: (transfer full): String describing the type of element, as
* an unordered list separated with slashes ('/'). See draft-klass.txt of the
* design docs for more details and common types. E.g: "Sink/File"
* @description: (transfer full): Sentence describing the purpose of the
* element. E.g: "Write stream to a file"
* @author: (transfer full): Name and contact details of the author(s). Use \n
* to separate multiple author metadata. E.g: "Joe Bloggs &lt;joe.blogs at
* foo.com&gt;"
*
* Sets the detailed information for a #GstDeviceProviderClass.
*
* > This function is for use in _class_init functions only.
*
* Same as gst_device_provider_class_set_metadata(), but @longname, @classification,
* @description, and @author must be static strings or inlined strings, as
* they will not be copied. (GStreamer plugins will be made resident once
* loaded, so this function can be used even from dynamically loaded plugins.)
*
* Since: 1.4
*/
void
gst_device_provider_class_set_static_metadata (GstDeviceProviderClass * klass,
const gchar * longname, const gchar * classification,
const gchar * description, const gchar * author)
{
GstStructure *s = (GstStructure *) klass->metadata;
GValue val = G_VALUE_INIT;
g_return_if_fail (GST_IS_DEVICE_PROVIDER_CLASS (klass));
g_return_if_fail (longname != NULL && *longname != '\0');
g_return_if_fail (classification != NULL && *classification != '\0');
g_return_if_fail (description != NULL && *description != '\0');
g_return_if_fail (author != NULL && *author != '\0');
g_value_init (&val, G_TYPE_STRING);
g_value_set_static_string (&val, longname);
gst_structure_id_set_value (s, GST_QUARK (ELEMENT_METADATA_LONGNAME), &val);
g_value_set_static_string (&val, classification);
gst_structure_id_set_value (s, GST_QUARK (ELEMENT_METADATA_KLASS), &val);
g_value_set_static_string (&val, description);
gst_structure_id_set_value (s, GST_QUARK (ELEMENT_METADATA_DESCRIPTION),
&val);
g_value_set_static_string (&val, author);
gst_structure_id_take_value (s, GST_QUARK (ELEMENT_METADATA_AUTHOR), &val);
}
/**
* gst_device_provider_class_get_metadata:
* @klass: class to get metadata for
* @key: the key to get
*
* Get metadata with @key in @klass.
*
* Returns: (nullable): the metadata for @key.
*
* Since: 1.4
*/
const gchar *
gst_device_provider_class_get_metadata (GstDeviceProviderClass * klass,
const gchar * key)
{
g_return_val_if_fail (GST_IS_DEVICE_PROVIDER_CLASS (klass), NULL);
g_return_val_if_fail (key != NULL, NULL);
return gst_structure_get_string ((GstStructure *) klass->metadata, key);
}
/**
* gst_device_provider_get_metadata:
* @provider: provider to get metadata for
* @key: the key to get
*
* Get metadata with @key in @provider.
*
* Returns: the metadata for @key.
*
* Since: 1.14
*/
const gchar *
gst_device_provider_get_metadata (GstDeviceProvider * provider,
const gchar * key)
{
g_return_val_if_fail (GST_IS_DEVICE_PROVIDER (provider), NULL);
g_return_val_if_fail (key != NULL, NULL);
return
gst_device_provider_class_get_metadata (GST_DEVICE_PROVIDER_GET_CLASS
(provider), key);
}
/**
* gst_device_provider_get_devices:
* @provider: A #GstDeviceProvider
*
* Gets a list of devices that this provider understands. This may actually
* probe the hardware if the provider is not currently started.
*
* Returns: (transfer full) (element-type GstDevice): a #GList of
* #GstDevice
*
* Since: 1.4
*/
GList *
gst_device_provider_get_devices (GstDeviceProvider * provider)
{
GstDeviceProviderClass *klass;
GList *devices = NULL;
gboolean started;
GList *item;
g_return_val_if_fail (GST_IS_DEVICE_PROVIDER (provider), NULL);
klass = GST_DEVICE_PROVIDER_GET_CLASS (provider);
g_mutex_lock (&provider->priv->start_lock);
started = (provider->priv->started_count > 0);
if (started) {
GST_OBJECT_LOCK (provider);
for (item = provider->devices; item; item = item->next)
devices = g_list_prepend (devices, gst_object_ref (item->data));
GST_OBJECT_UNLOCK (provider);
} else if (klass->probe)
devices = klass->probe (provider);
g_mutex_unlock (&provider->priv->start_lock);
return devices;
}
/**
* gst_device_provider_start:
* @provider: A #GstDeviceProvider
*
* Starts providering the devices. This will cause #GST_MESSAGE_DEVICE_ADDED
* and #GST_MESSAGE_DEVICE_REMOVED messages to be posted on the provider's bus
* when devices are added or removed from the system.
