// Copyright (C) 2004-2024 Artifex Software, Inc.

//

// This file is part of MuPDF.

//

// MuPDF is free software: you can redistribute it and/or modify it under the

// terms of the GNU Affero General Public License as published by the Free

// Software Foundation, either version 3 of the License, or (at your option)

// any later version.

//

// MuPDF 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 Affero General Public License for more

// details.

//

// You should have received a copy of the GNU Affero General Public License

// along with MuPDF. If not, see <https://www.gnu.org/licenses/agpl-3.0.en.html>

//

// Alternative licensing terms are available from the licensor.

// For commercial licensing, see <https://www.artifex.com/> or contact

// Artifex Software, Inc., 39 Mesa Street, Suite 108A, San Francisco,

// CA 94129, USA, for further information.

#include "mupdf/fitz.h"

#include "mupdf/pdf.h"

#include <string.h>

int

pdf_obj_num_is_stream(fz_context *ctx, pdf_document *doc, int num)

{

  pdf_xref_entry *entry;

  if (num <= 0 || num >= pdf_xref_len(ctx, doc))

    return 0;

  fz_try(ctx)

    entry = pdf_cache_object(ctx, doc, num);

  fz_catch(ctx)

  {

    fz_rethrow_if(ctx, FZ_ERROR_TRYLATER);

    fz_rethrow_if(ctx, FZ_ERROR_SYSTEM);

    fz_report_error(ctx);

    return 0;

  }

  return entry->stm_ofs != 0 || entry->stm_buf;

}

int

pdf_is_stream(fz_context *ctx, pdf_obj *ref)

{

  pdf_document *doc = pdf_get_indirect_document(ctx, ref);

  if (doc)

    return pdf_obj_num_is_stream(ctx, doc, pdf_to_num(ctx, ref));

  return 0;

}

/*

 * Scan stream dictionary for an explicit /Crypt filter

 */

static int

pdf_stream_has_crypt(fz_context *ctx, pdf_obj *stm)

{

  pdf_obj *filters;

  pdf_obj *obj;

  int i;

  filters = pdf_dict_geta(ctx, stm, PDF_NAME(Filter), PDF_NAME(F));

  if (filters)

  {

    if (pdf_name_eq(ctx, filters, PDF_NAME(Crypt)))

      return 1;

    if (pdf_is_array(ctx, filters))

    {

      int n = pdf_array_len(ctx, filters);

      for (i = 0; i < n; i++)

      {

        obj = pdf_array_get(ctx, filters, i);

        if (pdf_name_eq(ctx, obj, PDF_NAME(Crypt)))

          return 1;

      }

    }

  }

  return 0;

}

static fz_jbig2_globals *

pdf_load_jbig2_globals(fz_context *ctx, pdf_obj *dict)

{

  fz_jbig2_globals *globals;

  fz_buffer *buf = NULL;

  fz_var(buf);

  if ((globals = pdf_find_item(ctx, fz_drop_jbig2_globals_imp, dict)) != NULL)

    return globals;

  if (pdf_mark_obj(ctx, dict))

    fz_throw(ctx, FZ_ERROR_FORMAT, "cyclic reference when loading JBIG2 globals");

  fz_try(ctx)

  {

    buf = pdf_load_stream(ctx, dict);

    globals = fz_load_jbig2_globals(ctx, buf);

    if (globals)

      pdf_store_item(ctx, dict, globals, fz_buffer_storage(ctx, buf, NULL));

  }

  fz_always(ctx)

  {

    fz_drop_buffer(ctx, buf);

    pdf_unmark_obj(ctx, dict);

  }

  fz_catch(ctx)

  {

    fz_rethrow(ctx);

  }

  return globals;

}

static void

build_compression_params(fz_context *ctx, pdf_obj *f, pdf_obj *p, fz_compression_params *params)

{

  params->type = FZ_IMAGE_RAW;

  if (pdf_name_eq(ctx, f, PDF_NAME(CCITTFaxDecode)) || pdf_name_eq(ctx, f, PDF_NAME(CCF)))

