/* exif-data.c
 *
 * Copyright (c) 2001 Lutz Mueller <lutz@users.sourceforge.net>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the
 * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA  02110-1301  USA.
 */

#include <config.h>

#include <libexif/exif-mnote-data.h>
#include <libexif/exif-data.h>
#include <libexif/exif-ifd.h>
#include <libexif/exif-mnote-data-priv.h>
#include <libexif/exif-utils.h>
#include <libexif/exif-loader.h>
#include <libexif/exif-log.h>
#include <libexif/i18n.h>
#include <libexif/exif-system.h>

#include <libexif/canon/exif-mnote-data-canon.h>
#include <libexif/fuji/exif-mnote-data-fuji.h>
#include <libexif/olympus/exif-mnote-data-olympus.h>
#include <libexif/pentax/exif-mnote-data-pentax.h>

#include <math.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>

#undef JPEG_MARKER_SOI
#define JPEG_MARKER_SOI  0xd8
#undef JPEG_MARKER_APP0
#define JPEG_MARKER_APP0 0xe0
#undef JPEG_MARKER_APP1
#define JPEG_MARKER_APP1 0xe1

#define CHECKOVERFLOW(offset,datasize,structsize) (( offset >= datasize) || (structsize > datasize) || (offset > datasize - structsize ))

static const unsigned char ExifHeader[] = {0x45, 0x78, 0x69, 0x66, 0x00, 0x00};

struct _ExifDataPrivate
{
	ExifByteOrder order;

	ExifMnoteData *md;

	ExifLog *log;
	ExifMem *mem;

	unsigned int ref_count;

	/* Temporarily used while loading data */
	unsigned int offset_mnote;

	ExifDataOption options;
	ExifDataType data_type;
};

static void *
exif_data_alloc (ExifData *data, unsigned int i)
{
	void *d;

	if (!data || !i) 
		return NULL;

	d = exif_mem_alloc (data->priv->mem, i);
	if (d) 
		return d;

	EXIF_LOG_NO_MEMORY (data->priv->log, "ExifData", i);
	return NULL;
}

ExifMnoteData *
exif_data_get_mnote_data (ExifData *d)
{
	return (d && d->priv) ? d->priv->md : NULL;
}

ExifData *
exif_data_new (void)
{
	ExifMem *mem = exif_mem_new_default ();
	ExifData *d = exif_data_new_mem (mem);

	exif_mem_unref (mem);

	return d;
}

ExifData *
exif_data_new_mem (ExifMem *mem)
{
	ExifData *data;
	unsigned int i;

	if (!mem) 
		return NULL;

	data = exif_mem_alloc (mem, sizeof (ExifData));
	if (!data) 
		return (NULL);
	data->priv = exif_mem_alloc (mem, sizeof (ExifDataPrivate));
	if (!data->priv) { 
	  	exif_mem_free (mem, data); 
		return (NULL); 
	}
	data->priv->ref_count = 1;

	data->priv->mem = mem;
	exif_mem_ref (mem);

	for (i = 0; i < EXIF_IFD_COUNT; i++) {
		data->ifd[i] = exif_content_new_mem (data->priv->mem);
		if (!data->ifd[i]) {
			exif_data_free (data);
			return (NULL);
		}
		data->ifd[i]->parent = data;
	}

	/* Default options */
#ifndef NO_VERBOSE_TAG_STRINGS
	/*
	 * When the tag list is compiled away, setting this option prevents
	 * any tags from being loaded
	 */
	exif_data_set_option (data, EXIF_DATA_OPTION_IGNORE_UNKNOWN_TAGS);
#endif
	exif_data_set_option (data, EXIF_DATA_OPTION_FOLLOW_SPECIFICATION);

	/* Default data type: none */
	exif_data_set_data_type (data, EXIF_DATA_TYPE_COUNT);

	return (data);
}

ExifData *
exif_data_new_from_data (const unsigned char *data, unsigned int size)
{
	ExifData *edata;

	edata = exif_data_new ();
	exif_data_load_data (edata, data, size);
	return (edata);
}

static int
exif_data_load_data_entry (ExifData *data, ExifEntry *entry,
			   const unsigned char *d,
			   unsigned int size, unsigned int offset)
{
	unsigned int s, doff;

	entry->tag        = exif_get_short (d + offset + 0, data->priv->order);
	entry->format     = exif_get_short (d + offset + 2, data->priv->order);
	entry->components = exif_get_long  (d + offset + 4, data->priv->order);

	/* FIXME: should use exif_tag_get_name_in_ifd here but entry->parent 
	 * has not been set yet
	 */
	exif_log (data->priv->log, EXIF_LOG_CODE_DEBUG, "ExifData",
		  "Loading entry 0x%x ('%s')...", entry->tag,
		  exif_tag_get_name (entry->tag));

	/* {0,1,2,4,8} x { 0x00000000 .. 0xffffffff } 
	 *   -> { 0x000000000 .. 0x7fffffff8 } */
	s = exif_format_get_size(entry->format) * entry->components;
	if ((s < entry->components) || (s == 0)){
		return 0;
	}

	/*
	 * Size? If bigger than 4 bytes, the actual data is not
	 * in the entry but somewhere else (offset).
	 */
	if (s > 4)
		doff = exif_get_long (d + offset + 8, data->priv->order);
	else
		doff = offset + 8;

