1 | /* vi: set sw=4 ts=4: */
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2 | /*
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3 | * bare bones 'talk to modem' program - similar to 'cu -l $device'
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4 | * inspired by mgetty's microcom
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5 | *
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6 | * Copyright (C) 2008 by Vladimir Dronnikov <dronnikov@gmail.com>
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7 | *
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8 | * Licensed under GPLv2, see file LICENSE in this source tree.
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9 | */
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10 |
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11 | //usage:#define microcom_trivial_usage
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12 | //usage: "[-d DELAY] [-t TIMEOUT] [-s SPEED] [-X] TTY"
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13 | //usage:#define microcom_full_usage "\n\n"
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14 | //usage: "Copy bytes for stdin to TTY and from TTY to stdout\n"
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15 | //usage: "\n -d Wait up to DELAY ms for TTY output before sending every"
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16 | //usage: "\n next byte to it"
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17 | //usage: "\n -t Exit if both stdin and TTY are silent for TIMEOUT ms"
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18 | //usage: "\n -s Set serial line to SPEED"
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19 | //usage: "\n -X Disable special meaning of NUL and Ctrl-X from stdin"
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20 |
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21 | #include "libbb.h"
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22 |
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23 | // set raw tty mode
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24 | static void xget1(int fd, struct termios *t, struct termios *oldt)
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25 | {
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26 | tcgetattr(fd, oldt);
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27 | *t = *oldt;
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28 | cfmakeraw(t);
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29 | // t->c_lflag &= ~(ISIG|ICANON|ECHO|IEXTEN);
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30 | // t->c_iflag &= ~(BRKINT|IXON|ICRNL);
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31 | // t->c_oflag &= ~(ONLCR);
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32 | // t->c_cc[VMIN] = 1;
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33 | // t->c_cc[VTIME] = 0;
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34 | }
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35 |
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36 | static int xset1(int fd, struct termios *tio, const char *device)
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37 | {
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38 | int ret = tcsetattr(fd, TCSAFLUSH, tio);
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39 |
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40 | if (ret) {
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41 | bb_perror_msg("can't tcsetattr for %s", device);
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42 | }
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43 | return ret;
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44 | }
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45 |
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46 | int microcom_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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47 | int microcom_main(int argc UNUSED_PARAM, char **argv)
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48 | {
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49 | int sfd;
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50 | int nfd;
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51 | struct pollfd pfd[2];
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52 | struct termios tio0, tiosfd, tio;
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53 | char *device_lock_file;
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54 | enum {
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55 | OPT_X = 1 << 0, // do not respect Ctrl-X, Ctrl-@
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56 | OPT_s = 1 << 1, // baudrate
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57 | OPT_d = 1 << 2, // wait for device response, ms
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58 | OPT_t = 1 << 3, // timeout, ms
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59 | };
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60 | speed_t speed = 9600;
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61 | int delay = -1;
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62 | int timeout = -1;
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63 | unsigned opts;
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64 |
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65 | // fetch options
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66 | opt_complementary = "=1:s+:d+:t+"; // exactly one arg, numeric options
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67 | opts = getopt32(argv, "Xs:d:t:", &speed, &delay, &timeout);
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68 | // argc -= optind;
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69 | argv += optind;
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70 |
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71 | // try to create lock file in /var/lock
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72 | device_lock_file = (char *)bb_basename(argv[0]);
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73 | device_lock_file = xasprintf("/var/lock/LCK..%s", device_lock_file);
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74 | sfd = open(device_lock_file, O_CREAT | O_WRONLY | O_TRUNC | O_EXCL, 0644);
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75 | if (sfd < 0) {
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76 | // device already locked -> bail out
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77 | if (errno == EEXIST)
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78 | bb_perror_msg_and_die("can't create '%s'", device_lock_file);
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79 | // can't create lock -> don't care
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80 | if (ENABLE_FEATURE_CLEAN_UP)
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81 | free(device_lock_file);
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82 | device_lock_file = NULL;
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83 | } else {
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84 | // %4d to make concurrent mgetty (if any) happy.
