probe: infrastructure for run-time features probing

include/vlc_probe.h

+/*****************************************************************************
+ * vlc_probe.h: service probing interface
+ *****************************************************************************
+ * Copyright (C) 2009 Rémi Denis-Courmont
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation; either version 2.1 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
+ *****************************************************************************/
+
+#ifndef VLC_PROBE_H
+# define VLC_PROBE_H 1
+
+# include <stdlib.h>
+
+/**
+ * \file
+ * This file defines functions and structures to run-time probe VLC extensions
+ */
+
+# ifdef __cplusplus
+extern "C" {
+# endif
+
+VLC_EXPORT(void *, vlc_probe, (vlc_object_t *, const char *,
+                               size_t *restrict));
+#define vlc_probe(obj, cap, pcount) \
+        vlc_probe(VLC_OBJECT(obj), cap, pcount)
+
+struct vlc_probe_t
+{
+    VLC_COMMON_MEMBERS
+
+    void  *list;
+    size_t count;
+};
+
+typedef struct vlc_probe_t vlc_probe_t;
+
+static inline int vlc_probe_add(vlc_probe_t *obj, const void *data,
+                                size_t len)
+{
+    char *tab = (char *)realloc (obj->list, (obj->count + 1) * len);
+
+    if (unlikely(tab == NULL))
+        return VLC_ENOMEM;
+    memcpy(tab + (obj->count * len), data, len);
+    obj->list = tab;
+    obj->count++;
+    return VLC_SUCCESS;
+}
+
+# define VLC_PROBE_CONTINUE VLC_EGENERIC
+# define VLC_PROBE_STOP     VLC_SUCCESS
+
+# ifdef __cplusplus
+}
+# endif
+
+#endif

src/Makefile.am

@@ -88,6 +88,7 @@ pluginsinclude_HEADERS = \
 	../include/vlc_picture_pool.h \
 	../include/vlc_playlist.h \
 	../include/vlc_plugin.h \
+	../include/vlc_probe.h \
 	../include/vlc_rand.h \
 	../include/vlc_services_discovery.h \
 	../include/vlc_sql.h \
@@ -402,6 +403,7 @@ SOURCES_libvlc_common = \
 	text/iso_lang.c \
 	text/iso-639_def.h \
 	misc/md5.c \
+	misc/probe.c \
 	misc/rand.c \
 	misc/mtime.c \
 	misc/block.c \

src/misc/probe.c

+/*****************************************************************************
+ * probe.c : run-time service listing
+ *****************************************************************************
+ * Copyright © 2009 Rémi Denis-Courmont
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation; either version 2.1 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
+ *****************************************************************************/
+
+#ifdef HAVE_CONFIG_H
+# include "config.h"
+#endif
+
+#include <vlc_common.h>
+#include <vlc_probe.h>
+#include "libvlc.h"
+
+#undef vlc_probe
+void *vlc_probe (vlc_object_t *obj,
+                 const char *capability, size_t *restrict pcount)
+{
+    vlc_probe_t *probe = vlc_custom_create (obj, sizeof(*probe),
+                                            VLC_OBJECT_GENERIC, "probe");
+    if (unlikely(probe == NULL))
+    {
+        *pcount = 0;
+        return NULL;
+    }
+    probe->list = NULL;
+    probe->count = 0;
+
+    module_t *mod = module_need (probe, capability, NULL, false);
+    if (mod != NULL)
+        module_unneed (probe, mod);
+
+    void *ret = probe->list;
+    *pcount = probe->count;
+    vlc_object_release (probe);
+    return ret;
+}