	/* Sanity checks */
	if (doff >= size) {
		exif_log (data->priv->log, EXIF_LOG_CODE_DEBUG, "ExifData",
				  "Tag starts past end of buffer (%u > %u)", doff, size);
		return 0;
	}

	if (s > size - doff) {
		exif_log (data->priv->log, EXIF_LOG_CODE_DEBUG, "ExifData",
				  "Tag data goes past end of buffer (%u > %u)", doff+s, size);
		return 0;
	}

	entry->data = exif_data_alloc (data, s);
	if (entry->data) {
		entry->size = s;
		memcpy (entry->data, d + doff, s);
	} else {
		EXIF_LOG_NO_MEMORY(data->priv->log, "ExifData", s);
		return 0;
	}

	/* If this is the MakerNote, remember the offset */
	if (entry->tag == EXIF_TAG_MAKER_NOTE) {
		if (!entry->data) {
			exif_log (data->priv->log, EXIF_LOG_CODE_DEBUG, "ExifData",
					  "MakerNote found with empty data");	
		} else if (entry->size > 6) {
			exif_log (data->priv->log,
					       EXIF_LOG_CODE_DEBUG, "ExifData",
					       "MakerNote found (%02x %02x %02x %02x "
					       "%02x %02x %02x...).",
					       entry->data[0], entry->data[1], entry->data[2],
					       entry->data[3], entry->data[4], entry->data[5],
					       entry->data[6]);
		}
		data->priv->offset_mnote = doff;
	}
	return 1;
}

static void
exif_data_save_data_entry (ExifData *data, ExifEntry *e,
			   unsigned char **d, unsigned int *ds,
			   unsigned int offset)
{
	unsigned int doff, s;
	unsigned int ts;

	if (!data || !data->priv) 
		return;

	/*
	 * Each entry is 12 bytes long. The memory for the entry has
	 * already been allocated.
	 */
	exif_set_short (*d + 6 + offset + 0,
			data->priv->order, (ExifShort) e->tag);
	exif_set_short (*d + 6 + offset + 2,
			data->priv->order, (ExifShort) e->format);

	if (!(data->priv->options & EXIF_DATA_OPTION_DONT_CHANGE_MAKER_NOTE)) {
		/* If this is the maker note tag, update it. */
		if ((e->tag == EXIF_TAG_MAKER_NOTE) && data->priv->md) {
			/* TODO: this is using the wrong ExifMem to free e->data */
			exif_mem_free (data->priv->mem, e->data);
			e->data = NULL;
			e->size = 0;
			exif_mnote_data_set_offset (data->priv->md, *ds - 6);
			exif_mnote_data_save (data->priv->md, &e->data, &e->size);
			e->components = e->size;
			if (exif_format_get_size (e->format) != 1) {
				/* e->format is taken from input code,
				 * but we need to make sure it is a 1 byte
				 * entity due to the multiplication below. */
				e->format = EXIF_FORMAT_UNDEFINED;
			}
		}
	}

	exif_set_long  (*d + 6 + offset + 4,
			data->priv->order, e->components);

	/*
	 * Size? If bigger than 4 bytes, the actual data is not in
	 * the entry but somewhere else.
	 */
	s = exif_format_get_size (e->format) * e->components;
	if (s > 4) {
		unsigned char *t;
		doff = *ds - 6;
		ts = *ds + s;

		/*
		 * According to the TIFF specification,
		 * the offset must be an even number. If we need to introduce
		 * a padding byte, we set it to 0.
		 */
		if (s & 1)
			ts++;
		t = exif_mem_realloc (data->priv->mem, *d, ts);
		if (!t) {
			EXIF_LOG_NO_MEMORY (data->priv->log, "ExifData", ts);
		  	return;
		}
		*d = t;
		*ds = ts;
		exif_set_long (*d + 6 + offset + 8, data->priv->order, doff);
		if (s & 1) 
			*(*d + *ds - 1) = '\0';

	} else
		doff = offset + 8;

	/* Write the data. Fill unneeded bytes with 0. Do not crash with
	 * e->data is NULL */
	if (e->data) {
		unsigned int len = s;
		if (e->size < s) len = e->size;
		memcpy (*d + 6 + doff, e->data, len);
	} else {
		memset (*d + 6 + doff, 0, s);
	}
	if (s < 4) 
		memset (*d + 6 + doff + s, 0, (4 - s));
}

static void
exif_data_load_data_thumbnail (ExifData *data, const unsigned char *d,
			       unsigned int ds, ExifLong o, ExifLong s)
{
	/* Sanity checks */
	if (o >= ds) {
		exif_log (data->priv->log, EXIF_LOG_CODE_DEBUG, "ExifData", "Bogus thumbnail offset (%u).", o);
		return;
	}
	if (CHECKOVERFLOW(o,ds,s)) {
		exif_log (data->priv->log, EXIF_LOG_CODE_DEBUG, "ExifData", "Bogus thumbnail size (%u), max would be %u.", s, ds-o);
		return;
	}
	if (data->data) 
		exif_mem_free (data->priv->mem, data->data);
	if (!(data->data = exif_data_alloc (data, s))) {
		EXIF_LOG_NO_MEMORY (data->priv->log, "ExifData", s);
		data->size = 0;
		return;
	}
	data->size = s;
	memcpy (data->data, d + o, s);
}

#undef CHECK_REC
#define CHECK_REC(i) 					\
if ((i) == ifd) {				\
	exif_log (data->priv->log, EXIF_LOG_CODE_DEBUG, \
		"ExifData", "Recursive entry in IFD "	\
		"'%s' detected. Skipping...",		\
		exif_ifd_get_name (i));			\
	break;						\
}							\
if (data->ifd[(i)]->count) {				\
	exif_log (data->priv->log, EXIF_LOG_CODE_DEBUG,	\
		"ExifData", "Attempt to load IFD "	\
		"'%s' multiple times detected. "	\
		"Skipping...",				\
		exif_ifd_get_name (i));			\
	break;						\
}

