buffer.c revision 99060 
1/*
2 * Author: Tatu Ylonen <ylo@cs.hut.fi>
3 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
4 *                    All rights reserved
5 * Functions for manipulating fifo buffers (that can grow if needed).
6 *
7 * As far as I am concerned, the code I have written for this software
8 * can be used freely for any purpose.  Any derived versions of this
9 * software must be clearly marked as such, and if the derived work is
10 * incompatible with the protocol description in the RFC file, it must be
11 * called by a name other than "ssh" or "Secure Shell".
12 */
13
14#include "includes.h"
15RCSID("$OpenBSD: buffer.c,v 1.16 2002/06/26 08:54:18 markus Exp $");
16
17#include "xmalloc.h"
18#include "buffer.h"
19#include "log.h"
20
21/* Initializes the buffer structure. */
22
23void
24buffer_init(Buffer *buffer)
25{
26	buffer->alloc = 4096;
27	buffer->buf = xmalloc(buffer->alloc);
28	buffer->offset = 0;
29	buffer->end = 0;
30}
31
32/* Frees any memory used for the buffer. */
33
34void
35buffer_free(Buffer *buffer)
36{
37	memset(buffer->buf, 0, buffer->alloc);
38	xfree(buffer->buf);
39}
40
41/*
42 * Clears any data from the buffer, making it empty.  This does not actually
43 * zero the memory.
44 */
45
46void
47buffer_clear(Buffer *buffer)
48{
49	buffer->offset = 0;
50	buffer->end = 0;
51}
52
53/* Appends data to the buffer, expanding it if necessary. */
54
55void
56buffer_append(Buffer *buffer, const void *data, u_int len)
57{
58	void *p;
59	p = buffer_append_space(buffer, len);
60	memcpy(p, data, len);
61}
62
63/*
64 * Appends space to the buffer, expanding the buffer if necessary. This does
65 * not actually copy the data into the buffer, but instead returns a pointer
66 * to the allocated region.
67 */
68
69void *
70buffer_append_space(Buffer *buffer, u_int len)
71{
72	void *p;
73
74	if (len > 0x100000)
75		fatal("buffer_append_space: len %u not supported", len);
76
77	/* If the buffer is empty, start using it from the beginning. */
78	if (buffer->offset == buffer->end) {
79		buffer->offset = 0;
80		buffer->end = 0;
81	}
82restart:
83	/* If there is enough space to store all data, store it now. */
84	if (buffer->end + len < buffer->alloc) {
85		p = buffer->buf + buffer->end;
86		buffer->end += len;
87		return p;
88	}
89	/*
90	 * If the buffer is quite empty, but all data is at the end, move the
91	 * data to the beginning and retry.
92	 */
93	if (buffer->offset > buffer->alloc / 2) {
94		memmove(buffer->buf, buffer->buf + buffer->offset,
95			buffer->end - buffer->offset);
96		buffer->end -= buffer->offset;
97		buffer->offset = 0;
98		goto restart;
99	}
100	/* Increase the size of the buffer and retry. */
101	buffer->alloc += len + 32768;
102	if (buffer->alloc > 0xa00000)
103		fatal("buffer_append_space: alloc %u not supported",
104		    buffer->alloc);
105	buffer->buf = xrealloc(buffer->buf, buffer->alloc);
106	goto restart;
107	/* NOTREACHED */
108}
109
110/* Returns the number of bytes of data in the buffer. */
111
112u_int
113buffer_len(Buffer *buffer)
114{
115	return buffer->end - buffer->offset;
116}
117
118/* Gets data from the beginning of the buffer. */
119
120void
121buffer_get(Buffer *buffer, void *buf, u_int len)
122{
123	if (len > buffer->end - buffer->offset)
124		fatal("buffer_get: trying to get more bytes %d than in buffer %d",
125		    len, buffer->end - buffer->offset);
126	memcpy(buf, buffer->buf + buffer->offset, len);
127	buffer->offset += len;
128}
129
130/* Consumes the given number of bytes from the beginning of the buffer. */
131
132void
133buffer_consume(Buffer *buffer, u_int bytes)
134{
135	if (bytes > buffer->end - buffer->offset)
136		fatal("buffer_consume: trying to get more bytes than in buffer");
137	buffer->offset += bytes;
138}
139
140/* Consumes the given number of bytes from the end of the buffer. */
141
142void
143buffer_consume_end(Buffer *buffer, u_int bytes)
144{
145	if (bytes > buffer->end - buffer->offset)
146		fatal("buffer_consume_end: trying to get more bytes than in buffer");
147	buffer->end -= bytes;
148}
149
150/* Returns a pointer to the first used byte in the buffer. */
151
152void *
153buffer_ptr(Buffer *buffer)
154{
155	return buffer->buf + buffer->offset;
156}
157
158/* Dumps the contents of the buffer to stderr. */
159
160void
161buffer_dump(Buffer *buffer)
162{
163	int i;
164	u_char *ucp = buffer->buf;
165
166	for (i = buffer->offset; i < buffer->end; i++) {
167		fprintf(stderr, "%02x", ucp[i]);
168		if ((i-buffer->offset)%16==15)
169			fprintf(stderr, "\r\n");
170		else if ((i-buffer->offset)%2==1)
171			fprintf(stderr, " ");
172	}
173	fprintf(stderr, "\r\n");
174}
175