mirror of
https://git.postgresql.org/git/postgresql.git
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564 lines
9.3 KiB
C
564 lines
9.3 KiB
C
/*
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* mbuf.c
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* Memory buffer operations.
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*
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* Copyright (c) 2005 Marko Kreen
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $PostgreSQL: pgsql/contrib/pgcrypto/mbuf.c,v 1.5 2009/06/11 14:48:52 momjian Exp $
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*/
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#include "postgres.h"
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#include "px.h"
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#include "mbuf.h"
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#define STEP (16*1024)
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struct MBuf
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{
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uint8 *data;
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uint8 *data_end;
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uint8 *read_pos;
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uint8 *buf_end;
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bool no_write;
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bool own_data;
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};
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int
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mbuf_avail(MBuf *mbuf)
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{
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return mbuf->data_end - mbuf->read_pos;
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}
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int
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mbuf_size(MBuf *mbuf)
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{
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return mbuf->data_end - mbuf->data;
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}
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int
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mbuf_tell(MBuf *mbuf)
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{
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return mbuf->read_pos - mbuf->data;
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}
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int
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mbuf_free(MBuf *mbuf)
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{
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if (mbuf->own_data)
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{
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memset(mbuf->data, 0, mbuf->buf_end - mbuf->data);
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px_free(mbuf->data);
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}
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px_free(mbuf);
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return 0;
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}
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static void
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prepare_room(MBuf *mbuf, int block_len)
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{
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uint8 *newbuf;
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unsigned newlen;
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if (mbuf->data_end + block_len <= mbuf->buf_end)
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return;
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newlen = (mbuf->buf_end - mbuf->data)
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+ ((block_len + STEP + STEP - 1) & -STEP);
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newbuf = px_realloc(mbuf->data, newlen);
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mbuf->buf_end = newbuf + newlen;
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mbuf->data_end = newbuf + (mbuf->data_end - mbuf->data);
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mbuf->read_pos = newbuf + (mbuf->read_pos - mbuf->data);
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mbuf->data = newbuf;
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return;
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}
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int
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mbuf_append(MBuf *dst, const uint8 *buf, int len)
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{
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if (dst->no_write)
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{
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px_debug("mbuf_append: no_write");
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return PXE_BUG;
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}
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prepare_room(dst, len);
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memcpy(dst->data_end, buf, len);
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dst->data_end += len;
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return 0;
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}
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MBuf *
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mbuf_create(int len)
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{
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MBuf *mbuf;
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if (!len)
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len = 8192;
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mbuf = px_alloc(sizeof *mbuf);
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mbuf->data = px_alloc(len);
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mbuf->buf_end = mbuf->data + len;
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mbuf->data_end = mbuf->data;
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mbuf->read_pos = mbuf->data;
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mbuf->no_write = false;
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mbuf->own_data = true;
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return mbuf;
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}
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MBuf *
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mbuf_create_from_data(const uint8 *data, int len)
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{
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MBuf *mbuf;
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mbuf = px_alloc(sizeof *mbuf);
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mbuf->data = (uint8 *) data;
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mbuf->buf_end = mbuf->data + len;
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mbuf->data_end = mbuf->data + len;
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mbuf->read_pos = mbuf->data;
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mbuf->no_write = true;
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mbuf->own_data = false;
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return mbuf;
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}
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int
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mbuf_grab(MBuf *mbuf, int len, uint8 **data_p)
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{
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if (len > mbuf_avail(mbuf))
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len = mbuf_avail(mbuf);
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mbuf->no_write = true;
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*data_p = mbuf->read_pos;
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mbuf->read_pos += len;
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return len;
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}
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int
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mbuf_rewind(MBuf *mbuf)
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{
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mbuf->read_pos = mbuf->data;
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return 0;
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}
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int
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mbuf_steal_data(MBuf *mbuf, uint8 **data_p)
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{
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int len = mbuf_size(mbuf);
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mbuf->no_write = true;
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mbuf->own_data = false;
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*data_p = mbuf->data;
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mbuf->data = mbuf->data_end = mbuf->read_pos = mbuf->buf_end = NULL;
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return len;
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}
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/*
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* PullFilter
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*/
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struct PullFilter
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{
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PullFilter *src;
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const PullFilterOps *op;
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int buflen;
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uint8 *buf;
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int pos;
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void *priv;
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};
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int
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pullf_create(PullFilter **pf_p, const PullFilterOps *op, void *init_arg, PullFilter *src)
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{
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PullFilter *pf;
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void *priv;
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int res;
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if (op->init != NULL)