/*! Calculate the recursion cost added by one level of IFD loading.
 *
 * The work performed is related to the cost in the exponential relation
 *   work=1.1**cost
 */
static unsigned int
level_cost(unsigned int n)
{
    static const double log_1_1 = 0.09531017980432493;

	/* Adding 0.1 protects against the case where n==1 */
	return ceil(log(n + 0.1)/log_1_1);
}

/*! Load data for an IFD.
 *
 * \param[in,out] data #ExifData
 * \param[in] ifd IFD to load
 * \param[in] d pointer to buffer containing raw IFD data
 * \param[in] ds size of raw data in buffer at \c d
 * \param[in] offset offset into buffer at \c d at which IFD starts
 * \param[in] recursion_cost factor indicating how expensive this recursive
 * call could be
 */
static void
exif_data_load_data_content (ExifData *data, ExifIfd ifd,
			     const unsigned char *d,
			     unsigned int ds, unsigned int offset, unsigned int recursion_cost)
{
	ExifLong o, thumbnail_offset = 0, thumbnail_length = 0;
	ExifShort n;
	ExifEntry *entry;
	unsigned int i;
	ExifTag tag;

	if (!data || !data->priv) 
		return;

	/* check for valid ExifIfd enum range */
	if ((((int)ifd) < 0) || ( ((int)ifd) >= EXIF_IFD_COUNT))
	  return;

	if (recursion_cost > 170) {
		/*
		 * recursion_cost is a logarithmic-scale indicator of how expensive this
		 * recursive call might end up being. It is an indicator of the depth of
		 * recursion as well as the potential for worst-case future recursive
		 * calls. Since it's difficult to tell ahead of time how often recursion
		 * will occur, this assumes the worst by assuming every tag could end up
		 * causing recursion.
		 * The value of 170 was chosen to limit typical EXIF structures to a
		 * recursive depth of about 6, but pathological ones (those with very
		 * many tags) to only 2.
		 */
		exif_log (data->priv->log, EXIF_LOG_CODE_CORRUPT_DATA, "ExifData",
			  "Deep/expensive recursion detected!");
		return;
	}

	/* Read the number of entries */
	if (CHECKOVERFLOW(offset, ds, 2)) {
		exif_log (data->priv->log, EXIF_LOG_CODE_CORRUPT_DATA, "ExifData",
			  "Tag data past end of buffer (%u+2 > %u)", offset, ds);
		return;
	}
	n = exif_get_short (d + offset, data->priv->order);
	exif_log (data->priv->log, EXIF_LOG_CODE_DEBUG, "ExifData",
	          "Loading %hu entries...", n);
	offset += 2;

	/* Check if we have enough data. */
	if (CHECKOVERFLOW(offset, ds, 12*n)) {
		n = (ds - offset) / 12;
		exif_log (data->priv->log, EXIF_LOG_CODE_DEBUG, "ExifData",
				  "Short data; only loading %hu entries...", n);
	}

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

		tag = exif_get_short (d + offset + 12 * i, data->priv->order);
		switch (tag) {
		case EXIF_TAG_EXIF_IFD_POINTER:
		case EXIF_TAG_GPS_INFO_IFD_POINTER:
		case EXIF_TAG_INTEROPERABILITY_IFD_POINTER:
		case EXIF_TAG_JPEG_INTERCHANGE_FORMAT_LENGTH:
		case EXIF_TAG_JPEG_INTERCHANGE_FORMAT:
			o = exif_get_long (d + offset + 12 * i + 8,
					   data->priv->order);
			if (o >= ds) {
				exif_log (data->priv->log, EXIF_LOG_CODE_CORRUPT_DATA, "ExifData",
					  "Tag data past end of buffer (%u > %u)", offset+2, ds);
				return;
			}
			/* FIXME: IFD_POINTER tags aren't marked as being in a
			 * specific IFD, so exif_tag_get_name_in_ifd won't work
			 */
			exif_log (data->priv->log, EXIF_LOG_CODE_DEBUG, "ExifData",
				  "Sub-IFD entry 0x%x ('%s') at %u.", tag,
				  exif_tag_get_name(tag), o);
			switch (tag) {
			case EXIF_TAG_EXIF_IFD_POINTER:
				CHECK_REC (EXIF_IFD_EXIF);
				exif_data_load_data_content (data, EXIF_IFD_EXIF, d, ds, o,
					recursion_cost + level_cost(n));
				break;
			case EXIF_TAG_GPS_INFO_IFD_POINTER:
				CHECK_REC (EXIF_IFD_GPS);
				exif_data_load_data_content (data, EXIF_IFD_GPS, d, ds, o,
					recursion_cost + level_cost(n));
				break;
			case EXIF_TAG_INTEROPERABILITY_IFD_POINTER:
				CHECK_REC (EXIF_IFD_INTEROPERABILITY);
				exif_data_load_data_content (data, EXIF_IFD_INTEROPERABILITY, d, ds, o,
					recursion_cost + level_cost(n));
				break;
			case EXIF_TAG_JPEG_INTERCHANGE_FORMAT:
				thumbnail_offset = o;
				if (thumbnail_offset && thumbnail_length)
					exif_data_load_data_thumbnail (data, d,
								       ds, thumbnail_offset,
								       thumbnail_length);
				break;
			case EXIF_TAG_JPEG_INTERCHANGE_FORMAT_LENGTH:
				thumbnail_length = o;
				if (thumbnail_offset && thumbnail_length)
					exif_data_load_data_thumbnail (data, d,
								       ds, thumbnail_offset,
								       thumbnail_length);
				break;
			default:
				return;
			}
			break;
		default:

