path: root/Build/source/texk/dvipdfmx/src/pdfobj.c

/*  $Header: /home/cvsroot/dvipdfmx/src/pdfobj.c,v 1.72 2010/02/07 12:53:44 chofchof Exp $

    This is dvipdfmx, an eXtended version of dvipdfm by Mark A. Wicks.

    Copyright (C) 2007 by Jin-Hwan Cho and Shunsaku Hirata,
    the dvipdfmx project team <dvipdfmx@project.ktug.or.kr>
    
    Copyright (C) 1998, 1999 by Mark A. Wicks <mwicks@kettering.edu>

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

#if HAVE_CONFIG_H
#include "config.h"
#endif

#include <ctype.h>
#include <string.h>

#include "system.h"
#include "mem.h"
#include "error.h"
#include "mfileio.h"
#include "dpxutil.h"
#include "pdflimits.h"
#include "pdfencrypt.h"
#include "pdfparse.h"

#ifdef HAVE_ZLIB
#include <zlib.h>
#endif /* HAVE_ZLIB */

#include "pdfobj.h"
#include "pdfdev.h"

#define STREAM_ALLOC_SIZE      4096u
#define ARRAY_ALLOC_SIZE       256
#define IND_OBJECTS_ALLOC_SIZE 512

#define OBJ_NO_OBJSTM   (1 << 0)
/* Objects with this flag will not be put into an object stream.
   For instance, all stream objects have this flag set.          */
#define OBJ_NO_ENCRYPT  (1 << 1)
/* Objects with this flag will not be encrypted.
   This implies OBJ_NO_OBJSTM if encryption is turned on.        */

/* Any of these types can be represented as follows */
struct pdf_obj 
{
  int type;

  unsigned long  label;  /* Only used for indirect objects
			    all other "label" to zero */
  unsigned short generation;  /* Only used if "label" is used */
  unsigned refcount;  /* Number of links to this object */
  int      flags;
  void    *data;
};

struct pdf_boolean
{
  char  value;
};

struct pdf_number
{
  double value;
};

struct pdf_string
{
  unsigned char *string;
  unsigned short length;
};

struct pdf_name
{
  char *name;
};

struct pdf_array
{
  unsigned long max;
  unsigned long size;
  struct pdf_obj **values;
};

struct pdf_dict
{
  struct pdf_obj  *key;
  struct pdf_obj  *value;
  struct pdf_dict *next;
};

struct pdf_stream
{
  struct pdf_obj *dict;
  unsigned char  *stream;
  long           *objstm_data;    /* used for object streams */
  unsigned long   stream_length;
  unsigned long   max_length;
  unsigned char   _flags;
};

struct pdf_indirect
{
  pdf_file      *pf;
  unsigned long label;
  unsigned short generation;
};

typedef void                pdf_null;
typedef struct pdf_boolean  pdf_boolean;
typedef struct pdf_number   pdf_number;
typedef struct pdf_string   pdf_string;
typedef struct pdf_name     pdf_name;
typedef struct pdf_array    pdf_array;
typedef struct pdf_dict     pdf_dict;
typedef struct pdf_stream   pdf_stream;
typedef struct pdf_indirect pdf_indirect;

static FILE *pdf_output_file = NULL;

static long pdf_output_file_position = 0;
static long pdf_output_line_position = 0;
static long compression_saved        = 0;

#define FORMAT_BUF_SIZE 4096
static char format_buffer[FORMAT_BUF_SIZE];

typedef struct xref_entry
{
  unsigned char  type;       /* object storage type              */
  unsigned long  field2;     /* offset in file or object stream  */
  unsigned short field3;     /* generation or index              */
  pdf_obj       *direct;     /* used for imported objects        */
  pdf_obj       *indirect;   /* used for imported objects        */
} xref_entry;

static xref_entry *output_xref;

static unsigned long pdf_max_ind_objects;
static unsigned long next_label;

static unsigned long startxref;

struct pdf_file
{
  FILE       *file;
  pdf_obj    *trailer;
  xref_entry *xref_table;
  pdf_obj    *catalog;
  long        num_obj;
  long        file_size;
  int         version;
};

static pdf_obj *output_stream;

#define OBJSTM_MAX_OBJS  200
/* the limit is only 100 for linearized PDF */

static int enc_mode;
static int doc_enc_mode;

static pdf_obj *trailer_dict;
static pdf_obj *xref_stream;

/* Internal static routines */

static int check_for_pdf_version (FILE *file);

static void pdf_flush_obj (pdf_obj *object, FILE *file);
static void pdf_label_obj (pdf_obj *object);
static void pdf_write_obj (pdf_obj *object, FILE *file);

static void  set_objstm_data (pdf_obj *objstm, long *data);
static long *get_objstm_data (pdf_obj *objstm);
static void  release_objstm  (pdf_obj *objstm);

static void pdf_out_char (FILE *file, char c);
static void pdf_out      (FILE *file, const void *buffer, long length);

static void release_indirect (pdf_indirect *data);
static void write_indirect   (pdf_indirect *indirect, FILE *file);

static void release_boolean (pdf_obj *data);
static void write_boolean   (pdf_boolean *data, FILE *file);

static void release_null (pdf_null *data);
static void write_null   (pdf_null *data, FILE *file);

static void release_number (pdf_number *number);
static void write_number   (pdf_number *number, FILE *file);

static void write_string   (pdf_string *str, FILE *file);
static void release_string (pdf_string *str);

static void write_name   (pdf_name *name, FILE *file);
static void release_name (pdf_name *name);

static void write_array   (pdf_array *array, FILE *file);
static void release_array (pdf_array *array);

static void write_dict   (pdf_dict *dict, FILE *file);
static void release_dict (pdf_dict *dict);

static void write_stream   (pdf_stream *stream, FILE *file);
static void release_stream (pdf_stream *stream);

static int  verbose = 0;
static char compression_level = 9;

void
pdf_set_compression (int level)
{
#ifndef   HAVE_ZLIB
  ERROR("You don't have compression compiled in. Possibly libz wasn't found by configure.");
#else
#ifndef HAVE_ZLIB_COMPRESS2
  if (level != 0) 
    WARN("Unable to set compression level -- your zlib doesn't have compress2().");
#endif
  if (level >= 0 && level <= 9) 
    compression_level = level;
  else {
    ERROR("set_compression: invalid compression level: %d", level);
  }
#endif /* !HAVE_ZLIB */

  return;
}

static unsigned pdf_version = PDF_VERSION_DEFAULT;

void
pdf_set_version (unsigned version)
{
  /* Don't forget to update CIDFont_stdcc_def[] in cid.c too! */
  if (version >= PDF_VERSION_MIN && version <= PDF_VERSION_MAX) {
    pdf_version = version;
  }
}

unsigned
pdf_get_version (void)
{
  return pdf_version;
}

int
pdf_obj_get_verbose(void)
{
  return verbose;
}

void
pdf_obj_set_verbose(void)
{
  verbose++;
}

static pdf_obj *current_objstm = NULL;
static int do_objstm;

static void
add_xref_entry (unsigned long label, unsigned char type, unsigned long field2, unsigned short field3)
{
  if (label >= pdf_max_ind_objects) {
    pdf_max_ind_objects = (label/IND_OBJECTS_ALLOC_SIZE+1)*IND_OBJECTS_ALLOC_SIZE;
    output_xref = RENEW(output_xref, pdf_max_ind_objects, xref_entry);
  }

  output_xref[label].type   = type;
  output_xref[label].field2 = field2;
  output_xref[label].field3 = field3;
  output_xref[label].direct   = NULL;
  output_xref[label].indirect = NULL;
}

#define BINARY_MARKER "%\344\360\355\370\n"
void
pdf_out_init (const char *filename, int do_encryption)
{
  char v;

  output_xref = NULL;
  pdf_max_ind_objects = 0;
  add_xref_entry(0, 0, 0, 0xffff);
  next_label = 1;

  if (pdf_version >= 5) {
    xref_stream = pdf_new_stream(STREAM_COMPRESS);
    xref_stream->flags |= OBJ_NO_ENCRYPT;
    trailer_dict = pdf_stream_dict(xref_stream);
    pdf_add_dict(trailer_dict, pdf_new_name("Type"), pdf_new_name("XRef"));
    do_objstm = 1;
  } else {
    xref_stream = NULL;
    trailer_dict = pdf_new_dict();
    do_objstm = 0;
  }

  output_stream = NULL;

  pdf_output_file = MFOPEN(filename, FOPEN_WBIN_MODE);
  if (!pdf_output_file) {
    if (strlen(filename) < 128)
      ERROR("Unable to open \"%s\".", filename);
    else
      ERROR("Unable to open file.");
  }
  pdf_out(pdf_output_file, "%PDF-1.", strlen("%PDF-1."));
  v = '0' + pdf_version;
  pdf_out(pdf_output_file, &v, 1);
  pdf_out(pdf_output_file, "\n", 1);
  pdf_out(pdf_output_file, BINARY_MARKER, strlen(BINARY_MARKER));

  enc_mode = 0;
  doc_enc_mode = do_encryption;
}

static void
dump_xref_table (void)
{
  long length;
  unsigned long i;

  pdf_out(pdf_output_file, "xref\n", 5);

  length = sprintf(format_buffer, "%d %lu\n", 0, next_label);
  pdf_out(pdf_output_file, format_buffer, length);

  /*
   * Every space counts.  The space after the 'f' and 'n' is * *essential*.
   * The PDF spec says the lines must be 20 characters long including the
   * end of line character.
   */
  for (i = 0; i < next_label; i++) {
    unsigned char type = output_xref[i].type;
    if (type > 1)
      ERROR("object type %hu not allowed in xref table", type);
    length = sprintf(format_buffer, "%010lu %05hu %c \n",
		     output_xref[i].field2, output_xref[i].field3,
		     type ? 'n' : 'f');
    pdf_out(pdf_output_file, format_buffer, length);
  }
}

static void
dump_trailer_dict (void)
{
  pdf_out(pdf_output_file, "trailer\n", 8);
  enc_mode = 0;
  write_dict(trailer_dict->data, pdf_output_file);
  pdf_release_obj(trailer_dict);
  pdf_out_char(pdf_output_file, '\n');
}

/*
 * output a PDF 1.5 cross-reference stream;
 * contributed by Matthias Franz (March 21, 2007)
 */
static void
dump_xref_stream (void)
{
  unsigned long pos, i;
  unsigned poslen;
  unsigned char buf[7] = {0, 0, 0, 0, 0};

  pdf_obj *w;

