exif-loader.c

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/* exif-loader.c
 *
 * Copyright © 2002 Lutz Müller <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., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 */

#include <config.h>

#include <libexif/exif-loader.h>
#include <libexif/exif-utils.h>
#include <libexif/i18n.h>

#include <stdlib.h>
#include <string.h>
#include <stdio.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
#undef JPEG_MARKER_APP2
#define JPEG_MARKER_APP2 0xe2
#undef JPEG_MARKER_APP13
#define JPEG_MARKER_APP13 0xed
#undef JPEG_MARKER_COM
#define JPEG_MARKER_COM 0xfe

typedef enum {
        EL_READ = 0,
        EL_READ_SIZE_BYTE_24,
        EL_READ_SIZE_BYTE_16,
        EL_READ_SIZE_BYTE_08,
        EL_READ_SIZE_BYTE_00,
        EL_SKIP_BYTES,
        EL_EXIF_FOUND,
} ExifLoaderState;

typedef enum {
        EL_DATA_FORMAT_UNKNOWN,
        EL_DATA_FORMAT_EXIF,
        EL_DATA_FORMAT_JPEG,
        EL_DATA_FORMAT_FUJI_RAW
} ExifLoaderDataFormat;

struct _ExifLoader {
        ExifLoaderState state;
        ExifLoaderDataFormat data_format;

        /* Small buffer used for detection of format */
        unsigned char b[12];
        unsigned char b_len;

        unsigned int size;
        unsigned char *buf;
        unsigned int bytes_read;

        unsigned int ref_count;

        ExifLog *log;
        ExifMem *mem;
};

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

static void *
exif_loader_alloc (ExifLoader *l, unsigned int i)
{
        void *d;

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

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

        EXIF_LOG_NO_MEMORY (l->log, "ExifLog", i);
        return NULL;
}

#undef  MIN
#define MIN(a, b)  (((a) < (b)) ? (a) : (b))

void
exif_loader_write_file (ExifLoader *l, const char *path)
{
        FILE *f;
        int size;
        unsigned char data[1024];

        if (!l) 
                return;

        f = fopen (path, "rb");
        if (!f) {
                exif_log (l->log, EXIF_LOG_CODE_NONE, "ExifLoader",
                          _("The file '%s' could not be opened."), path);
                return;
        }
        while (1) {
                size = fread (data, 1, sizeof (data), f);
                if (size <= 0) 
                        break;
                if (!exif_loader_write (l, data, size)) 
                        break;
        }
        fclose (f);
}

static unsigned int
exif_loader_copy (ExifLoader *eld, unsigned char *buf, unsigned int len)
{
        if (!eld || (len && !buf) || (eld->bytes_read >= eld->size)) 
                return 0;

        /* If needed, allocate the buffer. */
        if (!eld->buf) 
                eld->buf = exif_loader_alloc (eld, eld->size);
        if (!eld->buf) 
                return 0;

        /* Copy memory */
        len = MIN (len, eld->size - eld->bytes_read);
        memcpy (eld->buf + eld->bytes_read, buf, len);
        eld->bytes_read += len;

        return (eld->bytes_read >= eld->size) ? 0 : 1;
}

unsigned char
exif_loader_write (ExifLoader *eld, unsigned char *buf, unsigned int len)
{
        unsigned int i;

        if (!eld || (len && !buf)) 
                return 0;

        switch (eld->state) {
        case EL_EXIF_FOUND:
                return exif_loader_copy (eld, buf, len);
        case EL_SKIP_BYTES:
                if (eld->size > len) { 
                        eld->size -= len; 
                        return 1; 
                }
                len -= eld->size;
                buf += eld->size;
                eld->size = 0;
                eld->b_len = 0;
                switch (eld->data_format) {
                case EL_DATA_FORMAT_FUJI_RAW:
                        eld->state = EL_READ_SIZE_BYTE_24;
                        break;
                default:
                        eld->state = EL_READ;
                        break;
                }
                break;
        default:
                break;
        }

        exif_log (eld->log, EXIF_LOG_CODE_DEBUG, "ExifLoader",
                  "Scanning %i byte(s) of data...", len);

        /*
         * First fill the small buffer. Only continue if the buffer
         * is filled. Note that EXIF data contains at least 12 bytes.
         */
        i = MIN (len, sizeof (eld->b) - eld->b_len);
        if (i) {
                memcpy (&eld->b[eld->b_len], buf, i);
                eld->b_len += i;
                if (eld->b_len < sizeof (eld->b)) 
                        return 1;
                buf += i;
                len -= i;
        }

        switch (eld->data_format) {
        case EL_DATA_FORMAT_UNKNOWN:

                /* Check the small buffer against known formats. */
                if (!memcmp (eld->b, "FUJIFILM", 8)) {

                        /* Skip to byte 84. There is another offset there. */
                        eld->data_format = EL_DATA_FORMAT_FUJI_RAW;
                        eld->size = 84;
                        eld->state = EL_SKIP_BYTES;
                        eld->size = 84;