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{
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res = op->init(&priv, init_arg, src);
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if (res < 0)
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return res;
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}
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else
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{
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priv = init_arg;
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res = 0;
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}
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pf = px_alloc(sizeof(*pf));
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memset(pf, 0, sizeof(*pf));
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pf->buflen = res;
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pf->op = op;
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pf->priv = priv;
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pf->src = src;
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if (pf->buflen > 0)
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{
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pf->buf = px_alloc(pf->buflen);
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pf->pos = 0;
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}
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else
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{
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pf->buf = NULL;
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pf->pos = 0;
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}
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*pf_p = pf;
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return 0;
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}
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void
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pullf_free(PullFilter *pf)
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{
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if (pf->op->free)
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pf->op->free(pf->priv);
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if (pf->buf)
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{
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memset(pf->buf, 0, pf->buflen);
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px_free(pf->buf);
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}
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memset(pf, 0, sizeof(*pf));
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px_free(pf);
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}
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/* may return less data than asked, 0 means eof */
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int
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pullf_read(PullFilter *pf, int len, uint8 **data_p)
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{
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int res;
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if (pf->op->pull)
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{
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if (pf->buflen && len > pf->buflen)
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len = pf->buflen;
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res = pf->op->pull(pf->priv, pf->src, len, data_p,
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pf->buf, pf->buflen);
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}
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else
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res = pullf_read(pf->src, len, data_p);
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return res;
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}
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int
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pullf_read_max(PullFilter *pf, int len, uint8 **data_p, uint8 *tmpbuf)
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{
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int res,
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total;
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uint8 *tmp;
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res = pullf_read(pf, len, data_p);
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if (res <= 0 || res == len)
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return res;
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/* read was shorter, use tmpbuf */
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memcpy(tmpbuf, *data_p, res);
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*data_p = tmpbuf;
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len -= res;
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total = res;
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while (len > 0)
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{
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res = pullf_read(pf, len, &tmp);
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if (res < 0)
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{
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/* so the caller must clear only on success */
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memset(tmpbuf, 0, total);
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return res;
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}
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if (res == 0)
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break;
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memcpy(tmpbuf + total, tmp, res);
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total += res;
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}
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return total;
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}
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/*
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* caller wants exatly len bytes and dont bother with references
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*/
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int
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pullf_read_fixed(PullFilter *src, int len, uint8 *dst)
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{
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int res;
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uint8 *p;
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res = pullf_read_max(src, len, &p, dst);
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if (res < 0)
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return res;
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if (res != len)
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{
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px_debug("pullf_read_fixed: need=%d got=%d", len, res);
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return PXE_MBUF_SHORT_READ;
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}
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if (p != dst)
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memcpy(dst, p, len);
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return 0;
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}
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/*
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* read from MBuf
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*/
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static int
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pull_from_mbuf(void *arg, PullFilter *src, int len,
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uint8 **data_p, uint8 *buf, int buflen)
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{
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MBuf *mbuf = arg;
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return mbuf_grab(mbuf, len, data_p);
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}
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static const struct PullFilterOps mbuf_reader = {
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NULL, pull_from_mbuf, NULL
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};
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int
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pullf_create_mbuf_reader(PullFilter **mp_p, MBuf *src)
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{
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return pullf_create(mp_p, &mbuf_reader, src, NULL);
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}
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/*
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* PushFilter
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*/
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struct PushFilter
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{
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PushFilter *next;
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const PushFilterOps *op;
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int block_size;
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uint8 *buf;
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int pos;
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void *priv;
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};
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int
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pushf_create(PushFilter **mp_p, const PushFilterOps *op, void *init_arg, PushFilter *next)
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{
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PushFilter *mp;
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void *priv;
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int res;
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if (op->init != NULL)
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{
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res = op->init(next, init_arg, &priv);
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if (res < 0)
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return res;
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}
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else
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{
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priv = init_arg;