  /* determine the necessary size of the offset field */
  pos = startxref; /* maximal offset value */
  poslen = 1;
  while (pos >>= 8)
    poslen++;

  w = pdf_new_array();
  pdf_add_array(w, pdf_new_number(1));      /* type                */
  pdf_add_array(w, pdf_new_number(poslen)); /* offset (big-endian) */
  pdf_add_array(w, pdf_new_number(2));      /* generation          */
  pdf_add_dict(trailer_dict, pdf_new_name("W"), w);

  /* We need the xref entry for the xref stream right now */
  add_xref_entry(next_label-1, 1, startxref, 0);

  for (i = 0; i < next_label; i++) {
    unsigned j;
    unsigned short f3;
    buf[0] = output_xref[i].type;
    pos = output_xref[i].field2;
    for (j = poslen; j--; ) {
      buf[1+j] = (unsigned char) pos;
      pos >>= 8;
    }
    f3 = output_xref[i].field3;
    buf[poslen+1] = (unsigned char) (f3 >> 8);
    buf[poslen+2] = (unsigned char) (f3);
    pdf_add_stream(xref_stream, &buf, poslen+3);
  }

  pdf_release_obj(xref_stream);
}

void
pdf_out_flush (void)
{
  if (pdf_output_file) {
    long length;

    /* Flush current object stream */
    if (current_objstm) {
      release_objstm(current_objstm);
      current_objstm =NULL;
    }

    /*
     * Label xref stream - we need the number of correct objects
     * for the xref stream dictionary (= trailer).
     * Labelling it in pdf_out_init (with 1)  does not work (why?).
     */
    if (xref_stream)
      pdf_label_obj(xref_stream);

    /* Record where this xref is for trailer */
    startxref = pdf_output_file_position;

    pdf_add_dict(trailer_dict, pdf_new_name("Size"),
		 pdf_new_number(next_label));

    if (xref_stream)
      dump_xref_stream();
    else {
      dump_xref_table();
      dump_trailer_dict();
    }

    /* Done with xref table */
    RELEASE(output_xref);

    pdf_out(pdf_output_file, "startxref\n", 10);
    length = sprintf(format_buffer, "%lu\n", startxref);
    pdf_out(pdf_output_file, format_buffer, length);
    pdf_out(pdf_output_file, "%%EOF\n", 6);

    MESG("\n");
    if (verbose) {
      if (compression_level > 0) {
	MESG("Compression saved %ld bytes%s\n", compression_saved,
	     pdf_version < 5 ? ". Try \"-V 5\" for better compression" : "");
      }
    }
    MESG("%ld bytes written", pdf_output_file_position);

    MFCLOSE(pdf_output_file);
  }
}

void
pdf_error_cleanup (void)
{
  /*
   * This routine is the cleanup required for an abnormal exit.
   * For now, simply close the file.
   */
  if (pdf_output_file)
    MFCLOSE(pdf_output_file);
}


void
pdf_set_root (pdf_obj *object)
{
  if (pdf_add_dict(trailer_dict, pdf_new_name("Root"), pdf_ref_obj(object))) {
    ERROR("Root object already set!");
  }
  /* Adobe Readers don't like a document catalog inside an encrypted
   * object stream, although the PDF v1.5 spec seems to allow this.
   * Note that we don't set OBJ_NO_ENCRYPT since the name dictionary in
   * a document catalog may contain strings, which should be encrypted.
   */
  if (doc_enc_mode)
    object->flags |= OBJ_NO_OBJSTM;
}

void
pdf_set_info (pdf_obj *object)
{
  if (pdf_add_dict(trailer_dict, pdf_new_name("Info"), pdf_ref_obj(object))) {
    ERROR ("Info object already set!");
  }
}

void
pdf_set_id (pdf_obj *id)
{
  if (pdf_add_dict(trailer_dict, pdf_new_name("ID"), id)) {
    ERROR ("ID already set!");
  }
}

void
pdf_set_encrypt (pdf_obj *encrypt)
{
  if (pdf_add_dict(trailer_dict, pdf_new_name("Encrypt"), pdf_ref_obj(encrypt))) {
    ERROR("Encrypt object already set!");
  }
  encrypt->flags |= OBJ_NO_ENCRYPT;
}

static
void pdf_out_char (FILE *file, char c)
{
  if (output_stream && file ==  pdf_output_file)
    pdf_add_stream(output_stream, &c, 1);
  else {
    fputc(c, file);
    /* Keep tallys for xref table *only* if writing a pdf file. */
    if (file == pdf_output_file) {
      pdf_output_file_position += 1;
      if (c == '\n')
        pdf_output_line_position  = 0;
      else
        pdf_output_line_position += 1;
    }
  }
}

#define pdf_out_xchar(f,c) do {\
  int __tmpnum;\
  __tmpnum = ((c) >> 4) & 0x0f;\
  pdf_out_char((f), (((__tmpnum) >= 10) ? (__tmpnum)+'W' : (__tmpnum)+'0'));\
  __tmpnum = (c) & 0x0f;\
  pdf_out_char((f), (((__tmpnum) >= 10) ? (__tmpnum)+'W' : (__tmpnum)+'0'));\
} while (0)

static
void pdf_out (FILE *file, const void *buffer, long length)
{
  if (output_stream && file ==  pdf_output_file)
    pdf_add_stream(output_stream, buffer, length);
  else {
    fwrite(buffer, 1, length, file);
    /* Keep tallys for xref table *only* if writing a pdf file */
    if (file == pdf_output_file) {
      pdf_output_file_position += length;
      pdf_output_line_position += length;
      /* "foo\nbar\n "... */
      if (length > 0 &&
	((const char *)buffer)[length-1] == '\n')
        pdf_output_line_position = 0;
    }
  }
}

/*  returns 1 if a white-space character is necessary to separate
    an object of type1 followed by an object of type2              */
static
int pdf_need_white (int type1, int type2)
{
  return !(type1 == PDF_STRING || type1 == PDF_ARRAY || type1 == PDF_DICT ||
	   type2 == PDF_STRING || type2 == PDF_NAME ||
	   type2 == PDF_ARRAY || type2 == PDF_DICT);
}

static
void pdf_out_white (FILE *file)
{
  if (file == pdf_output_file && pdf_output_line_position >= 80) {
    pdf_out_char(file, '\n');
  } else {
    pdf_out_char(file, ' ');
  }
}

#define TYPECHECK(o,t) if (!(o) || (o)->type != (t)) {\
  ERROR("typecheck: Invalid object type: %d %d (line %d)", (o) ? (o)->type : -1, (t), __LINE__);\
}

#define INVALIDOBJ(o)  ((o) == NULL || (o)->type <= 0 || (o)->type > PDF_UNDEFINED)

static pdf_obj *
pdf_new_obj(int type)
{
  pdf_obj *result;

  result = NEW(1, pdf_obj);
  result->type  = type;
  result->data  = NULL;
  result->label      = 0;
  result->generation = 0;
  result->refcount   = 1;
  result->flags      = 0;

  if (INVALIDOBJ(result))
    ERROR("Invalid object type: %d", type);

  return result;
}

int
pdf_obj_typeof (pdf_obj *object)
{
  if (INVALIDOBJ(object))
    return PDF_OBJ_INVALID;

  return object->type;
}

static void
pdf_label_obj (pdf_obj *object)
{
  if (INVALIDOBJ(object))
    ERROR("pdf_label_obj(): passed invalid object.");

  /*
   * Don't change label on an already labeled object. Ignore such calls.
   */
  if (object->label == 0) {
    object->label      = next_label++;
    object->generation = 0;
  }
}

/*
 * Transfer the label assigned to the object src to the object dst.
 * The object dst must not yet have been labeled.
 */
void
pdf_transfer_label (pdf_obj *dst, pdf_obj *src)
{
  ASSERT(dst && !dst->label && src);

  dst->label      = src->label;
  dst->generation = src->generation;
  src->label      = 0;
  src->generation = 0;
}

/*
 * This doesn't really copy the object, but allows  it to be used without
 * fear that somebody else will free it.
 */
pdf_obj *
pdf_link_obj (pdf_obj *object)
{
  if (INVALIDOBJ(object))
    ERROR("pdf_link_obj(): passed invalid object.");

  object->refcount += 1;

  return object;
}


pdf_obj *
pdf_ref_obj (pdf_obj *object)
{
  if (INVALIDOBJ(object))
    ERROR("pdf_ref_obj(): passed invalid object.");
  
  if (object->refcount == 0) {
    MESG("\nTrying to refer already released object!!!\n");
    pdf_write_obj(object, stderr);
    ERROR("Cannot continue...");
  }

  if (PDF_OBJ_INDIRECTTYPE(object)) {
    return pdf_link_obj(object);
  } else {
    if (object->label == 0) {
      pdf_label_obj(object);
    }
    return pdf_new_indirect(NULL, object->label, object->generation);
  }
}

static void
release_indirect (pdf_indirect *data)
{
  RELEASE(data);
}

static void
write_indirect (pdf_indirect *indirect, FILE *file)
{
  long length;

  ASSERT(!indirect->pf);

  length = sprintf(format_buffer, "%lu %hu R", indirect->label, indirect->generation);
  pdf_out(file, format_buffer, length);
}

/* The undefined object is used as a placeholder in pdfnames.c
 * for objects which are referenced before they are defined.
 */
pdf_obj *
pdf_new_undefined (void)
{
  pdf_obj *result;

  result = pdf_new_obj(PDF_UNDEFINED);
  result->data = NULL;

  return result;
}

pdf_obj *
pdf_new_null (void)
{
  pdf_obj *result;

  result = pdf_new_obj(PDF_NULL);
  result->data = NULL;

  return result;
}

static void
release_null (pdf_null *obj)
{
  return;
}

static void
write_null (pdf_null *obj, FILE *file)
{
  pdf_out(file, "null", 4);
}

pdf_obj *
pdf_new_boolean (char value)
{
  pdf_obj     *result;
  pdf_boolean *data;

  result = pdf_new_obj(PDF_BOOLEAN);
  data   = NEW(1, pdf_boolean);
  data->value  = value;
  result->data = data;

  return result;
}

static void
release_boolean (pdf_obj *data)
{
  RELEASE (data);
}

static void
write_boolean (pdf_boolean *data, FILE *file)
{
  if (data->value) {
    pdf_out(file, "true", 4);
  } else {
    pdf_out(file, "false", 5);
  }
}

#if 0
void
pdf_set_boolean (pdf_obj *object, char value)
{
  pdf_boolean *data;

  TYPECHECK(object, PDF_BOOLEAN);

  data = object->data;
  data->value = value;
}
#endif

char
pdf_boolean_value (pdf_obj *object)
{
  pdf_boolean *data;

