text: /*
   * 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 "avio_internal.h"
  #include "apetag.h"
  #include "internal.h"
  
  #define APE_TAG_FLAG_CONTAINS_HEADER  (1 << 31)
  #define APE_TAG_FLAG_CONTAINS_FOOTER  (1 << 30)
  #define APE_TAG_FLAG_IS_HEADER        (1 << 29)
  #define APE_TAG_FLAG_IS_BINARY        (1 << 1)
  
  static int ape_tag_read_field(AVFormatContext *s)
  {
      AVIOContext *pb = s->pb;
      uint8_t key[1024], *value;
      uint32_t size, flags;
      int i, c;
  
      size = avio_rl32(pb);  /* field size */
      flags = avio_rl32(pb); /* 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;
      if (flags & APE_TAG_FLAG_IS_BINARY) {
          uint8_t filename[1024];
          enum AVCodecID id;
          AVStream *st = avformat_new_stream(s, NULL);
          if (!st)
              return AVERROR(ENOMEM);
  
          size -= avio_get_str(pb, size, filename, sizeof(filename));
          if (size <= 0) {
              av_log(s, AV_LOG_WARNING, "Skipping binary tag '%s'.\n", key);
              return 0;
          }
  
          av_dict_set(&st->metadata, key, filename, 0);
  
          if ((id = ff_guess_image2_codec(filename)) != AV_CODEC_ID_NONE) {
              AVPacket pkt;
              int ret;
  
              ret = av_get_packet(s->pb, &pkt, size);
              if (ret < 0) {
                  av_log(s, AV_LOG_ERROR, "Error reading cover art.\n");
                  return ret;
              }
  
              st->disposition      |= AV_DISPOSITION_ATTACHED_PIC;
              st->codec->codec_type = AVMEDIA_TYPE_VIDEO;
              st->codec->codec_id   = id;
  
              st->attached_pic              = pkt;
              st->attached_pic.stream_index = st->index;
              st->attached_pic.flags       |= AV_PKT_FLAG_KEY;
          } else {
              st->codec->extradata = av_malloc(size + FF_INPUT_BUFFER_PADDING_SIZE);
              if (!st->codec->extradata)
                  return AVERROR(ENOMEM);
              if (avio_read(pb, st->codec->extradata, size) != size) {
                  av_freep(&st->codec->extradata);
                  return AVERROR(EIO);
              }
              st->codec->extradata_size = size;
              st->codec->codec_type = AVMEDIA_TYPE_ATTACHMENT;
          }
      } else {
          value = av_malloc(size+1);
          if (!value)
              return AVERROR(ENOMEM);
          c = avio_read(pb, value, size);
          if (c < 0) {
              av_free(value);
              return c;
          }
          value[c] = 0;
          av_dict_set(&s->metadata, key, value, AV_DICT_DONT_STRDUP_VAL);
      }
      return 0;
  }
  
  int64_t ff_ape_parse_tag(AVFormatContext *s)
  {
      AVIOContext *pb = s->pb;
      int64_t file_size = avio_size(pb);
      uint32_t val, fields, tag_bytes;
      uint8_t buf[8];
      int64_t tag_start;
      int i;
  
      if (file_size < APE_TAG_FOOTER_BYTES)
          return 0;
  
      avio_seek(pb, file_size - APE_TAG_FOOTER_BYTES, SEEK_SET);
  
      avio_read(pb, buf, 8);     /* APETAGEX */
      if (strncmp(buf, APE_TAG_PREAMBLE, 8)) {
          return 0;
      }
  
      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 0;
      }
  
      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 0;
      }
  
      if (tag_bytes > file_size - APE_TAG_FOOTER_BYTES) {
          av_log(s, AV_LOG_ERROR, "Invalid tag size %u.\n", tag_bytes);
          return 0;
      }
      tag_start = file_size - tag_bytes - APE_TAG_FOOTER_BYTES;
  
      fields = avio_rl32(pb);    /* number of fields */
      if (fields > 65536) {
          av_log(s, AV_LOG_ERROR, "Too many tag fields (%d)\n", fields);
          return 0;
      }
  
      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 0;
      }
  
      avio_seek(pb, file_size - tag_bytes, SEEK_SET);
  
      for (i=0; i<fields; i++)
          if (ape_tag_read_field(s) < 0) break;
  
      return tag_start;
  }
  
  static int string_is_ascii(const uint8_t *str)
  {
      while (*str && *str >= 0x20 && *str <= 0x7e ) str++;
      return !*str;
  }
  
  int ff_ape_write_tag(AVFormatContext *s)
  {
      AVDictionaryEntry *e = NULL;
      int size, ret, count = 0;
      AVIOContext *dyn_bc = NULL;
      uint8_t *dyn_buf = NULL;
  
      if ((ret = avio_open_dyn_buf(&dyn_bc)) < 0)
          goto end;
  
      // flags
      avio_wl32(dyn_bc, APE_TAG_FLAG_CONTAINS_HEADER | APE_TAG_FLAG_CONTAINS_FOOTER |
                       APE_TAG_FLAG_IS_HEADER);
      ffio_fill(dyn_bc, 0, 8);             // reserved
  
      while ((e = av_dict_get(s->metadata, "", e, AV_DICT_IGNORE_SUFFIX))) {
          int val_len;
  
          if (!string_is_ascii(e->key)) {
              av_log(s, AV_LOG_WARNING, "Non ASCII keys are not allowed\n");
              continue;
          }
  
          val_len = strlen(e->value);
          avio_wl32(dyn_bc, val_len);            // value length
          avio_wl32(dyn_bc, 0);                  // item flags
          avio_put_str(dyn_bc, e->key);          // key
          avio_write(dyn_bc, e->value, val_len); // value
          count++;
      }
      if (!count)
          goto end;
  
      size = avio_close_dyn_buf(dyn_bc, &dyn_buf);
      if (size <= 0)
          goto end;
      size += 20;
  
      // header
      avio_write(s->pb, "APETAGEX", 8);   // id
      avio_wl32(s->pb, APE_TAG_VERSION);  // version
      avio_wl32(s->pb, size);
      avio_wl32(s->pb, count);
  
      avio_write(s->pb, dyn_buf, size - 20);
  
      // footer
      avio_write(s->pb, "APETAGEX", 8);   // id
      avio_wl32(s->pb, APE_TAG_VERSION);  // version
      avio_wl32(s->pb, size);             // size
      avio_wl32(s->pb, count);            // tag count
  
      // flags
      avio_wl32(s->pb, APE_TAG_FLAG_CONTAINS_HEADER | APE_TAG_FLAG_CONTAINS_FOOTER);
      ffio_fill(s->pb, 0, 8);             // reserved
  
  end:
      if (dyn_bc && !dyn_buf)
          avio_close_dyn_buf(dyn_bc, &dyn_buf);
      av_freep(&dyn_buf);
  
      return ret;
  }
  