tag_parse.cpp

FreeAMP(MP3播放)程序源代码-用来研究MP3解码

// $Id: tag_parse.cpp,v 1.2 2001/01/16 21:08:01 robert Exp $

// id3lib: a C++ library for creating and manipulating id3v1/v2 tags
// Copyright 1999, 2000  Scott Thomas Haug

// This library is free software; you can redistribute it and/or modify it
// under the terms of the GNU Library General Public License as published by
// the Free Software Foundation; either version 2 of the License, or (at your
// option) any later version.
//
// This library 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 Library General Public
// License for more details.
//
// You should have received a copy of the GNU Library General Public License
// along with this library; if not, write to the Free Software Foundation,
// Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

// The id3lib authors encourage improvements and optimisations to be sent to
// the id3lib coordinator.  Please see the README file for details on where to
// send such submissions.  See the AUTHORS file for a list of people who have
// contributed to id3lib.  See the ChangeLog file for a list of changes to
// id3lib.  These files are distributed with id3lib at
// http://download.sourceforge.net/id3lib/

#include "config.h"
#include "id3config.h"
#ifdef HAVE_ZLIB
#include <zlib.h>
#endif
#include <string.h>
#include <memory.h>

#include "tag_impl.h"
#include "utils.h"
#include "io_decorators.h"
#include "io_helpers.h"
#include "io_strings.h"
#include "readers.h"

using namespace dami;

namespace
{
  bool parseFrames(ID3_TagImpl& tag, ID3_Reader& rdr)
  { 
    ID3_Reader::pos_type beg = rdr.getCur();
    io::ExitTrigger et(rdr, beg);
    ID3_Reader::pos_type last_pos = beg;
    size_t totalSize = 0; 
    size_t frameSize = 0; 
    while (!rdr.atEnd() && rdr.peekChar() != '\0')
    { 
      ID3D_NOTICE( "id3::v2::parseFrames(): rdr.getBeg() = " << rdr.getBeg() );
      ID3D_NOTICE( "id3::v2::parseFrames(): rdr.getCur() = " << rdr.getCur() );
      ID3D_NOTICE( "id3::v2::parseFrames(): rdr.getEnd() = " << rdr.getEnd() );
      last_pos = rdr.getCur();
      ID3_Frame* f = new ID3_Frame; 
      f->SetSpec(tag.GetSpec());
      bool goodParse = f->Parse(rdr);
      frameSize = rdr.getCur() - last_pos;
      ID3D_NOTICE( "id3::v2::parseFrames(): frameSize = " << frameSize );
      totalSize += frameSize;
      