  TYPECHECK(object, PDF_BOOLEAN);

  data = object->data;

  return data->value;
}

pdf_obj *
pdf_new_number (double value)
{
  pdf_obj    *result;
  pdf_number *data;

  result = pdf_new_obj(PDF_NUMBER);
  data   = NEW(1, pdf_number);
  data->value  = value;
  result->data = data;

  return result;
}

static void
release_number (pdf_number *data)
{
  RELEASE (data);
}

static void
write_number (pdf_number *number, FILE *file)
{
  int count;

  count = pdf_sprint_number(format_buffer, number->value);

  pdf_out(file, format_buffer, count);
}


void
pdf_set_number (pdf_obj *object, double value)
{
  pdf_number *data;

  TYPECHECK(object, PDF_NUMBER);

  data = object->data;
  data->value = value;
}

double
pdf_number_value (pdf_obj *object)
{
  pdf_number *data;

  TYPECHECK(object, PDF_NUMBER);

  data = object->data;

  return data->value;
}

pdf_obj *
pdf_new_string (const void *str, unsigned length)
{
  pdf_obj    *result;
  pdf_string *data;

  ASSERT(str);

  result = pdf_new_obj(PDF_STRING);
  data   = NEW(1, pdf_string);
  result->data = data;

  data->length = length;
  data->string = NEW(length+1, unsigned char);
  memcpy(data->string, str, length);
  /* Shouldn't assume NULL terminated. */
  data->string[length] = '\0';

  return result;
}

void *
pdf_string_value (pdf_obj *object)
{
  pdf_string *data;

  TYPECHECK(object, PDF_STRING);

  data = object->data;

  return data->string;
}

unsigned
pdf_string_length (pdf_obj *object)
{
  pdf_string *data;

  TYPECHECK(object, PDF_STRING);

  data = object->data;

  return (unsigned) (data->length);
}

/*
 * This routine escapes non printable characters and control
 * characters in an output string.
 */
int
pdfobj_escape_str (char *buffer, int bufsize, const unsigned char *s, int len)
{
  int result = 0;
  int i;

  for (i = 0; i < len; i++) {
    unsigned char ch;

    ch = s[i];
    if (result > bufsize - 4)
      ERROR("pdfobj_escape_str: Buffer overflow");

    /*
     * We always write three octal digits. Optimization only gives few Kb
     * smaller size for most documents when zlib compressed.
     */
    if (ch < 32 || ch > 126) {
      buffer[result++] = '\\';
#if 0
      if (i < len - 1 && !isdigit(s[i+1]))
	result += sprintf(buffer+result, "%o", ch);
      else
	result += sprintf(buffer+result, "%03o", ch);
#endif
      result += sprintf(buffer+result, "%03o", ch);
    } else {
      switch (ch) {
      case '(':
	buffer[result++] = '\\';
	buffer[result++] = '(';
	break;
      case ')':
	buffer[result++] = '\\';
	buffer[result++] = ')';
	break;
      case '\\':
	buffer[result++] = '\\';
	buffer[result++] = '\\';
	break;
      default:
	buffer[result++] = ch;
	break;
      }
    }
  }

  return result;
}

static void
write_string (pdf_string *str, FILE *file)
{
  unsigned char *s;
  char wbuf[FORMAT_BUF_SIZE]; /* Shouldn't use format_buffer[]. */
  int  nescc = 0, i, count;

  s = str->string;

  if (enc_mode)
    pdf_encrypt_data(s, str->length);

  /*
   * Count all ASCII non-printable characters.
   */
  for (i = 0; i < str->length; i++) {
    if (!isprint(s[i]))
      nescc++;
  }
  /*
   * If the string contains much escaped chars, then we write it as
   * ASCII hex string.
   */
  if (nescc > str->length / 3) {
    pdf_out_char(file, '<');
    for (i = 0; i < str->length; i++) {
      pdf_out_xchar(file, s[i]);
    }
    pdf_out_char(file, '>');
  } else {
    pdf_out_char(file, '(');
    /*
     * This section of code probably isn't speed critical.  Escaping the
     * characters in the string one at a time may seem slow, but it's
     * safe if the formatted string length exceeds FORMAT_BUF_SIZE.
     * Occasionally you see some long strings in PDF.  pdfobj_escape_str
     * is also used for strings of text with no kerning.  These must be
     * handled as quickly as possible since there are so many of them.
     */ 
    for (i = 0; i < str->length; i++) {
      count = pdfobj_escape_str(wbuf, FORMAT_BUF_SIZE, &(s[i]), 1);
      pdf_out(file, wbuf, count);
    }
    pdf_out_char(file, ')');
  }
}

static void
release_string (pdf_string *data)
{
  if (data->string != NULL) {
    RELEASE(data->string);
    data->string = NULL;
  }
  RELEASE(data);
}

void
pdf_set_string (pdf_obj *object, unsigned char *str, unsigned length)
{
  pdf_string *data;

  TYPECHECK(object, PDF_STRING);

  data = object->data;
  if (data->string != 0) {
    RELEASE(data->string);
  }
  if (length != 0) {
    data->length = length;
    data->string = NEW(length + 1, unsigned char);
    memcpy(data->string, str, length);
    data->string[length] = '\0';
  } else {
    data->length = 0;
    data->string = NULL;
  }
}

/* Name does *not* include the /. */ 
pdf_obj *
pdf_new_name (const char *name)
{
  pdf_obj  *result;
  unsigned  length;
  pdf_name *data;

  result = pdf_new_obj(PDF_NAME);
  data   = NEW (1, pdf_name);
  result->data = data;
  length = strlen(name);
  if (length != 0) {
    data->name = NEW(length+1, char);
    memcpy(data->name, name, length);
    data->name[length] = '\0';
  } else {
    data->name = NULL;
  }

  return result;
}

static void
write_name (pdf_name *name, FILE *file)
{
  char *s;
  int i, length;

  s      = name->name;
  length = name->name ? strlen(name->name) : 0;
  /*
   * From PDF Reference, 3rd ed., p.33:
   *
   *  Beginning with PDF 1.2, any character except null (character code 0)
   *  may be included in a name by writing its 2-digit hexadecimal code,
   *  preceded bythe number sign character (#); see implementation notes 3
   *  and 4 in Appendix H. This syntax is required in order to represent
   *  any of the delimiter or white-space characters or the number sign
   *  character itself; it is recommended but not required for characters
   *  whose codes are outside the range 33 (!) to 126 (~).
   */
#ifndef is_delim
  /* Avoid '{' and '}' for PostScript compatibility? */
#define is_delim(c) ((c) == '(' || (c) == '/' || \
                     (c) == '<' || (c) == '>' || \
                     (c) == '[' || (c) == ']' || \
                     (c) == '{' || (c) == '}' || \
                     (c) == '%')
#endif
  pdf_out_char(file, '/');
  for (i = 0; i < length; i++) {
    if (s[i] < '!' || s[i] > '~' || s[i] == '#' || is_delim(s[i])) {
      /*     ^ "space" is here. */
      pdf_out_char (file, '#');
      pdf_out_xchar(file, s[i]);
    } else {
      pdf_out_char (file, s[i]);
    }
  }
}

static void
release_name (pdf_name *data)
{
  if (data->name != NULL) {
    RELEASE(data->name);
    data->name = NULL;
  }
  RELEASE(data);
}

#if 0
void
pdf_set_name (pdf_obj *object, const char *name)
{
  pdf_name *data;
  unsigned length;

  TYPECHECK(object, PDF_NAME);

  length = strlen(name);
  data   = object->data;
  if (data->name != NULL) {
    RELEASE(data->name);
  }
  if (length != 0) {
    data->name = NEW(length+1, char);
    memcpy(data->name, name, length);
    data->name[length] = 0;
  } else {
    data->name = NULL;
  }
}
#endif

char *
pdf_name_value (pdf_obj *object)
{
  pdf_name *data;

  TYPECHECK(object, PDF_NAME);

  data = object->data;

  return data->name;
}

/*
 * We do not have pdf_name_length() since '\0' is not allowed
 * in PDF name object.
 */

pdf_obj *
pdf_new_array (void)
{
  pdf_obj   *result;
  pdf_array *data;

  result = pdf_new_obj(PDF_ARRAY);
  data   = NEW(1, pdf_array);
  data->values = NULL;
  data->max    = 0;
  data->size   = 0;
  result->data = data;

  return result;
}

static void
write_array (pdf_array *array, FILE *file)
{
  pdf_out_char(file, '[');
  if (array->size > 0) {
    unsigned long i;
    int type1 = PDF_UNDEFINED, type2;
    
    for (i = 0; i < array->size; i++) {
      if (array->values[i]) {
	type2 = array->values[i]->type;
	if (type1 != PDF_UNDEFINED && pdf_need_white(type1, type2))
	  pdf_out_white(file);
	type1 = type2;
	pdf_write_obj(array->values[i], file);
      } else
	WARN("PDF array element #ld undefined.", i);
    }
  }
  pdf_out_char(file, ']');
}

pdf_obj *
pdf_get_array (pdf_obj *array, long idx)
{
  pdf_obj   *result = NULL;
  pdf_array *data;

  TYPECHECK(array, PDF_ARRAY);

  data = array->data;
  if (idx < 0)
    result = data->values[idx + data->size];
  else if (idx < data->size) {
    result = data->values[idx];
  }

  return result;
}

unsigned int
pdf_array_length (pdf_obj *array)
{
  pdf_array *data;

  TYPECHECK(array, PDF_ARRAY);

  data = (pdf_array *) array->data;

  return (unsigned int) data->size;
}

static void
release_array (pdf_array *data)
{
  unsigned long i;

  if (data->values) {
    for (i = 0; i < data->size; i++) {
      pdf_release_obj(data->values[i]);
      data->values[i] = NULL;
    }
    RELEASE(data->values);
    data->values = NULL;
  }
  RELEASE(data);
}

/*
 * The name pdf_add_array is misleading. It behaves differently than
 * pdf_add_dict(). This should be pdf_push_array().
 */
void
pdf_add_array (pdf_obj *array, pdf_obj *object)
{
  pdf_array *data;

  TYPECHECK(array, PDF_ARRAY);

  data = array->data;
  if (data->size >= data->max) {
    data->max   += ARRAY_ALLOC_SIZE;
    data->values = RENEW(data->values, data->max, pdf_obj *);
  }
  data->values[data->size] = object;
  data->size++;

  return;
}

#if 0
void
pdf_put_array (pdf_obj *array, unsigned idx, pdf_obj *object)
{
  pdf_array *data;
  long       i;

