src/misc/objres.c

   1 /*****************************************************************************
   2  * objres.c: vlc_object_t resources
   3  *****************************************************************************
   4  * Copyright (C) 2017 Rémi Denis-Courmont
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU Lesser General Public License as published by
   8  * the Free Software Foundation; either version 2.1 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  14  * GNU Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public License
  17  * along with this program; if not, write to the Free Software Foundation,
  18  * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  19  *****************************************************************************/
  20
  21 #ifdef HAVE_CONFIG_H
  22 # include "config.h"
  23 #endif
  24
  25 #include <assert.h>
  26 #include <errno.h>
  27 #include <stdlib.h>
  28 #include <stddef.h>
  29 #include <string.h>
  30
  31 #include <vlc_common.h>
  32
  33 #include "libvlc.h"
  34 #include "variables.h"
  35
  36 struct vlc_res
  37 {
  38     struct vlc_res *prev;
  39     void (*release)(void *);
  40     max_align_t payload[];
  41 };
  42
  43 static struct vlc_res **vlc_obj_res(vlc_object_t *obj)
  44 {
  45     return &vlc_internals(obj)->resources;
  46 }
  47
  48 void *vlc_objres_new(size_t size, void (*release)(void *))
  49 {
  50     if (unlikely(add_overflow(sizeof (struct vlc_res), size, &size)))
  51     {
  52         errno = ENOMEM;
  53         return NULL;
  54     }
  55
  56     struct vlc_res *res = malloc(size);
  57     if (unlikely(res == NULL))
  58         return NULL;
  59
  60     res->release = release;
  61     return res->payload;
  62 }
  63
  64 void vlc_objres_push(vlc_object_t *obj, void *data)
  65 {
  66     struct vlc_res **restrict pp = vlc_obj_res(obj);
  67     struct vlc_res *res = container_of(data, struct vlc_res, payload);
  68
  69     res->prev = *pp;
  70     *pp = res;
  71 }
  72
  73 static void *vlc_objres_pop(vlc_object_t *obj)
  74 {
  75     struct vlc_res **restrict pp = vlc_obj_res(obj);
  76     struct vlc_res *res = *pp;
  77
  78     if (res == NULL)
  79         return NULL;
  80     *pp = res->prev;
  81     return res->payload;
  82 }
  83
  84 void vlc_objres_clear(vlc_object_t *obj)
  85 {
  86     void *data;
  87
  88     while ((data = vlc_objres_pop(obj)) != NULL)
  89     {
  90         struct vlc_res *res = container_of(data, struct vlc_res, payload);
  91
  92         res->release(res->payload);
  93         free(res);
  94     }
  95 }
  96
  97 void vlc_objres_remove(vlc_object_t *obj, void *data,
  98                        bool (*match)(void *, void *))
  99 {
 100     struct vlc_res **restrict pp = vlc_obj_res(obj);
 101
 102     /* With a doubly-linked list, this function could have constant complexity.
 103      * But that would require one more pointer per resource.
 104      *
 105      * Any given list should contain a fairly small number of resources,
 106      * and in most cases, the resources are destroyed implicitly by
 107      * vlc_objres_clear().
 108      */
 109     for (;;)
 110     {
 111         struct vlc_res *res = *pp;
 112
 113         assert(res != NULL); /* invalid free? */
 114
 115         if (match(res->payload, data))
 116         {
 117             *pp = res->prev;
 118             res->release(res->payload);
 119             free(res);
 120             return;
 121         }
 122
 123         pp = &res->prev;
 124     }
 125 }
 126
 127 static void dummy_release(void *data)
 128 {
 129     (void) data;
 130 }
 131
 132 static bool ptrcmp(void *a, void *b)
 133 {
 134     return a == b;
 135 }
 136
 137 void *vlc_obj_malloc(vlc_object_t *obj, size_t size)
 138 {
 139     void *ptr = vlc_objres_new(size, dummy_release);
 140     if (likely(ptr != NULL))
 141         vlc_objres_push(obj, ptr);
 142     return ptr;
 143 }
 144
 145 void *vlc_obj_calloc(vlc_object_t *obj, size_t nmemb, size_t size)
 146 {
 147     size_t tabsize;
 148     if (unlikely(mul_overflow(nmemb, size, &tabsize)))
 149     {
 150         errno = ENOMEM;
 151         return NULL;
 152     }
 153
 154     void *ptr = vlc_obj_malloc(obj, tabsize);
 155     if (likely(ptr != NULL))
 156         memset(ptr, 0, tabsize);
 157     return ptr;
 158 }
 159
 160 static void *vlc_obj_memdup(vlc_object_t *obj, const void *base, size_t len)
 161 {
 162     void *ptr = vlc_obj_malloc(obj, len);
 163     if (likely(ptr != NULL))
 164         memcpy(ptr, base, len);
 165     return ptr;
 166 }
 167
 168 char *vlc_obj_strdup(vlc_object_t *obj, const char *str)
 169 {
 170     return vlc_obj_memdup(obj, str, strlen(str) + 1);
 171 }
 172
 173 void vlc_obj_free(vlc_object_t *obj, void *ptr)
 174 {
 175     vlc_objres_remove(obj, ptr, ptrcmp);
 176 }