1 | /* minilogd.c |
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2 | * |
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3 | * A pale imitation of syslogd. Most notably, doesn't write anything |
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4 | * anywhere except possibly back to syslogd. |
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5 | * |
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6 | * Copyright (c) 1999-2001 Red Hat, Inc. All rights reserved. |
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7 | * |
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8 | * This program is free software; you can redistribute it and/or modify |
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9 | * it under the terms of the GNU General Public License, version 2, |
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10 | * as published by the Free Software Foundation. |
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11 | * |
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12 | * This program is distributed in the hope that it will be useful, |
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13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
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14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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15 | * GNU General Public License for more details. |
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16 | * |
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17 | * You should have received a copy of the GNU General Public License |
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18 | * along with this program; if not, write to the Free Software |
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19 | * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA |
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20 | * |
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21 | */ |
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22 | |
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23 | #include <errno.h> |
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24 | #include <fcntl.h> |
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25 | #include <signal.h> |
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26 | #include <stdio.h> |
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27 | #include <stdlib.h> |
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28 | #include <syslog.h> |
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29 | #include <unistd.h> |
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30 | |
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31 | #include <sys/poll.h> |
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32 | #include <sys/socket.h> |
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33 | #include <sys/stat.h> |
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34 | #include <sys/un.h> |
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35 | |
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36 | static int we_own_log=0; |
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37 | static char **buffer=NULL; |
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38 | static int buflines=0; |
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39 | |
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40 | int debug; |
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41 | |
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42 | int recvsock; |
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43 | |
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44 | void alarm_handler(int x) { |
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45 | alarm(0); |
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46 | close(recvsock); |
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47 | recvsock = -1; |
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48 | } |
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49 | |
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50 | void freeBuffer() { |
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51 | struct sockaddr_un addr; |
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52 | int sock; |
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53 | int x=0,conn; |
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54 | |
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55 | bzero(&addr,sizeof(addr)); |
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56 | addr.sun_family = AF_LOCAL; |
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57 | strncpy(addr.sun_path,_PATH_LOG,sizeof(addr.sun_path)-1); |
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58 | /* wait for klogd to hit syslog */ |
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59 | sleep(2); |
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60 | sock = socket(AF_LOCAL, SOCK_DGRAM,0); |
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61 | conn=connect(sock,(struct sockaddr *) &addr,sizeof(addr)); |
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62 | while (x<buflines) { |
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63 | if (!conn) write(sock,buffer[x],strlen(buffer[x])+1); |
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64 | free(buffer[x]); |
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65 | x++; |
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66 | } |
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67 | } |
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68 | |
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69 | void cleanup(int exitcode) { |
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70 | /* If we own the log, unlink it before trying to free our buffer. |
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71 | * Otherwise, sending the buffer to /dev/log doesn't make much sense.... */ |
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72 | if (we_own_log) { |
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73 | perror("wol"); |
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74 | unlink(_PATH_LOG); |
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75 | } |
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76 | /* Don't try to free buffer if we were called from a signal handler */ |
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77 | if (exitcode<=0) { |
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78 | if (buffer) freeBuffer(); |
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79 | exit(exitcode); |
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80 | } else |
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81 | exit(exitcode+128); |
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82 | } |
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83 | |
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84 | void runDaemon(int sock) { |
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85 | struct sockaddr_un addr; |
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86 | int x,len,done=0; |
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87 | int addrlen = sizeof(struct sockaddr_un); |
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88 | char *message; |
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89 | struct stat s1,s2; |
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90 | struct pollfd pfds; |
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91 | |
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92 | daemon(0,-1); |
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93 | /* try not to leave stale sockets lying around */ |
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94 | /* Hopefully, we won't actually get any of these */ |
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95 | signal(SIGHUP,cleanup); |
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96 | signal(SIGINT,cleanup); |
