buffer.h 2.53 KB
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/* buffer.h
 *
 * A bare-bones string stream.
 */

/* nettle, low-level cryptographics library
 *
 * Copyright (C) 2002 Niels Möller
 *  
 * The nettle library is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 2.1 of the License, or (at your
 * option) any later version.
 * 
 * The nettle library 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 Lesser General Public
 * License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public License
 * along with the nettle library; see the file COPYING.LIB.  If not, write to
 * the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
 * MA 02111-1307, USA.
 */
 
#ifndef NETTLE_BUFFER_H_INCLUDED
#define NETTLE_BUFFER_H_INCLUDED

#include <inttypes.h>

struct nettle_buffer
{
  uint8_t *contents;
  /* Allocated size */
  unsigned alloc;
  
  /* If GROW is NULL, no reallocation is done. Otherwise, it should be
   * a function that reallocates the contents to at least the size SIZE
   * + LENGTH. It can return 0 if allocation fails. Furthermore, if
   * GROW is called with LENGTH = 0, it should deallocate the buffer
   * space. */
  int (*grow)(struct nettle_buffer *buffer, unsigned length);

  /* Current size */
  unsigned size;
};

/* Initializes a buffer that uses plain realloc */
void
nettle_buffer_init(struct nettle_buffer *buffer);

/* Initializes a buffer of fix size */
void
nettle_buffer_init_size(struct nettle_buffer *buffer,
			unsigned length, uint8_t *space);

void
nettle_buffer_clear(struct nettle_buffer *buffer);

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/* FIXME: Put the comparison buffer->size + length > buffer->alloc
 * inside this macro. */
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#define NETTLE_BUFFER_GROW(o, l) ((o)->grow && (o)->grow((o), l))

#define NETTLE_BUFFER_PUTC(buffer, c) \
( (((buffer)->size < (buffer)->alloc) || NETTLE_BUFFER_GROW((buffer), 1)) \
  && ((buffer)->contents[(buffer)->size++] = (c), 1) )

int
nettle_buffer_write(struct nettle_buffer *buffer,
		    unsigned length, const uint8_t *data);

/* Like nettle_buffer_write, but instead of copying data to the
 * buffer, it returns a pointer to the area where the caller can copy
 * the data. The pointer is valid only until the next call that can
 * reallocate the buffer. */
uint8_t *
nettle_buffer_space(struct nettle_buffer *buffer,
		    unsigned length);

#endif /* NETTLE_BUFFER_H_INCLUDED */