postgresql/contrib/pgcrypto/mbuf.c
2010-09-20 22:08:53 +02:00

564 lines
9.2 KiB
C

/*
* mbuf.c
* Memory buffer operations.
*
* Copyright (c) 2005 Marko Kreen
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* contrib/pgcrypto/mbuf.c
*/
#include "postgres.h"
#include "px.h"
#include "mbuf.h"
#define STEP (16*1024)
struct MBuf
{
uint8 *data;
uint8 *data_end;
uint8 *read_pos;
uint8 *buf_end;
bool no_write;
bool own_data;
};
int
mbuf_avail(MBuf *mbuf)
{
return mbuf->data_end - mbuf->read_pos;
}
int
mbuf_size(MBuf *mbuf)
{
return mbuf->data_end - mbuf->data;
}
int
mbuf_tell(MBuf *mbuf)
{
return mbuf->read_pos - mbuf->data;
}
int
mbuf_free(MBuf *mbuf)
{
if (mbuf->own_data)
{
memset(mbuf->data, 0, mbuf->buf_end - mbuf->data);
px_free(mbuf->data);
}
px_free(mbuf);
return 0;
}
static void
prepare_room(MBuf *mbuf, int block_len)
{
uint8 *newbuf;
unsigned newlen;
if (mbuf->data_end + block_len <= mbuf->buf_end)
return;
newlen = (mbuf->buf_end - mbuf->data)
+ ((block_len + STEP + STEP - 1) & -STEP);
newbuf = px_realloc(mbuf->data, newlen);
mbuf->buf_end = newbuf + newlen;
mbuf->data_end = newbuf + (mbuf->data_end - mbuf->data);
mbuf->read_pos = newbuf + (mbuf->read_pos - mbuf->data);
mbuf->data = newbuf;
return;
}
int
mbuf_append(MBuf *dst, const uint8 *buf, int len)
{
if (dst->no_write)
{
px_debug("mbuf_append: no_write");
return PXE_BUG;
}
prepare_room(dst, len);
memcpy(dst->data_end, buf, len);
dst->data_end += len;
return 0;
}
MBuf *
mbuf_create(int len)
{
MBuf *mbuf;
if (!len)
len = 8192;
mbuf = px_alloc(sizeof *mbuf);
mbuf->data = px_alloc(len);
mbuf->buf_end = mbuf->data + len;
mbuf->data_end = mbuf->data;
mbuf->read_pos = mbuf->data;
mbuf->no_write = false;
mbuf->own_data = true;
return mbuf;
}
MBuf *
mbuf_create_from_data(const uint8 *data, int len)
{
MBuf *mbuf;
mbuf = px_alloc(sizeof *mbuf);
mbuf->data = (uint8 *) data;
mbuf->buf_end = mbuf->data + len;
mbuf->data_end = mbuf->data + len;
mbuf->read_pos = mbuf->data;
mbuf->no_write = true;
mbuf->own_data = false;
return mbuf;
}
int
mbuf_grab(MBuf *mbuf, int len, uint8 **data_p)
{
if (len > mbuf_avail(mbuf))
len = mbuf_avail(mbuf);
mbuf->no_write = true;
*data_p = mbuf->read_pos;
mbuf->read_pos += len;
return len;
}
int
mbuf_rewind(MBuf *mbuf)
{
mbuf->read_pos = mbuf->data;
return 0;
}
int
mbuf_steal_data(MBuf *mbuf, uint8 **data_p)
{
int len = mbuf_size(mbuf);
mbuf->no_write = true;
mbuf->own_data = false;
*data_p = mbuf->data;
mbuf->data = mbuf->data_end = mbuf->read_pos = mbuf->buf_end = NULL;
return len;
}
/*
* PullFilter
*/
struct PullFilter
{
PullFilter *src;
const PullFilterOps *op;
int buflen;
uint8 *buf;
int pos;
void *priv;
};
int
pullf_create(PullFilter **pf_p, const PullFilterOps *op, void *init_arg, PullFilter *src)
{
PullFilter *pf;
void *priv;
int res;
if (op->init != NULL)
{
res = op->init(&priv, init_arg, src);
if (res < 0)
return res;
}
else
{
priv = init_arg;
res = 0;
}
pf = px_alloc(sizeof(*pf));
memset(pf, 0, sizeof(*pf));
pf->buflen = res;
pf->op = op;
pf->priv = priv;
pf->src = src;
if (pf->buflen > 0)
{
pf->buf = px_alloc(pf->buflen);
pf->pos = 0;
}
else
{
pf->buf = NULL;
pf->pos = 0;
}
*pf_p = pf;
return 0;
}
void
pullf_free(PullFilter *pf)
{
if (pf->op->free)
pf->op->free(pf->priv);
if (pf->buf)
{
memset(pf->buf, 0, pf->buflen);
px_free(pf->buf);
}
memset(pf, 0, sizeof(*pf));
px_free(pf);
}
/* may return less data than asked, 0 means eof */
int
pullf_read(PullFilter *pf, int len, uint8 **data_p)
{
int res;
if (pf->op->pull)
{
if (pf->buflen && len > pf->buflen)
len = pf->buflen;
res = pf->op->pull(pf->priv, pf->src, len, data_p,
pf->buf, pf->buflen);
}
else
res = pullf_read(pf->src, len, data_p);
return res;
}
int
pullf_read_max(PullFilter *pf, int len, uint8 **data_p, uint8 *tmpbuf)
{
int res,
total;
uint8 *tmp;
res = pullf_read(pf, len, data_p);
if (res <= 0 || res == len)