  TYPECHECK(array, PDF_ARRAY);

  data = array->data;
  if (idx + 1 > data->max) {
    data->max   += ARRAY_ALLOC_SIZE;
    data->values = RENEW(data->values, data->max, pdf_obj *);
  }
  /*
   * Rangecheck error in PostScript interpreters if
   * idx > data->size - 1. But pdf_new_array() doesn't set
   * array size, pdf_add_array() dynamically increases size
   * of array. This might confusing...
   */
  if (idx + 1 > data->size) {
    for (i = data->size; i < idx; i++)
      data->values[i] = pdf_new_null(); /* release_array() won't work without this */
    data->values[idx] = object;
    data->size = idx + 1;
  } else {
    if (data->values[idx])
      pdf_release_obj(data->values[idx]);
    data->values[idx] = object;
  }
}

/* Easily leaks memory... */
pdf_obj *
pdf_shift_array (pdf_obj *array)
{
  pdf_obj   *result = NULL;
  pdf_array *data;

  TYPECHECK(array, PDF_ARRAY);

  data = array->data;
  if (data->size > 0) {
    int i;

    result = data->values[0];
    for (i = 1; i < data->size; i++)
      data->values[i-1] = data->values[i];
    data->size--;
  }

  return result;
}
#endif

/* Prepend an object to an array */
void
pdf_unshift_array (pdf_obj *array, pdf_obj *object)
{
  pdf_array *data;
  int        i;

  TYPECHECK(array, PDF_ARRAY);

  data = array->data;
  if (data->size >= data->max) {
    data->max   += ARRAY_ALLOC_SIZE;
    data->values = RENEW(data->values, data->max, pdf_obj *);
  }
  for (i = 0; i < data->size; i++)
    data->values[i+1] = data->values[i];
  data->values[0] = object;
  data->size++;
}

#if 0
pdf_obj *
pdf_pop_array (pdf_obj *array)
{
  pdf_obj   *result;
  pdf_array *data;

  TYPECHECK(array, PDF_ARRAY);

  data = array->data;
  if (data->size > 0) {
    result = data->values[data->size - 1];
    data->size--;
  } else {
    result = NULL;
  }

  return result;
}
#endif


static void
write_dict (pdf_dict *dict, FILE *file)
{
#if 0
  pdf_out (file, "<<\n", 3); /* dropping \n saves few kb. */
#else
  pdf_out (file, "<<", 2);
#endif
  while (dict->key != NULL) {
    pdf_write_obj(dict->key, file);
    if (pdf_need_white(PDF_NAME, (dict->value)->type)) {
      pdf_out_white(file);
    }
    pdf_write_obj(dict->value, file);
#if 0
    pdf_out_char (file, '\n'); /* removing this saves few kb. */
#endif
    dict = dict->next;
  }
  pdf_out(file, ">>", 2);
}

pdf_obj *
pdf_new_dict (void)
{
  pdf_obj  *result;
  pdf_dict *data;

  result = pdf_new_obj(PDF_DICT);
  data   = NEW(1, pdf_dict);
  data->key    = NULL;
  data->value  = NULL;
  data->next   = NULL;
  result->data = data;

  return result;
}

static void
release_dict (pdf_dict *data)
{
  pdf_dict *next;

  while (data != NULL && data->key != NULL) {
    pdf_release_obj(data->key);
    pdf_release_obj(data->value);
    data->key   = NULL;
    data->value = NULL;
    next = data->next;
    RELEASE(data);
    data = next;
  }
  RELEASE(data);
}

/* Array is ended by a node with NULL this pointer */
/* pdf_add_dict returns 0 if the key is new and non-zero otherwise */
int
pdf_add_dict (pdf_obj *dict, pdf_obj *key, pdf_obj *value)
{
  pdf_dict *data, *new_node;

  TYPECHECK(dict, PDF_DICT);
  TYPECHECK(key,  PDF_NAME);

  /* It seems that NULL is sometimes used for null object... */
  if (value != NULL && INVALIDOBJ(value))
    ERROR("pdf_add_dict(): Passed invalid value");

  /* If this key already exists, simply replace the value */
  for (data = dict->data; data->key != NULL; data = data->next) {
    if (!strcmp(pdf_name_value(key), pdf_name_value(data->key))) {
      /* Release the old value */
      pdf_release_obj(data->value);
      /* Release the new key (we don't need it) */
      pdf_release_obj(key);
      data->value = value;
      return 1;
    }
  }
  /*
   * We didn't find the key. We build a new "end" node and add
   * the new key just before the end
   */
  new_node = NEW (1, pdf_dict);
  new_node->key = NULL;
  new_node->value = NULL;
  new_node->next = NULL;
  data->next  = new_node;
  data->key   = key;
  data->value = value;
  return 0;
}

#if 0
void
pdf_put_dict (pdf_obj *dict, const char *key, pdf_obj *value)
{
  pdf_dict *data;

  TYPECHECK(dict, PDF_DICT);

  if (!key) {
    ERROR("pdf_put_dict(): Passed invalid key.");
  }
  /* It seems that NULL is sometimes used for null object... */
  if (value != NULL && INVALIDOBJ(value)) {
    ERROR("pdf_add_dict(): Passed invalid value.");
  }

  data = dict->data;

  while (data->key != NULL) {
    if (!strcmp(key, pdf_name_value(data->key))) {
      pdf_release_obj(data->value);
      data->value = value;
      break;
    }
    data = data->next;
  }

  /*
   * If we didn't find the key, build a new "end" node and add
   * the new key just before the end
   */
  if (data->key == NULL) {
    pdf_dict *new_node;

    new_node = NEW (1, pdf_dict);
    new_node->key   = NULL;
    new_node->value = NULL;
    new_node->next  = NULL;
    data->next  = new_node;
    data->key   = pdf_new_name(key);
    data->value = value;
  }
}
#endif

/* pdf_merge_dict makes a link for each item in dict2 before stealing it */
void
pdf_merge_dict (pdf_obj *dict1, pdf_obj *dict2)
{
  pdf_dict *data;

  TYPECHECK(dict1, PDF_DICT);
  TYPECHECK(dict2, PDF_DICT);

  data = dict2->data;
  while (data->key != NULL) {
    pdf_add_dict(dict1, pdf_link_obj(data->key), pdf_link_obj(data->value));
    data = data->next;
  }
}

int
pdf_foreach_dict (pdf_obj *dict,
		  int (*proc) (pdf_obj *, pdf_obj *, void *), void *pdata)
{
  int       error = 0;
  pdf_dict *data;

  ASSERT(proc);

  TYPECHECK(dict, PDF_DICT);

  data = dict->data;
  while (!error &&
	 data->key != NULL) {
    error = proc(data->key, data->value, pdata);
    data = data->next;
  }

  return error;
}

#define pdf_match_name(o,s) ((o) && (s) && !strcmp(((pdf_name *)(o)->data)->name, (s)))
pdf_obj *
pdf_lookup_dict (pdf_obj *dict, const char *name)
{
  pdf_dict *data;

  ASSERT(name);

  TYPECHECK(dict, PDF_DICT);

  data = dict->data;
  while (data->key != NULL) {
    if (!strcmp(name, pdf_name_value(data->key))) {
      return data->value;
    }
    data = data->next;
  }

  return NULL;
}

/* Returns array of dictionary keys */
pdf_obj *
pdf_dict_keys (pdf_obj *dict)
{
  pdf_obj  *keys;
  pdf_dict *data;

  TYPECHECK(dict, PDF_DICT);

  keys = pdf_new_array();
  for (data = dict->data; (data &&
			   data->key != NULL); data = data->next) {
    /* We duplicate name object rather than linking keys.
     * If we forget to free keys, broken PDF is generated.
     */
    pdf_add_array(keys, pdf_new_name(pdf_name_value(data->key)));
  }

  return keys;
}

void
pdf_remove_dict (pdf_obj *dict, const char *name)
{
  pdf_dict *data, **data_p;

  TYPECHECK(dict, PDF_DICT);

  data   = dict->data;
  data_p = (pdf_dict **) (void *) &(dict->data);
  while (data->key != NULL) {
    if (pdf_match_name(data->key, name)) {
      pdf_release_obj(data->key);
      pdf_release_obj(data->value);
      *data_p = data->next;
      RELEASE(data);
      break;
    }
    data_p = &(data->next);
    data   = data->next;
  }
}

pdf_obj *
pdf_new_stream (int flags)
{
  pdf_obj    *result;
  pdf_stream *data;

  result = pdf_new_obj(PDF_STREAM);
  data   = NEW(1, pdf_stream);
  /*
   * Although we are using an arbitrary pdf_object here, it must have
   * type=PDF_DICT and cannot be an indirect reference.  This will be
   * checked by the output routine.
   */
  data->dict   = pdf_new_dict();
  data->_flags = flags;
  data->stream = NULL;
  data->stream_length = 0;
  data->max_length    = 0;
  data->objstm_data = NULL;

  result->data = data;
  result->flags |= OBJ_NO_OBJSTM;

  return result;
}

static void
write_stream (pdf_stream *stream, FILE *file)
{
  unsigned char *filtered;
  unsigned long  filtered_length;
  unsigned long  buffer_length;
  unsigned char *buffer;

  /*
   * Always work from a copy of the stream. All filters read from
   * "filtered" and leave their result in "filtered".
   */
#if 0
  filtered = NEW(stream->stream_length + 1, unsigned char);
#endif
  filtered = NEW(stream->stream_length, unsigned char);
  memcpy(filtered, stream->stream, stream->stream_length);
  filtered_length = stream->stream_length;

#if 0
  if (stream->stream_length < 10)
    stream->_flags &= ^STREAM_COMPRESS;
#endif

#ifdef HAVE_ZLIB
  /* Apply compression filter if requested */
  if (stream->stream_length > 0 &&
      (stream->_flags & STREAM_COMPRESS) &&
      compression_level > 0) {

    pdf_obj *filters = pdf_lookup_dict(stream->dict, "Filter");

    buffer_length = filtered_length + filtered_length/1000 + 14;
    buffer = NEW(buffer_length, unsigned char);
    {
      pdf_obj *filter_name = pdf_new_name("FlateDecode");

      if (filters)
        /*
         * FlateDecode is the first filter to be applied to the stream.
         */
        pdf_unshift_array(filters, filter_name);
      else
        /*
         * Adding the filter as a name instead of a one-element array
         * is crucial because otherwise Adobe Reader cannot read the
         * cross-reference stream any more, cf. the PDF v1.5 Errata.
         */
        pdf_add_dict(stream->dict, pdf_new_name("Filter"), filter_name);
    }
#ifdef HAVE_ZLIB_COMPRESS2    
    if (compress2(buffer, &buffer_length, filtered,
		  filtered_length, compression_level)) {
      ERROR("Zlib error");
    }
#else 
    if (compress(buffer, &buffer_length, filtered,
		 filtered_length)) {
      ERROR ("Zlib error");
    }
#endif /* HAVE_ZLIB_COMPRESS2 */
    RELEASE(filtered);
    compression_saved += filtered_length - buffer_length
      - (filters ? strlen("/FlateDecode "): strlen("/Filter/FlateDecode\n"));

    filtered        = buffer;
    filtered_length = buffer_length;
  }
#endif /* HAVE_ZLIB */

