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/*
This file is part of libextractor.
Copyright (C) 2005, 2009, 2012 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 3, 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., 51 Franklin Street, Fifth Floor,
Boston, MA 02110-1301, USA.
*/
/**
* @file plugins/thumbnailgtk_extractor.c
* @author Christian Grothoff
* @brief this extractor produces a binary (!) encoded
* thumbnail of images (using gdk pixbuf). The bottom
* of the file includes a decoder method that can be used
* to reproduce the 128x128 PNG thumbnails. We use
* libmagic to test if the input data is actually an
* image before trying to give it to gdk-pixbuf.
*/
#include "platform.h"
#include "extractor.h"
#include <magic.h>
#include <glib.h>
#include <gdk-pixbuf/gdk-pixbuf.h>
/**
* Target size for the thumbnails (width and height).
*/
#define THUMBSIZE 128
/**
* Maximum image size supported (to avoid unreasonable
* allocations)
*/
#define MAX_IMAGE_SIZE (32 * 1024 * 1024)
/**
* Global handle to MAGIC data.
*/
static magic_t magic;
/**
* Main method for the gtk-thumbnailer plugin.
*
* @param ec extraction context
*/
void
EXTRACTOR_thumbnailgtk_extract_method (struct EXTRACTOR_ExtractContext *ec)
{
GdkPixbufLoader *loader;
GdkPixbuf *in;
GdkPixbuf *out;
size_t length;
char *thumb;
unsigned long width;
unsigned long height;
char format[64];
void *data;
uint64_t size;
size_t off;
ssize_t iret;
void *buf;
const char *mime;
if (-1 == (iret = ec->read (ec->cls,
&data,
16 * 1024)))
return;
if (NULL == (mime = magic_buffer (magic, data, iret)))
return;
if (0 != strncmp (mime,
"image/",
strlen ("image/")))
return; /* not an image */
/* read entire image into memory */
size = ec->get_size (ec->cls);
if (UINT64_MAX == size)
size = MAX_IMAGE_SIZE; /* unknown size, cap at max */
if (size > MAX_IMAGE_SIZE)
return; /* FAR too big to be an image */
if (NULL == (buf = malloc (size)))
return; /* too big to fit into memory on this system */
/* start with data already read */
memcpy (buf, data, iret);
off = iret;
while (off < size)
{
iret = ec->read (ec->cls, &data, size - off);
if (iret <= 0)
{
/* io error */
free (buf);
return;
}
memcpy (buf + off, data, iret);
off += iret;
}
loader = gdk_pixbuf_loader_new ();
gdk_pixbuf_loader_write (loader,
buf,
size, NULL);
free (buf);
in = gdk_pixbuf_loader_get_pixbuf (loader);
gdk_pixbuf_loader_close (loader, NULL);
if (NULL == in)
{
g_object_unref (loader);
return;
}
g_object_ref (in);
g_object_unref (loader);
height = gdk_pixbuf_get_height (in);
width = gdk_pixbuf_get_width (in);
snprintf (format,
sizeof (format),
"%ux%u",
(unsigned int) width,
(unsigned int) height);
if (0 != ec->proc (ec->cls,
"thumbnailgtk",
EXTRACTOR_METATYPE_IMAGE_DIMENSIONS,
EXTRACTOR_METAFORMAT_UTF8,
"text/plain",
format,
strlen (format) + 1))
{
g_object_unref (in);
return;
}
if ((height <= THUMBSIZE) && (width <= THUMBSIZE))
{
g_object_unref (in);
return;
}
if (height > THUMBSIZE)
{
width = width * THUMBSIZE / height;
height = THUMBSIZE;
}
if (width > THUMBSIZE)
{
height = height * THUMBSIZE / width;
width = THUMBSIZE;
}
if ( (0 == height) || (0 == width) )
{
g_object_unref (in);
return;
}
out = gdk_pixbuf_scale_simple (in, width, height,
GDK_INTERP_BILINEAR);
g_object_unref (in);
thumb = NULL;
length = 0;
if (NULL == out)
return;
if (! gdk_pixbuf_save_to_buffer (out, &thumb,
&length,
"png", NULL,
"compression", "9",
NULL))
{
g_object_unref (out);
return;
}
g_object_unref (out);
if (NULL == thumb)
return;
ec->proc (ec->cls,
"thumbnailgtk",
EXTRACTOR_METATYPE_THUMBNAIL,
EXTRACTOR_METAFORMAT_BINARY,
"image/png",
thumb, length);
free (thumb);
}
/**
* This plugin sometimes is installed under the alias 'thumbnail'.
* So we need to provide a second entry method.
*
* @param ec extraction context
*/
void
EXTRACTOR_thumbnail_extract_method (struct EXTRACTOR_ExtractContext *ec)
{
EXTRACTOR_thumbnailgtk_extract_method (ec);
}
/**
* Initialize glib and load magic file.
*/
void __attribute__ ((constructor))
thumbnailgtk_gobject_init ()
{
#if !GLIB_CHECK_VERSION(2, 35, 0)
g_type_init ();
#endif
magic = magic_open (MAGIC_MIME_TYPE);
if (0 != magic_load (magic, NULL))
{
/* FIXME: how to deal with errors? */
}
}
/**
* Destructor for the library, cleans up.
*/
void __attribute__ ((destructor))
thumbnailgtk_ltdl_fini ()
{
if (NULL != magic)
{
magic_close (magic);
magic = NULL;
}
}
/* end of thumbnailgtk_extractor.c */
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