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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
  19  * USA.
  20  */
  21
  22 #include <config.h>
  23 #include <stdio.h>
  24 #include <stdlib.h>
  25 #include <string.h>
  26 #include <errno.h>
  27 #include <assert.h>
  28
  29 #include "errors.h"
  30 #include "iobuf.h"
  31 #include "memory.h"
  32 #include "util.h"
  33 #include "filter.h"
  34
  35
  36
  37 /****************
  38  * This filter is used to collect a message digest
  39  */
  40 int
  41 md_filter( void *opaque, int control,
  42                IOBUF a, byte *buf, size_t *ret_len)
  43 {
  44     size_t size = *ret_len;
  45     md_filter_context_t *mfx = opaque;
  46     int i, rc=0;
  47
  48     if( control == IOBUFCTRL_UNDERFLOW ) {
  49         if( mfx->maxbuf_size && size > mfx->maxbuf_size )
  50             size = mfx->maxbuf_size;
  51         i = iobuf_read( a, buf, size );
  52         if( i == -1 ) i = 0;
  53         if( i ) {
  54             md_write(mfx->md, buf, i );
  55             if( mfx->md2 )
  56                 md_write(mfx->md2, buf, i );
  57         }
  58         else
  59             rc = -1; /* eof */
  60         *ret_len = i;
  61     }
  62     else if( control == IOBUFCTRL_DESC )
  63         *(char**)buf = "md_filter";
  64     return rc;
  65 }
  66
  67
  68 void
  69 free_md_filter_context( md_filter_context_t *mfx )
  70 {
  71     md_close(mfx->md);
  72     md_close(mfx->md2);
  73     mfx->md = NULL;
  74     mfx->md2 = NULL;
  75     mfx->maxbuf_size = 0;
  76 }
  77