src/misc/sort.c

   1 /******************************************************************************
   2  * sort.c: sort back-end
   3  ******************************************************************************
   4  * Copyright © 2019 VLC authors and VideoLAN
   5  * Copyright © 2018 Rémi Denis-Courmont
   6  *
   7  * This program is free software; you can redistribute it and/or modify it
   8  * under the terms of the GNU Lesser General Public License as published by
   9  * the Free Software Foundation; either version 2.1 of the License, or
  10  * (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  15  * GNU Lesser General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General Public License
  18  * along with this program; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  20  *****************************************************************************/
  21
  22 #ifdef HAVE_CONFIG_H
  23 # include <config.h>
  24 #endif
  25
  26 #include <vlc_common.h>
  27 #include <vlc_sort.h>
  28
  29 static thread_local struct
  30 {
  31     int (*compar)(const void *, const void *, void *);
  32     void *arg;
  33 } state;
  34
  35 static int compar_wrapper(const void *a, const void *b)
  36 {
  37     return state.compar(a, b, state.arg);
  38 }
  39
  40 /* Follow the upcoming POSIX prototype, coming from GNU/libc.
  41  * Note that this differs from the BSD prototype. */
  42
  43 VLC_WEAK void vlc_qsort(void *base, size_t nmemb, size_t size,
  44                         int (*compar)(const void *, const void *, void *),
  45                         void *arg)
  46 {
  47     int (*saved_compar)(const void *, const void *, void *) = state.compar;
  48     void *saved_arg = state.arg;
  49
  50     state.compar = compar;
  51     state.arg = arg;
  52
  53     qsort(base, nmemb, size, compar_wrapper);
  54
  55     /* Restore state for nested reentrant calls */
  56     state.compar = saved_compar;
  57     state.arg = saved_arg;
  58 }