meta: add ID3 parsing helper

modules/meta_engine/ID3Tag.h

@@ -0,0 +1,80 @@
+/*****************************************************************************
+ * ID3Tag.h : ID3v2 Parsing Helper
+ *****************************************************************************
+ * Copyright (C) 2016 VLC authors and VideoLAN
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation; either version 2.1 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
+ *****************************************************************************/
+#ifndef ID3TAG_H
+#define ID3TAG_H
+
+static uint32_t ID3TAG_ReadSize( const uint8_t *p_buffer, bool b_syncsafe )
+{
+    if( !b_syncsafe )
+        return GetDWBE( p_buffer );
+    return ( (uint32_t)p_buffer[3] & 0x7F ) |
+            (( (uint32_t)p_buffer[2] & 0x7F ) << 7) |
+            (( (uint32_t)p_buffer[1] & 0x7F ) << 14) |
+            (( (uint32_t)p_buffer[0] & 0x7F ) << 21);
+}
+
+static bool ID3TAG_IsTag( const uint8_t *p_buffer, bool b_footer )
+{
+    return( memcmp(p_buffer, (b_footer) ? "3DI" : "ID3", 3) == 0 &&
+            p_buffer[3] < 0xFF &&
+            p_buffer[4] < 0xFF &&
+           ((GetDWBE(&p_buffer[6]) & 0x80808080) == 0) );
+}
+
+static size_t ID3TAG_Parse( const uint8_t *p_peek, size_t i_peek,
+                            int (*pf_callback)(uint32_t, const uint8_t *, size_t, void *), void *p_priv )
+{
+    size_t i_total_size = 0;
+    uint32_t i_ID3size = 0;
+    if( i_peek > 10 && ID3TAG_IsTag( p_peek, false ) )
+    {
+        const bool b_syncsafe = p_peek[5] & 0x80;
+        i_ID3size = ID3TAG_ReadSize( &p_peek[6], true );
+        if( i_ID3size > i_peek - 10 )
+            return 0;
+        i_total_size = i_ID3size + 10;
+        const uint8_t *p_frame = &p_peek[10];
+        while( i_ID3size > 10 )
+        {
+            uint32_t i_tagname = VLC_FOURCC( p_frame[0], p_frame[1], p_frame[2], p_frame[3] );
+            uint32_t i_framesize = ID3TAG_ReadSize( &p_frame[4], b_syncsafe ) + 10;
+            if( i_framesize > i_ID3size )
+                return 0;
+
+            if( i_framesize > 10 &&
+                pf_callback( i_tagname, &p_frame[10], i_framesize - 10, p_priv ) != VLC_SUCCESS )
+                break;
+
+            p_frame += i_framesize;
+            i_ID3size -= i_framesize;
+        }
+    }
+
+    /* Count footer if any */
+    if( i_total_size && i_peek - i_total_size >= 10 &&
+        ID3TAG_IsTag( &p_peek[i_total_size], true ) )
+    {
+        i_total_size += 10;
+    }
+
+    return i_total_size;
+}
+
+#endif // ID3TAG_H