1/*
2 * Dropbear SSH
3 *
4 * Copyright (c) 2002-2004 Matt Johnston
5 * All rights reserved.
6 *
7 * Permission is hereby granted, free of charge, to any person obtaining a copy
8 * of this software and associated documentation files (the "Software"), to deal
9 * in the Software without restriction, including without limitation the rights
10 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
11 * copies of the Software, and to permit persons to whom the Software is
12 * furnished to do so, subject to the following conditions:
13 *
14 * The above copyright notice and this permission notice shall be included in
15 * all copies or substantial portions of the Software.
16 *
17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
18 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
20 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
21 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
22 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
23 * SOFTWARE. */
24
25#include "includes.h"
26#include "dbutil.h"
27#include "circbuffer.h"
28
29#define MAX_CBUF_SIZE 100000000
30
31circbuffer * cbuf_new(unsigned int size) {
32
33	circbuffer *cbuf = NULL;
34
35	if (size > MAX_CBUF_SIZE) {
36		dropbear_exit("bad cbuf size");
37	}
38
39	cbuf = (circbuffer*)m_malloc(sizeof(circbuffer));
40	cbuf->data = (unsigned char*)m_malloc(size);
41	cbuf->used = 0;
42	cbuf->readpos = 0;
43	cbuf->writepos = 0;
44	cbuf->size = size;
45
46	return cbuf;
47}
48
49void cbuf_free(circbuffer * cbuf) {
50
51	m_free(cbuf->data);
52	m_free(cbuf);
53}
54
55unsigned int cbuf_getused(circbuffer * cbuf) {
56
57	return cbuf->used;
58
59}
60
61unsigned int cbuf_getavail(circbuffer * cbuf) {
62
63	return cbuf->size - cbuf->used;
64
65}
66
67unsigned int cbuf_readlen(circbuffer *cbuf) {
68
69	dropbear_assert(((2*cbuf->size)+cbuf->writepos-cbuf->readpos)%cbuf->size == cbuf->used%cbuf->size);
70	dropbear_assert(((2*cbuf->size)+cbuf->readpos-cbuf->writepos)%cbuf->size == (cbuf->size-cbuf->used)%cbuf->size);
71
72	if (cbuf->used == 0) {
73		TRACE(("cbuf_readlen: unused buffer"))
74		return 0;
75	}
76
77	if (cbuf->readpos < cbuf->writepos) {
78		return cbuf->writepos - cbuf->readpos;
79	}
80
81	return cbuf->size - cbuf->readpos;
82}
83
84unsigned int cbuf_writelen(circbuffer *cbuf) {
85
86	dropbear_assert(cbuf->used <= cbuf->size);
87	dropbear_assert(((2*cbuf->size)+cbuf->writepos-cbuf->readpos)%cbuf->size == cbuf->used%cbuf->size);
88	dropbear_assert(((2*cbuf->size)+cbuf->readpos-cbuf->writepos)%cbuf->size == (cbuf->size-cbuf->used)%cbuf->size);
89
90	if (cbuf->used == cbuf->size) {
91		TRACE(("cbuf_writelen: full buffer"))
92		return 0; /* full */
93	}
94
95	if (cbuf->writepos < cbuf->readpos) {
96		return cbuf->readpos - cbuf->writepos;
97	}
98
99	return cbuf->size - cbuf->writepos;
100}
101
102unsigned char* cbuf_readptr(circbuffer *cbuf, unsigned int len) {
103	if (len > cbuf_readlen(cbuf)) {
104		dropbear_exit("bad cbuf read");
105	}
106
107	return &cbuf->data[cbuf->readpos];
108}
109
110unsigned char* cbuf_writeptr(circbuffer *cbuf, unsigned int len) {
111
112	if (len > cbuf_writelen(cbuf)) {
113		dropbear_exit("bad cbuf write");
114	}
115
116	return &cbuf->data[cbuf->writepos];
117}
118
119void cbuf_incrwrite(circbuffer *cbuf, unsigned int len) {
120	if (len > cbuf_writelen(cbuf)) {
121		dropbear_exit("bad cbuf write");
122	}
123
124	cbuf->used += len;
125	dropbear_assert(cbuf->used <= cbuf->size);
126	cbuf->writepos = (cbuf->writepos + len) % cbuf->size;
127}
128
129
130void cbuf_incrread(circbuffer *cbuf, unsigned int len) {
131	if (len > cbuf_readlen(cbuf)) {
132		dropbear_exit("bad cbuf read");
133	}
134
135	dropbear_assert(cbuf->used >= len);
136	cbuf->used -= len;
137	cbuf->readpos = (cbuf->readpos + len) % cbuf->size;
138}
139