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mdfilter.c
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/* mdfilter.c - filter data and calculate a message digest
* Copyright (C) 1998, 1999, 2000, 2001 Free Software Foundation, Inc.
*
* This file is part of GnuPG.
*
* GnuPG 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 of the License, or
* (at your option) any later version.
*
* GnuPG 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 this program; if not, see <https://www.gnu.org/licenses/>.
*/
#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <npth.h>
#include "gpg.h"
#include "../common/status.h"
#include "../common/iobuf.h"
#include "../common/util.h"
#include "filter.h"
/****************
* This filter is used to collect a message digest
*/
int
md_filter( void *opaque, int control,
IOBUF a, byte *buf, size_t *ret_len)
{
size_t size = *ret_len;
md_filter_context_t *mfx = opaque;
int i, rc=0;
if( control == IOBUFCTRL_UNDERFLOW ) {
if( mfx->maxbuf_size && size > mfx->maxbuf_size )
size = mfx->maxbuf_size;
i = iobuf_read( a, buf, size );
if( i == -1 ) i = 0;
if( i ) {
gcry_md_write(mfx->md, buf, i );
if( mfx->md2 )
gcry_md_write(mfx->md2, buf, i );
}
else
rc = -1; /* eof */
*ret_len = i;
}
else if( control == IOBUFCTRL_DESC )
mem2str (buf, "md_filter", *ret_len);
return rc;
}
void
free_md_filter_context( md_filter_context_t *mfx )
{
gcry_md_close(mfx->md);
gcry_md_close(mfx->md2);
mfx->md = NULL;
mfx->md2 = NULL;
mfx->maxbuf_size = 0;
}
/****************
* Threaded implementation for hashing.
*/
struct md_thd_filter_context {
gcry_md_hd_t md;
npth_t thd;
/**/
npth_mutex_t mutex;
npth_cond_t cond;
size_t bufsize;
unsigned int produce : 1;
unsigned int consume : 1;
ssize_t written0;
ssize_t written1;
unsigned char buf[1];
};
static void
lock_md (struct md_thd_filter_context *mfx)
{
int rc = npth_mutex_lock (&mfx->mutex);
if (rc)
log_fatal ("%s: failed to acquire mutex: %s\n", __func__,
gpg_strerror (gpg_error_from_errno (rc)));
}
static void
unlock_md (struct md_thd_filter_context * mfx)
{
int rc = npth_mutex_unlock (&mfx->mutex);
if (rc)
log_fatal ("%s: failed to release mutex: %s\n", __func__,
gpg_strerror (gpg_error_from_errno (rc)));
}
static int
get_buffer_to_hash (struct md_thd_filter_context *mfx,
unsigned char **r_buf, size_t *r_len)
{
int rc = 0;
lock_md (mfx);
if ((mfx->consume == 0 && mfx->written0 < 0)
|| (mfx->consume != 0 && mfx->written1 < 0))
{
rc = npth_cond_wait (&mfx->cond, &mfx->mutex);
if (rc)
{
unlock_md (mfx);
return -1;
}
}
if (mfx->consume == 0)
{
*r_buf = mfx->buf;
*r_len = mfx->written0;
}
else
{
*r_buf = mfx->buf + mfx->bufsize;
*r_len = mfx->written1;
}
unlock_md (mfx);
return 0;
}
static int
put_buffer_to_recv (struct md_thd_filter_context *mfx)
{
int rc = 0;
lock_md (mfx);
if (mfx->consume == 0)
{
mfx->written0 = -1;
mfx->consume = 1;
}
else
{
mfx->written1 = -1;
mfx->consume = 0;
}
rc = npth_cond_signal (&mfx->cond);
if (rc)
{
unlock_md (mfx);
return -1;
}
unlock_md (mfx);
return 0;
}
static int
get_buffer_to_fill (struct md_thd_filter_context *mfx,
unsigned char **r_buf, size_t len)
{
