[1765] | 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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