1 | /* vi: set sw=4 ts=4: */
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2 | /*-------------------------------------------------------------------------
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3 | * Filename: xmodem.c
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4 | * Copyright: Copyright (C) 2001, Hewlett-Packard Company
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5 | * Author: Christopher Hoover <ch@hpl.hp.com>
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6 | * Description: xmodem functionality for uploading of kernels
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7 | * and the like
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8 | * Created at: Thu Dec 20 01:58:08 PST 2001
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9 | *-----------------------------------------------------------------------*/
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10 | /*
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11 | * xmodem.c: xmodem functionality for uploading of kernels and
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12 | * the like
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13 | *
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14 | * Copyright (C) 2001 Hewlett-Packard Laboratories
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15 | *
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16 | * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
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17 | *
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18 | * This was originally written for blob and then adapted for busybox.
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19 | *
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20 | */
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21 |
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22 | #include "libbb.h"
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23 |
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24 | #define SOH 0x01
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25 | #define STX 0x02
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26 | #define EOT 0x04
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27 | #define ACK 0x06
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28 | #define NAK 0x15
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29 | #define BS 0x08
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30 |
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31 | /*
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32 |
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33 | Cf:
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34 |
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35 | http://www.textfiles.com/apple/xmodem
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36 | http://www.phys.washington.edu/~belonis/xmodem/docxmodem.txt
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37 | http://www.phys.washington.edu/~belonis/xmodem/docymodem.txt
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38 | http://www.phys.washington.edu/~belonis/xmodem/modmprot.col
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39 |
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40 | */
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41 |
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42 | #define TIMEOUT 1
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43 | #define TIMEOUT_LONG 10
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44 | #define MAXERRORS 10
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45 |
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46 | static int read_byte(int fd, unsigned int timeout)
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47 | {
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48 | char buf[1];
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49 | int n;
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50 |
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51 | alarm(timeout);
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52 |
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53 | n = read(fd, &buf, 1);
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54 |
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55 | alarm(0);
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56 |
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57 | if (n == 1)
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58 | return buf[0] & 0xff;
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59 | else
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60 | return -1;
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61 | }
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62 |
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63 | static int receive(char *error_buf, size_t error_buf_size,
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64 | int ttyfd, int filefd)
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65 | {
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66 | char blockBuf[1024];
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67 | unsigned int errors = 0;
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68 | unsigned int wantBlockNo = 1;
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69 | unsigned int length = 0;
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70 | int docrc = 1;
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71 | char nak = 'C';
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72 | unsigned int timeout = TIMEOUT_LONG;
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73 |
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74 | #define note_error(fmt,args...) \
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75 | snprintf(error_buf, error_buf_size, fmt,##args)
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76 |
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77 | /* Flush pending input */
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78 | tcflush(ttyfd, TCIFLUSH);
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79 |
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80 | /* Ask for CRC; if we get errors, we will go with checksum */
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81 | write(ttyfd, &nak, 1);
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82 |
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83 | for (;;) {
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84 | int blockBegin;
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85 | int blockNo, blockNoOnesCompl;
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86 | int blockLength;
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87 | int cksum = 0;
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88 | int crcHi = 0;
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89 | int crcLo = 0;
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90 |
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91 | blockBegin = read_byte(ttyfd, timeout);
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92 | if (blockBegin < 0)
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93 | goto timeout;
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94 |
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95 | timeout = TIMEOUT;
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96 | nak = NAK;
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97 |
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98 | switch (blockBegin) {
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99 | case SOH:
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100 | case STX:
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101 | break;
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102 |
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103 | case EOT:
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104 | nak = ACK;
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105 | write(ttyfd, &nak, 1);
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106 | goto done;
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107 |
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108 | default:
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109 | goto error;
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110 | }
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111 |
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112 | /* block no */
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113 | blockNo = read_byte(ttyfd, TIMEOUT);
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114 | if (blockNo < 0)
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115 | goto timeout;
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116 |
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117 | /* block no one's compliment */
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118 | blockNoOnesCompl = read_byte(ttyfd, TIMEOUT);
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119 | if (blockNoOnesCompl < 0)
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120 | goto timeout;
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121 |
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122 | if (blockNo != (255 - blockNoOnesCompl)) {
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123 | note_error("bad block ones compl");
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124 | goto error;
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125 | }
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126 |
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127 | blockLength = (blockBegin == SOH) ? 128 : 1024;
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128 |
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129 | {
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130 | int i;
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131 |
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132 | for (i = 0; i < blockLength; i++) {
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133 | int cc = read_byte(ttyfd, TIMEOUT);
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134 | if (cc < 0)
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135 | goto timeout;
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136 | blockBuf[i] = cc;
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137 | }
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138 | }
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139 |
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140 | if (docrc) {
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141 | crcHi = read_byte(ttyfd, TIMEOUT);
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142 | if (crcHi < 0)
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143 | goto timeout;
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144 |
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145 | crcLo = read_byte(ttyfd, TIMEOUT);
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146 | if (crcLo < 0)
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147 | goto timeout;
