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mbuf.h

/*
 * mbuf.h
 *          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.
 *
 * $PostgreSQL: pgsql/contrib/pgcrypto/mbuf.h,v 1.2 2005/10/15 02:49:06 momjian Exp $
 */

#ifndef __PX_MBUF_H
#define __PX_MBUF_H

typedef struct MBuf MBuf;
typedef struct PushFilter PushFilter;
typedef struct PullFilter PullFilter;
typedef struct PushFilterOps PushFilterOps;
typedef struct PullFilterOps PullFilterOps;

struct PushFilterOps
{
      /*
       * should return needed buffer size, 0- no buffering, <0 on error if NULL,
       * no buffering, and priv=init_arg
       */
      int               (*init) (PushFilter * next, void *init_arg, void **priv_p);

      /*
       * send data to next.  should consume all? if null, it will be simply
       * copied (in-place) returns 0 on error
       */
      int               (*push) (PushFilter * next, void *priv,
                                                       const uint8 *src, int len);
      int               (*flush) (PushFilter * next, void *priv);
      void        (*free) (void *priv);
};

struct PullFilterOps
{
      /*
       * should return needed buffer size, 0- no buffering, <0 on error if NULL,
       * no buffering, and priv=init_arg
       */
      int               (*init) (void **priv_p, void *init_arg, PullFilter * src);

      /*
       * request data from src, put result ptr to data_p can use ptr from src or
       * use buf as work area if NULL in-place copy
       */
      int               (*pull) (void *priv, PullFilter * src, int len,
                                                       uint8 **data_p, uint8 *buf, int buflen);
      void        (*free) (void *priv);
};

/*
 * Memory buffer
 */
MBuf     *mbuf_create(int len);
MBuf     *mbuf_create_from_data(const uint8 *data, int len);
int               mbuf_tell(MBuf * mbuf);
int               mbuf_avail(MBuf * mbuf);
int               mbuf_size(MBuf * mbuf);
int               mbuf_grab(MBuf * mbuf, int len, uint8 **data_p);
int               mbuf_steal_data(MBuf * mbuf, uint8 **data_p);
int               mbuf_append(MBuf * dst, const uint8 *buf, int cnt);
int               mbuf_rewind(MBuf * mbuf);
int               mbuf_free(MBuf * mbuf);

/*
 * Push filter
 */
int pushf_create(PushFilter ** res, const PushFilterOps * ops, void *init_arg,
                   PushFilter * next);
int               pushf_write(PushFilter * mp, const uint8 *data, int len);
void        pushf_free_all(PushFilter * mp);
void        pushf_free(PushFilter * mp);
int               pushf_flush(PushFilter * mp);

int               pushf_create_mbuf_writer(PushFilter ** mp_p, MBuf * mbuf);

/*
 * Pull filter
 */
int pullf_create(PullFilter ** res, const PullFilterOps * ops,
                   void *init_arg, PullFilter * src);
int               pullf_read(PullFilter * mp, int len, uint8 **data_p);
int pullf_read_max(PullFilter * mp, int len,
                     uint8 **data_p, uint8 *tmpbuf);
void        pullf_free(PullFilter * mp);
int               pullf_read_fixed(PullFilter * src, int len, uint8 *dst);

int               pullf_create_mbuf_reader(PullFilter ** pf_p, MBuf * mbuf);

#define GETBYTE(pf, dst) \
      do { \
            uint8 __b; \
            int __res = pullf_read_fixed(pf, 1, &__b); \
            if (__res < 0) \
                  return __res; \
            (dst) = __b; \
      } while (0)

#endif   /* __PX_MBUF_H */

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