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res = 0;
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}
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mp = px_alloc(sizeof(*mp));
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memset(mp, 0, sizeof(*mp));
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mp->block_size = res;
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mp->op = op;
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mp->priv = priv;
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mp->next = next;
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if (mp->block_size > 0)
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{
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mp->buf = px_alloc(mp->block_size);
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mp->pos = 0;
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}
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else
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{
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mp->buf = NULL;
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mp->pos = 0;
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}
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*mp_p = mp;
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return 0;
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}
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void
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pushf_free(PushFilter *mp)
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{
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if (mp->op->free)
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mp->op->free(mp->priv);
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if (mp->buf)
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{
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memset(mp->buf, 0, mp->block_size);
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px_free(mp->buf);
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}
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memset(mp, 0, sizeof(*mp));
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px_free(mp);
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}
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void
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pushf_free_all(PushFilter *mp)
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{
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PushFilter *tmp;
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while (mp)
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{
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tmp = mp->next;
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pushf_free(mp);
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mp = tmp;
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}
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}
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static int
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wrap_process(PushFilter *mp, const uint8 *data, int len)
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{
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int res;
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if (mp->op->push != NULL)
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res = mp->op->push(mp->next, mp->priv, data, len);
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else
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res = pushf_write(mp->next, data, len);
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if (res > 0)
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return PXE_BUG;
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return res;
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}
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/* consumes all data, returns len on success */
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int
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pushf_write(PushFilter *mp, const uint8 *data, int len)
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{
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int need,
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res;
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/*
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* no buffering
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*/
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if (mp->block_size <= 0)
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return wrap_process(mp, data, len);
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/*
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* try to empty buffer
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*/
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need = mp->block_size - mp->pos;
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if (need > 0)
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{
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if (len < need)
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{
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memcpy(mp->buf + mp->pos, data, len);
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mp->pos += len;
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return 0;
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}
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memcpy(mp->buf + mp->pos, data, need);
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len -= need;
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data += need;
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}
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/*
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* buffer full, process
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*/
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res = wrap_process(mp, mp->buf, mp->block_size);
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if (res < 0)
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return res;
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mp->pos = 0;
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/*
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* now process directly from data
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*/
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while (len > 0)
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{
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if (len > mp->block_size)
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{
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res = wrap_process(mp, data, mp->block_size);
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if (res < 0)
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return res;
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data += mp->block_size;
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len -= mp->block_size;
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}
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else
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{
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memcpy(mp->buf, data, len);
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mp->pos += len;
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break;
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}
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}
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return 0;
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}
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int
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pushf_flush(PushFilter *mp)
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{
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int res;
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while (mp)
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{
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if (mp->block_size > 0)
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{
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res = wrap_process(mp, mp->buf, mp->pos);
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if (res < 0)
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return res;
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}
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if (mp->op->flush)
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{
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res = mp->op->flush(mp->next, mp->priv);
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if (res < 0)
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return res;
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}
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mp = mp->next;
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}
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return 0;
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}
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/*
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* write to MBuf
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*/
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static int
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push_into_mbuf(PushFilter *next, void *arg, const uint8 *data, int len)
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{
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int res = 0;
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MBuf *mbuf = arg;
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if (len > 0)
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res = mbuf_append(mbuf, data, len);
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return res < 0 ? res : 0;
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}
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static const struct PushFilterOps mbuf_filter = {
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NULL, push_into_mbuf, NULL, NULL
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};
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int
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pushf_create_mbuf_writer(PushFilter **res, MBuf *dst)
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{
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return pushf_create(res, &mbuf_filter, dst, NULL);
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}
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