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Member "libextractor-1.11/src/plugins/gif_extractor.c" (30 Jan 2021, 4024 Bytes) of package /linux/privat/libextractor-1.11.tar.gz:

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    1 /*
    2      This file is part of libextractor.
    3      Copyright (C) 2012 Vidyut Samanta and Christian Grothoff
    4 
    5      libextractor is free software; you can redistribute it and/or modify
    6      it under the terms of the GNU General Public License as published
    7      by the Free Software Foundation; either version 3, or (at your
    8      option) any later version.
    9 
   10      libextractor is distributed in the hope that it will be useful, but
   11      WITHOUT ANY WARRANTY; without even the implied warranty of
   12      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   13      General Public License for more details.
   14 
   15      You should have received a copy of the GNU General Public License
   16      along with libextractor; see the file COPYING.  If not, write to the
   17      Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
   18      Boston, MA 02110-1301, USA.
   19  */
   20 /**
   21  * @file plugins/gif_extractor.c
   22  * @brief plugin to support GIF files
   23  * @author Christian Grothoff
   24  */
   25 #include "platform.h"
   26 #include "extractor.h"
   27 #include <gif_lib.h>
   28 
   29 
   30 /**
   31  * Callback invoked by libgif to read data.
   32  *
   33  * @param ft the file handle, including our extract context
   34  * @param bt where to write the data
   35  * @param arg number of bytes to read
   36  * @return -1 on error, otherwise number of bytes read
   37  */
   38 static int
   39 gif_READ_func (GifFileType *ft,
   40                GifByteType *bt,
   41                int arg)
   42 {
   43   struct EXTRACTOR_ExtractContext *ec = ft->UserData;
   44   void *data;
   45   ssize_t ret;
   46 
   47   ret = ec->read (ec->cls,
   48                   &data,
   49                   arg);
   50   if (-1 == ret)
   51     return -1;
   52   memcpy (bt, data, ret);
   53   return ret;
   54 }
   55 
   56 
   57 /**
   58  * Main entry method for the 'image/gif' extraction plugin.
   59  *
   60  * @param ec extraction context provided to the plugin
   61  */
   62 void
   63 EXTRACTOR_gif_extract_method (struct EXTRACTOR_ExtractContext *ec)
   64 {
   65   GifFileType *gif_file;
   66   GifRecordType gif_type;
   67   GifByteType *ext;
   68   int et;
   69   char dims[128];
   70 #if defined (GIF_LIB_VERSION) || GIFLIB_MAJOR <= 4
   71   if (NULL == (gif_file = DGifOpen (ec, &gif_READ_func)))
   72     return; /* not a GIF */
   73 #else
   74   int gif_error;
   75 
   76   gif_error = 0;
   77   gif_file = DGifOpen (ec, &gif_READ_func, &gif_error);
   78   if ((gif_file == NULL) || (gif_error != 0))
   79   {
   80     if (gif_file != NULL)
   81 #if GIFLIB_MAJOR < 5 || GIFLIB_MINOR < 1
   82       EGifCloseFile (gif_file);
   83 #else
   84       EGifCloseFile (gif_file, NULL);
   85 #endif
   86     return; /* not a GIF */
   87   }
   88 #endif
   89   if (0 !=
   90       ec->proc (ec->cls,
   91                 "gif",
   92                 EXTRACTOR_METATYPE_MIMETYPE,
   93                 EXTRACTOR_METAFORMAT_UTF8,
   94                 "text/plain",
   95                 "image/gif",
   96                 strlen ("image/gif") + 1))
   97     return;
   98   snprintf (dims,
   99             sizeof (dims),
  100             "%dx%d",
  101             gif_file->SHeight,
  102             gif_file->SWidth);
  103   if (0 !=
  104       ec->proc (ec->cls,
  105                 "gif",
  106                 EXTRACTOR_METATYPE_IMAGE_DIMENSIONS,
  107                 EXTRACTOR_METAFORMAT_UTF8,
  108                 "text/plain",
  109                 dims,
  110                 strlen (dims) + 1))
  111     return;
  112   while (1)
  113   {
  114     if (GIF_OK !=
  115         DGifGetRecordType (gif_file,
  116                            &gif_type))
  117       break;
  118     if (UNDEFINED_RECORD_TYPE == gif_type)
  119       break;
  120     if (EXTENSION_RECORD_TYPE != gif_type)
  121       continue;
  122     if (GIF_OK !=
  123         DGifGetExtension (gif_file, &et, &ext))
  124       continue;
  125     if (NULL == ext)
  126       continue;
  127     if (COMMENT_EXT_FUNC_CODE == et)
  128     {
  129       ec->proc (ec->cls,
  130                 "gif",
  131                 EXTRACTOR_METATYPE_COMMENT,
  132                 EXTRACTOR_METAFORMAT_C_STRING,
  133                 "text/plain",
  134                 (char*) &ext[1],
  135                 (uint8_t) ext[0]);
  136       break;
  137     }
  138     while ( (GIF_ERROR !=
  139              DGifGetExtensionNext (gif_file, &ext)) &&
  140             (NULL != ext) )
  141       ;                   /* keep going */
  142   }
  143 #if defined (GIF_LIB_VERSION) || GIFLIB_MAJOR < 5 || GIFLIB_MINOR < 1
  144   DGifCloseFile (gif_file);
  145 #else
  146   DGifCloseFile (gif_file, NULL);
  147 #endif
  148 }
  149 
  150 
  151 /* end of gif_extractor.c */