fix album art caching for files without artist/album tags

Closes: #5298
If a file has no metadata, but has a download URL, we download the image
and cache it using only the URL.
Thus files with attachments and empty tags always used the same image,
because we matched the image to the URL "attachment://X"

Add the title (or file name as fallback) to the cache name when using
attachments for files without artist/album meta.

src/playlist/art.c

@@ -63,7 +63,7 @@ static void ArtCacheCreateDir( const char *psz_dir )
 }
 
 static char* ArtCacheGetDirPath( const char *psz_arturl, const char *psz_artist,
-                                 const char *psz_album )
+                                 const char *psz_album,  const char *psz_title )
 {
     char *psz_dir;
     char *psz_cachedir = config_GetUserDir(VLC_CACHE_DIR);
@@ -83,14 +83,19 @@ static char* ArtCacheGetDirPath( const char *psz_arturl, const char *psz_artist,
     }
     else
     {
-        /* If artist or album missing cache by art download URL. The download
-           URL will be md5 hashed to form a valid cache filename. We assume that
-           psz_arturl is always the download URL and not the already hashed filename.
-           (We should never need to call this function if art has already been
-           downloaded anyway). */
+        /* If artist or album are missing, cache by art download URL.
+         * If the URL is an attachment://, add the title to the cache name.
+         * It will be md5 hashed to form a valid cache filename.
+         * We assume that psz_arturl is always the download URL and not the
+         * already hashed filename.
+         * (We should never need to call this function if art has already been
+         * downloaded anyway).
+         */
         struct md5_s md5;
         InitMD5( &md5 );
         AddMD5( &md5, psz_arturl, strlen( psz_arturl ) );
+        if( !strncmp( psz_arturl, "attachment://", 13 ) )
+            AddMD5( &md5, psz_title, strlen( psz_title ) );
         EndMD5( &md5 );
         char * psz_arturl_sanitized = psz_md5_hash( &md5 );
         if( asprintf( &psz_dir, "%s" DIR_SEP "art" DIR_SEP "arturl" DIR_SEP
@@ -108,6 +113,7 @@ static char *ArtCachePath( input_item_t *p_item )
     const char *psz_artist;
     const char *psz_album;
     const char *psz_arturl;
+    const char *psz_title;
 
     vlc_mutex_lock( &p_item->lock );
 
@@ -119,11 +125,15 @@ static char *ArtCachePath( input_item_t *p_item )
     psz_artist = vlc_meta_Get( p_item->p_meta, vlc_meta_Artist );
     psz_album = vlc_meta_Get( p_item->p_meta, vlc_meta_Album );
     psz_arturl = vlc_meta_Get( p_item->p_meta, vlc_meta_ArtworkURL );
+    psz_title = vlc_meta_Get( p_item->p_meta, vlc_meta_Title );
+    if( !psz_title )
+        psz_title = p_item->psz_name;
+
 
     if( (EMPTY_STR(psz_artist) || EMPTY_STR(psz_album) ) && !psz_arturl )
         goto end;
 
-    psz_path = ArtCacheGetDirPath( psz_arturl, psz_artist, psz_album );
+    psz_path = ArtCacheGetDirPath( psz_arturl, psz_artist, psz_album, psz_title );
 
 end:
     vlc_mutex_unlock( &p_item->lock );