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 char *get_error (void)
  34 {
  35     return vlc_threadvar_get (context);
  36 }
  37
  38 static void free_msg (void *msg)
  39 {
  40     if (msg != oom)
  41         free (msg);
  42 }
  43
  44 static void free_error (void)
  45 {
  46     free_msg (get_error ());
  47 }
  48
  49 static vlc_mutex_t lock = VLC_STATIC_MUTEX;
  50 static uintptr_t refs = 0;
  51
  52 void libvlc_threads_init (void)
  53 {
  54     vlc_mutex_lock (&lock);
  55     if (refs++ == 0)
  56         vlc_threadvar_create (&context, free_msg);
  57     vlc_mutex_unlock (&lock);
  58 }
  59
  60 void libvlc_threads_deinit (void)
  61 {
  62     vlc_mutex_lock (&lock);
  63     assert (refs > 0);
  64     if (--refs == 0)
  65     {
  66         free_error ();
  67         vlc_threadvar_delete (&context);
  68     }
  69     vlc_mutex_unlock (&lock);
  70 }
  71
  72 /**
  73  * Gets a human-readable error message for the last LibVLC error in the calling
  74  * thread. The resulting string is valid until another error occurs (at least
  75  * until the next LibVLC call).
  76  *
  77  * @return NULL if there was no error, a nul-terminated string otherwise.
  78  */
  79 const char *libvlc_errmsg (void)
  80 {
  81     return get_error ();
  82 }
  83
  84 /**
  85  * Clears the LibVLC error status for the current thread. This is optional.
  86  * By default, the error status is automatically overridden when a new error
  87  * occurs, and destroyed when the thread exits.
  88  */
  89 void libvlc_clearerr (void)
  90 {
  91     free_error ();
  92     vlc_threadvar_set (context, NULL);
  93 }
  94
  95 /**
  96  * Sets the LibVLC error status and message for the current thread.
  97  * Any previous error is overridden.
  98  * @return a nul terminated string (always)
  99  */
 100 const char *libvlc_vprinterr (const char *fmt, va_list ap)
 101 {
 102     char *msg;
 103
 104     assert (fmt != NULL);
 105     if (vasprintf (&msg, fmt, ap) == -1)
 106         msg = (char *)oom;
 107
 108     free_error ();
 109     vlc_threadvar_set (context, msg);
 110     return msg;
 111 }
 112
 113 /**
 114  * Sets the LibVLC error status and message for the current thread.
 115  * Any previous error is overridden.
 116  * @return a nul terminated string (always)
 117  */
 118 const char *libvlc_printerr (const char *fmt, ...)
 119 {
 120     va_list ap;
 121     const char *msg;
 122
 123     va_start (ap, fmt);
 124     msg = libvlc_vprinterr (fmt, ap);
 125     va_end (ap);
 126     return msg;
 127 }
 128