#if 0
  /*
   * An optional end-of-line marker preceding the "endstream" is
   * not part of stream data. See, PDF Reference 4th ed., p. 38.
   */
  /* Add a '\n' if the last character wasn't one */
  if (filtered_length > 0 &&
      filtered[filtered_length-1] != '\n') {
    filtered[filtered_length] = '\n';
    filtered_length++;
  }
#endif
  pdf_add_dict(stream->dict,
	       pdf_new_name("Length"), pdf_new_number(filtered_length));

  pdf_write_obj(stream->dict, file);

  pdf_out(file, "\nstream\n", 8);

  if (enc_mode)
    pdf_encrypt_data(filtered, filtered_length);

  if (filtered_length > 0) {
    pdf_out(file, filtered, filtered_length);
  }
  RELEASE(filtered);

  /*
   * This stream length "object" gets reset every time write_stream is
   * called for the stream object.
   * If this stream gets written more than once with different
   * filters, this could be a problem.
   */

  pdf_out(file, "\n", 1);
  pdf_out(file, "endstream", 9);
}

static void
release_stream (pdf_stream *stream)
{
  pdf_release_obj(stream->dict);
  stream->dict = NULL;

  if (stream->stream) {
    RELEASE(stream->stream);
    stream->stream = NULL;
  }

  if (stream->objstm_data) {
    RELEASE(stream->objstm_data);
    stream->objstm_data = NULL;
  }

  RELEASE(stream);
}

pdf_obj *
pdf_stream_dict (pdf_obj *stream)
{
  pdf_stream *data;

  TYPECHECK(stream, PDF_STREAM);

  data = stream->data;

  return data->dict;
}

const void *
pdf_stream_dataptr (pdf_obj *stream)
{
  pdf_stream *data;

  TYPECHECK(stream, PDF_STREAM);

  data = stream->data;

  return (const void *) data->stream;
}

long
pdf_stream_length (pdf_obj *stream)
{
  pdf_stream *data;

  TYPECHECK(stream, PDF_STREAM);

  data = stream->data;

  return (long) data->stream_length;
}

static void
set_objstm_data (pdf_obj *objstm, long *data) {
  TYPECHECK(objstm, PDF_STREAM);

  ((pdf_stream *) objstm->data)->objstm_data = data;
}

static long *
get_objstm_data (pdf_obj *objstm) {
  TYPECHECK(objstm, PDF_STREAM);

  return ((pdf_stream *) objstm->data)->objstm_data;
}

void
pdf_add_stream (pdf_obj *stream, const void *stream_data, long length)
{
  pdf_stream *data;

  TYPECHECK(stream, PDF_STREAM);

  if (length < 1)
    return;
  data = stream->data;
  if (data->stream_length + length > data->max_length) {
    data->max_length += length + STREAM_ALLOC_SIZE;
    data->stream      = RENEW(data->stream, data->max_length, unsigned char);
  }
  memcpy(data->stream + data->stream_length, stream_data, length);
  data->stream_length += length;
}

#if HAVE_ZLIB
#define WBUF_SIZE 4096
int
pdf_add_stream_flate (pdf_obj *dst, const void *data, long len)
{
  z_stream z;
  Bytef wbuf[WBUF_SIZE];

  z.zalloc = Z_NULL; z.zfree = Z_NULL; z.opaque = Z_NULL;

  z.next_in  = (Bytef *) data; z.avail_in  = len;
  z.next_out = (Bytef *) wbuf; z.avail_out = WBUF_SIZE;

  if (inflateInit(&z) != Z_OK) {
    WARN("inflateInit() failed.");
    return -1;
  }

  for (;;) {
    int status;
    status = inflate(&z, Z_NO_FLUSH);
    if (status == Z_STREAM_END)
      break;
    else if (status != Z_OK) {
      WARN("inflate() failed. Broken PDF file?");
      inflateEnd(&z);
      return -1;
    }

    if (z.avail_out == 0) {
      pdf_add_stream(dst, wbuf, WBUF_SIZE);
      z.next_out  = wbuf;
      z.avail_out = WBUF_SIZE;
    }
  }

  if (WBUF_SIZE - z.avail_out > 0)
    pdf_add_stream(dst, wbuf, WBUF_SIZE - z.avail_out);

  return (inflateEnd(&z) == Z_OK ? 0 : -1);
}
#endif


int
pdf_concat_stream (pdf_obj *dst, pdf_obj *src)
{
  const char *stream_data;
  long        stream_length;
  pdf_obj    *stream_dict;
  pdf_obj    *filter;

  if (!PDF_OBJ_STREAMTYPE(dst) || !PDF_OBJ_STREAMTYPE(src))
    ERROR("Invalid type.");

  stream_data   = pdf_stream_dataptr(src);
  stream_length = pdf_stream_length (src);
  stream_dict   = pdf_stream_dict   (src);

  if (pdf_lookup_dict(stream_dict, "DecodeParms")) {
    WARN("Streams with DecodeParams not supported.");
    return -1;
  }

  filter = pdf_lookup_dict(stream_dict, "Filter");
  if (!filter) {
    pdf_add_stream(dst, stream_data, stream_length);
    return 0;
#if HAVE_ZLIB
  } else {
    char *filter_name;
    if (PDF_OBJ_NAMETYPE(filter)) {
      filter_name = pdf_name_value(filter);
      if (filter_name && !strcmp(filter_name, "FlateDecode"))
	return pdf_add_stream_flate(dst, stream_data, stream_length);
      else {
	WARN("DecodeFilter \"%s\" not supported.", filter_name);
	return -1;
      }
    } else if (PDF_OBJ_ARRAYTYPE(filter)) {
      if (pdf_array_length(filter) > 1) {
	WARN("Multiple DecodeFilter not supported.");
	return -1;
      } else {
	filter_name = pdf_name_value(pdf_get_array(filter, 0));
	if (filter_name && !strcmp(filter_name, "FlateDecode"))
	  return pdf_add_stream_flate(dst, stream_data, stream_length);
	else {
	  WARN("DecodeFilter \"%s\" not supported.", filter_name);
	  return -1;
	}
      }
    } else
      ERROR("Broken PDF file?");
#endif /* HAVE_ZLIB */
  }

  return -1;
}

static pdf_obj *
pdf_stream_uncompress (pdf_obj *src) {
  pdf_obj *dst = pdf_new_stream(0);

  TYPECHECK(src, PDF_STREAM);

  pdf_merge_dict(pdf_stream_dict(dst), pdf_stream_dict(src));
  pdf_remove_dict(pdf_stream_dict(dst), "Length");
  pdf_concat_stream(dst, src);

  return dst;
}

#if 0
void
pdf_stream_set_flags (pdf_obj *stream, int flags)
{
  pdf_stream *data;

  TYPECHECK(stream, PDF_STREAM);

  data = stream->data;
  data->_flags = flags;
}

int
pdf_stream_get_flags (pdf_obj *stream)
{
  pdf_stream *data;

  TYPECHECK(stream, PDF_STREAM);

  data = stream->data;

  return data->_flags;
}
#endif

static void
pdf_write_obj (pdf_obj *object, FILE *file)
{
  if (object == NULL) {
    write_null(NULL, file);
    return;
  }

  if (INVALIDOBJ(object) || PDF_OBJ_UNDEFINED(object))
    ERROR("pdf_write_obj: Invalid object, type = %d\n", object->type);

  if (file == stderr)
    fprintf(stderr, "{%d}", object->refcount);

  switch (object->type) {
  case PDF_BOOLEAN:
    write_boolean(object->data, file);
    break;
  case PDF_NUMBER:
    write_number (object->data, file);
    break;
  case PDF_STRING:
    write_string (object->data, file);
    break;
  case PDF_NAME:
    write_name(object->data, file);
    break;
  case PDF_ARRAY:
    write_array(object->data, file);
    break;
  case PDF_DICT:
    write_dict (object->data, file);
    break;
  case PDF_STREAM:
    write_stream(object->data, file);
    break;
  case PDF_NULL:
    write_null(NULL, file);
    break;
  case PDF_INDIRECT:
    write_indirect(object->data, file);
    break;
  }
}

/* Write the object to the file */ 
static void
pdf_flush_obj (pdf_obj *object, FILE *file)
{
  long length;

  /*
   * Record file position
   */
  add_xref_entry(object->label, 1,
		 pdf_output_file_position, object->generation);
  length = sprintf(format_buffer, "%lu %hu obj\n", object->label, object->generation);
  enc_mode = doc_enc_mode && !(object->flags & OBJ_NO_ENCRYPT);
  pdf_enc_set_label(object->label);
  pdf_enc_set_generation(object->generation);
  pdf_out(file, format_buffer, length);
  pdf_write_obj(object, file);
  pdf_out(file, "\nendobj\n", 8);
}

static long
pdf_add_objstm (pdf_obj *objstm, pdf_obj *object)
{
  long *data, pos;

  TYPECHECK(objstm, PDF_STREAM);

  data = get_objstm_data(objstm);
  pos = ++data[0];

  data[2*pos]   = object->label;
  data[2*pos+1] = pdf_stream_length(objstm);

  add_xref_entry(object->label, 2, objstm->label, pos-1);
 
  /* redirect output into objstm */
  output_stream = objstm;
  enc_mode = 0;
  pdf_write_obj(object, pdf_output_file);
  pdf_out_char(pdf_output_file, '\n');
  output_stream = NULL;

  return pos;
}

static void
release_objstm (pdf_obj *objstm)
{
  long *data = get_objstm_data(objstm);
  long pos = data[0];
  pdf_obj *dict;
  pdf_stream *stream;
  unsigned char *old_buf;
  unsigned long old_length;
  stream = (pdf_stream *) objstm->data;

  /* Precede stream data by offset table */
  old_buf = stream->stream;
  old_length = stream->stream_length;
  /* Reserve 22 bytes for each entry (two 10 digit numbers plus two spaces) */
  stream->stream = NEW(old_length + 22*pos, unsigned char);
  stream->stream_length = 0;

