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 3 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, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 #include <config.h>
  21 #include <stdio.h>
  22 #include <stdlib.h>
  23 #include <string.h>
  24 #include <errno.h>
  25 #include <assert.h>
  26
  27 #include "gpg.h"
  28 #include "status.h"
  29 #include "iobuf.h"
  30 #include "util.h"
  31 #include "filter.h"
  32
  33
  34
  35 /****************
  36  * This filter is used to collect a message digest
  37  */
  38 int
  39 md_filter( void *opaque, int control,
  40                IOBUF a, byte *buf, size_t *ret_len)
  41 {
  42     size_t size = *ret_len;
  43     md_filter_context_t *mfx = opaque;
  44     int i, rc=0;
  45
  46     if( control == IOBUFCTRL_UNDERFLOW ) {
  47         if( mfx->maxbuf_size && size > mfx->maxbuf_size )
  48             size = mfx->maxbuf_size;
  49         i = iobuf_read( a, buf, size );
  50         if( i == -1 ) i = 0;
  51         if( i ) {
  52             gcry_md_write(mfx->md, buf, i );
  53             if( mfx->md2 )
  54                 gcry_md_write(mfx->md2, buf, i );
  55         }
  56         else
  57             rc = -1; /* eof */
  58         *ret_len = i;
  59     }
  60     else if( control == IOBUFCTRL_DESC )
  61         *(char**)buf = "md_filter";
  62     return rc;
  63 }
  64
  65
  66 void
  67 free_md_filter_context( md_filter_context_t *mfx )
  68 {
  69     gcry_md_close(mfx->md);
  70     gcry_md_close(mfx->md2);
  71     mfx->md = NULL;
  72     mfx->md2 = NULL;
  73     mfx->maxbuf_size = 0;
  74 }
  75