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/*
This file is part of libextractor.
(C) 2002, 2003, 2004 Vidyut Samanta and Christian Grothoff
libextractor 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, or (at your
option) any later version.
libextractor 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 libextractor; see the file COPYING. If not, write to the
Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.
*/
#include "platform.h"
#include "extractor.h"
#define M_SOI 0xD8 /* Start Of Image (beginning of datastream) */
#define M_EOI 0xD9 /* End Of Image (end of datastream) */
#define M_SOS 0xDA /* Start Of Scan (begins compressed data) */
#define M_APP12 0xEC
#define M_COM 0xFE /* COMment */
#define M_APP0 0xE0
/**
* Get the next character in the sequence and advance
* the pointer *data to the next location in the sequence.
* If we're at the end, return -1.
*/
#define NEXTC(data,end) ((*(data)<(end))?*((*(data))++):-1)
/* The macro does:
unsigned int NEXTC(unsigned char ** data, char * end) {
if (*data < end) {
char result = **data;
(*data)++;
return result;
} else
return -1;
}
*/
/**
* Read length, convert to unsigned int.
* All 2-byte quantities in JPEG markers are MSB first
* @return -1 on error
*/
static int
readLength (const unsigned char **data, const unsigned char *end)
{
int c1;
int c2;
c1 = NEXTC (data, end);
if (c1 == -1)
return -1;
c2 = NEXTC (data, end);
if (c2 == -1)
return -1;
return ((((unsigned int) c1) << 8) + ((unsigned int) c2)) - 2;
}
/**
* @return the next marker or -1 on error.
*/
static int
next_marker (const unsigned char **data, const unsigned char *end)
{
int c;
c = NEXTC (data, end);
while ((c != 0xFF) && (c != -1))
c = NEXTC (data, end);
do
{
c = NEXTC (data, end);
}
while ((c == 0xFF) && (c != -1));
return c;
}
static void
skip_variable (const unsigned char **data, const unsigned char *end)
{
int length;
length = readLength (data, end);
if (length < 0)
{
(*data) = end; /* skip to the end */
return;
}
/* Skip over length bytes */
(*data) += length;
}
static char *
process_COM (const unsigned char **data, const unsigned char *end)
{
unsigned int length;
int ch;
int pos;
char *comment;
length = readLength (data, end);
if (length <= 0)
return NULL;
comment = malloc (length + 1);
if (comment == NULL)
return NULL;
pos = 0;
while (length > 0)
{
ch = NEXTC (data, end);
if ((ch == '\r') || (ch == '\n'))
comment[pos++] = '\n';
else if (isprint ((unsigned char) ch))
comment[pos++] = ch;
length--;
}
comment[pos] = '\0';
return comment;
}
int
EXTRACTOR_jpeg_extract (const unsigned char *data,
size_t size,
EXTRACTOR_MetaDataProcessor proc,
void *proc_cls,
const char *options)
{
int c1;
int c2;
int marker;
const unsigned char *end;
char *tmp;
char val[128];
if (size < 0x12)
return 0;
end = &data[size];
c1 = NEXTC (&data, end);
c2 = NEXTC (&data, end);
if ((c1 != 0xFF) || (c2 != M_SOI))
return 0; /* not a JPEG */
if (0 != proc (proc_cls,
"jpeg",
EXTRACTOR_METATYPE_MIMETYPE,
EXTRACTOR_METAFORMAT_UTF8,
"text/plain",
"image/jpeg",
strlen ("image/jpeg")+1))
return 1;
while (1)
{
marker = next_marker (&data, end);
switch (marker)
{
case -1: /* end of file */
case M_SOS:
case M_EOI:
goto RETURN;
case M_APP0:
{
int len = readLength (&data, end);
if (len < 0x8)
goto RETURN;
if (0 == strncmp ((char *) data, "JFIF", 4))
{
switch (data[0x4])
{
case 1: /* dots per inch */
snprintf (val,
sizeof (val),
_("%ux%u dots per inch"),
(data[0x8] << 8) + data[0x9],
(data[0xA] << 8) + data[0xB]);
if (0 != proc (proc_cls,
"jpeg",
EXTRACTOR_METATYPE_IMAGE_RESOLUTION,
EXTRACTOR_METAFORMAT_UTF8,
"text/plain",
val,
strlen (val)+1))
return 1;
break;
case 2: /* dots per cm */
snprintf (val,
sizeof (val),
_("%ux%u dots per cm"),
(data[0x8] << 8) + data[0x9],
(data[0xA] << 8) + data[0xB]);
if (0 != proc (proc_cls,
"jpeg",
EXTRACTOR_METATYPE_IMAGE_RESOLUTION,
EXTRACTOR_METAFORMAT_UTF8,
"text/plain",
val,
strlen (val)+1))
return 1;
break;
case 0: /* no unit given */
snprintf (val,
sizeof (val),
_("%ux%u dots per inch?"),
(data[0x8] << 8) + data[0x9],
(data[0xA] << 8) + data[0xB]);
if (0 != proc (proc_cls,
"jpeg",
EXTRACTOR_METATYPE_IMAGE_RESOLUTION,
EXTRACTOR_METAFORMAT_UTF8,
"text/plain",
val,
strlen (val)+1))
return 1;
break;
default: /* unknown unit */
break;
}
}
data = &data[len];
break;
}
case 0xC0:
{
int len = readLength (&data, end);
if (len < 0x9)
goto RETURN;
snprintf (val,
sizeof (val),
"%ux%u",
(data[0x3] << 8) + data[0x4],
(data[0x1] << 8) + data[0x2]);
if (0 != proc (proc_cls,
"jpeg",
EXTRACTOR_METATYPE_IMAGE_DIMENSIONS,
EXTRACTOR_METAFORMAT_UTF8,
"text/plain",
val,
strlen (val)+1))
return 1;
data = &data[len];
break;
}
case M_COM:
case M_APP12:
tmp = process_COM (&data, end);
if (NULL == tmp)
break;
if (0 != proc (proc_cls,
"jpeg",
EXTRACTOR_METATYPE_COMMENT,
EXTRACTOR_METAFORMAT_UTF8,
"text/plain",
tmp,
strlen (tmp)+1))
{
free (tmp);
return 1;
}
free (tmp);
break;
default:
skip_variable (&data, end);
break;
}
}
RETURN:
return 0;
}
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