libmng_read.c

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/* ************************************************************************** */

MNG_LOCAL mng_retcode read_databuffer (mng_datap    pData,
                                       mng_uint8p   pBuf,
                                       mng_uint8p * pBufnext,
                                       mng_uint32   iSize,
                                       mng_uint32 * iRead)
{
  mng_retcode iRetcode;
  
#ifdef MNG_SUPPORT_TRACE
  MNG_TRACE (pData, MNG_FN_READ_DATABUFFER, MNG_LC_START)
#endif

  if (pData->bSuspensionmode)
  {
    mng_uint8p pTemp;
    mng_uint32 iTemp;

    *iRead = 0;                        /* let's be negative about the outcome */

    if (!pData->pSuspendbuf)           /* need to create a suspension buffer ? */
    {
      pData->iSuspendbufsize = MNG_SUSPENDBUFFERSIZE;
                                       /* so, create it */
      MNG_ALLOC (pData, pData->pSuspendbuf, pData->iSuspendbufsize)

      pData->iSuspendbufleft = 0;      /* make sure to fill it first time */
      pData->pSuspendbufnext = pData->pSuspendbuf;
    }
                                       /* more than our buffer can hold ? */
    if (iSize > pData->iSuspendbufsize)
    {
      mng_uint32 iRemain;

      if (!*pBufnext)                  /* first time ? */
      {
        if (pData->iSuspendbufleft)    /* do we have some data left ? */
        {                              /* then copy it */
          MNG_COPY (pBuf, pData->pSuspendbufnext, pData->iSuspendbufleft)
                                       /* fixup variables */
          *pBufnext              = pBuf + pData->iSuspendbufleft;
          pData->pSuspendbufnext = pData->pSuspendbuf;
          pData->iSuspendbufleft = 0;
        }
        else
        {
          *pBufnext              = pBuf;
        }
      }
                                       /* calculate how much to get */
      iRemain = iSize - (mng_uint32)(*pBufnext - pBuf);
                                       /* let's go get it */
      iRetcode = read_data (pData, *pBufnext, iRemain, &iTemp);
      if (iRetcode)
        return iRetcode;
                                       /* first read after suspension return 0 means EOF */
      if ((pData->iSuspendpoint) && (iTemp == 0))
      {                                /* that makes it final */
        mng_retcode iRetcode = mng_process_eof (pData);
        if (iRetcode)                  /* on error bail out */
          return iRetcode;
                                       /* indicate the source is depleted */
        *iRead = iSize - iRemain + iTemp;
      }
      else
      {
        if (iTemp < iRemain)           /* suspension required ? */
        {
          *pBufnext         = *pBufnext + iTemp;
          pData->bSuspended = MNG_TRUE;
        }
        else
        {
          *iRead = iSize;              /* got it all now ! */
        }
      }
    }
    else
    {                                  /* need to read some more ? */
      while ((!pData->bSuspended) && (!pData->bEOF) && (iSize > pData->iSuspendbufleft))
      {                                /* not enough space left in buffer ? */
        if (pData->iSuspendbufsize - pData->iSuspendbufleft -
            (mng_uint32)(pData->pSuspendbufnext - pData->pSuspendbuf) <
                                                          MNG_SUSPENDREQUESTSIZE)
        {
          if (pData->iSuspendbufleft)  /* then lets shift (if there's anything left) */
            MNG_COPY (pData->pSuspendbuf, pData->pSuspendbufnext, pData->iSuspendbufleft)
                                       /* adjust running pointer */
          pData->pSuspendbufnext = pData->pSuspendbuf;
        }
                                       /* still not enough room ? */
        if (pData->iSuspendbufsize - pData->iSuspendbufleft < MNG_SUSPENDREQUESTSIZE)
          MNG_ERROR (pData, MNG_INTERNALERROR)
                                       /* now read some more data */
        pTemp = pData->pSuspendbufnext + pData->iSuspendbufleft;

        iRetcode = read_data (pData, pTemp, MNG_SUSPENDREQUESTSIZE, &iTemp);
        if (iRetcode)
          return iRetcode;
                                       /* adjust fill-counter */
        pData->iSuspendbufleft += iTemp;
                                       /* first read after suspension returning 0 means EOF */
        if ((pData->iSuspendpoint) && (iTemp == 0))
        {                              /* that makes it final */
          mng_retcode iRetcode = mng_process_eof (pData);
          if (iRetcode)                /* on error bail out */
            return iRetcode;

          if (pData->iSuspendbufleft)  /* return the leftover scraps */
            MNG_COPY (pBuf, pData->pSuspendbufnext, pData->iSuspendbufleft)
                                       /* and indicate so */
          *iRead = pData->iSuspendbufleft;
          pData->pSuspendbufnext = pData->pSuspendbuf;
          pData->iSuspendbufleft = 0;
        }
        else
        {                              /* suspension required ? */
          if ((iSize > pData->iSuspendbufleft) && (iTemp < MNG_SUSPENDREQUESTSIZE))
            pData->bSuspended = MNG_TRUE;