			/*
			 * If we don't know the tag, don't fail. It could be that new 
			 * versions of the standard have defined additional tags. Note that
			 * 0 is a valid tag in the GPS IFD.
			 */
			if (!exif_tag_get_name_in_ifd (tag, ifd)) {

				/*
				 * Special case: Tag and format 0. That's against specification
				 * (at least up to 2.2). But Photoshop writes it anyways.
				 */
				if (!memcmp (d + offset + 12 * i, "\0\0\0\0", 4)) {
					exif_log (data->priv->log, EXIF_LOG_CODE_DEBUG, "ExifData",
						  "Skipping empty entry at position %u in '%s'.", i, 
						  exif_ifd_get_name (ifd));
					break;
				}
				exif_log (data->priv->log, EXIF_LOG_CODE_DEBUG, "ExifData",
					  "Unknown tag 0x%04x (entry %u in '%s'). Please report this tag "
					  "to <libexif-devel@lists.sourceforge.net>.", tag, i,
					  exif_ifd_get_name (ifd));
				if (data->priv->options & EXIF_DATA_OPTION_IGNORE_UNKNOWN_TAGS)
					break;
			}
			entry = exif_entry_new_mem (data->priv->mem);
			if (!entry) {
				  exif_log (data->priv->log, EXIF_LOG_CODE_NO_MEMORY, "ExifData",
                                          "Could not allocate memory");
				  return;
			}
			if (exif_data_load_data_entry (data, entry, d, ds,
						   offset + 12 * i))
				exif_content_add_entry (data->ifd[ifd], entry);
			exif_entry_unref (entry);
			break;
		}
	}
}

static int
cmp_func (const unsigned char *p1, const unsigned char *p2, ExifByteOrder o)
{
	ExifShort tag1 = exif_get_short (p1, o);
	ExifShort tag2 = exif_get_short (p2, o);

	return (tag1 < tag2) ? -1 : (tag1 > tag2) ? 1 : 0;
}

static int
cmp_func_intel (const void *elem1, const void *elem2)
{
	return cmp_func ((const unsigned char *) elem1,
			 (const unsigned char *) elem2, EXIF_BYTE_ORDER_INTEL);
}

static int
cmp_func_motorola (const void *elem1, const void *elem2)
{
	return cmp_func ((const unsigned char *) elem1,
			 (const unsigned char *) elem2, EXIF_BYTE_ORDER_MOTOROLA);
}

static void
exif_data_save_data_content (ExifData *data, ExifContent *ifd,
			     unsigned char **d, unsigned int *ds,
			     unsigned int offset)
{
	unsigned int j, n_ptr = 0, n_thumb = 0;
	ExifIfd i;
	unsigned char *t;
	unsigned int ts;

	if (!data || !data->priv || !ifd || !d || !ds) 
		return;

	for (i = 0; i < EXIF_IFD_COUNT; i++)
		if (ifd == data->ifd[i])
			break;
	if (i == EXIF_IFD_COUNT)
		return;	/* error */

	/*
	 * Check if we need some extra entries for pointers or the thumbnail.
	 */
	switch (i) {
	case EXIF_IFD_0:

		/*
		 * The pointer to IFD_EXIF is in IFD_0. The pointer to
		 * IFD_INTEROPERABILITY is in IFD_EXIF.
		 */
		if (data->ifd[EXIF_IFD_EXIF]->count ||
		    data->ifd[EXIF_IFD_INTEROPERABILITY]->count)
			n_ptr++;

		/* The pointer to IFD_GPS is in IFD_0. */
		if (data->ifd[EXIF_IFD_GPS]->count)
			n_ptr++;

		break;
	case EXIF_IFD_1:
		if (data->size)
			n_thumb = 2;
		break;
	case EXIF_IFD_EXIF:
		if (data->ifd[EXIF_IFD_INTEROPERABILITY]->count)
			n_ptr++;
	default:
		break;
	}

	/*
	 * Allocate enough memory for all entries
	 * and the number of entries.
	 */
	ts = *ds + (2 + (ifd->count + n_ptr + n_thumb) * 12 + 4);
	t = exif_mem_realloc (data->priv->mem, *d, ts);
	if (!t) {
		EXIF_LOG_NO_MEMORY (data->priv->log, "ExifData", ts);
	  	return;
	}
	*d = t;
	*ds = ts;

	/* Save the number of entries */
	exif_set_short (*d + 6 + offset, data->priv->order,
			(ExifShort) (ifd->count + n_ptr + n_thumb));
	offset += 2;

	/*
	 * Save each entry. Make sure that no memcpys from NULL pointers are
	 * performed
	 */
	exif_log (data->priv->log, EXIF_LOG_CODE_DEBUG, "ExifData",
		  "Saving %i entries (IFD '%s', offset: %i)...",
		  ifd->count, exif_ifd_get_name (i), offset);
	for (j = 0; j < ifd->count; j++) {
		if (ifd->entries[j]) {
			exif_data_save_data_entry (data, ifd->entries[j], d, ds,
				offset + 12 * j);
		}
	}

	offset += 12 * ifd->count;

	/* Now save special entries. */
	switch (i) {
	case EXIF_IFD_0:

