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+/* sh.c - toybox shell
+ *
+ * Copyright 2006 Rob Landley <rob@landley.net>
+ *
+ * The POSIX-2008/SUSv4 spec for this is at:
+ * http://opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html
+ * and http://opengroup.org/onlinepubs/9699919799/utilities/sh.html
+ *
+ * The first link describes the following shell builtins:
+ *
+ * break colon continue dot eval exec exit export readonly return set shift
+ * times trap unset
+ *
+ * The second link (the utilities directory) also contains specs for the
+ * following shell builtins:
+ *
+ * alias bg cd command fc fg getopts hash jobs kill read type ulimit
+ * umask unalias wait
+ *
+ * Things like the bash man page are good to read too.
+ *
+ * TODO: // Handle embedded NUL bytes in the command line.
+
+USE_SH(NEWTOY(cd, NULL, TOYFLAG_NOFORK))
+USE_SH(NEWTOY(exit, NULL, TOYFLAG_NOFORK))
+
+USE_SH(NEWTOY(sh, "c:i", TOYFLAG_BIN))
+USE_SH(OLDTOY(toysh, sh, "c:i", TOYFLAG_BIN))
+
+config SH
+ bool "sh (toysh)"
+ default n
+ help
+ usage: sh [-c command] [script]
+
+ Command shell. Runs a shell script, or reads input interactively
+ and responds to it.
+
+ -c command line to execute
+
+config SH_TTY
+ bool "Interactive shell (terminal control)"
+ default n
+ depends on SH
+ help
+ Add terminal control to toysh. This is necessary for interactive use,
+ so the shell isn't killed by CTRL-C.
+
+config SH_PROFILE
+ bool "Profile support"
+ default n
+ depends on SH_TTY
+ help
+ Read /etc/profile and ~/.profile when running interactively.
+
+ Also enables the built-in command "source".
+
+config SH_JOBCTL
+ bool "Job Control (fg, bg, jobs)"
+ default n
+ depends on SH_TTY
+ help
+ Add job control to toysh. This lets toysh handle CTRL-Z, and enables
+ the built-in commands "fg", "bg", and "jobs".
+
+ With pipe support, enable use of "&" to run background processes.
+
+config SH_FLOWCTL
+ bool "Flow control (if, while, for, functions)"
+ default n
+ depends on SH
+ help
+ Add flow control to toysh. This enables the if/then/else/fi,
+ while/do/done, and for/do/done constructs.
+
+ With pipe support, this enables the ability to define functions
+ using the "function name" or "name()" syntax, plus curly brackets
+ "{ }" to group commands.
+
+config SH_QUOTES
+ bool "Smarter argument parsing (quotes)"
+ default n
+ depends on SH
+ help
+ Add support for parsing "" and '' style quotes to the toysh command
+ parser, with lets arguments have spaces in them.
+
+config SH_WILDCARDS
+ bool "Wildcards ( ?*{,} )"
+ default n
+ depends on SH_QUOTES
+ help
+ Expand wildcards in argument names, ala "ls -l *.t?z" and
+ "rm subdir/{one,two,three}.txt".
+
+config SH_PROCARGS
+ bool "Executable arguments ( `` and $() )"
+ default n
+ depends on SH_QUOTES
+ help
+ Add support for executing arguments contianing $() and ``, using
+ the output of the command as the new argument value(s).
+
+ (Bash calls this "command substitution".)
+
+config SH_ENVVARS
+ bool "Environment variable support"
+ default n
+ depends on SH_QUOTES
+ help
+ Substitute environment variable values for $VARNAME or ${VARNAME},
+ and enable the built-in command "export".
+
+config SH_LOCALS
+ bool "Local variables"
+ default n
+ depends on SH_ENVVARS
+ help
+ Support for local variables, fancy prompts ($PS1), the "set" command,
+ and $?.
+
+config SH_ARRAYS
+ bool "Array variables"
+ default n
+ depends on SH_LOCALS
+ help
+ Support for ${blah[blah]} style array variables.