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97 | signal(SIGQUIT,cleanup); |
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98 | signal(SIGILL,cleanup); |
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99 | signal(SIGABRT,cleanup); |
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100 | signal(SIGFPE,cleanup); |
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101 | signal(SIGSEGV,cleanup); |
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102 | signal(SIGPIPE,cleanup); |
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103 | signal(SIGBUS,cleanup); |
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104 | signal(SIGTERM,cleanup); |
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105 | done = 0; |
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106 | /* Get stat info on /dev/log so we can later check to make sure we |
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107 | * still own it... */ |
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108 | if (stat(_PATH_LOG,&s1) != 0) |
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109 | memset(&s1, '\0', sizeof(struct stat)); |
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110 | while (!done) { |
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111 | pfds.fd = sock; |
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112 | pfds.events = POLLIN|POLLPRI; |
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113 | if ( ( (x=poll(&pfds,1,500))==-1) && errno !=EINTR) { |
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114 | perror("poll"); |
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115 | cleanup(-1); |
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116 | } |
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117 | if ( (x>0) && pfds.revents & (POLLIN | POLLPRI)) { |
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118 | message = calloc(8192,sizeof(char)); |
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119 | addrlen = sizeof(struct sockaddr_un); |
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120 | recvsock = accept(sock,(struct sockaddr *) &addr, &addrlen); |
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121 | if (recvsock == -1) |
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122 | continue; |
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123 | alarm(2); |
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124 | signal(SIGALRM, alarm_handler); |
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125 | len = recv(recvsock,message,8192,0); |
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126 | alarm(0); |
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127 | close(recvsock); |
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128 | if (len>0) { |
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129 | if (buflines < 200000) { |
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130 | if (buffer) |
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131 | buffer = realloc(buffer,(buflines+1)*sizeof(char *)); |
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132 | else |
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133 | buffer = malloc(sizeof(char *)); |
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134 | message[strlen(message)]='\n'; |
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135 | buffer[buflines]=message; |
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136 | buflines++; |
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137 | } |
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138 | } |
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139 | else { |
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140 | recvsock=-1; |
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141 | } |
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142 | } |
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143 | if ( (x>0) && ( pfds.revents & (POLLHUP | POLLNVAL)) ) |
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144 | done = 1; |
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145 | /* Check to see if syslogd's yanked our socket out from under us */ |
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146 | if ( (stat(_PATH_LOG,&s2)!=0) || |
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147 | (s1.st_ino != s2.st_ino ) || (s1.st_ctime != s2.st_ctime) || |
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148 | (s1.st_mtime != s2.st_mtime) ) { |
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149 | done = 1; |
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150 | we_own_log = 0; |
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151 | } |
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152 | } |
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153 | cleanup(0); |
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154 | } |
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155 | |
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156 | int main(int argc, char **argv) { |
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157 | struct sockaddr_un addr; |
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158 | int sock; |
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159 | int pid; |
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160 | |
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161 | /* option processing made simple... */ |
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162 | if (argc>1) debug=1; |
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163 | /* just in case */ |
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164 | sock = open("/dev/null",O_RDWR); |
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165 | dup2(sock,0); |
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166 | dup2(sock,1); |
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167 | dup2(sock,2); |
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168 | close(sock); |
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169 | |
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170 | bzero(&addr, sizeof(addr)); |
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171 | addr.sun_family = AF_LOCAL; |
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172 | strncpy(addr.sun_path,_PATH_LOG,sizeof(addr.sun_path)-1); |
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173 | sock = socket(AF_LOCAL, SOCK_STREAM,0); |
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174 | unlink(_PATH_LOG); |
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175 | /* Bind socket before forking, so we know if the server started */ |
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176 | if (!bind(sock,(struct sockaddr *) &addr, sizeof(addr))) { |
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177 | we_own_log = 1; |
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178 | listen(sock,5); |
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179 | if ((pid=fork())==-1) { |
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180 | perror("fork"); |
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181 | exit(3); |
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182 | } |
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183 | if (pid) { |
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184 | exit(0); |
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185 | } else { |
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186 | runDaemon(sock); |
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187 | /* shouldn't get back here... */ |
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188 | exit(4); |
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189 | } |
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190 | } else { |
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191 | exit(5); |
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192 | } |
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193 | } |
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