  {

    params->type = FZ_IMAGE_FAX;

    params->u.fax.k = pdf_dict_get_int_default(ctx, p, PDF_NAME(K), 0);

    params->u.fax.end_of_line = pdf_dict_get_bool_default(ctx, p, PDF_NAME(EndOfLine), 0);

    params->u.fax.encoded_byte_align = pdf_dict_get_bool_default(ctx, p, PDF_NAME(EncodedByteAlign), 0);

    params->u.fax.columns = pdf_dict_get_int_default(ctx, p, PDF_NAME(Columns), 1728);

    params->u.fax.rows = pdf_dict_get_int_default(ctx, p, PDF_NAME(Rows), 0);

    params->u.fax.end_of_block = pdf_dict_get_bool_default(ctx, p, PDF_NAME(EndOfBlock), 1);

    params->u.fax.black_is_1 = pdf_dict_get_bool_default(ctx, p, PDF_NAME(BlackIs1), 0);

  }

  else if (pdf_name_eq(ctx, f, PDF_NAME(DCTDecode)) || pdf_name_eq(ctx, f, PDF_NAME(DCT)))

  {

    params->type = FZ_IMAGE_JPEG;

    params->u.jpeg.color_transform = pdf_dict_get_int_default(ctx, p, PDF_NAME(ColorTransform), -1);

    params->u.jpeg.invert_cmyk = 0;

  }

  else if (pdf_name_eq(ctx, f, PDF_NAME(RunLengthDecode)) || pdf_name_eq(ctx, f, PDF_NAME(RL)))

  {

    params->type = FZ_IMAGE_RLD;

  }

  else if (pdf_name_eq(ctx, f, PDF_NAME(FlateDecode)) || pdf_name_eq(ctx, f, PDF_NAME(Fl)))

  {

    params->type = FZ_IMAGE_FLATE;

    params->u.flate.predictor = pdf_dict_get_int_default(ctx, p, PDF_NAME(Predictor), 1);

    params->u.flate.columns = pdf_dict_get_int_default(ctx, p, PDF_NAME(Columns), 1);

    params->u.flate.colors = pdf_dict_get_int_default(ctx, p, PDF_NAME(Colors), 1);

    params->u.flate.bpc = pdf_dict_get_int_default(ctx, p, PDF_NAME(BitsPerComponent), 8);

  }

  else if (pdf_name_eq(ctx, f, PDF_NAME(LZWDecode)) || pdf_name_eq(ctx, f, PDF_NAME(LZW)))

  {

    params->type = FZ_IMAGE_LZW;

    params->u.lzw.predictor = pdf_dict_get_int_default(ctx, p, PDF_NAME(Predictor), 1);

    params->u.lzw.columns = pdf_dict_get_int_default(ctx, p, PDF_NAME(Columns), 1);

    params->u.lzw.colors = pdf_dict_get_int_default(ctx, p, PDF_NAME(Colors), 1);

    params->u.lzw.bpc = pdf_dict_get_int_default(ctx, p, PDF_NAME(BitsPerComponent), 8);

    params->u.lzw.early_change = pdf_dict_get_int_default(ctx, p, PDF_NAME(EarlyChange), 1);

  }

  else if (pdf_name_eq(ctx, f, PDF_NAME(JBIG2Decode)))

  {

    pdf_obj *g = pdf_dict_get(ctx, p, PDF_NAME(JBIG2Globals));

    params->type = FZ_IMAGE_JBIG2;

    params->u.jbig2.globals = NULL;

    params->u.jbig2.embedded = 1; /* jbig2 streams are always embedded without file headers */

    if (g)

    {

      if (!pdf_is_stream(ctx, g))

        fz_warn(ctx, "jbig2 globals is not a stream, skipping globals");

      else

        params->u.jbig2.globals = pdf_load_jbig2_globals(ctx, g);

    }

  }

}

/*

 * Create a filter given a name and param dictionary.