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85 | // Mgetty treats 4-bytes lock files as binary,
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86 | // not text, PID. Making 5+ char file. Brrr...
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87 | fdprintf(sfd, "%4d\n", getpid());
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88 | close(sfd);
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89 | }
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90 |
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91 | // setup signals
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92 | bb_signals(0
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93 | + (1 << SIGHUP)
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94 | + (1 << SIGINT)
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95 | + (1 << SIGTERM)
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96 | + (1 << SIGPIPE)
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97 | , record_signo);
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98 |
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99 | // error exit code if we fail to open the device
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100 | bb_got_signal = 1;
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101 |
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102 | // open device
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103 | sfd = open_or_warn(argv[0], O_RDWR | O_NOCTTY | O_NONBLOCK);
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104 | if (sfd < 0)
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105 | goto done;
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106 | fcntl(sfd, F_SETFL, O_RDWR);
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107 |
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108 | // put device to "raw mode"
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109 | xget1(sfd, &tio, &tiosfd);
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110 | // set device speed
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111 | cfsetspeed(&tio, tty_value_to_baud(speed));
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112 | if (xset1(sfd, &tio, argv[0]))
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113 | goto done;
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114 |
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115 | // put stdin to "raw mode" (if stdin is a TTY),
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116 | // handle one character at a time
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117 | if (isatty(STDIN_FILENO)) {
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118 | xget1(STDIN_FILENO, &tio, &tio0);
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119 | if (xset1(STDIN_FILENO, &tio, "stdin"))
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120 | goto done;
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121 | }
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122 |
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123 | // main loop: check with poll(), then read/write bytes across
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124 | pfd[0].fd = sfd;
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125 | pfd[0].events = POLLIN;
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126 | pfd[1].fd = STDIN_FILENO;
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127 | pfd[1].events = POLLIN;
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128 |
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129 | bb_got_signal = 0;
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130 | nfd = 2;
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131 | // Not safe_poll: we want to exit on signal
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132 | while (!bb_got_signal && poll(pfd, nfd, timeout) > 0) {
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133 | if (nfd > 1 && pfd[1].revents) {
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134 | char c;
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135 | // read from stdin -> write to device
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136 | if (safe_read(STDIN_FILENO, &c, 1) < 1) {
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137 | // don't poll stdin anymore if we got EOF/error
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138 | nfd--;
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139 | goto skip_write;
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140 | }
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141 | // do we need special processing?
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142 | if (!(opts & OPT_X)) {
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143 | // ^@ sends Break
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144 | if (VINTR == c) {
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145 | tcsendbreak(sfd, 0);
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146 | goto skip_write;
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147 | }
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148 | // ^X exits
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149 | if (24 == c)
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150 | break;
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151 | }
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152 | write(sfd, &c, 1);
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153 | if (delay >= 0)
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154 | safe_poll(pfd, 1, delay);
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155 | skip_write: ;
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156 | }
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157 | if (pfd[0].revents) {
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158 | #define iobuf bb_common_bufsiz1
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159 | ssize_t len;
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160 | // read from device -> write to stdout
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161 | len = safe_read(sfd, iobuf, sizeof(iobuf));
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162 | if (len > 0)
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163 | full_write(STDOUT_FILENO, iobuf, len);
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164 | else {
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165 | // EOF/error -> bail out
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166 | bb_got_signal = SIGHUP;
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167 | break;
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168 | }
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169 | }
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170 | }
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171 |
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172 | // restore device mode
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173 | tcsetattr(sfd, TCSAFLUSH, &tiosfd);
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174 |
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175 | if (isatty(STDIN_FILENO))
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176 | tcsetattr(STDIN_FILENO, TCSAFLUSH, &tio0);
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177 |
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178 | done:
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179 | if (device_lock_file)
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180 | unlink(device_lock_file);
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181 |
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182 | return bb_got_signal;
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183 | }
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