Home | History | Annotate | Download | only in pending 
      1 /* sh.c - toybox shell
      2  *
      3  * Copyright 2006 Rob Landley <rob (at) landley.net>
      4  *
      5  * The POSIX-2008/SUSv4 spec for this is at:
      6  * http://opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html
      7  * and http://opengroup.org/onlinepubs/9699919799/utilities/sh.html
      8  *
      9  * The first link describes the following shell builtins:
     10  *
     11  *   break colon continue dot eval exec exit export readonly return set shift
     12  *   times trap unset
     13  *
     14  * The second link (the utilities directory) also contains specs for the
     15  * following shell builtins:
     16  *
     17  *   alias bg cd command fc fg getopts hash jobs kill read type ulimit
     18  *   umask unalias wait
     19  *
     20  * Things like the bash man page are good to read too.
     21  *
     22  * TODO: "make sh" doesn't work (nofork builtins need to be included)
     23  * TODO: test that $PS1 color changes work without stupid \[ \] hack
     24  * TODO: make fake pty wrapper for test infrastructure
     25  * TODO: // Handle embedded NUL bytes in the command line.
     26  * TODO: var=val command
     27  * existing but considered builtins: false kill pwd true
     28  * buitins: alias bg command fc fg getopts jobs newgrp read umask unalias wait
     29  * "special" builtins: break continue : . eval exec export readonly return set
     30  *   shift times trap unset
     31  * | & ; < > ( ) $ ` \ " ' <space> <tab> <newline>
     32  * * ? [ # ~ = %
     33  * ! { } case do done elif else esac fi for if in then until while
     34  * [[ ]] function select
     35  * $@ $* $# $? $- $$ $! $0
     36  * ENV HOME IFS LANG LC_ALL LINENO PATH PPID PS1 PS2 PS4 PWD
     37  * label:
     38  * TODO: test exit from "trap EXIT" doesn't recurse
     39 
     40 USE_SH(NEWTOY(cd, NULL, TOYFLAG_NOFORK))
     41 USE_SH(NEWTOY(exit, NULL, TOYFLAG_NOFORK))
     42 
     43 USE_SH(NEWTOY(sh, "c:i", TOYFLAG_BIN))
     44 USE_SH(OLDTOY(toysh, sh, TOYFLAG_BIN))
     45 // Login lies in argv[0], so add some aliases to catch that
     46 USE_SH(OLDTOY(-sh, sh, 0))
     47 USE_SH(OLDTOY(-toysh, sh, 0))
     48 
     49 config SH
     50   bool "sh (toysh)"
     51   default n
     52   help
     53     usage: sh [-c command] [script]
     54 
     55     Command shell.  Runs a shell script, or reads input interactively
     56     and responds to it.
     57 
     58     -c	command line to execute
     59     -i	interactive mode (default when STDIN is a tty)
     60 
     61 config CD
     62   bool
     63   default n
     64   depends on SH
     65   help
     66     usage: cd [-PL] [path]
     67 
     68     Change current directory.  With no arguments, go $HOME.
     69 
     70     -P	Physical path: resolve symlinks in path
     71     -L	Local path: .. trims directories off $PWD (default)
     72 
     73 config EXIT
     74   bool
     75   default n
     76   depends on SH
     77   help
     78     usage: exit [status]
     79 
     80     Exit shell.  If no return value supplied on command line, use value
     81     of most recent command, or 0 if none.
     82 */
     83 
     84 #define FOR_sh
     85 #include "toys.h"
     86 
     87 GLOBALS(
     88   char *command;
     89 
     90   long lineno;
     91 )
     92 
     93 // What we know about a single process.
     94 struct command {
     95   struct command *next;
     96   int flags;              // exit, suspend, && ||
     97   int pid;                // pid (or exit code)
     98   int argc;
     99   char *argv[0];
    100 };
    101 
    102 // A collection of processes piped into/waiting on each other.