 */

static fz_stream *

build_filter(fz_context *ctx, fz_stream *chain, pdf_document *doc, pdf_obj *f, pdf_obj *p, int num, int gen, fz_compression_params *params, int might_be_image)

{

  fz_compression_params local_params;

  local_params.u.jbig2.globals = NULL;

  if (params == NULL)

    params = &local_params;

  if (!might_be_image &&

    (pdf_name_eq(ctx, f, PDF_NAME(CCITTFaxDecode)) ||

      pdf_name_eq(ctx, f, PDF_NAME(CCF)) ||

      pdf_name_eq(ctx, f, PDF_NAME(DCTDecode)) ||

      pdf_name_eq(ctx, f, PDF_NAME(DCT)) ||

      pdf_name_eq(ctx, f, PDF_NAME(JBIG2Decode)) ||

      pdf_name_eq(ctx, f, PDF_NAME(JPXDecode))))

  {

    fz_warn(ctx, "Can't open image only stream for non-image purposes");

    return fz_open_memory(ctx, (unsigned char *)"", 0);

  }

  build_compression_params(ctx, f, p, params);

  /* If we were using params we were passed in, and we successfully

   * recognised the image type, we can use the existing filter and

   * shortstop here. */

  if (params != &local_params && params->type != FZ_IMAGE_RAW)

    return fz_keep_stream(ctx, chain); /* nothing to do */

  else if (params->type == FZ_IMAGE_JBIG2)

  {

    fz_stream *stm;

    fz_try(ctx)

      stm = fz_open_image_decomp_stream(ctx, chain, params, NULL);

    fz_always(ctx)

      fz_drop_jbig2_globals(ctx, local_params.u.jbig2.globals);

    fz_catch(ctx)

      fz_rethrow(ctx);

    return stm;

  }

  else if (params->type != FZ_IMAGE_RAW)

    return fz_open_image_decomp_stream(ctx, chain, params, NULL);

  else if (pdf_name_eq(ctx, f, PDF_NAME(ASCIIHexDecode)) || pdf_name_eq(ctx, f, PDF_NAME(AHx)))

    return fz_open_ahxd(ctx, chain);

  else if (pdf_name_eq(ctx, f, PDF_NAME(ASCII85Decode)) || pdf_name_eq(ctx, f, PDF_NAME(A85)))

    return fz_open_a85d(ctx, chain);

  else if (pdf_name_eq(ctx, f, PDF_NAME(JPXDecode)))

    return fz_keep_stream(ctx, chain); /* JPX decoding is special cased in the image loading code */

  else if (pdf_name_eq(ctx, f, PDF_NAME(Crypt)))

  {

    if (!doc->crypt)

      fz_warn(ctx, "crypt filter in unencrypted document");

    else

    {

      pdf_obj *name = pdf_dict_get(ctx, p, PDF_NAME(Name));

      if (pdf_is_name(ctx, name))

        return pdf_open_crypt_with_filter(ctx, chain, doc->crypt, name, num, gen);

    }

  }

  else

    fz_warn(ctx, "unknown filter name (%s)", pdf_to_name(ctx, f));

  return fz_keep_stream(ctx, chain);

}

/* Build filter, and assume ownership of chain */

static fz_stream *

build_filter_drop(fz_context *ctx, fz_stream *tail, pdf_document *doc, pdf_obj *f, pdf_obj *p, int num, int gen, fz_compression_params *params, int might_be_image)

{

  fz_stream *head;

  fz_try(ctx)

    head = build_filter(ctx, tail, doc, f, p, num, gen, params, might_be_image);

  fz_always(ctx)

    fz_drop_stream(ctx, tail);

  fz_catch(ctx)

    fz_rethrow(ctx);

  return head;

}

/*

 * Build a chain of filters given filter names and param dicts.

 * If chain is given, start filter chain with it.

 * Assume ownership of chain.

 */

static fz_stream *

build_filter_chain_drop(fz_context *ctx, fz_stream *chain, pdf_document *doc, pdf_obj *fs, pdf_obj *ps, int num, int gen, fz_compression_params *params, int might_be_image)

{

  fz_var(chain);

  fz_try(ctx)

  {

    int i, n = pdf_array_len(ctx, fs);

    for (i = 0; i < n; i++)

    {

      pdf_obj *f = pdf_array_get(ctx, fs, i);

      pdf_obj *p = pdf_array_get(ctx, ps, i);

      chain = build_filter_drop(ctx, chain, doc, f, p, num, gen, (i == n-1 ? params : NULL), might_be_image);

    }

  }

  fz_catch(ctx)

    fz_rethrow(ctx);

  return chain;

}

static fz_stream *

build_filter_chain(fz_context *ctx, fz_stream *chain, pdf_document *doc, pdf_obj *fs, pdf_obj *ps, int num, int gen, fz_compression_params *params, int might_be_image)

{

  return build_filter_chain_drop(ctx, fz_keep_stream(ctx, chain), doc, fs, ps, num, gen, params, might_be_image);

}

/*

 * Build a filter for reading raw stream data.