*
* Since the #GstDeviceProvider is a singleton,
* gst_device_provider_start() may already have been called by another
* user of the object, gst_device_provider_stop() needs to be called the same
* number of times.
*
* Returns: %TRUE if the device providering could be started
*
* Since: 1.4
*/
gboolean
gst_device_provider_start (GstDeviceProvider * provider)
{
GstDeviceProviderClass *klass;
gboolean ret = FALSE;
g_return_val_if_fail (GST_IS_DEVICE_PROVIDER (provider), FALSE);
klass = GST_DEVICE_PROVIDER_GET_CLASS (provider);
g_mutex_lock (&provider->priv->start_lock);
if (provider->priv->started_count > 0) {
provider->priv->started_count++;
ret = TRUE;
goto started;
}
if (klass->start)
ret = klass->start (provider);
if (ret) {
provider->priv->started_count++;
gst_bus_set_flushing (provider->priv->bus, FALSE);
}
started:
g_mutex_unlock (&provider->priv->start_lock);
return ret;
}
/**
* gst_device_provider_stop:
* @provider: A #GstDeviceProvider
*
* Decreases the use-count by one. If the use count reaches zero, this
* #GstDeviceProvider will stop providering the devices. This needs to be
* called the same number of times that gst_device_provider_start() was called.
*
* Since: 1.4
*/
void
gst_device_provider_stop (GstDeviceProvider * provider)
{
GstDeviceProviderClass *klass;
g_return_if_fail (GST_IS_DEVICE_PROVIDER (provider));
klass = GST_DEVICE_PROVIDER_GET_CLASS (provider);
g_mutex_lock (&provider->priv->start_lock);
if (provider->priv->started_count == 1) {
gst_bus_set_flushing (provider->priv->bus, TRUE);
if (klass->stop)
klass->stop (provider);
GST_OBJECT_LOCK (provider);
g_list_free_full (provider->devices, (GDestroyNotify) gst_object_unparent);
provider->devices = NULL;
GST_OBJECT_UNLOCK (provider);
} else if (provider->priv->started_count < 1) {
g_critical
("Trying to stop a GstDeviceProvider %s which is already stopped",
GST_OBJECT_NAME (provider));
}
provider->priv->started_count--;
g_mutex_unlock (&provider->priv->start_lock);
}
/**
* gst_device_provider_get_factory:
* @provider: a #GstDeviceProvider to request the device provider factory of.
*
* Retrieves the factory that was used to create this device provider.
*
* Returns: (transfer none): the #GstDeviceProviderFactory used for
* creating this device provider. no refcounting is needed.
*
* Since: 1.4
*/
GstDeviceProviderFactory *
gst_device_provider_get_factory (GstDeviceProvider * provider)
{
g_return_val_if_fail (GST_IS_DEVICE_PROVIDER (provider), NULL);
return GST_DEVICE_PROVIDER_GET_CLASS (provider)->factory;
}
/**
* gst_device_provider_can_provider:
* @provider: a #GstDeviceProvider
*
* If this function returns %TRUE, then the device provider can provider if
* devices are added or removed. Otherwise, it can only do static probing.
*
* Returns: %TRUE if the #GstDeviceProvider support providering, %FALSE otherwise
*/
gboolean
gst_device_provider_can_monitor (GstDeviceProvider * provider)
{
GstDeviceProviderClass *klass;
g_return_val_if_fail (GST_IS_DEVICE_PROVIDER (provider), FALSE);
klass = GST_DEVICE_PROVIDER_GET_CLASS (provider);
if (klass->start)
return TRUE;
else
return FALSE;
}
/**
* gst_device_provider_get_bus:
* @provider: a #GstDeviceProvider
*
* Gets the #GstBus of this #GstDeviceProvider
*
* Returns: (transfer full): a #GstBus
*
* Since: 1.4
*/
GstBus *
gst_device_provider_get_bus (GstDeviceProvider * provider)
{
g_return_val_if_fail (GST_IS_DEVICE_PROVIDER (provider), NULL);
return gst_object_ref (provider->priv->bus);
}
/**
* gst_device_provider_device_add:
* @provider: a #GstDeviceProvider
* @device: (transfer floating): a #GstDevice that has been added
*
* Posts a message on the provider's #GstBus to inform applications that
* a new device has been added.
*
* This is for use by subclasses.
*
* @device's reference count will be incremented, and any floating reference
* will be removed (see gst_object_ref_sink()).
