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buffer.c

/* Modified for use in Yafc by Martin Hedenfalk <mhe@stacken.kth.se>
 */

/*
 * Author: Tatu Ylonen <ylo@cs.hut.fi>
 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
 *                    All rights reserved
 * Functions for manipulating fifo buffers (that can grow if needed).
 *
 * As far as I am concerned, the code I have written for this software
 * can be used freely for any purpose.  Any derived versions of this
 * software must be clearly marked as such, and if the derived work is
 * incompatible with the protocol description in the RFC file, it must be
 * called by a name other than "ssh" or "Secure Shell".
 */

/*#include "includes.h"*/
/*RCSID("$OpenBSD: buffer.c,v 1.13 2001/04/12 19:15:24 markus Exp $");*/

#include "syshdr.h"
#include "ftp.h"
/*#include "xmalloc.h"*/
#include "buffer.h"
/*#include "log.h"*/


/* Initializes the buffer structure. */

void
buffer_init(Buffer *buffer)
{
      buffer->alloc = 4096;
      buffer->buf = xmalloc(buffer->alloc);
      buffer->offset = 0;
      buffer->end = 0;
}

/* Frees any memory used for the buffer. */

void
buffer_free(Buffer *buffer)
{
      memset(buffer->buf, 0, buffer->alloc);
      free(buffer->buf);
}

/*
 * Clears any data from the buffer, making it empty.  This does not actually
 * zero the memory.
 */

void
buffer_clear(Buffer *buffer)
{
      buffer->offset = 0;
      buffer->end = 0;
}

/* Appends data to the buffer, expanding it if necessary. */

void
buffer_append(Buffer *buffer, const char *data, u_int len)
{
      char *cp;
      buffer_append_space(buffer, &cp, len);
      memcpy(cp, data, len);
}

/*
 * Appends space to the buffer, expanding the buffer if necessary. This does
 * not actually copy the data into the buffer, but instead returns a pointer
 * to the allocated region.
 */

void
buffer_append_space(Buffer *buffer, char **datap, u_int len)
{
      /* If the buffer is empty, start using it from the beginning. */
      if (buffer->offset == buffer->end) {
            buffer->offset = 0;
            buffer->end = 0;
      }
restart:
      /* If there is enough space to store all data, store it now. */
      if (buffer->end + len < buffer->alloc) {
            *datap = buffer->buf + buffer->end;
            buffer->end += len;
            return;
      }
      /*
       * If the buffer is quite empty, but all data is at the end, move the
       * data to the beginning and retry.
       */
      if (buffer->offset > buffer->alloc / 2) {
            memmove(buffer->buf, buffer->buf + buffer->offset,
                  buffer->end - buffer->offset);
            buffer->end -= buffer->offset;
            buffer->offset = 0;
            goto restart;
      }
      /* Increase the size of the buffer and retry. */
      buffer->alloc += len + 32768;
      buffer->buf = xrealloc(buffer->buf, buffer->alloc);
      goto restart;
}

/* Returns the number of bytes of data in the buffer. */

u_int
buffer_len(Buffer *buffer)
{
      return buffer->end - buffer->offset;
}

/* Gets data from the beginning of the buffer. */

void
buffer_get(Buffer *buffer, char *buf, u_int len)
{
      if (len > buffer->end - buffer->offset) {
            ftp_err("buffer_get: trying to get more bytes %d than in buffer %d",
                        len, buffer->end - buffer->offset);
            len = buffer->end - buffer->offset;
      }
      memcpy(buf, buffer->buf + buffer->offset, len);
      buffer->offset += len;
}

/* Consumes the given number of bytes from the beginning of the buffer. */

void
buffer_consume(Buffer *buffer, u_int bytes)
{
      if (bytes > buffer->end - buffer->offset) {
            ftp_err("buffer_consume: trying to get more bytes than in buffer");
            bytes = buffer->end - buffer->offset;
      }
      buffer->offset += bytes;
}

/* Consumes the given number of bytes from the end of the buffer. */

void
buffer_consume_end(Buffer *buffer, u_int bytes)
{
      if (bytes > buffer->end - buffer->offset) {
            ftp_err("buffer_consume_end: trying to get more bytes than in buffer");
            bytes = buffer->end - buffer->offset;
      }
      buffer->end -= bytes;
}

/* Returns a pointer to the first used byte in the buffer. */

char *
buffer_ptr(Buffer *buffer)
{
      return buffer->buf + buffer->offset;
}

/* Dumps the contents of the buffer to stderr. */

void
buffer_dump(Buffer *buffer)
{
      int i;
      u_char *ucp = (u_char *) buffer->buf;

      for (i = buffer->offset; i < buffer->end; i++) {
            fprintf(stderr, "%02x", ucp[i]);
            if ((i-buffer->offset)%16==15)
                  fprintf(stderr, "\r\n");
            else if ((i-buffer->offset)%2==1)
                  fprintf(stderr, " ");
      }
      fprintf(stderr, "\r\n");
}

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