        }

        pData->iSuspendpoint = 0;      /* reset it here in case we loop back */
      }

      if ((!pData->bSuspended) && (!pData->bEOF))
      {                                /* return the data ! */
        MNG_COPY (pBuf, pData->pSuspendbufnext, iSize)

        *iRead = iSize;                /* returned it all */
                                       /* adjust suspension-buffer variables */
        pData->pSuspendbufnext += iSize;
        pData->iSuspendbufleft -= iSize;
      }
    }
  }
  else
  {
    iRetcode = read_data (pData, (mng_ptr)pBuf, iSize, iRead);
    if (iRetcode)
      return iRetcode;
    if (*iRead == 0)                   /* suspension required ? */
      pData->bSuspended = MNG_TRUE;
  }

  pData->iSuspendpoint = 0;            /* safely reset it here ! */

#ifdef MNG_SUPPORT_TRACE
  MNG_TRACE (pData, MNG_FN_READ_DATABUFFER, MNG_LC_END)
#endif

  return MNG_NOERROR;
}

/* ************************************************************************** */

MNG_LOCAL mng_retcode process_raw_chunk (mng_datap  pData,
                                         mng_uint8p pBuf,
                                         mng_uint32 iBuflen)
{
  /* the table-idea & binary search code was adapted from
     libpng 1.1.0 (pngread.c) */
  /* NOTE1: the table must remain sorted by chunkname, otherwise the binary
     search will break !!! (ps. watch upper-/lower-case chunknames !!) */
  /* NOTE2: the layout must remain equal to the header part of all the
     chunk-structures (yes, that means even the pNext and pPrev fields;
     it's wasting a bit of space, but hey, the code is a lot easier) */

  mng_chunk_header chunk_unknown = {MNG_UINT_HUH, mng_init_unknown, mng_free_unknown,
                                    mng_read_unknown, mng_write_unknown, mng_assign_unknown, 0, 0};