                } else if (!memcmp (eld->b + 2, ExifHeader, sizeof (ExifHeader))) {

                        /* Read the size (2 bytes). */
                        eld->data_format = EL_DATA_FORMAT_EXIF;
                        eld->state = EL_READ_SIZE_BYTE_08;
                }
        default:
                break;
        }

        for (i = 0; i < sizeof (eld->b); i++)
                switch (eld->state) {
                case EL_EXIF_FOUND:
                        if (!exif_loader_copy (eld, eld->b + i,
                                        sizeof (eld->b) - i)) 
                                return 0;
                        return exif_loader_copy (eld, buf, len);
                case EL_SKIP_BYTES:
                        eld->size--;
                        if (!eld->size) 
                                eld->state = EL_READ;
                        break;

                case EL_READ_SIZE_BYTE_24:
                        eld->size |= eld->b[i] << 24;
                        eld->state = EL_READ_SIZE_BYTE_16;
                        break;
                case EL_READ_SIZE_BYTE_16:
                        eld->size |= eld->b[i] << 16;
                        eld->state = EL_READ_SIZE_BYTE_08;
                        break;
                case EL_READ_SIZE_BYTE_08:
                        eld->size |= eld->b[i] << 8;
                        eld->state = EL_READ_SIZE_BYTE_00;
                        break;
                case EL_READ_SIZE_BYTE_00:
                        eld->size |= eld->b[i] << 0;
                        switch (eld->data_format) {
                        case EL_DATA_FORMAT_JPEG:
                                eld->state = EL_SKIP_BYTES;
                                eld->size -= 2;
                                break;
                        case EL_DATA_FORMAT_FUJI_RAW:
                                eld->data_format = EL_DATA_FORMAT_EXIF;
                                eld->state = EL_SKIP_BYTES;
                                eld->size -= 86;
                                break;
                        case EL_DATA_FORMAT_EXIF:
                                eld->state = EL_EXIF_FOUND;
                                break;
                        default:
                                break;
                        }
                        break;

                default:
                        switch (eld->b[i]) {
                        case JPEG_MARKER_APP1:
                                if (!memcmp (eld->b + i + 3, ExifHeader, MIN(sizeof (ExifHeader), MAX(0, sizeof (eld->b) - i - 3)))) {
                                        eld->data_format = EL_DATA_FORMAT_EXIF;
                                } else {
                                        eld->data_format = EL_DATA_FORMAT_JPEG; /* Probably JFIF - keep searching for APP1 EXIF*/
                                }
                                eld->size = 0;
                                eld->state = EL_READ_SIZE_BYTE_08;
                                break;
                        case JPEG_MARKER_APP0:
                        case JPEG_MARKER_APP2:
                        case JPEG_MARKER_APP13:
                        case JPEG_MARKER_COM:
                                eld->data_format = EL_DATA_FORMAT_JPEG;
                                eld->size = 0;
                                eld->state = EL_READ_SIZE_BYTE_08;
                                break;
                        case 0xff:
                        case JPEG_MARKER_SOI:
                                break;
                        default:
                                exif_log (eld->log,
                                        EXIF_LOG_CODE_CORRUPT_DATA,
                                        "ExifLoader", _("The data supplied "
                                                "does not seem to contain "
                                                "EXIF data."));
                                exif_loader_reset (eld);
                                return 0;
                        }
                }

        /*
         * If we reach this point, the buffer has not been big enough
         * to read all data we need. Fill it with new data.
         */
        eld->b_len = 0;
        return exif_loader_write (eld, buf, len);
}

ExifLoader *
exif_loader_new (void)
{
        ExifMem *mem = exif_mem_new_default ();
        ExifLoader *l = exif_loader_new_mem (mem);

        exif_mem_unref (mem);

        return l;
}

ExifLoader *
exif_loader_new_mem (ExifMem *mem)
{
        ExifLoader *loader;

        if (!mem) 
                return NULL;
        
        loader = exif_mem_alloc (mem, sizeof (ExifLoader));
        if (!loader) 
                return NULL;
        loader->ref_count = 1;

        loader->mem = mem;
        exif_mem_ref (mem);

        return loader;
}

void
exif_loader_ref (ExifLoader *loader)
{
        if (loader) 
                loader->ref_count++;
}

static void
exif_loader_free (ExifLoader *loader)
{
        ExifMem *mem;

        if (!loader) 
                return;

        mem = loader->mem;
        exif_loader_reset (loader);
        exif_mem_free (mem, loader);
        exif_mem_unref (mem);
}
        
void
exif_loader_unref (ExifLoader *loader)
{
        if (!loader) 
                return;
        if (!--loader->ref_count)
                exif_loader_free (loader);
}

void
exif_loader_reset (ExifLoader *loader)
{
        if (!loader) 
                return;
        exif_mem_free (loader->mem, loader->buf); loader->buf = NULL;
        loader->size = 0;
        loader->bytes_read = 0;
        loader->state = 0;
        loader->b_len = 0;
        loader->data_format = EL_DATA_FORMAT_UNKNOWN;
}

ExifData *
exif_loader_get_data (ExifLoader *loader)
{
        ExifData *ed;

        if (!loader) 
                return NULL;

        ed = exif_data_new_mem (loader->mem);
        exif_data_log (ed, loader->log);
        exif_data_load_data (ed, loader->buf, loader->bytes_read);

        return ed;
}

void
exif_loader_log (ExifLoader *loader, ExifLog *log)
{
        if (!loader) 
                return;
        exif_log_unref (loader->log);
        loader->log = log;
        exif_log_ref (log);
}

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