lib/error.c

   1 /*****************************************************************************
   2  * error.c: Error handling for libvlc
   3  *****************************************************************************
   4  * Copyright (C) 2009 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 #include "libvlc_internal.h"
  22
  23 #include <stdarg.h>
  24 #include <stdio.h>
  25 #include <assert.h>
  26 #include <vlc/libvlc.h>
  27
  28
  29 static const char oom[] = "Out of memory";
  30 /* TODO: use only one thread-specific key for whole libvlc */
  31 static vlc_threadvar_t context;
  32
  33 static vlc_mutex_t lock = VLC_STATIC_MUTEX;
  34 static uintptr_t refs = 0;
  35
  36 void libvlc_threads_init (void)
  37 {
  38     vlc_mutex_lock (&lock);
  39     if (refs++ == 0)
  40         vlc_threadvar_create (&context, free);
  41     vlc_mutex_unlock (&lock);
  42 }
  43
  44 void libvlc_threads_deinit (void)
  45 {
  46     vlc_mutex_lock (&lock);
  47     assert (refs > 0);
  48     if (--refs == 0)
  49         vlc_threadvar_delete (&context);
  50     vlc_mutex_unlock (&lock);
  51 }
  52
  53 static char *get_error (void)
  54 {
  55     return vlc_threadvar_get (context);
  56 }
  57
  58 static void free_error (void)
  59 {
  60     char *msg = get_error ();
  61     if (msg != oom)
  62         free (msg);
  63 }
  64
  65 /**
  66  * Gets a human-readable error message for the last LibVLC error in the calling
  67  * thread. The resulting string is valid until another error occurs (at least
  68  * until the next LibVLC call).
  69  *
  70  * @return NULL if there was no error, a nul-terminated string otherwise.
  71  */
  72 const char *libvlc_errmsg (void)
  73 {
  74     return get_error ();
  75 }
  76
  77 /**
  78  * Clears the LibVLC error status for the current thread. This is optional.
  79  * By default, the error status is automatically overridden when a new error
  80  * occurs, and destroyed when the thread exits.
  81  */
  82 void libvlc_clearerr (void)
  83 {
  84     free_error ();
  85     vlc_threadvar_set (context, NULL);
  86 }
  87
  88 /**
  89  * Sets the LibVLC error status and message for the current thread.
  90  * Any previous error is overridden.
  91  * @return a nul terminated string (always)
  92  */
  93 const char *libvlc_vprinterr (const char *fmt, va_list ap)
  94 {
  95     char *msg;
  96
  97     assert (fmt != NULL);
  98     if (vasprintf (&msg, fmt, ap) == -1)
  99         msg = (char *)oom;
 100
 101     free_error ();
 102     vlc_threadvar_set (context, msg);
 103     return msg;
 104 }
 105
 106 /**
 107  * Sets the LibVLC error status and message for the current thread.
 108  * Any previous error is overridden.
 109  * @return a nul terminated string (always)
 110  */
 111 const char *libvlc_printerr (const char *fmt, ...)
 112 {
 113     va_list ap;
 114     const char *msg;
 115
 116     va_start (ap, fmt);
 117     msg = libvlc_vprinterr (fmt, ap);
 118     va_end (ap);
 119     return msg;
 120 }
 121