		/*
		 * The pointer to IFD_EXIF is in IFD_0.
		 * However, the pointer to IFD_INTEROPERABILITY is in IFD_EXIF,
		 * therefore, if IFD_INTEROPERABILITY is not empty, we need
		 * IFD_EXIF even if latter is empty.
		 */
		if (data->ifd[EXIF_IFD_EXIF]->count ||
		    data->ifd[EXIF_IFD_INTEROPERABILITY]->count) {
			exif_set_short (*d + 6 + offset + 0, data->priv->order,
					EXIF_TAG_EXIF_IFD_POINTER);
			exif_set_short (*d + 6 + offset + 2, data->priv->order,
					EXIF_FORMAT_LONG);
			exif_set_long  (*d + 6 + offset + 4, data->priv->order,
					1);
			exif_set_long  (*d + 6 + offset + 8, data->priv->order,
					*ds - 6);
			exif_data_save_data_content (data,
						     data->ifd[EXIF_IFD_EXIF], d, ds, *ds - 6);
			offset += 12;
		}

		/* The pointer to IFD_GPS is in IFD_0, too. */
		if (data->ifd[EXIF_IFD_GPS]->count) {
			exif_set_short (*d + 6 + offset + 0, data->priv->order,
					EXIF_TAG_GPS_INFO_IFD_POINTER);
			exif_set_short (*d + 6 + offset + 2, data->priv->order,
					EXIF_FORMAT_LONG);
			exif_set_long  (*d + 6 + offset + 4, data->priv->order,
					1);
			exif_set_long  (*d + 6 + offset + 8, data->priv->order,
					*ds - 6);
			exif_data_save_data_content (data,
						     data->ifd[EXIF_IFD_GPS], d, ds, *ds - 6);
			offset += 12;
		}

		break;
	case EXIF_IFD_EXIF:

		/*
		 * The pointer to IFD_INTEROPERABILITY is in IFD_EXIF.
		 * See note above.
		 */
		if (data->ifd[EXIF_IFD_INTEROPERABILITY]->count) {
			exif_set_short (*d + 6 + offset + 0, data->priv->order,
					EXIF_TAG_INTEROPERABILITY_IFD_POINTER);
			exif_set_short (*d + 6 + offset + 2, data->priv->order,
					EXIF_FORMAT_LONG);
			exif_set_long  (*d + 6 + offset + 4, data->priv->order,
					1);
			exif_set_long  (*d + 6 + offset + 8, data->priv->order,
					*ds - 6);
			exif_data_save_data_content (data,
						     data->ifd[EXIF_IFD_INTEROPERABILITY], d, ds,
						     *ds - 6);
			offset += 12;
		}

		break;
	case EXIF_IFD_1:

		/*
		 * Information about the thumbnail (if any) is saved in
		 * IFD_1.
		 */
		if (data->size) {

			/* EXIF_TAG_JPEG_INTERCHANGE_FORMAT */
			exif_set_short (*d + 6 + offset + 0, data->priv->order,
					EXIF_TAG_JPEG_INTERCHANGE_FORMAT);
			exif_set_short (*d + 6 + offset + 2, data->priv->order,
					EXIF_FORMAT_LONG);
			exif_set_long  (*d + 6 + offset + 4, data->priv->order,
					1);
			exif_set_long  (*d + 6 + offset + 8, data->priv->order,
					*ds - 6);
			ts = *ds + data->size;
			t = exif_mem_realloc (data->priv->mem, *d, ts);
			if (!t) {
				EXIF_LOG_NO_MEMORY (data->priv->log, "ExifData",
						    ts);
			  	return;
			}
			*d = t;
			*ds = ts;
			memcpy (*d + *ds - data->size, data->data, data->size);
			offset += 12;

			/* EXIF_TAG_JPEG_INTERCHANGE_FORMAT_LENGTH */
			exif_set_short (*d + 6 + offset + 0, data->priv->order,
					EXIF_TAG_JPEG_INTERCHANGE_FORMAT_LENGTH);
			exif_set_short (*d + 6 + offset + 2, data->priv->order,
					EXIF_FORMAT_LONG);
			exif_set_long  (*d + 6 + offset + 4, data->priv->order,
					1);
			exif_set_long  (*d + 6 + offset + 8, data->priv->order,
					data->size);
			offset += 12;
		}

		break;
	default:
		break;
	}

	/* Sort the directory according to TIFF specification */
	qsort (*d + 6 + offset - (ifd->count + n_ptr + n_thumb) * 12,
	       (ifd->count + n_ptr + n_thumb), 12,
	       (data->priv->order == EXIF_BYTE_ORDER_INTEL) ? cmp_func_intel : cmp_func_motorola);

	/* Correctly terminate the directory */
	if (i == EXIF_IFD_0 && (data->ifd[EXIF_IFD_1]->count ||
				data->size)) {

		/*
		 * We are saving IFD 0. Tell where IFD 1 starts and save
		 * IFD 1.
		 */
		exif_set_long (*d + 6 + offset, data->priv->order, *ds - 6);
		exif_data_save_data_content (data, data->ifd[EXIF_IFD_1], d, ds,
					     *ds - 6);
	} else
		exif_set_long (*d + 6 + offset, data->priv->order, 0);
}

typedef enum {
	EXIF_DATA_TYPE_MAKER_NOTE_NONE		= 0,
	EXIF_DATA_TYPE_MAKER_NOTE_CANON		= 1,
	EXIF_DATA_TYPE_MAKER_NOTE_OLYMPUS	= 2,
	EXIF_DATA_TYPE_MAKER_NOTE_PENTAX	= 3,
	EXIF_DATA_TYPE_MAKER_NOTE_NIKON		= 4,
	EXIF_DATA_TYPE_MAKER_NOTE_CASIO		= 5,
	EXIF_DATA_TYPE_MAKER_NOTE_FUJI 		= 6
} ExifDataTypeMakerNote;