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148 | } else {
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149 | cksum = read_byte(ttyfd, TIMEOUT);
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150 | if (cksum < 0)
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151 | goto timeout;
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152 | }
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153 |
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154 | if (blockNo == ((wantBlockNo - 1) & 0xff)) {
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155 | /* a repeat of the last block is ok, just ignore it. */
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156 | /* this also ignores the initial block 0 which is */
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157 | /* meta data. */
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158 | goto next;
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159 | } else if (blockNo != (wantBlockNo & 0xff)) {
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160 | note_error("unexpected block no, 0x%08x, expecting 0x%08x", blockNo, wantBlockNo);
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161 | goto error;
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162 | }
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163 |
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164 | if (docrc) {
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165 | int crc = 0;
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166 | int i, j;
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167 | int expectedCrcHi;
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168 | int expectedCrcLo;
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169 |
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170 | for (i = 0; i < blockLength; i++) {
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171 | crc = crc ^ (int) blockBuf[i] << 8;
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172 | for (j = 0; j < 8; j++)
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173 | if (crc & 0x8000)
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174 | crc = crc << 1 ^ 0x1021;
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175 | else
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176 | crc = crc << 1;
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177 | }
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178 |
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179 | expectedCrcHi = (crc >> 8) & 0xff;
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180 | expectedCrcLo = crc & 0xff;
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181 |
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182 | if ((crcHi != expectedCrcHi) ||
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183 | (crcLo != expectedCrcLo)) {
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184 | note_error("crc error, expected 0x%02x 0x%02x, got 0x%02x 0x%02x", expectedCrcHi, expectedCrcLo, crcHi, crcLo);
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185 | goto error;
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186 | }
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187 | } else {
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188 | unsigned char expectedCksum = 0;
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189 | int i;
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190 |
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191 | for (i = 0; i < blockLength; i++)
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192 | expectedCksum += blockBuf[i];
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193 |
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194 | if (cksum != expectedCksum) {
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195 | note_error("checksum error, expected 0x%02x, got 0x%02x", expectedCksum, cksum);
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196 | goto error;
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197 | }
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198 | }
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199 |
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200 | wantBlockNo++;
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201 | length += blockLength;
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202 |
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203 | if (full_write(filefd, blockBuf, blockLength) < 0) {
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204 | note_error("write to file failed: %m");
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205 | goto fatal;
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206 | }
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207 |
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208 | next:
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209 | errors = 0;
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210 | nak = ACK;
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211 | write(ttyfd, &nak, 1);
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212 | continue;
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213 |
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214 | error:
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215 | timeout:
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216 | errors++;
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217 | if (errors == MAXERRORS) {
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218 | /* Abort */
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219 |
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220 | // if using crc, try again w/o crc
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221 | if (nak == 'C') {
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222 | nak = NAK;
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223 | errors = 0;
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224 | docrc = 0;
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225 | goto timeout;
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226 | }
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227 |
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228 | note_error("too many errors; giving up");
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229 |
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230 | fatal:
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231 | /* 5 CAN followed by 5 BS */
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232 | write(ttyfd, "\030\030\030\030\030\010\010\010\010\010", 10);
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233 | return -1;
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234 | }
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235 |
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236 | /* Flush pending input */
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237 | tcflush(ttyfd, TCIFLUSH);
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238 |
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239 | write(ttyfd, &nak, 1);
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240 | }
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241 |
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242 | done:
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243 | return length;
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244 |
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245 | #undef note_error
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246 | }
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247 |
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248 | static void sigalrm_handler(int ATTRIBUTE_UNUSED signum)
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249 | {
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250 | }
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251 |
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252 | int rx_main(int argc, char **argv);
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253 | int rx_main(int argc, char **argv)
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254 | {
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255 | char *fn;
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256 | int ttyfd, filefd;
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257 | struct termios tty, orig_tty;
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258 | struct sigaction act;
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259 | int n;
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260 | char error_buf[256];
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261 |
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262 | if (argc != 2)
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263 | bb_show_usage();
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264 |
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265 | fn = argv[1];
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266 | ttyfd = xopen(CURRENT_TTY, O_RDWR);
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267 | filefd = xopen(fn, O_RDWR|O_CREAT|O_TRUNC);
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268 |
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269 | if (tcgetattr(ttyfd, &tty) < 0)
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270 | bb_perror_msg_and_die("tcgetattr");
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271 |
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272 | orig_tty = tty;
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273 |
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274 | cfmakeraw(&tty);
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275 | tcsetattr(ttyfd, TCSAFLUSH, &tty);
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276 |
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277 | memset(&act, 0, sizeof(act));
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278 | act.sa_handler = sigalrm_handler;
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279 | sigaction(SIGALRM, &act, 0);
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280 |
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281 | n = receive(error_buf, sizeof(error_buf), ttyfd, filefd);
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282 |
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283 | close(filefd);
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284 |
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285 | tcsetattr(ttyfd, TCSAFLUSH, &orig_tty);
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286 |
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287 | if (n < 0)
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288 | bb_error_msg_and_die("\nreceive failed:\n %s", error_buf);
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289 |
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290 | fflush_stdout_and_exit(EXIT_SUCCESS);
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291 | }
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