include/vlc_objects.h

   1 /*****************************************************************************
   2  * vlc_objects.h: vlc_object_t definition and manipulation methods
   3  *****************************************************************************
   4  * Copyright (C) 2002-2008 VLC authors and VideoLAN
   5  *
   6  * Authors: Samuel Hocevar <sam@zoy.org>
   7  *
   8  * This program is free software; you can redistribute it and/or modify it
   9  * under the terms of the GNU Lesser General Public License as published by
  10  * the Free Software Foundation; either version 2.1 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  16  * GNU Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public License
  19  * along with this program; if not, write to the Free Software Foundation,
  20  * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  21  *****************************************************************************/
  22
  23 /**
  24  * \defgroup vlc_object VLC objects
  25  * \ingroup vlc
  26  * @{
  27  * \file
  28  * Common VLC object defintions
  29  */
  30
  31 /**
  32  * VLC object common members
  33  *
  34  * Common public properties for all VLC objects.
  35  * Object also have private properties maintained by the core, see
  36  * \ref vlc_object_internals_t
  37  */
  38 struct vlc_common_members
  39 {
  40     /** Object type name
  41      *
  42      * A constant string identifying the type of the object (for logging)
  43      */
  44     const char *object_type;
  45
  46     /** Log messages header
  47      *
  48      * Human-readable header for log messages. This is not thread-safe and
  49      * only used by VLM and Lua interfaces.
  50      */
  51     char *header;
  52
  53     int  flags;
  54
  55     /** Module probe flag
  56      *
  57      * A boolean during module probing when the probe is "forced".
  58      * See \ref module_need().
  59      */
  60     bool force;
  61
  62     /** LibVLC instance
  63      *
  64      * Root VLC object of the objects tree that this object belongs in.
  65      */
  66     libvlc_int_t *libvlc;
  67
  68     /** Parent object
  69      *
  70      * The parent VLC object in the objects tree. For the root (the LibVLC
  71      * instance) object, this is NULL.
  72      */
  73     vlc_object_t *parent;
  74 };
  75
  76 /**
  77  * Type-safe vlc_object_t cast
  78  *
  79  * This macro attempts to cast a pointer to a compound type to a
  80  * \ref vlc_object_t pointer in a type-safe manner.
  81  * It checks if the compound type actually starts with an embedded
  82  * \ref vlc_object_t structure.
  83  */
  84 #if !defined(__cplusplus)
  85 # define VLC_OBJECT(x) \
  86     _Generic((x)->obj, \
  87         struct vlc_common_members: (vlc_object_t *)(x) \
  88     )
  89 #else
  90 # define VLC_OBJECT(x) ((vlc_object_t *)(x))
  91 #endif
  92
  93 /* Object flags */
  94 #define OBJECT_FLAGS_QUIET       0x0002
  95 #define OBJECT_FLAGS_NOINTERACT  0x0004
  96
  97 /*****************************************************************************
  98  * The vlc_object_t type. Yes, it's that simple :-)
  99  *****************************************************************************/
 100 /** The main vlc_object_t structure */
 101 struct vlc_object_t
 102 {
 103     struct vlc_common_members obj;
 104 };
 105
 106 /* The root object */
 107 struct libvlc_int_t
 108 {
 109     struct vlc_common_members obj;
 110 };
 111
 112 /*****************************************************************************
 113  * Prototypes
 114  *****************************************************************************/
 115 VLC_API void *vlc_object_create( vlc_object_t *, size_t ) VLC_MALLOC VLC_USED;
 116 VLC_API vlc_object_t *vlc_object_find_name( vlc_object_t *, const char * ) VLC_USED VLC_DEPRECATED;
 117 VLC_API void * vlc_object_hold( vlc_object_t * );
 118 VLC_API void vlc_object_release( vlc_object_t * );
 119 VLC_API size_t vlc_list_children(vlc_object_t *, vlc_object_t **, size_t) VLC_USED;
 120 VLC_API char *vlc_object_get_name( const vlc_object_t * ) VLC_USED;
 121
 122 #define vlc_object_create(a,b) vlc_object_create( VLC_OBJECT(a), b )
 123
 124 #define vlc_object_find_name(a,b) \
 125     vlc_object_find_name( VLC_OBJECT(a),b)
 126
 127 #define vlc_object_hold(a) \
 128     vlc_object_hold( VLC_OBJECT(a) )
 129
 130 #define vlc_object_release(a) \
 131     vlc_object_release( VLC_OBJECT(a) )
 132
 133 /**
 134  * @defgroup objres Object resources
 135  *
 136  * The object resource functions tie resource allocation to an instance of
 137  * a module through a VLC object.
 138  * Such resource will be automatically freed, in first in last out order,
 139  * when the module instance associated with the VLC object is terminated.
 140  *
 141  * Specifically, if the module instance activation/probe function fails, the
 142  * resource will be freed immediately after the failure within
 143  * vlc_module_load(). If the activation succeeds, the resource will be freed
 144  * when the module instance is terminated with vlc_module_unload().
 145  *
 146  * This is a convenience mechanism to save explicit clean-up function calls
 147  * in modules.
 148  *
 149  * @{
 150  */
 151
 152 /**
 153  * Allocates memory for a module.
 154  *
 155  * This function allocates memory from the heap for a module instance.
 156  * The memory is uninitialized.
 157  *
 158  * @param obj VLC object to tie the memory allocation to
 159  * @param size byte size of the memory allocation
 160  *
 161  * @return a pointer to the allocated memory, or NULL on error (errno is set).
 162  */
 163 VLC_API VLC_MALLOC void *vlc_obj_malloc(vlc_object_t *obj, size_t size);
 164
 165 /**
 166  * Allocates a zero-initialized table for a module.
 167  *
 168  * This function allocates a table from the heap for a module instance.
 169  * The memory is initialized to all zeroes.
 170  *
 171  * @param obj VLC object to tie the memory allocation to
 172  * @param nmemb number of table entries
 173  * @param size byte size of a table entry
 174  *
 175  * @return a pointer to the allocated memory, or NULL on error (errno is set).
 176  */
 177 VLC_API VLC_MALLOC void *vlc_obj_calloc(vlc_object_t *obj, size_t nmemb,
 178                                         size_t size);
 179
 180 /**
 181  * Duplicates a string for a module.
 182  *
 183  * This function allocates a copy of a nul-terminated string for a module
 184  * instance.
 185  *
 186  * @param obj VLC object to tie the memory allocation to
 187  * @param str string to copy
 188  *
 189  * @return a pointer to the copy, or NULL on error (errno is set).
 190  */
 191 VLC_API VLC_MALLOC char *vlc_obj_strdup(vlc_object_t *obj, const char *str);
 192
 193 /**
 194  * Manually frees module memory.
 195  *
 196  * This function manually frees a resource allocated with vlc_obj_malloc(),
 197  * vlc_obj_calloc() or vlc_obj_strdup() before the module instance is
 198  * terminated. This is seldom necessary.
 199  *
 200  * @param obj VLC object that the allocation was tied to
 201  * @param ptr pointer to the allocated resource
 202  */
 203 VLC_API void vlc_obj_free(vlc_object_t *obj, void *ptr);
 204
 205 /** @} */
 206 /** @} */