  {
    long i = 2*pos, *val = data+2;
    while (i--) {
      long length = sprintf(format_buffer, "%ld ", *(val++));
      pdf_add_stream(objstm, format_buffer, length);
    }
  }

  dict = pdf_stream_dict(objstm);
  pdf_add_dict(dict, pdf_new_name("Type"), pdf_new_name("ObjStm"));
  pdf_add_dict(dict, pdf_new_name("N"), pdf_new_number(pos));
  pdf_add_dict(dict, pdf_new_name("First"), pdf_new_number(stream->stream_length));
  
  pdf_add_stream(objstm, old_buf, old_length);
  RELEASE(old_buf);
  pdf_release_obj(objstm);
}

void
pdf_release_obj (pdf_obj *object)
{
  if (object == NULL)
    return;
  if (INVALIDOBJ(object) || object->refcount <= 0) {
    MESG("\npdf_release_obj: object=%p, type=%d, refcount=%d\n",
	 object, object->type, object->refcount);
    pdf_write_obj(object, stderr);
    ERROR("pdf_release_obj:  Called with invalid object.");
  }
  object->refcount -= 1;
  if (object->refcount == 0) {
    /*
     * Nothing is using this object so it's okay to remove it.
     * Nonzero "label" means object needs to be written before it's destroyed.
     */
    if (object->label && pdf_output_file != NULL) {
      if (!do_objstm || object->flags & OBJ_NO_OBJSTM
	  || (doc_enc_mode && object->flags & OBJ_NO_ENCRYPT)
	  || object->generation)
	pdf_flush_obj(object, pdf_output_file);
      else {
        if (!current_objstm) {
	  long *data = NEW(2*OBJSTM_MAX_OBJS+2, long);
	  data[0] = data[1] = 0;
	  current_objstm = pdf_new_stream(STREAM_COMPRESS);
	  set_objstm_data(current_objstm, data);
	  pdf_label_obj(current_objstm);
	}
	if (pdf_add_objstm(current_objstm, object) == OBJSTM_MAX_OBJS) {
	  release_objstm(current_objstm);
	  current_objstm = NULL;
	}
      }
    }
    switch (object->type) {
    case PDF_BOOLEAN:
      release_boolean(object->data);
      break;
    case PDF_NULL:
      release_null(object->data);
      break;
    case PDF_NUMBER:
      release_number(object->data);
      break;
    case PDF_STRING:
      release_string(object->data);
      break;
    case PDF_NAME:
      release_name(object->data);
      break;
    case PDF_ARRAY:
      release_array(object->data);
      break;
    case PDF_DICT:
      release_dict(object->data);
      break;
    case PDF_STREAM:
      release_stream(object->data);
      break;
    case PDF_INDIRECT:
      release_indirect(object->data);
      break;
    }
    /* This might help detect freeing already freed objects */
    object->type = -1;
    object->data = NULL;
    RELEASE(object);
  }
}

static int
backup_line (FILE *pdf_input_file)
{
  int ch = -1;

  /*
   * Note: this code should work even if \r\n is eol. It could fail on a
   * machine where \n is eol and there is a \r in the stream --- Highly
   * unlikely in the last few bytes where this is likely to be used.
   */
  if (tell_position(pdf_input_file) > 1)
    do {
      seek_relative (pdf_input_file, -2);
    } while (tell_position(pdf_input_file) > 0 &&
	     (ch = fgetc(pdf_input_file)) >= 0 &&
	     (ch != '\n' && ch != '\r' ));
  if (ch < 0) {
    return 0;
  }

  return 1;
}

static long
find_xref (FILE *pdf_input_file)
{
  long xref_pos;
  int  tries = 10;

  do {
    long currentpos;

    if (!backup_line(pdf_input_file)) {
      tries = 0;
      break;
    }
    currentpos = tell_position(pdf_input_file);
    fread(work_buffer, sizeof(char), strlen("startxref"), pdf_input_file);
    seek_absolute(pdf_input_file, currentpos);
    tries--;
  } while (tries > 0 &&
	   strncmp(work_buffer, "startxref", strlen("startxref")));
  if (tries <= 0)
    return 0;

  /* Skip rest of this line */
  mfgets(work_buffer, WORK_BUFFER_SIZE, pdf_input_file);
  /* Next line of input file should contain actual xref location */
  mfgets(work_buffer, WORK_BUFFER_SIZE, pdf_input_file);

  {
    const char *start, *end;
    char *number;

    start = work_buffer;
    end   = start + strlen(work_buffer);
    skip_white(&start, end);
    number   = parse_number(&start, end);
    xref_pos = (long) atof(number);
    RELEASE(number);
  }

  return xref_pos;
}

/*
 * This routine must be called with the file pointer located
 * at the start of the trailer.
 */
static pdf_obj *
parse_trailer (pdf_file *pf)
{
  pdf_obj *result;
  /*
   * Fill work_buffer and hope trailer fits. This should
   * be made a bit more robust sometime.
   */
  if (fread(work_buffer, sizeof(char),
	    WORK_BUFFER_SIZE, pf->file) == 0 ||
      strncmp(work_buffer, "trailer", strlen("trailer"))) {
    WARN("No trailer.  Are you sure this is a PDF file?");
    WARN("buffer:\n->%s<-\n", work_buffer);
    result = NULL;
  } else {
    const char *p = work_buffer + strlen("trailer");
    skip_white(&p, work_buffer + WORK_BUFFER_SIZE);
    result = parse_pdf_dict(&p, work_buffer + WORK_BUFFER_SIZE, pf);
  }

  return result;
}

/*
 * This routine tries to estimate an upper bound for character position
 * of the end of the object, so it knows how big the buffer must be.
 * The parsing routines require that the entire object be read into
 * memory. It would be a major pain to rewrite them.  The worst case
 * is that an object before an xref table will grab the whole table
 * :-(
 */
static long
next_object_offset (pdf_file *pf, unsigned long obj_num)
{
  long  next = pf->file_size;  /* Worst case */
  long  i, curr;

  curr = pf->xref_table[obj_num].field2;
  /* Check all other type 1 objects to find next one */
  for (i = 0; i < pf->num_obj; i++) {
    if (pf->xref_table[i].type == 1 &&
        pf->xref_table[i].field2 > curr &&
        pf->xref_table[i].field2 < next)
      next = pf->xref_table[i].field2;
  }

  return  next;
}

#define checklabel(pf, n, g) ((n) > 0 && (n) < (pf)->num_obj && ( \
  ((pf)->xref_table[(n)].type == 1 && (pf)->xref_table[(n)].field3 == (g)) || \
  ((pf)->xref_table[(n)].type == 2 && !(g))))

pdf_obj *
pdf_new_indirect (pdf_file *pf, unsigned long obj_num, unsigned short obj_gen)
{
  pdf_obj      *result;
  pdf_indirect *indirect;

  indirect = NEW(1, pdf_indirect);
  indirect->pf         = pf;
  indirect->label      = obj_num;
  indirect->generation = obj_gen;

  result   = pdf_new_obj(PDF_INDIRECT);
  result->data = indirect;

  return result;
}

static pdf_obj *
pdf_read_object (unsigned long obj_num, unsigned short obj_gen,
		pdf_file *pf, long offset, long limit)
{
  long     length;
  char    *buffer;
  const char *p, *endptr;
  pdf_obj *result;

  length = limit - offset;

  if (length <= 0)
    return NULL;

  buffer = NEW(length + 1, char);

  seek_absolute(pf->file, offset);
  fread(buffer, sizeof(char), length, pf->file);

  p      = buffer;
  endptr = p + length;

  /* Check for obj_num and obj_gen */
  {
    const char   *q = p; /* <== p */
    char         *sp;
    unsigned long n, g;

    skip_white(&q, endptr);
    sp = parse_unsigned(&q, endptr);
    if (!sp) {
      RELEASE(buffer);
      return NULL;
    }
    n = strtoul(sp, NULL, 10);
    RELEASE(sp);

    skip_white(&q, endptr);
    sp = parse_unsigned(&q, endptr);
    if (!sp) {
      RELEASE(buffer);
      return NULL;
    }
    g = strtoul(sp, NULL, 10);
    RELEASE(sp);

    if (obj_num && (n != obj_num || g != obj_gen)) {
      RELEASE(buffer);
      return NULL;
    }

    p = q; /* ==> p */
  }


  skip_white(&p, endptr);
  if (memcmp(p, "obj", strlen("obj"))) {
    WARN("Didn't find \"obj\".");
    RELEASE(buffer);
    return NULL;
  }
  p += strlen("obj");

  result = parse_pdf_object(&p, endptr, pf);

  skip_white(&p, endptr);
  if (memcmp(p, "endobj", strlen("endobj"))) {
    WARN("Didn't find \"endobj\".");
    if (result)
      pdf_release_obj(result);
    result = NULL;
  }
  RELEASE(buffer);

  return result;
}

static pdf_obj *
read_objstm (pdf_file *pf, unsigned long num)
{
  unsigned long offset = pf->xref_table[num].field2;
  unsigned short gen = pf->xref_table[num].field3;
  long limit = next_object_offset(pf, num), n, first, *header = NULL;
  char *data = NULL, *q;
  const char *p, *endptr;
  int i;

  pdf_obj *objstm, *dict, *type, *n_obj, *first_obj;

  objstm = pdf_read_object(num, gen, pf, offset, limit);

  if (!PDF_OBJ_STREAMTYPE(objstm))
    goto error;

  {
    pdf_obj *tmp = pdf_stream_uncompress(objstm);
    if (!tmp)
      goto error;
    pdf_release_obj(objstm);
    objstm = tmp;
  }

  dict = pdf_stream_dict(objstm);

  type = pdf_lookup_dict(dict, "Type");
  if (!PDF_OBJ_NAMETYPE(type) ||
      strcmp(pdf_name_value(type), "ObjStm"))
    goto error;

  n_obj = pdf_lookup_dict(dict, "N");
  if (!PDF_OBJ_NUMBERTYPE(n_obj))
    goto error;
  n = (long) pdf_number_value(n_obj);

  first_obj = pdf_lookup_dict(dict, "First");
  if (!PDF_OBJ_NUMBERTYPE(first_obj))
    goto error;
  first = (long) pdf_number_value(first_obj);
  /* reject object streams without object data */
  if (first >= pdf_stream_length(objstm))
    goto error;

  header = NEW(2*(n+1), long);
  set_objstm_data(objstm, header);
  *(header++) = n;
  *(header++) = first;

