circbuffer.c

   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
  31 circbuffer * 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
  49 void cbuf_free(circbuffer * cbuf) {
  50
  51         m_free(cbuf->data);
  52         m_free(cbuf);
  53 }
  54
  55 unsigned int cbuf_getused(circbuffer * cbuf) {
  56
  57         return cbuf->used;
  58
  59 }
  60
  61 unsigned int cbuf_getavail(circbuffer * cbuf) {
  62
  63         return cbuf->size - cbuf->used;
  64
  65 }
  66
  67 unsigned 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
  84 unsigned 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
 102 unsigned 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
 110 unsigned 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
 119 void 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
 130 void 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 }