*
* Since: 1.4
*/
void
gst_device_provider_device_add (GstDeviceProvider * provider,
GstDevice * device)
{
GstMessage *message;
g_return_if_fail (GST_IS_DEVICE_PROVIDER (provider));
g_return_if_fail (GST_IS_DEVICE (device));
if (!gst_object_set_parent (GST_OBJECT (device), GST_OBJECT (provider))) {
GST_WARNING_OBJECT (provider, "Could not parent device %p to provider,"
" it already has a parent", device);
return;
}
GST_OBJECT_LOCK (provider);
/* Take an additional reference so we can be sure nobody removed it from the
* provider in the meantime and we can safely emit the message */
gst_object_ref (device);
provider->devices = g_list_prepend (provider->devices, device);
GST_OBJECT_UNLOCK (provider);
message = gst_message_new_device_added (GST_OBJECT (provider), device);
gst_bus_post (provider->priv->bus, message);
gst_object_unref (device);
}
/**
* gst_device_provider_device_remove:
* @provider: a #GstDeviceProvider
* @device: a #GstDevice that has been removed
*
* Posts a message on the provider's #GstBus to inform applications that
* a device has been removed.
*
* This is for use by subclasses.
*
* Since: 1.4
*/
void
gst_device_provider_device_remove (GstDeviceProvider * provider,
GstDevice * device)
{
GstMessage *message;
GList *item;
g_return_if_fail (GST_IS_DEVICE_PROVIDER (provider));
g_return_if_fail (GST_IS_DEVICE (device));
GST_OBJECT_LOCK (provider);
item = g_list_find (provider->devices, device);
if (item) {
provider->devices = g_list_delete_link (provider->devices, item);
}
GST_OBJECT_UNLOCK (provider);
message = gst_message_new_device_removed (GST_OBJECT (provider), device);
g_signal_emit_by_name (device, "removed");
gst_bus_post (provider->priv->bus, message);
if (item)
gst_object_unparent (GST_OBJECT (device));
}
/**
* gst_device_provider_get_hidden_providers:
* @provider: a #GstDeviceProvider
*
* Get the provider factory names of the #GstDeviceProvider instances that
* are hidden by @provider.
*
* Returns: (transfer full) (array zero-terminated=1) (element-type gchar*):
* a list of hidden providers factory names or %NULL when
* nothing is hidden by @provider. Free with g_strfreev.
*
* Since: 1.6
*/
gchar **
gst_device_provider_get_hidden_providers (GstDeviceProvider * provider)
{
GList *walk;
guint i, len;
gchar **res = NULL;
g_return_val_if_fail (GST_IS_DEVICE_PROVIDER (provider), NULL);
GST_OBJECT_LOCK (provider);
len = g_list_length (provider->priv->hidden_providers);
if (len == 0)
goto done;
res = g_new (gchar *, len + 1);
for (i = 0, walk = provider->priv->hidden_providers; walk;
walk = g_list_next (walk), i++)
res[i] = g_strdup (walk->data);
res[i] = NULL;
done:
GST_OBJECT_UNLOCK (provider);
return res;
}
/**
* gst_device_provider_hide_provider:
* @provider: a #GstDeviceProvider
* @name: a provider factory name
*
* Make @provider hide the devices from the factory with @name.
*
* This function is used when @provider will also provide the devices reported
* by provider factory @name. A monitor should stop monitoring the
* device provider with @name to avoid duplicate devices.
*
* Since: 1.6
*/
void
gst_device_provider_hide_provider (GstDeviceProvider * provider,
const gchar * name)
{
GList *find;
const gchar *hidden_name = NULL;
g_return_if_fail (GST_IS_DEVICE_PROVIDER (provider));
g_return_if_fail (name != NULL);
GST_OBJECT_LOCK (provider);
find =
g_list_find_custom (provider->priv->hidden_providers, name,
(GCompareFunc) g_strcmp0);
if (find == NULL) {
hidden_name = name;
provider->priv->hidden_providers =
g_list_prepend (provider->priv->hidden_providers, g_strdup (name));
}
GST_OBJECT_UNLOCK (provider);
if (hidden_name)
g_signal_emit (provider, gst_device_provider_signals[PROVIDER_HIDDEN],
0, hidden_name);
}
/**
* gst_device_provider_unhide_provider:
* @provider: a #GstDeviceProvider
* @name: a provider factory name
*
* Make @provider unhide the devices from factory @name.
*
* This function is used when @provider will no longer provide the devices
* reported by provider factory @name. A monitor should start
* monitoring the devices from provider factory @name in order to see
* all devices again.
*
* Since: 1.6
*/
void
gst_device_provider_unhide_provider (GstDeviceProvider * provider,
const gchar * name)
{
GList *find;
gchar *unhidden_name = NULL;
g_return_if_fail (GST_IS_DEVICE_PROVIDER (provider));
g_return_if_fail (name != NULL);
GST_OBJECT_LOCK (provider);
find =
g_list_find_custom (provider->priv->hidden_providers, name,
(GCompareFunc) g_strcmp0);
if (find) {
unhidden_name = find->data;
provider->priv->hidden_providers =
g_list_delete_link (provider->priv->hidden_providers, find);
}
GST_OBJECT_UNLOCK (provider);
if (unhidden_name) {
g_signal_emit (provider,
gst_device_provider_signals[PROVIDER_UNHIDDEN], 0, unhidden_name);
g_free (unhidden_name);
}
}