  /* avoid parsing beyond offset table */
  data = NEW(first + 1, char);
  memcpy(data, pdf_stream_dataptr(objstm), first);
  data[first] = 0;

  p      = data;
  endptr = p + first;
  i = 2*n;
  while (i--) {
    *(header++) = strtoul(p, &q, 10);
    if (q == p)
      goto error;
    p = q;
  }

  /* Any garbage after last entry? */
  skip_white(&p, endptr);
  if (p != endptr)
    goto error;
  RELEASE(data);
  
  return pf->xref_table[num].direct = objstm;

 error:
  WARN("Cannot parse object stream.");
  if (data)
    RELEASE(data);
  if (objstm)
    pdf_release_obj(objstm);
  return NULL;
}

/* Label without corresponding object definition are replaced by the
 * null object, as required by the PDF spec. This is important to parse
 * several cross-reference sections.
 */ 
static pdf_obj *
pdf_get_object (pdf_file *pf, unsigned long obj_num, unsigned short obj_gen)
{
  pdf_obj *result;

  if (!checklabel(pf, obj_num, obj_gen)) {
    WARN("Trying to read nonexistent or deleted object: %lu %u",
         obj_num, obj_gen);
    return pdf_new_null();
  }

  if ((result = pf->xref_table[obj_num].direct)) {
    return pdf_link_obj(result);
  }

  if (pf->xref_table[obj_num].type == 1) {
    /* type == 1 */
    unsigned long offset;
    long limit;
    offset = pf->xref_table[obj_num].field2;
    limit  = next_object_offset(pf, obj_num);
    result = pdf_read_object(obj_num, obj_gen, pf, offset, limit);
  } else {
    /* type == 2 */
    unsigned long  objstm_num = pf->xref_table[obj_num].field2;
    unsigned short index = pf->xref_table[obj_num].field3;
    pdf_obj *objstm;
    long *data, n, first, length;
    const char *p, *q;

    if (objstm_num >= pf->num_obj ||
	pf->xref_table[objstm_num].type != 1 ||
	!((objstm = pf->xref_table[objstm_num].direct) ||
	  (objstm = read_objstm(pf, objstm_num))))
      goto error;

    data = get_objstm_data(objstm);
    n = *(data++);
    first = *(data++);

    if (index >= n || data[2*index] != obj_num)
      goto error;

    length = pdf_stream_length(objstm);
    p = (const char *) pdf_stream_dataptr(objstm) + first + data[2*index+1];
    q = p + (index == n-1 ? length : first+data[2*index+3]);
    result = parse_pdf_object(&p, q, pf);
    if (!result)
      goto error;
  }

  /* Make sure the caller doesn't free this object */
  pf->xref_table[obj_num].direct = pdf_link_obj(result);

  return result;

 error:
  WARN("Could not read object from object stream.");
  return pdf_new_null();
}

#define OBJ_FILE(o) (((pdf_indirect *)((o)->data))->pf)
#define OBJ_NUM(o)  (((pdf_indirect *)((o)->data))->label)
#define OBJ_GEN(o)  (((pdf_indirect *)((o)->data))->generation)

/* pdf_deref_obj always returns a link instead of the original   */
/* It never return the null object, but the NULL pointer instead */
pdf_obj *
pdf_deref_obj (pdf_obj *obj)
{
  int count = PDF_OBJ_MAX_DEPTH;

  if (obj)
    obj = pdf_link_obj(obj);

  while (PDF_OBJ_INDIRECTTYPE(obj) && --count) {
    pdf_file *pf = OBJ_FILE(obj);
    unsigned long  obj_num = OBJ_NUM(obj);
    unsigned short obj_gen = OBJ_GEN(obj);
    ASSERT(pf);
    pdf_release_obj(obj);
    obj = pdf_get_object(pf, obj_num, obj_gen);
  }

  if (!count)
    ERROR("Loop in object hierarchy detected. Broken PDF file?");

  if (PDF_OBJ_NULLTYPE(obj)) {
    pdf_release_obj(obj);
    return NULL;
  } else
    return obj;
}

static void
extend_xref (pdf_file *pf, long new_size) 
{
  unsigned long i;

  pf->xref_table = RENEW(pf->xref_table, new_size, xref_entry);
  for (i = pf->num_obj; i < new_size; i++) {
    pf->xref_table[i].direct   = NULL;
    pf->xref_table[i].indirect = NULL;
    pf->xref_table[i].type     = 0;
    pf->xref_table[i].field3 = 0;
    pf->xref_table[i].field2 = 0L;
  }
  pf->num_obj = new_size;
}

static int
parse_xref_table (pdf_file *pf, long xref_pos)
{
  FILE         *pdf_input_file = pf->file;
  unsigned long first, size;
  unsigned long i, offset;
  unsigned int  obj_gen;
  char          flag;
  int           r;

  /*
   * This routine reads one xref segment. It may be called multiple times
   * on the same file.  xref tables sometimes come in pieces.
   */

  seek_absolute(pf->file, xref_pos);

  mfgets(work_buffer, WORK_BUFFER_SIZE, pdf_input_file);
  if (memcmp(work_buffer, "xref", strlen("xref"))) {
    /* Might be an xref stream and not an xref table */
    return 0;
  }
  /* Next line in file has first item and size of table */
  for (;;) {
    unsigned long current_pos;

    current_pos = tell_position(pdf_input_file);
    if (mfgets(work_buffer, WORK_BUFFER_SIZE, pdf_input_file) == NULL) {
      WARN("Premature end of PDF file while parsing xref table.");
      return -1;
    }
    if (!strncmp(work_buffer, "trailer", strlen ("trailer"))) {
      /*
       * Backup... This is ugly, but it seems like the safest thing to
       * do.  It is possible the trailer dictionary starts on the same
       * logical line as the word trailer.  In that case, the mfgets
       * call might have started to read the trailer dictionary and
       * parse_trailer would fail.
       */
      seek_absolute(pdf_input_file, current_pos);
      break;
    }
    sscanf(work_buffer, "%lu %lu", &first, &size);
    if (pf->num_obj < first + size) {
      extend_xref(pf, first + size);
    }

    for (i = first; i < first + size; i++) {
      fread(work_buffer, sizeof(char), 20, pdf_input_file);
      /*
       * Don't overwrite positions that have already been set by a
       * modified xref table.  We are working our way backwards
       * through the reference table, so we only set "position" 
       * if it hasn't been set yet.
       */
      work_buffer[19] = 0;
      offset = 0UL; obj_gen = 0; flag = 0;
      r = sscanf(work_buffer, "%010lu %05u %c", &offset, &obj_gen, &flag);
      if ( r != 3 ||
          ((flag != 'n' && flag != 'f') ||
           (flag == 'n' &&
           (offset >= pf->file_size || (offset > 0 && offset < 4))))) {
        WARN("Invalid xref table entry [%lu]. PDF file is corrupt...", i);
        return -1;
      }
      if (!pf->xref_table[i].field2) {
	pf->xref_table[i].type   = (flag == 'n');
	pf->xref_table[i].field2 = offset;
	pf->xref_table[i].field3 = obj_gen;	
      }
    }
  }

  return  1;
}

static unsigned long
parse_xrefstm_field (const char **p, int length, unsigned long def)
{
  unsigned long val = 0;

  if (!length)
    return def;

  while (length--) {
    val <<= 8;
    val |= (unsigned char) *((*p)++);
  }

  return val;
}

static int
parse_xrefstm_subsec (pdf_file *pf,
		      const char **p, long *length,
		      int *W, int wsum,
		      long first, long size) {
  xref_entry *e;

  if ((*length -= wsum*size) < 0)
    return -1;

  if (pf->num_obj < first+size)
    extend_xref(pf, first+size);  /* TODO: change! why? */

  e = pf->xref_table + first;
  while (size--) {
    unsigned char  type;
    unsigned long  field2;
    unsigned short field3;

    type = (unsigned char) parse_xrefstm_field(p, W[0], 1);
    if (type > 2)
      WARN("Unknown cross-reference stream entry type.");
    else if (!W[1] || (type != 1 && !W[2]))
      return -1;

    field2 = (unsigned long)  parse_xrefstm_field(p, W[1], 0);
    field3 = (unsigned short) parse_xrefstm_field(p, W[2], 0);

    if (!e->field2) {
      e->type   = type;
      e->field2 = field2;
      e->field3 = field3;	
      }
    e++;
  }

  return 0;
}

static int
parse_xref_stream (pdf_file *pf, long xref_pos, pdf_obj **trailer)
{
  pdf_obj *xrefstm, *size_obj, *W_obj, *index_obj;
  unsigned long size;
  long length;
  int W[3], i, wsum = 0;
  const char *p;

  xrefstm = pdf_read_object(0, 0, pf, xref_pos, pf->file_size);
  if (!PDF_OBJ_STREAMTYPE(xrefstm))
    goto error;

  {
    pdf_obj *tmp = pdf_stream_uncompress(xrefstm);
    if (!tmp)
      goto error;
    pdf_release_obj(xrefstm);
    xrefstm = tmp;
  }

  *trailer = pdf_link_obj(pdf_stream_dict(xrefstm));

  size_obj = pdf_lookup_dict(*trailer, "Size");
  if (!PDF_OBJ_NUMBERTYPE(size_obj))
    goto error;
  size = (unsigned long) pdf_number_value(size_obj);

  length = pdf_stream_length(xrefstm);