+
+config SH_PIPES
+ bool "Pipes and redirects ( | > >> < << & && | || () ; )"
+ default n
+ depends on SH
+ help
+ Support multiple commands on the same command line. This includes
+ | pipes, > >> < redirects, << here documents, || && conditional
+ execution, () subshells, ; sequential execution, and (with job
+ control) & background processes.
+
+config SH_BUILTINS
+ bool "Builtin commands"
+ default n
+ depends on SH
+ help
+ Adds the commands exec, fg, bg, help, jobs, pwd, export, source, set,
+ unset, read, alias.
+
+config EXIT
+ bool
+ default n
+ depends on SH
+ help
+ usage: exit [status]
+
+ Exit shell. If no return value supplied on command line, use value
+ of most recent command, or 0 if none.
+
+config CD
+ bool
+ default n
+ depends on SH
+ help
+ usage: cd [path]
+
+ Change current directory. With no arguments, go to $HOME.
+
+config CD_P
+ bool # "-P support for cd"
+ default n
+ depends on SH
+ help
+ usage: cd [-PL]
+
+ -P Physical path: resolve symlinks in path.
+ -L Cancel previous -P and restore default behavior.
+*/
+
+#define FOR_sh
+#include "toys.h"
+
+GLOBALS(
+ char *command;
+)
+
+// A single executable, its arguments, and other information we know about it.
+#define SH_FLAG_EXIT 1
+#define SH_FLAG_SUSPEND 2
+#define SH_FLAG_PIPE 4
+#define SH_FLAG_AND 8
+#define SH_FLAG_OR 16
+#define SH_FLAG_AMP 32
+#define SH_FLAG_SEMI 64
+#define SH_FLAG_PAREN 128
+
+// What we know about a single process.
+struct command {
+ struct command *next;
+ int flags; // exit, suspend, && ||
+ int pid; // pid (or exit code)
+ int argc;
+ char *argv[0];
+};
+
+// A collection of processes piped into/waiting on each other.
+struct pipeline {
+ struct pipeline *next;
+ int job_id;
+ struct command *cmd;
+ char *cmdline; // Unparsed line for display purposes
+ int cmdlinelen; // How long is cmdline?
+};
+
+// Parse one word from the command line, appending one or more argv[] entries
+// to struct command. Handles environment variable substitution and
+// substrings. Returns pointer to next used byte, or NULL if it
+// hit an ending token.
+static char *parse_word(char *start, struct command **cmd)
+{
+ char *end;
+
+ // Detect end of line (and truncate line at comment)
+ if (CFG_SH_PIPES && strchr("><&|(;", *start)) return 0;
+
+ // Grab next word. (Add dequote and envvar logic here)
+ end = start;
+ while (*end && !isspace(*end)) end++;
+ (*cmd)->argv[(*cmd)->argc++] = xstrndup(start, end-start);
+
+ // Allocate more space if there's no room for NULL terminator.
+
+ if (!((*cmd)->argc & 7))
+ *cmd=xrealloc(*cmd,
+ sizeof(struct command) + ((*cmd)->argc+8)*sizeof(char *));
+ (*cmd)->argv[(*cmd)->argc] = 0;
+ return end;
+}
+
+// Parse a line of text into a pipeline.
+// Returns a pointer to the next line.
+
+static char *parse_pipeline(char *cmdline, struct pipeline *line)
+{
+ struct command **cmd = &(line->cmd);
+ char *start = line->cmdline = cmdline;
+
+ if (!cmdline) return 0;
+
+ if (CFG_SH_JOBCTL) line->cmdline = cmdline;
+
+ // Parse command into argv[]
+ for (;;) {
+ char *end;
+
+ // Skip leading whitespace and detect end of line.
