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probe.c

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00001 /*
00002  * probe.c
00003  * Copyright 2009-2010 John Lindgren
00004  *
00005  * This file is part of Audacious.
00006  *
00007  * Audacious is free software: you can redistribute it and/or modify it under
00008  * the terms of the GNU General Public License as published by the Free Software
00009  * Foundation, version 2 or version 3 of the License.
00010  *
00011  * Audacious is distributed in the hope that it will be useful, but WITHOUT ANY
00012  * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
00013  * A PARTICULAR PURPOSE. See the GNU General Public License for more details.
00014  *
00015  * You should have received a copy of the GNU General Public License along with
00016  * Audacious. If not, see <http://www.gnu.org/licenses/>.
00017  *
00018  * The Audacious team does not consider modular code linking to Audacious or
00019  * using our public API to be a derived work.
00020  */
00021 
00022 #include <stdio.h>
00023 #include <string.h>
00024 
00025 #include <libaudcore/audstrings.h>
00026 
00027 #include "debug.h"
00028 #include "misc.h"
00029 #include "playlist.h"
00030 #include "plugin.h"
00031 #include "plugins.h"
00032 #include "probe-buffer.h"
00033 
00034 typedef struct
00035 {
00036     gchar * filename;
00037     VFSFile * handle;
00038     gboolean buffered;
00039     PluginHandle * plugin;
00040 }
00041 ProbeState;
00042 
00043 static gboolean check_opened (ProbeState * state)
00044 {
00045     if (state->handle != NULL)
00046         return TRUE;
00047 
00048     AUDDBG ("Opening %s.\n", state->filename);
00049     if ((state->buffered = vfs_is_remote (state->filename)))
00050         state->handle = probe_buffer_new (state->filename);
00051     else
00052         state->handle = vfs_fopen (state->filename, "r");
00053 
00054     if (state->handle != NULL)
00055         return TRUE;
00056 
00057     AUDDBG ("FAILED.\n");
00058     return FALSE;
00059 }
00060 
00061 static gboolean probe_func (PluginHandle * plugin, ProbeState * state)
00062 {
00063     AUDDBG ("Trying %s.\n", plugin_get_name (plugin));
00064     InputPlugin * decoder = plugin_get_header (plugin);
00065     if (decoder == NULL)
00066         return TRUE;
00067 
00068     if (decoder->is_our_file_from_vfs != NULL)
00069     {
00070         if (! check_opened (state))
00071             return FALSE;
00072 
00073         if (state->buffered)
00074             probe_buffer_set_decoder (state->handle, plugin_get_name (plugin));
00075 
00076         if (decoder->is_our_file_from_vfs (state->filename, state->handle))
00077         {
00078             state->plugin = plugin;
00079             return FALSE;
00080         }
00081 
00082         if (vfs_fseek (state->handle, 0, SEEK_SET) < 0)
00083             return FALSE;
00084     }
00085     else if (decoder->is_our_file != NULL)
00086     {
00087         if (decoder->is_our_file (state->filename))
00088         {
00089             state->plugin = plugin;
00090             return FALSE;
00091         }
00092     }
00093 
00094     return TRUE;
00095 }
00096 
00097 /* Optimization: If we have found plugins with a key match, assume that at least
00098  * one of them will succeed.  This means that we need not check the very last
00099  * plugin.  (If there is only one, we do not need to check it at all.)  This is
00100  * implemented as follows:
00101  *
00102  * 1. On the first call, assume until further notice the plugin passed is the
00103  *    last one and will therefore succeed.
00104  * 2. On a subsequent call, think twice and probe the plugin we assumed would
00105  *    succeed.  If it does in fact succeed, then we are done.  If not, assume
00106  *    similarly that the plugin passed in this call is the last one.