      if (frameSize == 0)
      { 
        // There is a problem. 
        // If the frame size is 0, then we can't progress. 
        ID3D_WARNING( "id3::v2::parseFrames(): frame size is 0, can't " <<
                      "continue parsing frames");
        delete f; 
        // Break for now. 
        break; 
      } 
      else if (!goodParse) 
      { 
        // bad parse!  we can't attach this frame.
        ID3D_WARNING( "id3::v2::parseFrames(): bad parse, deleting frame");
        delete f; 
      } 
      else if (f->GetID() != ID3FID_METACOMPRESSION) 
      { 
        ID3D_NOTICE( "id3::v2::parseFrames(): attaching non-compressed " <<
                     "frame");
        // a good, uncompressed frame.  attach away! 
        tag.AttachFrame(f); 
      } 
#ifdef HAVE_ZLIB
      else 
      { 
        ID3D_NOTICE( "id3::v2::parseFrames(): parsing ID3v2.2.1 " <<
                     "compressed frame");
        // hmm.  an ID3v2.2.1 compressed frame.  It contains 1 or more
        // compressed frames.  Uncompress and call parseFrames recursively.
        ID3_Field* fld = f->GetField(ID3FN_DATA);
        if (fld)
        {
          ID3_MemoryReader mr(fld->GetRawBinary(), fld->BinSize());
          ID3_Reader::char_type ch = mr.readChar();
          if (ch != 'z') 
          { 
            // unknown compression method 
            ID3D_WARNING( "id3::v2::parseFrames(): unknown compression id " <<
                          " = '" << ch << "'" );
          } 
          else 
          { 
            uint32 newSize = io::readBENumber(mr, sizeof(uint32));
            size_t oldSize = f->GetDataSize() - sizeof(uint32) - 1;
            io::CompressedReader cr(mr, newSize);
            parseFrames(tag, cr);
            if (!cr.atEnd())
            {
              // hmm.  it didn't parse the entire uncompressed data.  wonder
              // why.
              ID3D_WARNING( "id3::v2::parseFrames(): didn't parse entire " <<
                            "id3v2.2.1 compressed memory stream");
            }
          }
        }
        delete f;
      }
#endif
      et.setExitPos(rdr.getCur());
    } 
    if (rdr.peekChar() == '\0')
    {
      ID3D_NOTICE( "id3::v2::parseFrames: done parsing, padding at postion " << 
                   rdr.getCur() );
    }
    else
    {
      ID3D_NOTICE( "id3::v2::parseFrames: done parsing, [cur, end] = [" << 
                   rdr.getCur() << ", " << rdr.getEnd() << "]" );
    }
    return true;
  }
};
 
bool id3::v2::parse(ID3_TagImpl& tag, ID3_Reader& reader)
{
  ID3_Reader::pos_type beg = reader.getCur();
  io::ExitTrigger et(reader);
  
  ID3_TagHeader hdr;

  io::WindowedReader wr(reader, ID3_TagHeader::SIZE);
  
  if (!hdr.Parse(wr) || wr.getCur() == beg)
  {
    ID3D_NOTICE( "id3::v2::parse(): parsing header failes" );
    return false;
  }
  
  tag.SetSpec(hdr.GetSpec());

  size_t dataSize = hdr.GetDataSize();
  ID3D_NOTICE( "ID3_TagImpl::Parse(ID3_Reader&): dataSize = " << dataSize);

  wr.setWindow(wr.getCur(), dataSize);
  et.setExitPos(wr.getEnd());

  ID3D_NOTICE( "ID3_TagImpl::Parse(ID3_Reader&): data window beg = " << wr.getBeg() );
  ID3D_NOTICE( "ID3_TagImpl::Parse(ID3_Reader&): data window cur = " << wr.getCur() );
  ID3D_NOTICE( "ID3_TagImpl::Parse(ID3_Reader&): data window end = " << wr.getEnd() );
  tag.SetExtended(hdr.GetExtended());
  if (!hdr.GetUnsync())
  {
    tag.SetUnsync(false);
    parseFrames(tag, wr);
  }
  else
  {
    // The buffer has been unsynced.  It will have to be resynced to be 
    // readable.  This has to be done a character at a time.  
    //
    // The original reader may be reading in characters from a file.  Doing
    // this a character at a time is quite slow.  To improve performance, read
    // in the entire buffer into a string, then create an UnsyncedReader from
    // the string.
    //
    // It might be better to implement a BufferedReader so that the details
    // of this can be abstracted away behind a class
    tag.SetUnsync(true);
    BString raw = io::readAllBinary(wr);
    io::BStringReader bsr(raw);
    io::UnsyncedReader ur(bsr);
    ID3D_NOTICE( "ID3_TagImpl::Parse(ID3_Reader&): unsync beg = " << ur.getBeg() );
    ID3D_NOTICE( "ID3_TagImpl::Parse(ID3_Reader&): unsync cur = " << ur.getCur() );
    ID3D_NOTICE( "ID3_TagImpl::Parse(ID3_Reader&): unsync end = " << ur.getEnd() );