    103 struct pipeline {
    104   struct pipeline *next;
    105   int job_id;
    106   struct command *cmd;
    107   char *cmdline;         // Unparsed line for display purposes
    108   int cmdlinelen;        // How long is cmdline?
    109 };
    110 
    111 void cd_main(void)
    112 {
    113   char *dest = *toys.optargs ? *toys.optargs : getenv("HOME");
    114 
    115   xchdir(dest ? dest : "/");
    116 }
    117 
    118 void exit_main(void)
    119 {
    120   exit(*toys.optargs ? atoi(*toys.optargs) : 0);
    121 }
    122 
    123 // Parse one word from the command line, appending one or more argv[] entries
    124 // to struct command.  Handles environment variable substitution and
    125 // substrings.  Returns pointer to next used byte, or NULL if it
    126 // hit an ending token.
    127 static char *parse_word(char *start, struct command **cmd)
    128 {
    129   char *end;
    130 
    131   // Detect end of line (and truncate line at comment)
    132   if (strchr("><&|(;", *start)) return 0;
    133 
    134   // Grab next word.  (Add dequote and envvar logic here)
    135   end = start;
    136   while (*end && !isspace(*end)) end++;
    137   (*cmd)->argv[(*cmd)->argc++] = xstrndup(start, end-start);
    138 
    139   // Allocate more space if there's no room for NULL terminator.
    140 
    141   if (!((*cmd)->argc & 7))
    142     *cmd=xrealloc(*cmd,
    143         sizeof(struct command) + ((*cmd)->argc+8)*sizeof(char *));
    144   (*cmd)->argv[(*cmd)->argc] = 0;
    145   return end;
    146 }
    147 
    148 // Parse a line of text into a pipeline.
    149 // Returns a pointer to the next line.
    150 
    151 static char *parse_pipeline(char *cmdline, struct pipeline *line)
    152 {
    153   struct command **cmd = &(line->cmd);
    154   char *start = line->cmdline = cmdline;
    155 
    156   if (!cmdline) return 0;
    157 
    158   line->cmdline = cmdline;
    159 
    160   // Parse command into argv[]
    161   for (;;) {
    162     char *end;
    163 
    164     // Skip leading whitespace and detect end of line.
    165     while (isspace(*start)) start++;
    166     if (!*start || *start=='#') {
    167       line->cmdlinelen = start-cmdline;
    168       return 0;
    169     }
    170 
    171     // Allocate next command structure if necessary
    172     if (!*cmd) *cmd = xzalloc(sizeof(struct command)+8*sizeof(char *));
    173 
    174     // Parse next argument and add the results to argv[]
    175     end = parse_word(start, cmd);
    176 
    177     // If we hit the end of this command, how did it end?
    178     if (!end) {
    179       if (*start) {
    180         if (*start==';') {
    181           start++;
    182           break;
    183         }
    184         // handle | & < > >> << || &&
    185       }
    186       break;
    187     }
    188     start = end;
    189   }
    190 
    191   line->cmdlinelen = start-cmdline;
    192 
    193   return start;
    194 }
    195 
    196 // Execute the commands in a pipeline
    197 static void run_pipeline(struct pipeline *line)
    198 {
    199   struct toy_list *tl;
    200   struct command *cmd = line->cmd;
    201   if (!cmd || !cmd->argc) return;
    202 
    203   tl = toy_find(cmd->argv[0]);
    204 
    205   // Is this command a builtin that should run in this process?
    206   if (tl && (tl->flags & TOYFLAG_NOFORK)) {
    207     struct toy_context temp;
    208     jmp_buf rebound;
    209 
    210     // This fakes lots of what toybox_main() does.
