g10/mdfilter.c

   1 /* mdfilter.c - filter data and calculate a message digest
   2  * Copyright (C) 1998, 1999, 2000, 2001 Free Software Foundation, Inc.
   3  *
   4  * This file is part of GnuPG.
   5  *
   6  * GnuPG is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * GnuPG is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  19  */
  20
  21 #include <config.h>
  22 #include <stdio.h>
  23 #include <stdlib.h>
  24 #include <string.h>
  25 #include <errno.h>
  26 #include <assert.h>
  27
  28 #include "errors.h"
  29 #include "iobuf.h"
  30 #include "memory.h"
  31 #include "util.h"
  32 #include "filter.h"
  33
  34
  35
  36 /****************
  37  * This filter is used to collect a message digest
  38  */
  39 int
  40 md_filter( void *opaque, int control,
  41                iobuf_t a, byte *buf, size_t *ret_len)
  42 {
  43     size_t size = *ret_len;
  44     md_filter_context_t *mfx = opaque;
  45     int i, rc=0;
  46
  47     if( control == IOBUFCTRL_UNDERFLOW ) {
  48         if( mfx->maxbuf_size && size > mfx->maxbuf_size )
  49             size = mfx->maxbuf_size;
  50         i = iobuf_read( a, buf, size );
  51         if( i == -1 ) i = 0;
  52         if( i ) {
  53             gcry_md_write(mfx->md, buf, i );
  54             if( mfx->md2 )
  55                 gcry_md_write(mfx->md2, buf, i );
  56         }
  57         else
  58             rc = -1; /* eof */
  59         *ret_len = i;
  60     }
  61     else if( control == IOBUFCTRL_DESC )
  62         *(char**)buf = "md_filter";
  63     return rc;
  64 }
  65
  66
  67 void
  68 free_md_filter_context( md_filter_context_t *mfx )
  69 {
  70     gcry_md_close (mfx->md);
  71     gcry_md_close (mfx->md2);
  72     mfx->md = NULL;
  73     mfx->md2 = NULL;
  74     mfx->maxbuf_size = 0;
  75 }
  76