1 | /* vi: set ts=4 :
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2 | *
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3 | * bbsh - busybox shell
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4 | *
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5 | * Copyright 2006 Rob Landley <rob@landley.net>
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6 | *
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7 | * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
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8 | */
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9 |
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10 | // A section of code that gets repeatedly or conditionally executed is stored
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11 | // as a string and parsed each time it's run.
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12 |
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13 |
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14 |
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15 | // Wheee, debugging.
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16 |
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17 | // Terminal control
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18 | #define ENABLE_BBSH_TTY 0
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19 |
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20 | // &, fg, bg, jobs. (ctrl-z with tty.)
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21 | #define ENABLE_BBSH_JOBCTL 0
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22 |
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23 | // Flow control (if, while, for, functions { })
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24 | #define ENABLE_BBSH_FLOWCTL 0
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25 |
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26 | #define ENABLE_BBSH_ENVVARS 0 // Environment variable support
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27 |
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28 | // Local and synthetic variables, fancy prompts, set, $?, etc.
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29 | #define ENABLE_BBSH_LOCALVARS 0
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30 |
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31 | // Pipes and redirects: | > < >> << && || & () ;
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32 | #define ENABLE_BBSH_PIPES 0
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33 |
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34 | /* Fun:
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35 |
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36 | echo `echo hello#comment " woot` and more
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37 | */
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38 |
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39 | #include "libbb.h"
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40 |
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41 | // A single executable, its arguments, and other information we know about it.
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42 | #define BBSH_FLAG_EXIT 1
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43 | #define BBSH_FLAG_SUSPEND 2
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44 | #define BBSH_FLAG_PIPE 4
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45 | #define BBSH_FLAG_AND 8
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46 | #define BBSH_FLAG_OR 16
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47 | #define BBSH_FLAG_AMP 32
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48 | #define BBSH_FLAG_SEMI 64
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49 | #define BBSH_FLAG_PAREN 128
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50 |
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51 | // What we know about a single process.
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52 | struct command {
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53 | struct command *next;
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54 | int flags; // exit, suspend, && ||
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55 | int pid; // pid (or exit code)
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56 | int argc;
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57 | char *argv[0];
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58 | };
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59 |
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60 | // A collection of processes piped into/waiting on each other.
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61 | struct pipeline {
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62 | struct pipeline *next;
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63 | int job_id;
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64 | struct command *cmd;
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65 | char *cmdline;
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66 | int cmdlinelen;
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67 | };
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68 |
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69 | static void free_list(void *list, void (*freeit)(void *data))
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70 | {
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71 | while (list) {
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72 | void **next = (void **)list;
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73 | void *list_next = *next;
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74 | freeit(list);
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75 | free(list);
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76 | list = list_next;
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77 | }
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78 | }
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79 |
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80 | // Parse one word from the command line, appending one or more argv[] entries
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81 | // to struct command. Handles environment variable substitution and
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82 | // substrings. Returns pointer to next used byte, or NULL if it
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83 | // hit an ending token.
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84 | static char *parse_word(char *start, struct command **cmd)
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85 | {
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86 | char *end;
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87 |
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88 | // Detect end of line (and truncate line at comment)
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89 | if (ENABLE_BBSH_PIPES && strchr("><&|(;", *start)) return 0;
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90 |
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91 | // Grab next word. (Add dequote and envvar logic here)
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92 | end = start;
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93 | end = skip_non_whitespace(end);
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94 | (*cmd)->argv[(*cmd)->argc++] = xstrndup(start, end-start);
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95 |
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96 | // Allocate more space if there's no room for NULL terminator.
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97 |
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98 | if (!((*cmd)->argc & 7))
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99 | *cmd = xrealloc(*cmd,
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100 | sizeof(struct command) + ((*cmd)->argc+8)*sizeof(char *));
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101 | (*cmd)->argv[(*cmd)->argc] = 0;
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102 | return end;
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103 | }
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104 |
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105 | // Parse a line of text into a pipeline.
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106 | // Returns a pointer to the next line.