+ while (isspace(*start)) start++;
+ if (!*start || *start=='#') {
+ if (CFG_SH_JOBCTL) line->cmdlinelen = start-cmdline;
+ return 0;
+ }
+
+ // Allocate next command structure if necessary
+ if (!*cmd) *cmd = xzalloc(sizeof(struct command)+8*sizeof(char *));
+
+ // Parse next argument and add the results to argv[]
+ end = parse_word(start, cmd);
+
+ // If we hit the end of this command, how did it end?
+ if (!end) {
+ if (CFG_SH_PIPES && *start) {
+ if (*start==';') {
+ start++;
+ break;
+ }
+ // handle | & < > >> << || &&
+ }
+ break;
+ }
+ start = end;
+ }
+
+ if (CFG_SH_JOBCTL) line->cmdlinelen = start-cmdline;
+
+ return start;
+}
+
+// Execute the commands in a pipeline
+static void run_pipeline(struct pipeline *line)
+{
+ struct toy_list *tl;
+ struct command *cmd = line->cmd;
+ if (!cmd || !cmd->argc) return;
+
+ tl = toy_find(cmd->argv[0]);
+ // Is this command a builtin that should run in this process?
+ if (tl && (tl->flags & TOYFLAG_NOFORK)) {
+ struct toy_context temp;
+ jmp_buf rebound;
+
+ // This fakes lots of what toybox_main() does.
+ memcpy(&temp, &toys, sizeof(struct toy_context));
+ memset(&toys, 0, sizeof(struct toy_context));
+
+ if (!setjmp(rebound)) {
+ toys.rebound = rebound;
+ toy_init(tl, cmd->argv);
+ tl->toy_main();
+ }
+ cmd->pid = toys.exitval;
+ if (toys.optargs != toys.argv+1) free(toys.optargs);
+ if (toys.old_umask) umask(toys.old_umask);
+ memcpy(&toys, &temp, sizeof(struct toy_context));
+ } else {
+ int status;
+
+ cmd->pid = vfork();
+ if (!cmd->pid) xexec(cmd->argv);
+ else waitpid(cmd->pid, &status, 0);
+
+ if (CFG_SH_FLOWCTL || CFG_SH_PIPES) {
+ if (WIFEXITED(status)) cmd->pid = WEXITSTATUS(status);
+ if (WIFSIGNALED(status)) cmd->pid = WTERMSIG(status);
+ }
+ }
+
+ return;
+}
+
+// Free the contents of a command structure
+static void free_cmd(void *data)
+{
+ struct command *cmd=(struct command *)data;
+
+ while(cmd->argc) free(cmd->argv[--cmd->argc]);
+}
+
+
+// Parse a command line and do what it says to do.
+static void handle(char *command)
+{
+ struct pipeline line;
+ char *start = command;
+
+ // Loop through commands in this line
+
+ for (;;) {
+
+ // Parse a group of connected commands
+
+ memset(&line,0,sizeof(struct pipeline));
+ start = parse_pipeline(start, &line);
+ if (!line.cmd) break;
+
+ // Run those commands
+
+ run_pipeline(&line);
+ llist_traverse(line.cmd, free_cmd);
+ }
+}
+
+void cd_main(void)
+{
+ char *dest = *toys.optargs ? *toys.optargs : getenv("HOME");
+ xchdir(dest);
+}
+
+void exit_main(void)
+{
+ exit(*toys.optargs ? atoi(*toys.optargs) : 0);
+}
+
+void sh_main(void)
+{
+ FILE *f;
+
+ // Set up signal handlers and grab control of this tty.
+ if (CFG_SH_TTY) {
+ if (isatty(0)) toys.optflags |= 1;
+ }
+ f = *toys.optargs ? xfopen(*toys.optargs, "r") : NULL;
+ if (TT.command) handle(TT.command);
+ else {
+ size_t cmdlen = 0;
+ for (;;) {
+ char *command = 0;
+ if (!f) xputc('$');
+ if (1 > getline(&command, &cmdlen, f ? f : stdin)) break;
+ handle(command);
+ free(command);
+ }
+ }
+
+ toys.exitval = 1;
+}