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  * $Id$
   6  *
   7  * Authors: Samuel Hocevar <sam@zoy.org>
   8  *
   9  * This program is free software; you can redistribute it and/or modify it
  10  * under the terms of the GNU Lesser General Public License as published by
  11  * the Free Software Foundation; either version 2.1 of the License, or
  12  * (at your option) any later version.
  13  *
  14  * This program is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  17  * GNU Lesser General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU Lesser General Public License
  20  * along with this program; if not, write to the Free Software Foundation,
  21  * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  22  *****************************************************************************/
  23
  24 /**
  25  * \defgroup vlc_object VLC objects
  26  * \ingroup vlc
  27  * @{
  28  * \file
  29  * Common VLC object defintions
  30  */
  31
  32 /**
  33  * VLC object common members
  34  *
  35  * Common public properties for all VLC objects.
  36  * Object also have private properties maintained by the core, see
  37  * \ref vlc_object_internals_t
  38  */
  39 struct vlc_common_members
  40 {
  41     /** Object type name
  42      *
  43      * A constant string identifying the type of the object (for logging)
  44      */
  45     const char *object_type;
  46
  47     /** Log messages header
  48      *
  49      * Human-readable header for log messages. This is not thread-safe and
  50      * only used by VLM and Lua interfaces.
  51      */
  52     char *header;
  53
  54     int  flags;
  55
  56     /** Module probe flag
  57      *
  58      * A boolean during module probing when the probe is "forced".
  59      * See \ref module_need().
  60      */
  61     bool force;
  62
  63     /** LibVLC instance
  64      *
  65      * Root VLC object of the objects tree that this object belongs in.
  66      */
  67     libvlc_int_t *libvlc;
  68
  69     /** Parent object
  70      *
  71      * The parent VLC object in the objects tree. For the root (the LibVLC
  72      * instance) object, this is NULL.
  73      */
  74     vlc_object_t *parent;
  75 };
  76
  77 /**
  78  * Type-safe vlc_object_t cast
  79  *
  80  * This macro attempts to cast a pointer to a compound type to a
  81  * \ref vlc_object_t pointer in a type-safe manner.
  82  * It checks if the compound type actually starts with an embedded
  83  * \ref vlc_object_t structure.
  84  */
  85 #if !defined(__cplusplus)
  86 # define VLC_OBJECT(x) \
  87     _Generic((x)->obj, \
  88         struct vlc_common_members: (vlc_object_t *)(x) \
  89     )
  90 #else
  91 # define VLC_OBJECT(x) ((vlc_object_t *)(x))
  92 #endif
  93
  94 /* Object flags */
  95 #define OBJECT_FLAGS_QUIET       0x0002
  96 #define OBJECT_FLAGS_NOINTERACT  0x0004
  97
  98 /*****************************************************************************
  99  * The vlc_object_t type. Yes, it's that simple :-)
 100  *****************************************************************************/
 101 /** The main vlc_object_t structure */
 102 struct vlc_object_t
 103 {
 104     struct vlc_common_members obj;
 105 };
 106
 107 /* The root object */
 108 struct libvlc_int_t
 109 {
 110     struct vlc_common_members obj;
 111 };
 112
 113 /*****************************************************************************
 114  * Prototypes
 115  *****************************************************************************/
 116 VLC_API void *vlc_object_create( vlc_object_t *, size_t ) VLC_MALLOC VLC_USED;
 117 VLC_API vlc_object_t *vlc_object_find_name( vlc_object_t *, const char * ) VLC_USED VLC_DEPRECATED;
 118 VLC_API void * vlc_object_hold( vlc_object_t * );
 119 VLC_API void vlc_object_release( vlc_object_t * );
 120 VLC_API size_t vlc_list_children(vlc_object_t *, vlc_object_t **, size_t) VLC_USED;
 121 VLC_API char *vlc_object_get_name( const vlc_object_t * ) VLC_USED;
 122
 123 #define vlc_object_create(a,b) vlc_object_create( VLC_OBJECT(a), b )
 124
 125 #define vlc_object_find_name(a,b) \
 126     vlc_object_find_name( VLC_OBJECT(a),b)
 127
 128 #define vlc_object_hold(a) \
 129     vlc_object_hold( VLC_OBJECT(a) )
 130
 131 #define vlc_object_release(a) \
 132     vlc_object_release( VLC_OBJECT(a) )
 133
 134 /**
 135  * @defgroup objres Object resources
 136  *
 137  * The object resource functions tie resource allocation to an instance of
 138  * a module through a VLC object.
 139  * Such resource will be automatically freed, in first in last out order,
 140  * when the module instance associated with the VLC object is terminated.
 141  *
 142  * Specifically, if the module instance activation/probe function fails, the
 143  * resource will be freed immediately after the failure within
 144  * vlc_module_load(). If the activation succeeds, the resource will be freed
 145  * when the module instance is terminated with vlc_module_unload().
 146  *
 147  * This is a convenience mechanism to save explicit clean-up function calls
 148  * in modules.
 149  *
 150  * @{
 151  */
 152
 153 /**
 154  * Allocates memory for a module.
 155  *
 156  * This function allocates memory from the heap for a module instance.
 157  * The memory is uninitialized.
 158  *
 159  * @param obj VLC object to tie the memory allocation to
 160  * @param size byte size of the memory allocation
 161  *
 162  * @return a pointer to the allocated memory, or NULL on error (errno is set).
 163  */
 164 VLC_API VLC_MALLOC void *vlc_obj_malloc(vlc_object_t *obj, size_t size);
 165
 166 /**
 167  * Allocates a zero-initialized table for a module.
 168  *
 169  * This function allocates a table from the heap for a module instance.
 170  * The memory is initialized to all zeroes.
 171  *
 172  * @param obj VLC object to tie the memory allocation to
 173  * @param nmemb number of table entries
 174  * @param size byte size of a table entry
 175  *
 176  * @return a pointer to the allocated memory, or NULL on error (errno is set).
 177  */
 178 VLC_API VLC_MALLOC void *vlc_obj_calloc(vlc_object_t *obj, size_t nmemb,
 179                                         size_t size);
 180
 181 /**
 182  * Duplicates a string for a module.
 183  *
 184  * This function allocates a copy of a nul-terminated string for a module
 185  * instance.
 186  *
 187  * @param obj VLC object to tie the memory allocation to
 188  * @param str string to copy
 189  *
 190  * @return a pointer to the copy, or NULL on error (errno is set).
 191  */
 192 VLC_API VLC_MALLOC char *vlc_obj_strdup(vlc_object_t *obj, const char *str);
 193
 194 /**
 195  * Manually frees module memory.
 196  *
 197  * This function manually frees a resource allocated with vlc_obj_malloc(),
 198  * vlc_obj_calloc() or vlc_obj_strdup() before the module instance is
 199  * terminated. This is seldom necessary.
 200  *
 201  * @param obj VLC object that the allocation was tied to
 202  * @param ptr pointer to the allocated resource
 203  */
 204 VLC_API void vlc_obj_free(vlc_object_t *obj, void *ptr);
 205
 206 /** @} */
 207 /** @} */