release/src/router/dropbear/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         if (size > 0) {
  41                 cbuf->data = (unsigned char*)m_malloc(size);
  42         }
  43         cbuf->used = 0;
  44         cbuf->readpos = 0;
  45         cbuf->writepos = 0;
  46         cbuf->size = size;
  47
  48         return cbuf;
  49 }
  50
  51 void cbuf_free(circbuffer * cbuf) {
  52
  53         m_burn(cbuf->data, cbuf->size);
  54         m_free(cbuf->data);
  55         m_free(cbuf);
  56 }
  57
  58 unsigned int cbuf_getused(circbuffer * cbuf) {
  59
  60         return cbuf->used;
  61
  62 }
  63
  64 unsigned int cbuf_getavail(circbuffer * cbuf) {
  65
  66         return cbuf->size - cbuf->used;
  67
  68 }
  69
  70 unsigned int cbuf_readlen(circbuffer *cbuf) {
  71
  72         dropbear_assert(((2*cbuf->size)+cbuf->writepos-cbuf->readpos)%cbuf->size == cbuf->used%cbuf->size);
  73         dropbear_assert(((2*cbuf->size)+cbuf->readpos-cbuf->writepos)%cbuf->size == (cbuf->size-cbuf->used)%cbuf->size);
  74
  75         if (cbuf->used == 0) {
  76                 TRACE(("cbuf_readlen: unused buffer"))
  77                 return 0;
  78         }
  79
  80         if (cbuf->readpos < cbuf->writepos) {
  81                 return cbuf->writepos - cbuf->readpos;
  82         }
  83
  84         return cbuf->size - cbuf->readpos;
  85 }
  86
  87 unsigned int cbuf_writelen(circbuffer *cbuf) {
  88
  89         dropbear_assert(cbuf->used <= cbuf->size);
  90         dropbear_assert(((2*cbuf->size)+cbuf->writepos-cbuf->readpos)%cbuf->size == cbuf->used%cbuf->size);
  91         dropbear_assert(((2*cbuf->size)+cbuf->readpos-cbuf->writepos)%cbuf->size == (cbuf->size-cbuf->used)%cbuf->size);
  92
  93         if (cbuf->used == cbuf->size) {
  94                 TRACE(("cbuf_writelen: full buffer"))
  95                 return 0; /* full */
  96         }
  97
  98         if (cbuf->writepos < cbuf->readpos) {
  99                 return cbuf->readpos - cbuf->writepos;
 100         }
 101
 102         return cbuf->size - cbuf->writepos;
 103 }
 104
 105 unsigned char* cbuf_readptr(circbuffer *cbuf, unsigned int len) {
 106         if (len > cbuf_readlen(cbuf)) {
 107                 dropbear_exit("Bad cbuf read");
 108         }
 109
 110         return &cbuf->data[cbuf->readpos];
 111 }
 112
 113 unsigned char* cbuf_writeptr(circbuffer *cbuf, unsigned int len) {
 114
 115         if (len > cbuf_writelen(cbuf)) {
 116                 dropbear_exit("Bad cbuf write");
 117         }
 118
 119         return &cbuf->data[cbuf->writepos];
 120 }
 121
 122 void cbuf_incrwrite(circbuffer *cbuf, unsigned int len) {
 123         if (len > cbuf_writelen(cbuf)) {
 124                 dropbear_exit("Bad cbuf write");
 125         }
 126
 127         cbuf->used += len;
 128         dropbear_assert(cbuf->used <= cbuf->size);
 129         cbuf->writepos = (cbuf->writepos + len) % cbuf->size;
 130 }
 131
 132
 133 void cbuf_incrread(circbuffer *cbuf, unsigned int len) {
 134         if (len > cbuf_readlen(cbuf)) {
 135                 dropbear_exit("Bad cbuf read");
 136         }
 137
 138         dropbear_assert(cbuf->used >= len);
 139         cbuf->used -= len;
 140         cbuf->readpos = (cbuf->readpos + len) % cbuf->size;
 141 }