lock_md (mfx);
if (len > mfx->bufsize)
{
unlock_md (mfx);
return GPG_ERR_BUFFER_TOO_SHORT;
}
if ((mfx->produce == 0 && mfx->written0 >= 0)
|| (mfx->produce != 0 && mfx->written1 >= 0))
{
int rc = npth_cond_wait (&mfx->cond, &mfx->mutex);
if (rc)
{
unlock_md (mfx);
return gpg_error_from_errno (rc);
}
}
if (mfx->produce == 0)
*r_buf = mfx->buf;
else
*r_buf = mfx->buf + mfx->bufsize;
unlock_md (mfx);
return 0;
}
static int
put_buffer_to_send (struct md_thd_filter_context *mfx, size_t len)
{
int rc;
lock_md (mfx);
if (mfx->produce == 0)
{
mfx->written0 = len;
mfx->produce = 1;
}
else
{
mfx->written1 = len;
mfx->produce = 0;
}
rc = npth_cond_signal (&mfx->cond);
if (rc)
{
unlock_md (mfx);
return gpg_error_from_errno (rc);
}
unlock_md (mfx);
/* Yield to the md_thread to let it compute the hash in parallel */
npth_usleep (0);
return 0;
}
static void *
md_thread (void *arg)
{
struct md_thd_filter_context *mfx = arg;
while (1)
{
unsigned char *buf;
size_t len;
if (get_buffer_to_hash (mfx, &buf, &len) < 0)
/* Error */
return NULL;
if (len == 0)
break;
npth_unprotect ();
gcry_md_write (mfx->md, buf, len);
npth_protect ();
if (put_buffer_to_recv (mfx) < 0)
/* Error */
return NULL;
}
return NULL;
}
int
md_thd_filter (void *opaque, int control,
IOBUF a, byte *buf, size_t *ret_len)
{
size_t size = *ret_len;
struct md_thd_filter_context **r_mfx = opaque;
struct md_thd_filter_context *mfx = *r_mfx;
int rc=0;
if (control == IOBUFCTRL_INIT)
{
npth_attr_t tattr;
size_t n;
n = 2 * iobuf_set_buffer_size (0) * 1024;
mfx = xtrymalloc (n + offsetof (struct md_thd_filter_context, buf));
if (!mfx)
return gpg_error_from_syserror ();
*r_mfx = mfx;
mfx->bufsize = n / 2;
mfx->consume = mfx->produce = 0;
mfx->written0 = -1;
mfx->written1 = -1;
rc = npth_mutex_init (&mfx->mutex, NULL);
if (rc)
{
return gpg_error_from_errno (rc);
}
rc = npth_cond_init (&mfx->cond, NULL);
if (rc)
{
npth_mutex_destroy (&mfx->mutex);
return gpg_error_from_errno (rc);
}
rc = npth_attr_init (&tattr);
if (rc)
{
npth_cond_destroy (&mfx->cond);
npth_mutex_destroy (&mfx->mutex);
return gpg_error_from_errno (rc);
}
npth_attr_setdetachstate (&tattr, NPTH_CREATE_JOINABLE);
rc = npth_create (&mfx->thd, &tattr, md_thread, mfx);
if (rc)
{
npth_cond_destroy (&mfx->cond);
npth_mutex_destroy (&mfx->mutex);
npth_attr_destroy (&tattr);
return gpg_error_from_errno (rc);
}
npth_attr_destroy (&tattr);
}
else if (control == IOBUFCTRL_UNDERFLOW)
{
int i;
unsigned char *md_buf = NULL;
i = iobuf_read (a, buf, size);
if (i == -1)
i = 0;
rc = get_buffer_to_fill (mfx, &md_buf, i);
if (rc)
return rc;
if (i)
memcpy (md_buf, buf, i);
rc = put_buffer_to_send (mfx, i);
if (rc)
return rc;
if (i == 0)
{
npth_join (mfx->thd, NULL);
rc = -1; /* eof */
}
*ret_len = i;
}
else if (control == IOBUFCTRL_FREE)
{
npth_cond_destroy (&mfx->cond);
npth_mutex_destroy (&mfx->mutex);
xfree (mfx);
*r_mfx = NULL;
}
else if (control == IOBUFCTRL_DESC)
mem2str (buf, "md_thd_filter", *ret_len);
return rc;
}
void
md_thd_filter_set_md (struct md_thd_filter_context *mfx, gcry_md_hd_t md)
{
mfx->md = md;
}

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