  mng_chunk_header chunk_table [] =
  {
#ifndef MNG_SKIPCHUNK_BACK
    {MNG_UINT_BACK, mng_init_back, mng_free_back, mng_read_back, mng_write_back, mng_assign_back, 0, 0},
#endif
#ifndef MNG_SKIPCHUNK_BASI
    {MNG_UINT_BASI, mng_init_basi, mng_free_basi, mng_read_basi, mng_write_basi, mng_assign_basi, 0, 0},
#endif
#ifndef MNG_SKIPCHUNK_CLIP
    {MNG_UINT_CLIP, mng_init_clip, mng_free_clip, mng_read_clip, mng_write_clip, mng_assign_clip, 0, 0},
#endif
#ifndef MNG_SKIPCHUNK_CLON
    {MNG_UINT_CLON, mng_init_clon, mng_free_clon, mng_read_clon, mng_write_clon, mng_assign_clon, 0, 0},
#endif
#ifndef MNG_NO_DELTA_PNG
#ifndef MNG_SKIPCHUNK_DBYK
    {MNG_UINT_DBYK, mng_init_dbyk, mng_free_dbyk, mng_read_dbyk, mng_write_dbyk, mng_assign_dbyk, 0, 0},
#endif
#endif
#ifndef MNG_SKIPCHUNK_DEFI
    {MNG_UINT_DEFI, mng_init_defi, mng_free_defi, mng_read_defi, mng_write_defi, mng_assign_defi, 0, 0},
#endif
#ifndef MNG_NO_DELTA_PNG
    {MNG_UINT_DHDR, mng_init_dhdr, mng_free_dhdr, mng_read_dhdr, mng_write_dhdr, mng_assign_dhdr, 0, 0},
#endif
#ifndef MNG_SKIPCHUNK_DISC
    {MNG_UINT_DISC, mng_init_disc, mng_free_disc, mng_read_disc, mng_write_disc, mng_assign_disc, 0, 0},
#endif
#ifndef MNG_NO_DELTA_PNG
#ifndef MNG_SKIPCHUNK_DROP
    {MNG_UINT_DROP, mng_init_drop, mng_free_drop, mng_read_drop, mng_write_drop, mng_assign_drop, 0, 0},
#endif
#endif
#ifndef MNG_SKIPCHUNK_LOOP
    {MNG_UINT_ENDL, mng_init_endl, mng_free_endl, mng_read_endl, mng_write_endl, mng_assign_endl, 0, 0},
#endif
#ifndef MNG_SKIPCHUNK_FRAM
    {MNG_UINT_FRAM, mng_init_fram, mng_free_fram, mng_read_fram, mng_write_fram, mng_assign_fram, 0, 0},
#endif
    {MNG_UINT_IDAT, mng_init_idat, mng_free_idat, mng_read_idat, mng_write_idat, mng_assign_idat, 0, 0},  /* 12-th element! */
    {MNG_UINT_IEND, mng_init_iend, mng_free_iend, mng_read_iend, mng_write_iend, mng_assign_iend, 0, 0},
    {MNG_UINT_IHDR, mng_init_ihdr, mng_free_ihdr, mng_read_ihdr, mng_write_ihdr, mng_assign_ihdr, 0, 0},
#ifndef MNG_NO_DELTA_PNG
#ifdef MNG_INCLUDE_JNG
    {MNG_UINT_IJNG, mng_init_ijng, mng_free_ijng, mng_read_ijng, mng_write_ijng, mng_assign_ijng, 0, 0},
#endif
    {MNG_UINT_IPNG, mng_init_ipng, mng_free_ipng, mng_read_ipng, mng_write_ipng, mng_assign_ipng, 0, 0},
#endif
#ifdef MNG_INCLUDE_JNG
    {MNG_UINT_JDAA, mng_init_jdaa, mng_free_jdaa, mng_read_jdaa, mng_write_jdaa, mng_assign_jdaa, 0, 0},
    {MNG_UINT_JDAT, mng_init_jdat, mng_free_jdat, mng_read_jdat, mng_write_jdat, mng_assign_jdat, 0, 0},
    {MNG_UINT_JHDR, mng_init_jhdr, mng_free_jhdr, mng_read_jhdr, mng_write_jhdr, mng_assign_jhdr, 0, 0},
    {MNG_UINT_JSEP, mng_init_jsep, mng_free_jsep, mng_read_jsep, mng_write_jsep, mng_assign_jsep, 0, 0},
    {MNG_UINT_JdAA, mng_init_jdaa, mng_free_jdaa, mng_read_jdaa, mng_write_jdaa, mng_assign_jdaa, 0, 0},
#endif
#ifndef MNG_SKIPCHUNK_LOOP
    {MNG_UINT_LOOP, mng_init_loop, mng_free_loop, mng_read_loop, mng_write_loop, mng_assign_loop, 0, 0},
#endif
#ifndef MNG_SKIPCHUNK_MAGN
    {MNG_UINT_MAGN, mng_init_magn, mng_free_magn, mng_read_magn, mng_write_magn, mng_assign_magn, 0, 0},
#endif
    {MNG_UINT_MEND, mng_init_mend, mng_free_mend, mng_read_mend, mng_write_mend, mng_assign_mend, 0, 0},
    {MNG_UINT_MHDR, mng_init_mhdr, mng_free_mhdr, mng_read_mhdr, mng_write_mhdr, mng_assign_mhdr, 0, 0},
#ifndef MNG_SKIPCHUNK_MOVE
    {MNG_UINT_MOVE, mng_init_move, mng_free_move, mng_read_move, mng_write_move, mng_assign_move, 0, 0},
#endif
#ifndef MNG_NO_DELTA_PNG
#ifndef MNG_SKIPCHUNK_ORDR
    {MNG_UINT_ORDR, mng_init_ordr, mng_free_ordr, mng_read_ordr, mng_write_ordr, mng_assign_ordr, 0, 0},
#endif
#endif
#ifndef MNG_SKIPCHUNK_PAST
    {MNG_UINT_PAST, mng_init_past, mng_free_past, mng_read_past, mng_write_past, mng_assign_past, 0, 0},
#endif
    {MNG_UINT_PLTE, mng_init_plte, mng_free_plte, mng_read_plte, mng_write_plte, mng_assign_plte, 0, 0},
#ifndef MNG_NO_DELTA_PNG
    {MNG_UINT_PPLT, mng_init_pplt, mng_free_pplt, mng_read_pplt, mng_write_pplt, mng_assign_pplt, 0, 0},
    {MNG_UINT_PROM, mng_init_prom, mng_free_prom, mng_read_prom, mng_write_prom, mng_assign_prom, 0, 0},
#endif
#ifndef MNG_SKIPCHUNK_SAVE
    {MNG_UINT_SAVE, mng_init_save, mng_free_save, mng_read_save, mng_write_save, mng_assign_save, 0, 0},
#endif
#ifndef MNG_SKIPCHUNK_SEEK
    {MNG_UINT_SEEK, mng_init_seek, mng_free_seek, mng_read_seek, mng_write_seek, mng_assign_seek, 0, 0},
#endif
#ifndef MNG_SKIPCHUNK_SHOW
    {MNG_UINT_SHOW, mng_init_show, mng_free_show, mng_read_show, mng_write_show, mng_assign_show, 0, 0},
#endif
#ifndef MNG_SKIPCHUNK_TERM
    {MNG_UINT_TERM, mng_init_term, mng_free_term, mng_read_term, mng_write_term, mng_assign_term, 0, 0},
#endif
#ifndef MNG_SKIPCHUNK_bKGD
    {MNG_UINT_bKGD, mng_init_bkgd, mng_free_bkgd, mng_read_bkgd, mng_write_bkgd, mng_assign_bkgd, 0, 0},
#endif
#ifndef MNG_SKIPCHUNK_cHRM
    {MNG_UINT_cHRM, mng_init_chrm, mng_free_chrm, mng_read_chrm, mng_write_chrm, mng_assign_chrm, 0, 0},
#endif