Add device autodetection

Original commit message from CVS:
Add device autodetection

sys/v4l/gstv4lelement.c

@@ -21,12 +21,19 @@
 #include <config.h>
 #endif
 
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <unistd.h>
+
 #include <string.h>
 #include "v4l_calls.h"
 #include "gstv4ltuner.h"
 #include "gstv4lxoverlay.h"
 #include "gstv4lcolorbalance.h"
 
+#include <gst/propertyprobe/propertyprobe.h>
+
 /* elementfactory information */
 static GstElementDetails gst_v4lelement_details = GST_ELEMENT_DETAILS (
   "Generic video4linux Element",
@@ -97,6 +104,156 @@ gst_v4l_interface_init (GstInterfaceClass *klass)
   klass->supported = gst_v4l_iface_supported;
 }
 
+static const GList *
+gst_v4l_probe_get_properties (GstPropertyProbe *probe)
+{
+  GObjectClass *klass = G_OBJECT_GET_CLASS (probe);
+  static GList *list = NULL;
+
+  if (!list) {
+    list = g_list_append (NULL, g_object_class_find_property (klass, "device"));
+  }
+
+  return list;
+}
+
+static gboolean
+gst_v4l_class_probe_devices (GstV4lElementClass *klass,
+			     gboolean            check)
+{
+  static gboolean init = FALSE;
+
+  if (!init && !check) {
+    gchar *dev_base[] = { "/dev/video", "/dev/v4l/video", NULL };
+    gint base, n, fd;
+
+    while (klass->devices) {
+      GList *item = klass->devices;
+      gchar *device = item->data;
+
+      klass->devices = g_list_remove (klass->devices, item);
+      g_free (device);
+    }
+
+    /* detect /dev entries */
+    for (n = 0; n < 64; n++) {
+      for (base = 0; dev_base[base] != NULL; base++) {
+        struct stat s;
+        gchar *device = g_strdup_printf ("%s%d", dev_base[base], n);
+
+        /* does the /dev/ entry exist at all? */
+        if (stat (device, &s) == 0) {
+          /* yes: is a device attached? */
+          if ((fd = open (device, O_RDONLY)) > 0 || errno == EBUSY) {
+            if (fd > 0)
+              close (fd);
+
+            klass->devices = g_list_append (klass->devices, device);
+            break;
+          }
+        }
+        g_free (device);
+      }
+    }
+
+    init = TRUE;
+  }
+
+  return init;
+}
+
+static void
+gst_v4l_probe_probe_property (GstPropertyProbe *probe,
+			      guint             prop_id,
+			      const GParamSpec *pspec)
+{
+  GstV4lElementClass *klass = GST_V4LELEMENT_GET_CLASS (probe);
+
+  switch (prop_id) {
+    case ARG_DEVICE:
+      gst_v4l_class_probe_devices (klass, FALSE);
+      break;
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (probe, prop_id, pspec);
+      break;
+  }
+}
+
+static gboolean
+gst_v4l_probe_needs_probe (GstPropertyProbe *probe,
+			   guint             prop_id,
+			   const GParamSpec *pspec)
+{
+  GstV4lElementClass *klass = GST_V4LELEMENT_GET_CLASS (probe);
+  gboolean ret = FALSE;
+
+  switch (prop_id) {
+    case ARG_DEVICE:
+      ret = !gst_v4l_class_probe_devices (klass, TRUE);
+      break;
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (probe, prop_id, pspec);
+      break;
+  }
+
+  return ret;
+}
+
+static GValueArray *
+gst_v4l_class_list_devices (GstV4lElementClass *klass)
+{
+  GValueArray *array;
+  GValue value = { 0 };
+  GList *item;
+
+  if (!klass->devices)
+    return NULL;
+
+  array = g_value_array_new (g_list_length (klass->devices));
+  item = klass->devices;
+  g_value_init (&value, G_TYPE_STRING);
+  while (item) {
+    gchar *device = item->data;
+
+    g_value_set_string (&value, device);
+    g_value_array_append (array, &value);
+
+    item = item->next;
+  }
+  g_value_unset (&value);
+
+  return array;
+}
+
+static GValueArray *
+gst_v4l_probe_get_values (GstPropertyProbe *probe,
+			  guint             prop_id,
+			  const GParamSpec *pspec)
+{
+  GstV4lElementClass *klass = GST_V4LELEMENT_GET_CLASS (probe);
+  GValueArray *array = NULL;
+
+  switch (prop_id) {
+    case ARG_DEVICE:
+      array = gst_v4l_class_list_devices (klass);
+      break;
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (probe, prop_id, pspec);
+      break;
+  }
+
+  return array;
+}
+
+static void
+gst_v4l_property_probe_interface_init (GstPropertyProbeInterface *iface)
+{
+  iface->get_properties = gst_v4l_probe_get_properties;
+  iface->probe_property = gst_v4l_probe_probe_property;
+  iface->needs_probe    = gst_v4l_probe_needs_probe;
+  iface->get_values     = gst_v4l_probe_get_values;
+}
+
 #define GST_TYPE_V4L_DEVICE_FLAGS (gst_v4l_device_get_type ())
 GType
 gst_v4l_device_get_type (void)
@@ -162,6 +319,11 @@ gst_v4lelement_get_type (void)
       NULL,
       NULL,
     };
+    static const GInterfaceInfo v4l_propertyprobe_info = {
+      (GInterfaceInitFunc) gst_v4l_property_probe_interface_init,
+      NULL,
+      NULL,
+    };
 
     v4lelement_type = g_type_register_static(GST_TYPE_ELEMENT,
 					     "GstV4lElement",
@@ -179,6 +341,9 @@ gst_v4lelement_get_type (void)
     g_type_add_interface_static (v4lelement_type,
 				 GST_TYPE_COLOR_BALANCE,
 				 &v4l_colorbalance_info);
+    g_type_add_interface_static (v4lelement_type,
+				 GST_TYPE_PROPERTY_PROBE,
+				 &v4l_propertyprobe_info);
   }
 
   return v4lelement_type;
@@ -189,9 +354,13 @@ static void
 gst_v4lelement_base_init (gpointer g_class)
 {
   GstElementClass *gstelement_class = GST_ELEMENT_CLASS (g_class);
+  GstV4lElementClass *klass = GST_V4LELEMENT_CLASS (g_class);
+
+  klass->devices = NULL;
   
   gst_element_class_set_details (gstelement_class, &gst_v4lelement_details);
 }
+
 static void
 gst_v4lelement_class_init (GstV4lElementClass *klass)
 {

sys/v4l/gstv4lelement.h

@@ -52,6 +52,8 @@ G_BEGIN_DECLS
   (G_TYPE_CHECK_INSTANCE_TYPE((obj),GST_TYPE_V4LELEMENT))
 #define GST_IS_V4LELEMENT_CLASS(obj) \
   (G_TYPE_CHECK_CLASS_TYPE((klass),GST_TYPE_V4LELEMENT))
+#define GST_V4LELEMENT_GET_CLASS(obj) \
+  (G_TYPE_INSTANCE_GET_CLASS ((obj), GST_TYPE_V4LELEMENT, GstV4lElementClass))
 
 typedef struct _GstV4lElement GstV4lElement;
 typedef struct _GstV4lElementClass GstV4lElementClass;
@@ -90,6 +92,9 @@ struct _GstV4lElement {
 struct _GstV4lElementClass {
   GstElementClass parent_class;
 
+  /* probed devices */
+  GList *devices;
+
   /* signals */
   void     (*open)           (GstElement  *element,
                               const gchar *device);