 * This is a null filter to constrain reading to the stream length (and to

 * allow for other people accessing the file), followed by a decryption

 * filter.

 *

 * orig_num and orig_gen are used purely to seed the encryption.

 */

static fz_stream *

pdf_open_raw_filter(fz_context *ctx, fz_stream *file_stm, pdf_document *doc, pdf_obj *stmobj, int num, int *orig_num, int *orig_gen, int64_t offset)

{

  pdf_xref_entry *x = NULL;

  fz_stream *null_stm, *crypt_stm;

  int hascrypt;

  int64_t len;

  if (num > 0 && num < pdf_xref_len(ctx, doc))

  {

    x = pdf_get_xref_entry(ctx, doc, num);

  }

  if (x == NULL)

  {

    /* We only end up here when called from pdf_open_stream_with_offset to parse new format XRef sections. */

    /* New style XRef sections must have generation number 0. */

    *orig_num = num;

    *orig_gen = 0;

  }

  else

  {

    *orig_num = x->num;

    *orig_gen = x->gen;

    if (x->stm_buf)

      return fz_open_buffer(ctx, x->stm_buf);

  }

  hascrypt = pdf_stream_has_crypt(ctx, stmobj);

  len = pdf_dict_get_int64(ctx, stmobj, PDF_NAME(Length));

  if (len < 0)

    len = 0;

  null_stm = fz_open_endstream_filter(ctx, file_stm, (uint64_t)len, offset);

  if (doc->crypt && !hascrypt)

  {

    fz_try(ctx)

      crypt_stm = pdf_open_crypt(ctx, null_stm, doc->crypt, *orig_num, *orig_gen);

    fz_always(ctx)

      fz_drop_stream(ctx, null_stm);

    fz_catch(ctx)

      fz_rethrow(ctx);

    return crypt_stm;

  }

  return null_stm;

}

/*

 * Construct a filter to decode a stream, constraining

 * to stream length and decrypting.

 */

static fz_stream *

pdf_open_filter(fz_context *ctx, pdf_document *doc, fz_stream *file_stm, pdf_obj *stmobj, int num, int64_t offset, fz_compression_params *imparams, int might_be_image)

{

  pdf_obj *filters = pdf_dict_geta(ctx, stmobj, PDF_NAME(Filter), PDF_NAME(F));

  pdf_obj *params = pdf_dict_geta(ctx, stmobj, PDF_NAME(DecodeParms), PDF_NAME(DP));

  int orig_num, orig_gen;

  fz_stream *rstm, *fstm;

  rstm = pdf_open_raw_filter(ctx, file_stm, doc, stmobj, num, &orig_num, &orig_gen, offset);

  fz_try(ctx)

  {

    if (pdf_is_name(ctx, filters))

      fstm = build_filter(ctx, rstm, doc, filters, params, orig_num, orig_gen, imparams, might_be_image);

    else if (pdf_array_len(ctx, filters) > 0)

      fstm = build_filter_chain(ctx, rstm, doc, filters, params, orig_num, orig_gen, imparams, might_be_image);

    else

    {

      if (imparams)

        imparams->type = FZ_IMAGE_RAW;

      fstm = fz_keep_stream(ctx, rstm);

    }

  }

  fz_always(ctx)

    fz_drop_stream(ctx, rstm);

  fz_catch(ctx)

    fz_rethrow(ctx);

  return fstm;

}

fz_stream *

pdf_open_inline_stream(fz_context *ctx, pdf_document *doc, pdf_obj *stmobj, int length, fz_stream *file_stm, fz_compression_params *imparams)

{

  pdf_obj *filters = pdf_dict_geta(ctx, stmobj, PDF_NAME(Filter), PDF_NAME(F));

  pdf_obj *params = pdf_dict_geta(ctx, stmobj, PDF_NAME(DecodeParms), PDF_NAME(DP));

  if (pdf_is_name(ctx, filters))

    return build_filter(ctx, file_stm, doc, filters, params, 0, 0, imparams, 1);

  else if (pdf_array_len(ctx, filters) > 0)

    return build_filter_chain(ctx, file_stm, doc, filters, params, 0, 0, imparams, 1);

  if (imparams)

    imparams->type = FZ_IMAGE_RAW;

  return fz_open_null_filter(ctx, file_stm, length, fz_tell(ctx, file_stm));

