buffer.c revision 60573 
1/*
2 *
3 * buffer.c
4 *
5 * Author: Tatu Ylonen <ylo@cs.hut.fi>
6 *
7 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
8 *                    All rights reserved
9 *
10 * Created: Sat Mar 18 04:15:33 1995 ylo
11 *
12 * Functions for manipulating fifo buffers (that can grow if needed).
13 *
14 */
15
16#include "includes.h"
17RCSID("$Id: buffer.c,v 1.6 2000/04/14 10:30:30 markus Exp $");
18
19#include "xmalloc.h"
20#include "buffer.h"
21#include "ssh.h"
22
23/* Initializes the buffer structure. */
24
25void
26buffer_init(Buffer *buffer)
27{
28	buffer->alloc = 4096;
29	buffer->buf = xmalloc(buffer->alloc);
30	buffer->offset = 0;
31	buffer->end = 0;
32}
33
34/* Frees any memory used for the buffer. */
35
36void
37buffer_free(Buffer *buffer)
38{
39	memset(buffer->buf, 0, buffer->alloc);
40	xfree(buffer->buf);
41}
42
43/*
44 * Clears any data from the buffer, making it empty.  This does not actually
45 * zero the memory.
46 */
47
48void
49buffer_clear(Buffer *buffer)
50{
51	buffer->offset = 0;
52	buffer->end = 0;
53}
54
55/* Appends data to the buffer, expanding it if necessary. */
56
57void
58buffer_append(Buffer *buffer, const char *data, unsigned int len)
59{
60	char *cp;
61	buffer_append_space(buffer, &cp, len);
62	memcpy(cp, data, len);
63}
64
65/*
66 * Appends space to the buffer, expanding the buffer if necessary. This does
67 * not actually copy the data into the buffer, but instead returns a pointer
68 * to the allocated region.
69 */
70
71void
72buffer_append_space(Buffer *buffer, char **datap, unsigned int len)
73{
74	/* If the buffer is empty, start using it from the beginning. */
75	if (buffer->offset == buffer->end) {
76		buffer->offset = 0;
77		buffer->end = 0;
78	}
79restart:
80	/* If there is enough space to store all data, store it now. */
81	if (buffer->end + len < buffer->alloc) {
82		*datap = buffer->buf + buffer->end;
83		buffer->end += len;
84		return;
85	}
86	/*
87	 * If the buffer is quite empty, but all data is at the end, move the
88	 * data to the beginning and retry.
89	 */
90	if (buffer->offset > buffer->alloc / 2) {
91		memmove(buffer->buf, buffer->buf + buffer->offset,
92			buffer->end - buffer->offset);
93		buffer->end -= buffer->offset;
94		buffer->offset = 0;
95		goto restart;
96	}
97	/* Increase the size of the buffer and retry. */
98	buffer->alloc += len + 32768;
99	buffer->buf = xrealloc(buffer->buf, buffer->alloc);
100	goto restart;
101}
102
103/* Returns the number of bytes of data in the buffer. */
104
105unsigned int
106buffer_len(Buffer *buffer)
107{
108	return buffer->end - buffer->offset;
109}
110
111/* Gets data from the beginning of the buffer. */
112
113void
114buffer_get(Buffer *buffer, char *buf, unsigned int len)
115{
116	if (len > buffer->end - buffer->offset)
117		fatal("buffer_get: trying to get more bytes than in buffer");
118	memcpy(buf, buffer->buf + buffer->offset, len);
119	buffer->offset += len;
120}
121
122/* Consumes the given number of bytes from the beginning of the buffer. */
123
124void
125buffer_consume(Buffer *buffer, unsigned int bytes)
126{
127	if (bytes > buffer->end - buffer->offset)
128		fatal("buffer_consume: trying to get more bytes than in buffer");
129	buffer->offset += bytes;
130}
131
132/* Consumes the given number of bytes from the end of the buffer. */
133
134void
135buffer_consume_end(Buffer *buffer, unsigned int bytes)
136{
137	if (bytes > buffer->end - buffer->offset)
138		fatal("buffer_consume_end: trying to get more bytes than in buffer");
139	buffer->end -= bytes;
140}
141
142/* Returns a pointer to the first used byte in the buffer. */
143
144char *
145buffer_ptr(Buffer *buffer)
146{
147	return buffer->buf + buffer->offset;
148}
149
150/* Dumps the contents of the buffer to stderr. */
151
152void
153buffer_dump(Buffer *buffer)
154{
155	int i;
156	unsigned char *ucp = (unsigned char *) buffer->buf;
157
158	for (i = buffer->offset; i < buffer->end; i++)
159		fprintf(stderr, " %02x", ucp[i]);
160	fprintf(stderr, "\n");
161}
162