/*! If MakerNote is recognized, load it.
 *
 * \param[in,out] data #ExifData
 * \param[in] d pointer to raw EXIF data
 * \param[in] ds length of data at d
 */
static void
interpret_maker_note(ExifData *data, const unsigned char *d, unsigned int ds)
{
	int mnoteid;
	ExifEntry* e = exif_data_get_entry (data, EXIF_TAG_MAKER_NOTE);
	if (!e)
		return;
	
	if ((mnoteid = exif_mnote_data_olympus_identify (data, e)) != 0) {
		exif_log (data->priv->log, EXIF_LOG_CODE_DEBUG,
			"ExifData", "Olympus MakerNote variant type %d", mnoteid);
		data->priv->md = exif_mnote_data_olympus_new (data->priv->mem);

	} else if ((mnoteid = exif_mnote_data_canon_identify (data, e)) != 0) {
		exif_log (data->priv->log, EXIF_LOG_CODE_DEBUG,
			"ExifData", "Canon MakerNote variant type %d", mnoteid);
		data->priv->md = exif_mnote_data_canon_new (data->priv->mem, data->priv->options);

	} else if ((mnoteid = exif_mnote_data_fuji_identify (data, e)) != 0) {
		exif_log (data->priv->log, EXIF_LOG_CODE_DEBUG,
			"ExifData", "Fuji MakerNote variant type %d", mnoteid);
		data->priv->md = exif_mnote_data_fuji_new (data->priv->mem);

	/* NOTE: Must do Pentax detection last because some of the
	 * heuristics are pretty general. */
	} else if ((mnoteid = exif_mnote_data_pentax_identify (data, e)) != 0) {
		exif_log (data->priv->log, EXIF_LOG_CODE_DEBUG,
			"ExifData", "Pentax MakerNote variant type %d", mnoteid);
		data->priv->md = exif_mnote_data_pentax_new (data->priv->mem);
	}

	/* 
	 * If we are able to interpret the maker note, do so.
	 */
	if (data->priv->md) {
		exif_mnote_data_log (data->priv->md, data->priv->log);
		exif_mnote_data_set_byte_order (data->priv->md,
						data->priv->order);
		exif_mnote_data_set_offset (data->priv->md,
					    data->priv->offset_mnote);
		exif_mnote_data_load (data->priv->md, d, ds);
	}
}

#define LOG_TOO_SMALL \
exif_log (data->priv->log, EXIF_LOG_CODE_CORRUPT_DATA, "ExifData", \
		_("Size of data too small to allow for EXIF data."));

void
exif_data_load_data (ExifData *data, const unsigned char *d_orig,
		     unsigned int ds)
{
	unsigned int l;
	ExifLong offset;
	ExifShort n;
	const unsigned char *d = d_orig;
	unsigned int len, fullds;

	if (!data || !data->priv || !d || !ds)
		return;

	exif_log (data->priv->log, EXIF_LOG_CODE_DEBUG, "ExifData",
		  "Parsing %i byte(s) EXIF data...\n", ds);

	/*
	 * It can be that the data starts with the EXIF header. If it does
	 * not, search the EXIF marker.
	 */
	if (ds < 6) {
		LOG_TOO_SMALL;
		return;
	}
	if (!memcmp (d, ExifHeader, 6)) {
		exif_log (data->priv->log, EXIF_LOG_CODE_DEBUG, "ExifData",
			  "Found EXIF header at start.");
	} else {
		while (ds >= 3) {
			while (ds && (d[0] == 0xff)) {
				d++;
				ds--;
			}

			/* JPEG_MARKER_SOI */
			if (ds && d[0] == JPEG_MARKER_SOI) {
				d++;
				ds--;
				continue;
			}

			/* JPEG_MARKER_APP1 */
			if (ds && d[0] == JPEG_MARKER_APP1)
				break;

			/* Skip irrelevant APP markers. The branch for APP1 must come before this,
			   otherwise this code block will cause APP1 to be skipped. This code path
			   is only relevant for files that are nonconformant to the EXIF
			   specification. For conformant files, the APP1 code path above will be
			   taken. */
			if (ds >= 3 && d[0] >= 0xe0 && d[0] <= 0xef) {  /* JPEG_MARKER_APPn */
				d++;
				ds--;
				l = (d[0] << 8) | d[1];
				if (l > ds)
					return;
				d += l;
				ds -= l;
				continue;
			}

			/* Unknown marker or data. Give up. */
			exif_log (data->priv->log, EXIF_LOG_CODE_CORRUPT_DATA,
				  "ExifData", _("EXIF marker not found."));
			return;
		}
		if (ds < 3) {
			LOG_TOO_SMALL;
			return;
		}
		d++;
		ds--;
		len = (d[0] << 8) | d[1];
		exif_log (data->priv->log, EXIF_LOG_CODE_DEBUG, "ExifData",
			  "We have to deal with %i byte(s) of EXIF data.",
			  len);
		d += 2;
		ds -= 2;
	}

	/*
	 * Verify the exif header
	 * (offset 2, length 6).
	 */
	if (ds < 6) {
		LOG_TOO_SMALL;
		return;
	}
	if (memcmp (d, ExifHeader, 6)) {
		exif_log (data->priv->log, EXIF_LOG_CODE_CORRUPT_DATA,
			  "ExifData", _("EXIF header not found."));
		return;
	}

	exif_log (data->priv->log, EXIF_LOG_CODE_DEBUG, "ExifData",
		  "Found EXIF header.");

	/* Sanity check the data length */
	if (ds < 14)
		return;

	/* The JPEG APP1 section can be no longer than 64 KiB (including a
	   16-bit length), so cap the data length to protect against overflow
	   in future offset calculations */
	fullds = ds;
	if (ds > 0xfffe)
		ds = 0xfffe;