return res;
/* read was shorter, use tmpbuf */
memcpy(tmpbuf, *data_p, res);
*data_p = tmpbuf;
len -= res;
total = res;
while (len > 0)
{
res = pullf_read(pf, len, &tmp);
if (res < 0)
{
/* so the caller must clear only on success */
memset(tmpbuf, 0, total);
return res;
}
if (res == 0)
break;
memcpy(tmpbuf + total, tmp, res);
total += res;
}
return total;
}
/*
* caller wants exatly len bytes and dont bother with references
*/
int
pullf_read_fixed(PullFilter *src, int len, uint8 *dst)
{
int res;
uint8 *p;
res = pullf_read_max(src, len, &p, dst);
if (res < 0)
return res;
if (res != len)
{
px_debug("pullf_read_fixed: need=%d got=%d", len, res);
return PXE_MBUF_SHORT_READ;
}
if (p != dst)
memcpy(dst, p, len);
return 0;
}
/*
* read from MBuf
*/
static int
pull_from_mbuf(void *arg, PullFilter *src, int len,
uint8 **data_p, uint8 *buf, int buflen)
{
MBuf *mbuf = arg;
return mbuf_grab(mbuf, len, data_p);
}
static const struct PullFilterOps mbuf_reader = {
NULL, pull_from_mbuf, NULL
};
int
pullf_create_mbuf_reader(PullFilter **mp_p, MBuf *src)
{
return pullf_create(mp_p, &mbuf_reader, src, NULL);
}
/*
* PushFilter
*/
struct PushFilter
{
PushFilter *next;
const PushFilterOps *op;
int block_size;
uint8 *buf;
int pos;
void *priv;
};
int
pushf_create(PushFilter **mp_p, const PushFilterOps *op, void *init_arg, PushFilter *next)
{
PushFilter *mp;
void *priv;
int res;
if (op->init != NULL)
{
res = op->init(next, init_arg, &priv);
if (res < 0)
return res;
}
else
{
priv = init_arg;
res = 0;
}
mp = px_alloc(sizeof(*mp));
memset(mp, 0, sizeof(*mp));
mp->block_size = res;
mp->op = op;
mp->priv = priv;
mp->next = next;
if (mp->block_size > 0)
{
mp->buf = px_alloc(mp->block_size);
mp->pos = 0;
}
else
{
mp->buf = NULL;
mp->pos = 0;
}
*mp_p = mp;
return 0;
}
void
pushf_free(PushFilter *mp)
{
if (mp->op->free)
mp->op->free(mp->priv);
if (mp->buf)
{
memset(mp->buf, 0, mp->block_size);
px_free(mp->buf);
}
memset(mp, 0, sizeof(*mp));
px_free(mp);
}
void
pushf_free_all(PushFilter *mp)
{
PushFilter *tmp;
while (mp)
{
tmp = mp->next;
pushf_free(mp);
mp = tmp;
}
}
static int
wrap_process(PushFilter *mp, const uint8 *data, int len)
{
int res;
if (mp->op->push != NULL)
res = mp->op->push(mp->next, mp->priv, data, len);
else
res = pushf_write(mp->next, data, len);
if (res > 0)
return PXE_BUG;
return res;
}
/* consumes all data, returns len on success */
int
pushf_write(PushFilter *mp, const uint8 *data, int len)
{
int need,
res;
/*
* no buffering
*/
if (mp->block_size <= 0)
return wrap_process(mp, data, len);
/*
* try to empty buffer
*/
need = mp->block_size - mp->pos;
if (need > 0)
{
if (len < need)
{
memcpy(mp->buf + mp->pos, data, len);
mp->pos += len;
return 0;
}
memcpy(mp->buf + mp->pos, data, need);
len -= need;
data += need;
}
/*
* buffer full, process
*/
res = wrap_process(mp, mp->buf, mp->block_size);
if (res < 0)
return res;
mp->pos = 0;
/*
* now process directly from data
*/
while (len > 0)
{
if (len > mp->block_size)
{
res = wrap_process(mp, data, mp->block_size);
if (res < 0)
return res;
data += mp->block_size;
len -= mp->block_size;
}
else
{
memcpy(mp->buf, data, len);
mp->pos += len;
break;
}
}
return 0;
}
int
pushf_flush(PushFilter *mp)
{
int res;
while (mp)
{
if (mp->block_size > 0)
{
res = wrap_process(mp, mp->buf, mp->pos);
if (res < 0)
return res;
}
if (mp->op->flush)
{
res = mp->op->flush(mp->next, mp->priv);
if (res < 0)
return res;
}
mp = mp->next;
}
return 0;
}
/*
* write to MBuf
*/
static int
push_into_mbuf(PushFilter *next, void *arg, const uint8 *data, int len)
{
int res = 0;
MBuf *mbuf = arg;
if (len > 0)
res = mbuf_append(mbuf, data, len);
return res < 0 ? res : 0;
}
static const struct PushFilterOps mbuf_filter = {
NULL, push_into_mbuf, NULL, NULL
};
int
pushf_create_mbuf_writer(PushFilter **res, MBuf *dst)
{
return pushf_create(res, &mbuf_filter, dst, NULL);
}