/*
  * APE tag handling
  * Copyright (c) 2007 Benjamin Zores <ben@geexbox.org>
  *  based upon libdemac from Dave Chapman.
  *
  * This file is part of FFmpeg.
  *
  * FFmpeg 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.
  *
  * FFmpeg 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 FFmpeg; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
 #include "libavutil/intreadwrite.h"

 #include "libavutil/dict.h"

 #include "avformat.h"

 #include "apetag.h"

 
 #define APE_TAG_VERSION               2000
 #define APE_TAG_FOOTER_BYTES          32
 #define APE_TAG_FLAG_CONTAINS_HEADER  (1 << 31)
 #define APE_TAG_FLAG_IS_HEADER        (1 << 29)
 
 static int ape_tag_read_field(AVFormatContext *s)
 {

     AVIOContext *pb = s->pb;

     uint8_t key[1024], *value;

     uint32_t size;

     int i, c;

     size = avio_rl32(pb);  /* field size */

     avio_skip(pb, 4);      /* field flags */

     for (i = 0; i < sizeof(key) - 1; i++) {

         c = avio_r8(pb);

         if (c < 0x20 || c > 0x7E)
             break;
         else
             key[i] = c;
     }
     key[i] = 0;
     if (c != 0) {
         av_log(s, AV_LOG_WARNING, "Invalid APE tag key '%s'.\n", key);
         return -1;
     }

     if (size >= UINT_MAX)
         return -1;
     value = av_malloc(size+1);
     if (!value)

         return AVERROR(ENOMEM);

     avio_read(pb, value, size);

     value[size] = 0;

     av_dict_set(&s->metadata, key, value, AV_DICT_DONT_STRDUP_VAL);

     return 0;
 }
 
 void ff_ape_parse_tag(AVFormatContext *s)
 {

     AVIOContext *pb = s->pb;

     int file_size = avio_size(pb);

     uint32_t val, fields, tag_bytes;
     uint8_t buf[8];
     int i;
 
     if (file_size < APE_TAG_FOOTER_BYTES)
         return;
 

     avio_seek(pb, file_size - APE_TAG_FOOTER_BYTES, SEEK_SET);

     avio_read(pb, buf, 8);     /* APETAGEX */

     if (strncmp(buf, "APETAGEX", 8)) {
         return;
     }
 

     val = avio_rl32(pb);       /* APE tag version */

     if (val > APE_TAG_VERSION) {
         av_log(s, AV_LOG_ERROR, "Unsupported tag version. (>=%d)\n", APE_TAG_VERSION);
         return;
     }
 

     tag_bytes = avio_rl32(pb); /* tag size */

     if (tag_bytes - APE_TAG_FOOTER_BYTES > (1024 * 1024 * 16)) {
         av_log(s, AV_LOG_ERROR, "Tag size is way too big\n");
         return;
     }
 

     fields = avio_rl32(pb);    /* number of fields */

     if (fields > 65536) {
         av_log(s, AV_LOG_ERROR, "Too many tag fields (%d)\n", fields);
         return;
     }
 

     val = avio_rl32(pb);       /* flags */

     if (val & APE_TAG_FLAG_IS_HEADER) {
         av_log(s, AV_LOG_ERROR, "APE Tag is a header\n");
         return;
     }
 

     avio_seek(pb, file_size - tag_bytes, SEEK_SET);

 
     for (i=0; i<fields; i++)
         if (ape_tag_read_field(s) < 0) break;
 }