  W_obj = pdf_lookup_dict(*trailer, "W");
  if (!PDF_OBJ_ARRAYTYPE(W_obj) || pdf_array_length(W_obj) != 3)
    goto error;

  for (i = 0; i < 3; i++) {
    pdf_obj *tmp = pdf_get_array(W_obj, i);
    if (!PDF_OBJ_NUMBERTYPE(tmp))
      goto error;
    wsum += (W[i] = (int) pdf_number_value(tmp));
  }

  p = pdf_stream_dataptr(xrefstm);

  index_obj = pdf_lookup_dict(*trailer, "Index");
  if (index_obj) {
    unsigned int index_len;
    if (!PDF_OBJ_ARRAYTYPE(index_obj) ||
	((index_len = pdf_array_length(index_obj)) % 2 ))
      goto error;

    i = 0;
    while (i < index_len) {
      pdf_obj *first = pdf_get_array(index_obj, i++);
      size_obj  = pdf_get_array(index_obj, i++);
      if (!PDF_OBJ_NUMBERTYPE(first) ||
	  !PDF_OBJ_NUMBERTYPE(size_obj) ||
	  parse_xrefstm_subsec(pf, &p, &length, W, wsum,
			       (long) pdf_number_value(first),
			       (long) pdf_number_value(size_obj)))
	goto error;
    }
  } else if (parse_xrefstm_subsec(pf, &p, &length, W, wsum, 0, size))
      goto error;

  if (length)
    WARN("Garbage in xref stream.");

  pdf_release_obj(xrefstm);

  return 1;

 error:
  WARN("Cannot parse cross-reference stream.");
  if (xrefstm)
    pdf_release_obj(xrefstm);
  if (*trailer) {
    pdf_release_obj(*trailer);
    *trailer = NULL;
  }
  return 0;
}

static pdf_obj *
read_xref (pdf_file *pf)
{
  pdf_obj *trailer = NULL, *main_trailer = NULL;
  long     xref_pos;

  if (!(xref_pos = find_xref(pf->file)))
    goto error;

  while (xref_pos) {
    pdf_obj *prev;

    int res = parse_xref_table(pf, xref_pos);
    if (res > 0) {
      /* cross-reference table */
      pdf_obj *xrefstm;

      if (!(trailer = parse_trailer(pf)))
	goto error;

      if (!main_trailer)
	main_trailer = pdf_link_obj(trailer);

      if ((xrefstm = pdf_lookup_dict(trailer, "XRefStm"))) {
	pdf_obj *new_trailer = NULL;
	if (PDF_OBJ_NUMBERTYPE(xrefstm) &&
	    parse_xref_stream(pf, (long) pdf_number_value(xrefstm),
			      &new_trailer))
	  pdf_release_obj(new_trailer);
	else
	  WARN("Skipping hybrid reference section.");
	/* Many PDF 1.5 xref streams use DecodeParms, which we cannot
	   parse. This way we can use at least xref tables in hybrid
	   documents. Or should we better stop parsing the file?
	*/
      }

    } else if (!res && parse_xref_stream(pf, xref_pos, &trailer)) {
      /* cross-reference stream */
      if (!main_trailer)
	main_trailer = pdf_link_obj(trailer);
    } else
      goto error;

    if ((prev = pdf_lookup_dict(trailer, "Prev"))) {
      if (PDF_OBJ_NUMBERTYPE(prev))
	xref_pos = (long) pdf_number_value(prev);
      else
	goto error;
    } else
      xref_pos = 0;

    pdf_release_obj(trailer);
  }

#if 0
  if (!pdf_lookup_dict(main_trailer, "Root")) {
      WARN("Trailer doesn't have catalog. Is this a correct PDF file?");
      goto error;
    }
#endif

  return main_trailer;

 error:
  WARN("Error while parsing PDF file.");
  if (trailer)
    pdf_release_obj(trailer);
  if (main_trailer)
    pdf_release_obj(main_trailer);
  return NULL;
}

static struct ht_table *pdf_files = NULL;

static pdf_file *
pdf_file_new (FILE *file)
{
  pdf_file *pf;
  ASSERT(file);
  pf = NEW(1, pdf_file);
  pf->file    = file;
  pf->trailer = NULL;
  pf->xref_table = NULL;
  pf->catalog = NULL;
  pf->num_obj = 0;
  pf->version = 0;

  seek_end(file);
  pf->file_size = tell_position(file);

  return pf;
}

static void
pdf_file_free (pdf_file *pf)
{
  unsigned long i;

  if (!pf) {
    return;
  }

  for (i = 0; i < pf->num_obj; i++) {
    if (pf->xref_table[i].direct)
      pdf_release_obj(pf->xref_table[i].direct);
    if (pf->xref_table[i].indirect)
      pdf_release_obj(pf->xref_table[i].indirect);
  }

  RELEASE(pf->xref_table);
  if (pf->trailer) {
    pdf_release_obj(pf->trailer);
    pf->trailer = NULL;
  }
  if (pf->catalog) {
    pdf_release_obj(pf->catalog);
    pf->catalog = NULL;
  }

  RELEASE(pf);  
}

void
pdf_files_init (void)
{
  pdf_files = NEW(1, struct ht_table);
  ht_init_table(pdf_files, (void (*)(void *)) pdf_file_free);
}

int
pdf_file_get_version (pdf_file *pf)
{
  ASSERT(pf);
  return pf->version;
}

#if 0
pdf_obj *
pdf_file_get_trailer (pdf_file *pf)
{
  ASSERT(pf);
  return pf->trailer;
}
#endif

pdf_obj *
pdf_file_get_catalog (pdf_file *pf)
{
  ASSERT(pf);
  return pf->catalog;
}

pdf_file *
pdf_open (const char *ident, FILE *file)
{
  pdf_file *pf;

  ASSERT(pdf_files);

  pf = (pdf_file *) ht_lookup_table(pdf_files, ident, strlen(ident));

  if (pf) {
    pf->file = file;
  } else {
    int version;
    pdf_obj *new_version;

    version = check_for_pdf_version(file);
    if (version < 0) {
      WARN("Not a PDF file.");
      return NULL;
    }

    pf = pdf_file_new(file);
    pf->version = version;

    if (!(pf->trailer = read_xref(pf)))
      goto error;

    if (pdf_lookup_dict(pf->trailer, "Encrypt")) {
      WARN("PDF document is encrypted.");
      goto error;
    }

    pf->catalog = pdf_deref_obj(pdf_lookup_dict(pf->trailer, "Root"));
    if (!PDF_OBJ_DICTTYPE(pf->catalog)) {
      WARN("Cannot read PDF document catalog. Broken PDF file?");
      goto error;
    }

    new_version = pdf_deref_obj(pdf_lookup_dict(pf->catalog, "Version"));
    if (new_version) {
      unsigned short minor;

      if (!PDF_OBJ_NAMETYPE(new_version) ||
	  sscanf(pdf_name_value(new_version), "1.%hu", &minor) != 1) {
	pdf_release_obj(new_version);
	WARN("Illegal Version entry in document catalog. Broken PDF file?");
	goto error;
      }

      if (pf->version < minor)
	pf->version = minor;

      pdf_release_obj(new_version);
    }

    ht_append_table(pdf_files, ident, strlen(ident), pf);
  }

  return pf;

 error:
  pdf_file_free(pf);
  return NULL;
}

void
pdf_close (pdf_file *pf)
{
  if (pf)
    pf->file = NULL;
}

void
pdf_files_close (void)
{
  ASSERT(pdf_files);
  ht_clear_table(pdf_files);
  RELEASE(pdf_files);
}

static int
check_for_pdf_version (FILE *file) 
{
  unsigned short minor;

  rewind(file);

  return (ungetc(fgetc(file), file) == '%' &&
	  fscanf(file, "%%PDF-1.%hu", &minor) == 1) ? minor : -1;
}

int
check_for_pdf (FILE *file) 
{
  return (check_for_pdf_version(file) >= 0);
}

static int CDECL
import_dict (pdf_obj *key, pdf_obj *value, void *pdata)
{
  pdf_obj *copy;
  pdf_obj *tmp;

  copy = (pdf_obj *) pdata;

  tmp  = pdf_import_object(value);
  if (!tmp) {
    return -1;
  }
  pdf_add_dict(copy, pdf_link_obj(key), tmp);

  return 0;
}

static pdf_obj loop_marker = { PDF_OBJ_INVALID, 0, 0, 0, 0, NULL };

static pdf_obj *
pdf_import_indirect (pdf_obj *object)
{
  pdf_file *pf = OBJ_FILE(object);
  unsigned long obj_num = OBJ_NUM(object);
  unsigned short obj_gen = OBJ_GEN(object);

  pdf_obj *ref;

  ASSERT(pf);

  if (!checklabel(pf, obj_num, obj_gen)) {
    WARN("Can't resolve object: %lu %u", obj_num, obj_gen);
    return pdf_new_null();
  }

  if ((ref = pf->xref_table[obj_num].indirect)) {
    if (ref == &loop_marker)
      ERROR("Loop in object hierarchy detected. Broken PDF file?");
    return  pdf_link_obj(ref);
  } else {
    pdf_obj *obj, *tmp;

    obj = pdf_get_object(pf, obj_num, obj_gen);

    /* We mark the reference to be able to detect loops */
    pf->xref_table[obj_num].indirect = &loop_marker;

    tmp = pdf_import_object(obj);
    
    pf->xref_table[obj_num].indirect = ref = pdf_ref_obj(tmp);
    
    pdf_release_obj(tmp);
    pdf_release_obj(obj);
    
    return  pdf_link_obj(ref);
  }
}

/*
 * pdf_import_object recursively copies the object and those
 * referenced by it and changes the indirect references so that
 * they refer to the current output file. New indirect references
 * are remembered, which avoids duplicating objects when they
 * are imported several times.
 */
pdf_obj *
pdf_import_object (pdf_obj *object)
{
  pdf_obj  *imported;
  pdf_obj  *tmp;
  int       i;

  switch (pdf_obj_typeof(object)) {

  case PDF_INDIRECT:
    if (OBJ_FILE(object)) {
      imported = pdf_import_indirect(object);
    } else {
      imported = pdf_link_obj(object);
    }
    break;

  case PDF_STREAM:
    {
      pdf_obj *stream_dict;

      tmp = pdf_import_object(pdf_stream_dict(object));
      if (!tmp)
	return NULL;

      imported    = pdf_new_stream(0);
      stream_dict = pdf_stream_dict(imported);
      pdf_merge_dict(stream_dict, tmp);
      pdf_release_obj(tmp);
      pdf_add_stream(imported,
		     pdf_stream_dataptr(object),
		     pdf_stream_length(object));
    }
    break;

  case PDF_DICT:

    imported = pdf_new_dict();
    if (pdf_foreach_dict(object, import_dict, imported) < 0) {
      pdf_release_obj(imported);
      return NULL;
    }

    break;

  case PDF_ARRAY:

    imported = pdf_new_array();
    for (i = 0; i < pdf_array_length(object); i++) {
      tmp = pdf_import_object(pdf_get_array(object, i));
      if (!tmp) {
	pdf_release_obj(imported);
	return NULL;
      }
      pdf_add_array(imported, tmp);
    }
    break;

  default:
    imported = pdf_link_obj(object);
  }

  return imported;
}


/* returns 0 if indirect references point to the same object */
int
pdf_compare_reference (pdf_obj *ref1, pdf_obj *ref2)
{
  pdf_indirect *data1, *data2;

  ASSERT(PDF_OBJ_INDIRECTTYPE(ref1) && PDF_OBJ_INDIRECTTYPE(ref2));

  data1 = (pdf_indirect *) ref1->data;
  data2 = (pdf_indirect *) ref2->data;

  return data1->pf != data2->pf || data1->label != data2->label
    || data1->generation != data2->generation;
}