	/* Byte order (offset 6, length 2) */
	if (!memcmp (d + 6, "II", 2))
		data->priv->order = EXIF_BYTE_ORDER_INTEL;
	else if (!memcmp (d + 6, "MM", 2))
		data->priv->order = EXIF_BYTE_ORDER_MOTOROLA;
	else {
		exif_log (data->priv->log, EXIF_LOG_CODE_CORRUPT_DATA,
			  "ExifData", _("Unknown encoding."));
		return;
	}

	/* Fixed value */
	if (exif_get_short (d + 8, data->priv->order) != 0x002a)
		return;

	/* IFD 0 offset */
	offset = exif_get_long (d + 10, data->priv->order);
	exif_log (data->priv->log, EXIF_LOG_CODE_DEBUG, "ExifData", 
		  "IFD 0 at %i.", (int) offset);

	/* ds is restricted to 16 bit above, so offset is restricted too, and offset+8 should not overflow. */
	if (offset > ds || offset + 6 + 2 > ds)
		return;

	/* Parse the actual exif data (usually offset 14 from start) */
	exif_data_load_data_content (data, EXIF_IFD_0, d + 6, ds - 6, offset, 0);

	/* IFD 1 offset */
	n = exif_get_short (d + 6 + offset, data->priv->order);
	/* offset < 2<<16, n is 16 bit at most, so this op will not overflow */
	if (offset + 6 + 2 + 12 * n + 4 > ds)
		return;

	offset = exif_get_long (d + 6 + offset + 2 + 12 * n, data->priv->order);
	if (offset) {
		exif_log (data->priv->log, EXIF_LOG_CODE_DEBUG, "ExifData",
			  "IFD 1 at %i.", (int) offset);

		/* Sanity check. ds is ensured to be above 6 above, offset is 16bit */
		if (offset > ds - 6) {
			exif_log (data->priv->log, EXIF_LOG_CODE_CORRUPT_DATA,
				  "ExifData", "Bogus offset of IFD1.");
		} else {
		   exif_data_load_data_content (data, EXIF_IFD_1, d + 6, ds - 6, offset, 0);
		}
	}

	/*
	 * If we got an EXIF_TAG_MAKER_NOTE, try to interpret it. Some
	 * cameras use pointers in the maker note tag that point to the
	 * space between IFDs. Here is the only place where we have access
	 * to that data.
	 */
	interpret_maker_note(data, d, fullds);

	/* Fixup tags if requested */
	if (data->priv->options & EXIF_DATA_OPTION_FOLLOW_SPECIFICATION)
		exif_data_fix (data);
}

void
exif_data_save_data (ExifData *data, unsigned char **d, unsigned int *ds)
{
	if (ds)
		*ds = 0;	/* This means something went wrong */

	if (!data || !d || !ds)
		return;

	/* Header */
	*ds = 14;
	*d = exif_data_alloc (data, *ds);
	if (!*d)  {
		*ds = 0;
		return;
	}
	memcpy (*d, ExifHeader, 6);

	/* Order (offset 6) */
	if (data->priv->order == EXIF_BYTE_ORDER_INTEL) {
		memcpy (*d + 6, "II", 2);
	} else {
		memcpy (*d + 6, "MM", 2);
	}

	/* Fixed value (2 bytes, offset 8) */
	exif_set_short (*d + 8, data->priv->order, 0x002a);

	/*
	 * IFD 0 offset (4 bytes, offset 10).
	 * We will start 8 bytes after the
	 * EXIF header (2 bytes for order, another 2 for the test, and
	 * 4 bytes for the IFD 0 offset make 8 bytes together).
	 */
	exif_set_long (*d + 10, data->priv->order, 8);

	/* Now save IFD 0. IFD 1 will be saved automatically. */
	exif_log (data->priv->log, EXIF_LOG_CODE_DEBUG, "ExifData",
		  "Saving IFDs...");
	exif_data_save_data_content (data, data->ifd[EXIF_IFD_0], d, ds,
				     *ds - 6);
	exif_log (data->priv->log, EXIF_LOG_CODE_DEBUG, "ExifData",
		  "Saved %i byte(s) EXIF data.", *ds);
}

ExifData *
exif_data_new_from_file (const char *path)
{
	ExifData *edata;
	ExifLoader *loader;

	loader = exif_loader_new ();
	exif_loader_write_file (loader, path);
	edata = exif_loader_get_data (loader);
	exif_loader_unref (loader);

	return (edata);
}

void
exif_data_ref (ExifData *data)
{
	if (!data)
		return;

	data->priv->ref_count++;
}

void
exif_data_unref (ExifData *data)
{
	if (!data) 
		return;

	data->priv->ref_count--;
	if (!data->priv->ref_count) 
		exif_data_free (data);
}

void
exif_data_free (ExifData *data)
{
	unsigned int i;
	ExifMem *mem = (data && data->priv) ? data->priv->mem : NULL;

	if (!data) 
		return;

	for (i = 0; i < EXIF_IFD_COUNT; i++) {
		if (data->ifd[i]) {
			exif_content_unref (data->ifd[i]);
			data->ifd[i] = NULL;
		}
	}

	if (data->data) {
		exif_mem_free (mem, data->data);
		data->data = NULL;
	}

	if (data->priv) {
		if (data->priv->log) {
			exif_log_unref (data->priv->log);
			data->priv->log = NULL;
		}
		if (data->priv->md) {
			exif_mnote_data_unref (data->priv->md);
			data->priv->md = NULL;
		}
		exif_mem_free (mem, data->priv);
		exif_mem_free (mem, data);
	}

	exif_mem_unref (mem);
}

void
exif_data_dump (ExifData *data)
{
	unsigned int i;

	if (!data)
		return;

	for (i = 0; i < EXIF_IFD_COUNT; i++) {
		if (data->ifd[i] && data->ifd[i]->count) {
			printf ("Dumping IFD '%s'...\n",
				exif_ifd_get_name (i));
			exif_content_dump (data->ifd[i], 0);
		}
	}

	if (data->data) {
		printf ("%i byte(s) thumbnail data available: ", data->size);
		if (data->size >= 4) {
			printf ("0x%02x 0x%02x ... 0x%02x 0x%02x\n",
				data->data[0], data->data[1],
				data->data[data->size - 2],
				data->data[data->size - 1]);
		}
	}
}