    // Now read the UnsyncedReader into another string, and parse the frames
    // from the string.  This is done so that 1. the unsynced reader is 
    // unsynced exactly once, removing the possibility of multiple unsyncings
    // of the same string, and 2) so that calls to readChars aren't done a 
    // character at a time for every call
    BString synced = io::readAllBinary(ur);
    io::BStringReader sr(synced);
    parseFrames(tag, sr);
  }

  return true;
}

void ID3_TagImpl::ParseFile()
{
  ifstream file;
  if (ID3E_NoError != openReadableFile(this->GetFileName(), file))
  {
    // log this...
    return;
  }
  ID3_IFStreamReader ifsr(file);
  io::WindowedReader wr(ifsr);
  wr.setBeg(wr.getCur());

  _file_tags.clear();
  _file_size = getFileSize(file);

  ID3_Reader::pos_type beg  = wr.getBeg();
  ID3_Reader::pos_type cur  = wr.getCur();
  ID3_Reader::pos_type end  = wr.getEnd();

  ID3_Reader::pos_type last = cur;

  if (_tags_to_parse.test(ID3TT_ID3V2))
  {
    do
    {
      last = cur;
      // Parse tags at the beginning of the file first...
      if (id3::v2::parse(*this, wr))
      {
        _file_tags.add(ID3TT_ID3V2);
      }
      cur  = wr.getCur();
      wr.setBeg(cur);
    } while (!wr.atEnd() && cur > last);
  }

  _prepended_bytes = cur - beg;

  cur = wr.setCur(end);
  do
  {
    last = cur;
    ID3D_NOTICE( "ID3_TagImpl::ParseFile(): beg = " << wr.getBeg() );
    ID3D_NOTICE( "ID3_TagImpl::ParseFile(): cur = " << wr.getCur() );
    ID3D_NOTICE( "ID3_TagImpl::ParseFile(): end = " << wr.getEnd() );
    // ...then the tags at the end
    ID3D_NOTICE( "ID3_TagImpl::ParseFile(): musicmatch? cur = " << wr.getCur() );
    if (_tags_to_parse.test(ID3TT_MUSICMATCH) && mm::parse(*this, wr))
    {
      ID3D_NOTICE( "ID3_TagImpl::ParseFile(): musicmatch! cur = " << wr.getCur() );
      _file_tags.add(ID3TT_MUSICMATCH);
      wr.setEnd(wr.getCur());
    }
    ID3D_NOTICE( "ID3_TagImpl::ParseFile(): lyr3v1? cur = " << wr.getCur() );
    if (_tags_to_parse.test(ID3TT_LYRICS3) && lyr3::v1::parse(*this, wr))
    {
      ID3D_NOTICE( "ID3_TagImpl::ParseFile(): lyr3v1! cur = " << wr.getCur() );
      _file_tags.add(ID3TT_LYRICS3);
      wr.setEnd(wr.getCur());
    }
    ID3D_NOTICE( "ID3_TagImpl::ParseFile(): lyr3v2? cur = " << wr.getCur() );
    if (_tags_to_parse.test(ID3TT_LYRICS3V2) && lyr3::v2::parse(*this, wr))
    {
      ID3D_NOTICE( "ID3_TagImpl::ParseFile(): lyr3v2! cur = " << wr.getCur() );
      _file_tags.add(ID3TT_ID3V1);
      wr.setEnd(wr.getCur());
    }
    ID3D_NOTICE( "ID3_TagImpl::ParseFile(): id3v1? cur = " << wr.getCur() );
    if (_tags_to_parse.test(ID3TT_ID3V1) && id3::v1::parse(*this, wr))
    {
      ID3D_NOTICE( "ID3_TagImpl::ParseFile(): id3v1! cur = " << wr.getCur() );
      wr.setEnd(wr.getCur());
      _file_tags.add(ID3TT_ID3V1);
    }
    cur = wr.getCur();
  } while (cur != last);
  _appended_bytes = end - cur;
}