}

void

pdf_load_compressed_inline_image(fz_context *ctx, pdf_document *doc, pdf_obj *dict, int length, fz_stream *file_stm, int indexed, fz_compressed_image *image)

{

  fz_stream *istm = NULL, *leech = NULL, *decomp = NULL;

  fz_pixmap *pixmap = NULL;

  fz_compressed_buffer *bc;

  int dummy_l2factor = 0;

  fz_var(istm);

  fz_var(leech);

  fz_var(decomp);

  fz_var(pixmap);

  bc = fz_new_compressed_buffer(ctx);

  fz_try(ctx)

  {

    bc->buffer = fz_new_buffer(ctx, 1024);

    istm = pdf_open_inline_stream(ctx, doc, dict, length, file_stm, &bc->params);

    leech = fz_open_leecher(ctx, istm, bc->buffer);

    decomp = fz_open_image_decomp_stream(ctx, leech, &bc->params, &dummy_l2factor);

    pixmap = fz_decomp_image_from_stream(ctx, decomp, image, NULL, indexed, 0, NULL);

    fz_set_compressed_image_buffer(ctx, image, bc);

  }

  fz_always(ctx)

  {

    fz_drop_stream(ctx, istm);

    fz_drop_stream(ctx, leech);

    fz_drop_stream(ctx, decomp);

    fz_drop_pixmap(ctx, pixmap);

  }

  fz_catch(ctx)

  {

    fz_drop_compressed_buffer(ctx, bc);

    fz_rethrow(ctx);

  }

}

fz_stream *

pdf_open_raw_stream_number(fz_context *ctx, pdf_document *doc, int num)

{

  pdf_xref_entry *x;

  int orig_num, orig_gen;

  x = pdf_cache_object(ctx, doc, num);

  if (x->stm_ofs == 0)

    fz_throw(ctx, FZ_ERROR_FORMAT, "object is not a stream");

  return pdf_open_raw_filter(ctx, doc->file, doc, x->obj, num, &orig_num, &orig_gen, x->stm_ofs);

}

static fz_stream *

pdf_open_image_stream(fz_context *ctx, pdf_document *doc, int num, fz_compression_params *params, int might_be_image)

{

  pdf_xref_entry *x;

  x = pdf_cache_object(ctx, doc, num);

  if (x->stm_ofs == 0 && x->stm_buf == NULL)

    fz_throw(ctx, FZ_ERROR_FORMAT, "object is not a stream");

  return pdf_open_filter(ctx, doc, doc->file, x->obj, num, x->stm_ofs, params, might_be_image);

}

fz_stream *

pdf_open_stream_number(fz_context *ctx, pdf_document *doc, int num)

{

  return pdf_open_image_stream(ctx, doc, num, NULL, 1);

}

fz_stream *

pdf_open_stream_with_offset(fz_context *ctx, pdf_document *doc, int num, pdf_obj *dict, int64_t stm_ofs)

{

  if (stm_ofs == 0)

    fz_throw(ctx, FZ_ERROR_FORMAT, "object is not a stream");

  return pdf_open_filter(ctx, doc, doc->file, dict, num, stm_ofs, NULL, 1);

}

fz_buffer *

pdf_load_raw_stream_number(fz_context *ctx, pdf_document *doc, int num)

{

  fz_stream *stm;

  pdf_obj *dict;

  int64_t len;

  fz_buffer *buf = NULL;

  pdf_xref_entry *x;

  if (num > 0 && num < pdf_xref_len(ctx, doc))

  {

    x = pdf_get_xref_entry_no_null(ctx, doc, num);

    if (x->stm_buf)

      return fz_keep_buffer(ctx, x->stm_buf);

  }

  dict = pdf_load_object(ctx, doc, num);

  fz_try(ctx)

    len = pdf_dict_get_int64(ctx, dict, PDF_NAME(Length));

  fz_always(ctx)

    pdf_drop_obj(ctx, dict);

  fz_catch(ctx)

    fz_rethrow(ctx);

  stm = pdf_open_raw_stream_number(ctx, doc, num);

  if (len < 0)

    len = 1024;

  fz_try(ctx)

    buf = fz_read_all(ctx, stm, (size_t)len);

  fz_always(ctx)

    fz_drop_stream(ctx, stm);

  fz_catch(ctx)

    fz_rethrow(ctx);

  return buf;