ExifByteOrder
exif_data_get_byte_order (ExifData *data)
{
	if (!data)
		return (0);

	return (data->priv->order);
}

void
exif_data_foreach_content (ExifData *data, ExifDataForeachContentFunc func,
			   void *user_data)
{
	unsigned int i;

	if (!data || !func)
		return;

	for (i = 0; i < EXIF_IFD_COUNT; i++)
		func (data->ifd[i], user_data);
}

typedef struct _ByteOrderChangeData ByteOrderChangeData;
struct _ByteOrderChangeData {
	ExifByteOrder old, new;
};

static void
entry_set_byte_order (ExifEntry *e, void *data)
{
	ByteOrderChangeData *d = data;

	if (!e)
		return;

	exif_array_set_byte_order (e->format, e->data, e->components, d->old, d->new);
}

static void
content_set_byte_order (ExifContent *content, void *data)
{
	exif_content_foreach_entry (content, entry_set_byte_order, data);
}

void
exif_data_set_byte_order (ExifData *data, ExifByteOrder order)
{
	ByteOrderChangeData d;

	if (!data || (order == data->priv->order))
		return;

	d.old = data->priv->order;
	d.new = order;
	exif_data_foreach_content (data, content_set_byte_order, &d);
	data->priv->order = order;
	if (data->priv->md)
		exif_mnote_data_set_byte_order (data->priv->md, order);
}

void
exif_data_log (ExifData *data, ExifLog *log)
{
	unsigned int i;

	if (!data || !data->priv) 
		return;
	exif_log_unref (data->priv->log);
	data->priv->log = log;
	exif_log_ref (log);

	for (i = 0; i < EXIF_IFD_COUNT; i++)
		exif_content_log (data->ifd[i], log);
}

/* Used internally within libexif */
ExifLog *exif_data_get_log (ExifData *);
ExifLog *
exif_data_get_log (ExifData *data)
{
	if (!data || !data->priv) 
		return NULL;
	return data->priv->log;
}

static const struct {
	ExifDataOption option;
	const char *name;
	const char *description;
} exif_data_option[] = {
	{EXIF_DATA_OPTION_IGNORE_UNKNOWN_TAGS, N_("Ignore unknown tags"),
	 N_("Ignore unknown tags when loading EXIF data.")},
	{EXIF_DATA_OPTION_FOLLOW_SPECIFICATION, N_("Follow specification"),
	 N_("Add, correct and remove entries to get EXIF data that follows "
	    "the specification.")},
	{EXIF_DATA_OPTION_DONT_CHANGE_MAKER_NOTE, N_("Do not change maker note"),
	 N_("When loading and resaving Exif data, save the maker note unmodified."
	    " Be aware that the maker note can get corrupted.")},
	{0, NULL, NULL}
};

const char *
exif_data_option_get_name (ExifDataOption o)
{
	unsigned int i;

	for (i = 0; exif_data_option[i].name; i++)
		if (exif_data_option[i].option == o) 
			break;
	return _(exif_data_option[i].name);
}

const char *
exif_data_option_get_description (ExifDataOption o)
{
	unsigned int i;

	for (i = 0; exif_data_option[i].description; i++)
		if (exif_data_option[i].option == o) 
			break;
	return _(exif_data_option[i].description);
}

void
exif_data_set_option (ExifData *d, ExifDataOption o)
{
	if (!d) 
		return;

	d->priv->options |= o;
}

void
exif_data_unset_option (ExifData *d, ExifDataOption o)
{
	if (!d) 
		return;

	d->priv->options &= ~o;
}

static void
fix_func (ExifContent *c, void *UNUSED(data))
{
	switch (exif_content_get_ifd (c)) {
	case EXIF_IFD_1:
		if (c->parent->data)
			exif_content_fix (c);
		else if (c->count) {
			exif_log (c->parent->priv->log, EXIF_LOG_CODE_DEBUG, "exif-data",
				  "No thumbnail but entries on thumbnail. These entries have been "
				  "removed.");
			while (c->count) {
				unsigned int cnt = c->count;
				exif_content_remove_entry (c, c->entries[c->count - 1]);
				if (cnt == c->count) {
					/* safety net */
					exif_log (c->parent->priv->log, EXIF_LOG_CODE_DEBUG, "exif-data",
					"failed to remove last entry from entries.");
					c->count--;
				}
			}
		}
		break;
	default:
		exif_content_fix (c);
	}
}

void
exif_data_fix (ExifData *d)
{
	exif_data_foreach_content (d, fix_func, NULL);
}

void
exif_data_set_data_type (ExifData *d, ExifDataType dt)
{
	if (!d || !d->priv) 
		return;

	d->priv->data_type = dt;
}

ExifDataType
exif_data_get_data_type (ExifData *d)
{
	return (d && d->priv) ? d->priv->data_type : EXIF_DATA_TYPE_UNKNOWN;
}