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/*
* 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 1.9 2000/12/19 23:17:55 markus Exp $");
#include "xmalloc.h"
#include "buffer.h"
#include "ssh.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);
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 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)
fatal("buffer_get: trying to get more bytes than in buffer");
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. */
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]);
fprintf(stderr, "\n");
}
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