}

static size_t

pdf_guess_filter_length(size_t len, const char *filter)

{

  size_t nlen = len;

  /* First ones get smaller, no overflow check required. */

  if (!strcmp(filter, "ASCIIHexDecode"))

    return len / 2;

  else if (!strcmp(filter, "ASCII85Decode"))

    return len * 4 / 5;

  if (!strcmp(filter, "FlateDecode"))

    nlen = len * 3;

  else if (!strcmp(filter, "RunLengthDecode"))

    nlen = len * 3;

  else if (!strcmp(filter, "LZWDecode"))

    nlen = len * 2;

  /* Live with a bad estimate - we'll malloc up as we go, but

   * it's probably destined to fail anyway. */

  if (nlen < len)

    return len;

  return nlen;

}

/* Check if an entry has a cached stream and return whether it is directly

 * reusable. A buffer is directly reusable only if the stream is

 * uncompressed, or if it is compressed purely a compression method we can

 * return details of in fz_compression_params.

 *

 * If the stream is reusable return 1, and set params as required, otherwise

 * return 0. */

static int

can_reuse_buffer(fz_context *ctx, pdf_xref_entry *entry, fz_compression_params *params)

{

  pdf_obj *f;

  pdf_obj *p;

  if (!entry || !entry->obj || !entry->stm_buf)

    return 0;

  if (params)

    params->type = FZ_IMAGE_RAW;

  f = pdf_dict_geta(ctx, entry->obj, PDF_NAME(Filter), PDF_NAME(F));

  /* If there are no filters, it's uncompressed, and we can use it */

  if (!f)

    return 1;

  p = pdf_dict_geta(ctx, entry->obj, PDF_NAME(DecodeParms), PDF_NAME(DP));

  if (pdf_is_array(ctx, f))

  {

    int len = pdf_array_len(ctx, f);

    /* Empty array of filters. Its uncompressed. We can cope. */

    if (len == 0)

      return 1;

    /* 1 filter is the most we can hope to cope with - if more,*/

    if (len != 1)

      return 0;

    p = pdf_array_get(ctx, p, 0);

  }

  if (pdf_is_null(ctx, f))

    return 1; /* Null filter is uncompressed */

  if (!pdf_is_name(ctx, f))

    return 0;

  /* There are filters, so unless we have the option of shortstopping,

   * we can't use the existing buffer. */

  if (!params)

    return 0;

  build_compression_params(ctx, f, p, params);

  return (params->type == FZ_IMAGE_RAW) ? 0 : 1;

}

static fz_buffer *

pdf_load_image_stream(fz_context *ctx, pdf_document *doc, int num, fz_compression_params *params, int *truncated, size_t worst_case)

{

  fz_stream *stm = NULL;

  pdf_obj *dict, *obj;

  int i, n;

  size_t len;

  fz_buffer *buf;

  fz_var(buf);

  if (num > 0 && num < pdf_xref_len(ctx, doc))

  {

    pdf_xref_entry *entry = pdf_get_xref_entry(ctx, doc, num);

    /* Return ref to existing buffer, but only if uncompressed,

     * or shortstoppable */

    if (can_reuse_buffer(ctx, entry, params))

      return fz_keep_buffer(ctx, entry->stm_buf);

  }

  dict = pdf_load_object(ctx, doc, num);

  fz_try(ctx)

  {

    int64_t ilen = pdf_dict_get_int64(ctx, dict, PDF_NAME(Length));

    if (ilen < 0)

      ilen = 0;

    len = (size_t)ilen;

    /* In 32 bit builds, we might find a length being too

     * large for a size_t. */

    if ((int64_t)len != ilen)

      fz_throw(ctx, FZ_ERROR_LIMIT, "Stream too large");

    obj = pdf_dict_get(ctx, dict, PDF_NAME(Filter));

    len = pdf_guess_filter_length(len, pdf_to_name(ctx, obj));

    n = pdf_array_len(ctx, obj);

    for (i = 0; i < n; i++)

      len = pdf_guess_filter_length(len, pdf_array_get_name(ctx, obj, i));

