text: /*
   * 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 1.19 2003/09/18 07:54:48 markus Exp $");
  
  #include "xmalloc.h"
  #include "buffer.h"
  #include "log.h"
  
  /* Initializes the buffer structure. */
  
  void
  buffer_init(Buffer *buffer)
  {
  	const u_int len = 4096;
  
  	buffer->alloc = 0;
  	buffer->buf = xmalloc(len);
  	buffer->alloc = len;
  	buffer->offset = 0;
  	buffer->end = 0;
  }
  
  /* Frees any memory used for the buffer. */
  
  void
  buffer_free(Buffer *buffer)
  {
  	if (buffer->alloc > 0) {
  		memset(buffer->buf, 0, buffer->alloc);
  		buffer->alloc = 0;
  		xfree(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 void *data, u_int len)
  {
  	void *p;
  	p = buffer_append_space(buffer, len);
  	memcpy(p, 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, u_int len)
  {
  	u_int newlen;
  	void *p;
  
  	if (len > 0x100000)
  		fatal("buffer_append_space: len %u not supported", 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) {
  		p = buffer->buf + buffer->end;
  		buffer->end += len;
  		return p;
  	}
  	/*
  	 * 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. */
  	
  	newlen = buffer->alloc + len + 32768;
  	if (newlen > 0xa00000)
  		fatal("buffer_append_space: alloc %u not supported",
  		    newlen);
  	buffer->buf = xrealloc(buffer->buf, newlen);
  	buffer->alloc = newlen;
  	goto restart;
  	/* NOTREACHED */
  }
  
  /* 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, void *buf, u_int len)
  {
  	if (len > buffer->end - buffer->offset)
  		fatal("buffer_get: trying to get more bytes %d than in buffer %d",
  		    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)
  		fatal("buffer_consume: trying to get more bytes than in buffer");
  	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)
  		fatal("buffer_consume_end: trying to get more bytes than in buffer");
  	buffer->end -= bytes;
  }
  
  /* Returns a pointer to the first used byte in the buffer. */
  
  void *
  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 = 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");
  }
  