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 void libvlc_setup_threads (bool init)
  34 {
  35     static vlc_mutex_t lock = VLC_STATIC_MUTEX;
  36     static uintptr_t refs = 0;
  37
  38     vlc_mutex_lock (&lock);
  39     if (init)
  40     {
  41         if (refs++ == 0)
  42             vlc_threadvar_create (&context, free);
  43     }
  44     else
  45     {
  46         assert (refs > 0);
  47         if (--refs == 0)
  48             vlc_threadvar_delete (&context);
  49     }
  50     vlc_mutex_unlock (&lock);
  51 }
  52
  53 void libvlc_init_threads (void)
  54 {
  55     libvlc_setup_threads (true);
  56 }
  57
  58 void libvlc_deinit_threads (void)
  59 {
  60     libvlc_setup_threads (false);
  61 }
  62
  63 static char *get_error (void)
  64 {
  65     return vlc_threadvar_get (context);
  66 }
  67
  68 static void free_error (void)
  69 {
  70     char *msg = get_error ();
  71     if (msg != oom)
  72         free (msg);
  73 }
  74
  75 /**
  76  * Gets a human-readable error message for the last LibVLC error in the calling
  77  * thread. The resulting string is valid until another error occurs (at least
  78  * until the next LibVLC call).
  79  *
  80  * @return NULL if there was no error, a nul-terminated string otherwise.
  81  */
  82 const char *libvlc_errmsg (void)
  83 {
  84     return get_error ();
  85 }
  86
  87 /**
  88  * Clears the LibVLC error status for the current thread. This is optional.
  89  * By default, the error status is automatically overridden when a new error
  90  * occurs, and destroyed when the thread exits.
  91  */
  92 void libvlc_clearerr (void)
  93 {
  94     free_error ();
  95     vlc_threadvar_set (context, NULL);
  96 }
  97
  98 /**
  99  * Sets the LibVLC error status and message for the current thread.
 100  * Any previous error is overridden.
 101  * @return a nul terminated string (always)
 102  */
 103 const char *libvlc_vprinterr (const char *fmt, va_list ap)
 104 {
 105     char *msg;
 106
 107     assert (fmt != NULL);
 108     if (vasprintf (&msg, fmt, ap) == -1)
 109         msg = (char *)oom;
 110
 111     free_error ();
 112     vlc_threadvar_set (context, msg);
 113     return msg;
 114 }
 115
 116 /**
 117  * Sets the LibVLC error status and message for the current thread.
 118  * Any previous error is overridden.
 119  * @return a nul terminated string (always)
 120  */
 121 const char *libvlc_printerr (const char *fmt, ...)
 122 {
 123     va_list ap;
 124     const char *msg;
 125
 126     va_start (ap, fmt);
 127     msg = libvlc_vprinterr (fmt, ap);
 128     va_end (ap);
 129     return msg;
 130 }
 131