    211     memcpy(&temp, &toys, sizeof(struct toy_context));
    212     memset(&toys, 0, sizeof(struct toy_context));
    213 
    214     if (!setjmp(rebound)) {
    215       toys.rebound = &rebound;
    216       toy_init(tl, cmd->argv);
    217       tl->toy_main();
    218     }
    219     cmd->pid = toys.exitval;
    220     if (toys.optargs != toys.argv+1) free(toys.optargs);
    221     if (toys.old_umask) umask(toys.old_umask);
    222     memcpy(&toys, &temp, sizeof(struct toy_context));
    223   } else {
    224     int status;
    225 
    226     cmd->pid = vfork();
    227     if (!cmd->pid) xexec(cmd->argv);
    228     else waitpid(cmd->pid, &status, 0);
    229 
    230     if (WIFEXITED(status)) cmd->pid = WEXITSTATUS(status);
    231     if (WIFSIGNALED(status)) cmd->pid = WTERMSIG(status);
    232   }
    233 
    234   return;
    235 }
    236 
    237 // Free the contents of a command structure
    238 static void free_cmd(void *data)
    239 {
    240   struct command *cmd=(struct command *)data;
    241 
    242   while(cmd->argc) free(cmd->argv[--cmd->argc]);
    243 }
    244 
    245 
    246 // Parse a command line and do what it says to do.
    247 static void handle(char *command)
    248 {
    249   struct pipeline line;
    250   char *start = command;
    251 
    252   // Loop through commands in this line
    253 
    254   for (;;) {
    255 
    256     // Parse a group of connected commands
    257 
    258     memset(&line,0,sizeof(struct pipeline));
    259     start = parse_pipeline(start, &line);
    260     if (!line.cmd) break;
    261 
    262     // Run those commands
    263 
    264     run_pipeline(&line);
    265     llist_traverse(line.cmd, free_cmd);
    266   }
    267 }
    268 
    269 static void do_prompt(void)
    270 {
    271   char *prompt = getenv("PS1"), *s, c, cc;
    272 
    273   if (!prompt) prompt = "\\$ ";
    274   while (*prompt) {
    275     c = *(prompt++);
    276 
    277     if (c=='!') {
    278       if (*prompt=='!') prompt++;
    279       else {
    280         printf("%ld", TT.lineno);
    281         continue;
    282       }
    283     } else if (c=='\\') {
    284       cc = *(prompt++);
    285       if (!cc) goto down;
    286 
    287       // \nnn \dD{}hHjlstT@AuvVwW!#$
    288       // Ignore bash's "nonprintable" hack; query our cursor position instead.
    289       if (cc=='[' || cc==']') continue;
    290       else if (cc=='$') putchar(getuid() ? '$' : '#');
    291       else if (cc=='h' || cc=='H') {
    292         *toybuf = 0;
    293         gethostname(toybuf, sizeof(toybuf)-1);
    294         if (cc=='h' && (s = strchr(toybuf, '.'))) *s = 0;
    295         fputs(toybuf, stdout);
    296       } else if (cc=='s') fputs(getbasename(*toys.argv), stdout);
    297       else {
    298         if (!(c = unescape(cc))) {
    299           c = '\\';
    300           prompt--;
    301         }
    302 
    303         goto down;
    304       }
    305       continue;
    306     }
    307 down:
    308     putchar(c);
    309   }
    310 }
    311 
    312 void sh_main(void)
    313 {
    314   FILE *f = 0;
    315 
    316   // Set up signal handlers and grab control of this tty.
    317   if (isatty(0)) toys.optflags |= FLAG_i;
    318 
    319   if (*toys.optargs) f = xfopen(*toys.optargs, "r");
    320   if (TT.command) handle(xstrdup(TT.command));
    321   else {
    322     size_t cmdlen = 0;
    323     for (;;) {
    324       char *command = 0;
    325 
    326       // TODO: parse escapes in prompt
    327       if (!f) do_prompt();
    328       if (1 > getline(&command, &cmdlen, f ? f : stdin)) break;
    329       handle(command);
    330       free(command);
    331     }
    332   }
    333 
    334   toys.exitval = 1;
    335 }
    336