00107  */
00108 
00109 static gboolean probe_func_fast (PluginHandle * plugin, ProbeState * state)
00110 {
00111     if (state->plugin != NULL)
00112     {
00113         PluginHandle * prev = state->plugin;
00114         state->plugin = NULL;
00115 
00116         if (prev != NULL && ! probe_func (prev, state))
00117             return FALSE;
00118     }
00119 
00120     AUDDBG ("Guessing %s.\n", plugin_get_name (plugin));
00121     state->plugin = plugin;
00122     return TRUE;
00123 }
00124 
00125 static void probe_by_scheme (ProbeState * state)
00126 {
00127     gchar * s = strstr (state->filename, "://");
00128     gchar c;
00129 
00130     if (s == NULL)
00131         return;
00132 
00133     AUDDBG ("Probing by scheme.\n");
00134     c = s[3];
00135     s[3] = 0;
00136     input_plugin_for_key (INPUT_KEY_SCHEME, state->filename, (PluginForEachFunc)
00137      probe_func_fast, state);
00138     s[3] = c;
00139 }
00140 
00141 static void probe_by_extension (ProbeState * state)
00142 {
00143     gchar * s = strrchr (state->filename, '.');
00144 
00145     if (s == NULL)
00146         return;
00147 
00148     AUDDBG ("Probing by extension.\n");
00149     s = g_ascii_strdown (s + 1, -1);
00150 
00151     gchar * q = strrchr (s, '?');
00152     if (q != NULL)
00153         * q = 0;
00154 
00155     input_plugin_for_key (INPUT_KEY_EXTENSION, s, (PluginForEachFunc)
00156      probe_func_fast, state);
00157     g_free (s);
00158 }
00159 
00160 static void probe_by_mime (ProbeState * state)
00161 {
00162     gchar * mime;
00163 
00164     if (! check_opened (state))
00165         return;
00166 
00167     if ((mime = vfs_get_metadata (state->handle, "content-type")) == NULL)
00168         return;
00169 
00170     AUDDBG ("Probing by MIME type.\n");
00171     input_plugin_for_key (INPUT_KEY_MIME, mime, (PluginForEachFunc)
00172      probe_func_fast, state);
00173     g_free (mime);
00174 }
00175 
00176 static void probe_by_content (ProbeState * state)
00177 {
00178     AUDDBG ("Probing by content.\n");
00179     plugin_for_each (PLUGIN_TYPE_INPUT, (PluginForEachFunc) probe_func, state);
00180 }
00181 
00182 InputPlugin * file_find_decoder (const gchar * filename, gboolean fast)
00183 {
00184     ProbeState state;
00185 
00186     AUDDBG ("Probing %s.\n", filename);
00187     state.plugin = NULL;
00188     state.filename = filename_split_subtune (filename, NULL);
00189     state.handle = NULL;
00190 
00191     probe_by_scheme (& state);
00192 
00193     if (state.plugin != NULL)
00194         goto DONE;
00195 
00196     probe_by_extension (& state);
00197 
00198     if (state.plugin != NULL || fast)
00199         goto DONE;
00200 
00201     probe_by_mime (& state);
00202 
00203     if (state.plugin != NULL)
00204         goto DONE;
00205 
00206     probe_by_content (& state);
00207 
00208 DONE:
00209     g_free (state.filename);
00210 
00211     if (state.handle != NULL)
00212         vfs_fclose (state.handle);
00213 
00214     return (state.plugin != NULL) ? plugin_get_header (state.plugin) : NULL;
00215 }
00216 
00217 Tuple * file_read_tuple (const gchar * filename, InputPlugin * decoder)
00218 {
00219     if (decoder->get_song_tuple != NULL)
00220         return decoder->get_song_tuple (filename);
00221 
00222     if (decoder->probe_for_tuple != NULL)
00223     {
00224         VFSFile * handle = vfs_fopen (filename, "r");
00225         Tuple * tuple;
00226 
00227         if (handle == NULL)
00228             return NULL;
00229 
00230         tuple = decoder->probe_for_tuple (filename, handle);
00231         vfs_fclose (handle);
00232         return tuple;
00233     }
00234 
00235     return NULL;
00236 }
00237 
00238 gboolean file_read_image (const gchar * filename, InputPlugin * decoder,
00239  void * * data, gint * size)
00240 {
00241     VFSFile * handle;
00242     gboolean success;
00243 
00244     if (decoder->get_song_image == NULL)
00245         return FALSE;
00246 
00247     handle = vfs_fopen (filename, "r");
00248     success = decoder->get_song_image (filename, handle, data, size);
00249 
00250     if (handle != NULL)
00251         vfs_fclose (handle);
00252 
00253     return success;
00254 }
00255 
00256 gboolean file_can_write_tuple (const gchar * filename, InputPlugin * decoder)
00257 {
00258     return (decoder->update_song_tuple != NULL);
00259 }
00260 
00261 gboolean file_write_tuple (const gchar * filename, InputPlugin * decoder,
00262  const Tuple * tuple)
00263 {
00264     VFSFile * handle;
00265     gboolean success;
00266 
00267     if (decoder->update_song_tuple == NULL)
00268         return FALSE;
00269 
00270     handle = vfs_fopen (filename, "r+");
00271 
00272     if (handle == NULL)
00273         return FALSE;
00274 
00275     success = decoder->update_song_tuple (tuple, handle);
00276     vfs_fclose (handle);
00277 
00278     if (success)
00279         playlist_rescan_file (filename);
00280 
00281     return success;
00282 }
00283 
00284 gboolean custom_infowin (const gchar * filename, InputPlugin * decoder)
00285 {
00286     if (decoder->file_info_box == NULL)
00287         return FALSE;
00288 
00289     decoder->file_info_box (filename);
00290     return TRUE;
00291 }

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