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107 |
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108 | static char *parse_pipeline(char *cmdline, struct pipeline *line)
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109 | {
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110 | struct command **cmd = &(line->cmd);
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111 | char *start = line->cmdline = cmdline;
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112 |
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113 | if (!cmdline) return 0;
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114 |
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115 | if (ENABLE_BBSH_JOBCTL) line->cmdline = cmdline;
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116 |
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117 | // Parse command into argv[]
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118 | for (;;) {
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119 | char *end;
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120 |
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121 | // Skip leading whitespace and detect end of line.
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122 | start = skip_whitespace(start);
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123 | if (!*start || *start=='#') {
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124 | if (ENABLE_BBSH_JOBCTL) line->cmdlinelen = start-cmdline;
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125 | return 0;
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126 | }
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127 |
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128 | // Allocate next command structure if necessary
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129 | if (!*cmd) *cmd = xzalloc(sizeof(struct command)+8*sizeof(char *));
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130 |
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131 | // Parse next argument and add the results to argv[]
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132 | end = parse_word(start, cmd);
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133 |
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134 | // If we hit the end of this command, how did it end?
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135 | if (!end) {
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136 | if (ENABLE_BBSH_PIPES && *start) {
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137 | if (*start==';') {
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138 | start++;
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139 | break;
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140 | }
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141 | // handle | & < > >> << || &&
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142 | }
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143 | break;
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144 | }
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145 | start = end;
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146 | }
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147 |
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148 | if (ENABLE_BBSH_JOBCTL) line->cmdlinelen = start-cmdline;
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149 |
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150 | return start;
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151 | }
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152 |
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153 | // Execute the commands in a pipeline
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154 | static int run_pipeline(struct pipeline *line)
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155 | {
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156 | struct command *cmd = line->cmd;
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157 | if (!cmd || !cmd->argc) return 0;
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158 |
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159 | // Handle local commands. This is totally fake and plastic.
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160 | if (cmd->argc==2 && !strcmp(cmd->argv[0],"cd"))
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161 | chdir(cmd->argv[1]);
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162 | else if (!strcmp(cmd->argv[0],"exit"))
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163 | exit(cmd->argc>1 ? atoi(cmd->argv[1]) : 0);
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164 | else {
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165 | int status;
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166 | pid_t pid=fork();
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167 | if (!pid) {
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168 | run_applet_and_exit(cmd->argv[0],cmd->argc,cmd->argv);
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169 | execvp(cmd->argv[0],cmd->argv);
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170 | printf("No %s",cmd->argv[0]);
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171 | exit(1);
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172 | } else waitpid(pid, &status, 0);
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173 | }
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174 |
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175 | return 0;
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176 | }
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177 |
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178 | static void free_cmd(void *data)
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179 | {
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180 | struct command *cmd=(struct command *)data;
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181 |
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182 | while (cmd->argc) free(cmd->argv[--cmd->argc]);
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183 | }
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184 |
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185 |
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186 | static void handle(char *command)
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187 | {
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188 | struct pipeline line;
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189 | char *start = command;
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190 |
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191 | for (;;) {
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192 | memset(&line,0,sizeof(struct pipeline));
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193 | start = parse_pipeline(start, &line);
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194 | if (!line.cmd) break;
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195 |
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196 | run_pipeline(&line);
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197 | free_list(line.cmd, free_cmd);
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198 | }
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199 | }
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200 |
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201 | int bbsh_main(int argc, char **argv);
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202 | int bbsh_main(int argc, char **argv)
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203 | {
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204 | char *command=NULL;
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205 | FILE *f;
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206 |
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207 | getopt32(argv, "c:", &command);
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208 |
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209 | f = argv[optind] ? xfopen(argv[optind],"r") : NULL;
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210 | if (command) handle(command);
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211 | else {
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212 | unsigned cmdlen=0;
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213 | for (;;) {
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214 | if (!f) putchar('$');
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215 | if (1 > getline(&command, &cmdlen,f ? : stdin)) break;
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216 |
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217 | handle(command);
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218 | }
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219 | if (ENABLE_FEATURE_CLEAN_UP) free(command);
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220 | }
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221 |
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222 | return 1;
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223 | }
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