  }

  fz_always(ctx)

  {

    pdf_drop_obj(ctx, dict);

  }

  fz_catch(ctx)

  {

    fz_rethrow(ctx);

  }

  stm = pdf_open_image_stream(ctx, doc, num, params, 1);

  fz_try(ctx)

  {

    buf = fz_read_best(ctx, stm, len, truncated, worst_case);

  }

  fz_always(ctx)

  {

    fz_drop_stream(ctx, stm);

  }

  fz_catch(ctx)

  {

    fz_rethrow(ctx);

  }

  return buf;

}

fz_buffer *

pdf_load_stream_number(fz_context *ctx, pdf_document *doc, int num)

{

  return pdf_load_image_stream(ctx, doc, num, NULL, NULL, 0);

}

fz_compressed_buffer *

pdf_load_compressed_stream(fz_context *ctx, pdf_document *doc, int num, size_t worst_case)

{

  fz_compressed_buffer *bc = fz_new_compressed_buffer(ctx);

  fz_try(ctx)

  {

    bc->buffer = pdf_load_image_stream(ctx, doc, num, &bc->params, NULL, worst_case);

  }

  fz_catch(ctx)

  {

    fz_free(ctx, bc);

    fz_rethrow(ctx);

  }

  return bc;

}

static fz_stream *

pdf_open_object_array(fz_context *ctx, pdf_document *doc, pdf_obj *list)

{

  fz_stream *stm;

  int i, n;

  n = pdf_array_len(ctx, list);

  stm = fz_open_concat(ctx, n, 1);

  for (i = 0; i < n; i++)

  {

    pdf_obj *obj = pdf_array_get(ctx, list, i);

    fz_try(ctx)

      fz_concat_push_drop(ctx, stm, pdf_open_stream(ctx, obj));

    fz_catch(ctx)

    {

      if (fz_caught(ctx) == FZ_ERROR_TRYLATER || fz_caught(ctx) == FZ_ERROR_SYSTEM)

      {

        fz_drop_stream(ctx, stm);

        fz_rethrow(ctx);

      }

      fz_report_error(ctx);

      fz_warn(ctx, "cannot load content stream part %d/%d", i + 1, n);

    }

  }

  return stm;

}

fz_stream *

pdf_open_contents_stream(fz_context *ctx, pdf_document *doc, pdf_obj *obj)

{

  int num;

  if (pdf_is_array(ctx, obj))

    return pdf_open_object_array(ctx, doc, obj);

  num = pdf_to_num(ctx, obj);

  if (pdf_is_stream(ctx, obj))

    return pdf_open_image_stream(ctx, doc, num, NULL, 0);

  fz_warn(ctx, "content stream is not a stream (%d 0 R)", num);

  return fz_open_memory(ctx, (unsigned char *)"", 0);

}

fz_buffer *pdf_load_raw_stream(fz_context *ctx, pdf_obj *ref)

{

  if (pdf_is_stream(ctx, ref))

    return pdf_load_raw_stream_number(ctx, pdf_get_indirect_document(ctx, ref), pdf_to_num(ctx, ref));

  fz_throw(ctx, FZ_ERROR_FORMAT, "object is not a stream");

}

fz_buffer *pdf_load_stream(fz_context *ctx, pdf_obj *ref)

{

  if (pdf_is_stream(ctx, ref))

    return pdf_load_stream_number(ctx, pdf_get_indirect_document(ctx, ref), pdf_to_num(ctx, ref));

  fz_throw(ctx, FZ_ERROR_FORMAT, "object is not a stream");

}

fz_stream *pdf_open_raw_stream(fz_context *ctx, pdf_obj *ref)

{

  if (pdf_is_stream(ctx, ref))

    return pdf_open_raw_stream_number(ctx, pdf_get_indirect_document(ctx, ref), pdf_to_num(ctx, ref));

  fz_throw(ctx, FZ_ERROR_FORMAT, "object is not a stream");

}

fz_stream *pdf_open_stream(fz_context *ctx, pdf_obj *ref)

{

  if (pdf_is_stream(ctx, ref))

    return pdf_open_stream_number(ctx, pdf_get_indirect_document(ctx, ref), pdf_to_num(ctx, ref));

  fz_throw(ctx, FZ_ERROR_FORMAT, "object is not a stream");

}