lash.c

shell-HHARM9200.rar 华恒 AT91rm9200 中Busybox shell的源代码

					return 1;
				}

				prog->redirects[i].filename = buf;
				while (*chptr && !isspace(*chptr))
					*buf++ = *chptr++;

				src = chptr - 1;	/* we src++ later */
				prog->argv[argc_l] = ++buf;
				break;

			case '|':			/* pipe */
				/* finish this command */
				if (*prog->argv[argc_l] || saw_quote)
					argc_l++;
				if (!argc_l) {
					bb_error_msg("empty command in pipe");
					free_job(job);
					job->num_progs=0;
					return 1;
				}
				prog->argv[argc_l] = NULL;

				/* and start the next */
				job->num_progs++;
				job->progs = xrealloc(job->progs,
									  sizeof(*job->progs) * job->num_progs);
				prog = job->progs + (job->num_progs - 1);
				prog->num_redirects = 0;
				prog->redirects = NULL;
				prog->is_stopped = 0;
				prog->family = job;
				argc_l = 0;

				argv_alloced = 5;
				prog->argv = xmalloc(sizeof(*prog->argv) * argv_alloced);
				prog->argv[0] = ++buf;

				src++;
				while (*src && isspace(*src))
					src++;

				if (!*src) {
					bb_error_msg("empty command in pipe");
					free_job(job);
					job->num_progs=0;
					return 1;
				}
				src--;			/* we'll ++ it at the end of the loop */

				break;
#endif

#ifdef CONFIG_LASH_JOB_CONTROL
			case '&':			/* background */
				*inbg = 1;
#endif
			case ';':			/* multiple commands */
				done = 1;
				return_command = *command_ptr + (src - *command_ptr) + 1;
				break;

			case '\\':
				src++;
				if (!*src) {
					bb_error_msg("character expected after \\");
					free_job(job);
					return 1;
				}
				if (*src == '*' || *src == '[' || *src == ']'
					|| *src == '?') *buf++ = '\\';
				/* fallthrough */
			default:
				*buf++ = *src;
			}

		src++;
	}

	if (*prog->argv[argc_l] || saw_quote) {
		argc_l++;
	}
	if (!argc_l) {
		free_job(job);
		return 0;
	}
	prog->argv[argc_l] = NULL;

	if (!return_command) {
		job->text = xmalloc(strlen(*command_ptr) + 1);
		strcpy(job->text, *command_ptr);
	} else {
		/* This leaves any trailing spaces, which is a bit sloppy */
		count = return_command - *command_ptr;
		job->text = xmalloc(count + 1);
		strncpy(job->text, *command_ptr, count);
		job->text[count] = '\0';
	}

	*command_ptr = return_command;

	return 0;
}

/* Run the child_prog, no matter what kind of command it uses.
 */
static int pseudo_exec(struct child_prog *child)
{
	struct built_in_command *x;
#ifdef CONFIG_FEATURE_SH_STANDALONE_SHELL
	char *name;
#endif

	/* Check if the command matches any of the non-forking builtins.
	 * Depending on context, this might be redundant.  But it's
	 * easier to waste a few CPU cycles than it is to figure out
	 * if this is one of those cases.
	 */
	for (x = bltins; x->cmd; x++) {
		if (strcmp(child->argv[0], x->cmd) == 0 ) {
			_exit(x->function(child));
		}
	}

	/* Check if the command matches any of the forking builtins. */
	for (x = bltins_forking; x->cmd; x++) {
		if (strcmp(child->argv[0], x->cmd) == 0) {
			bb_applet_name=x->cmd;
			_exit (x->function(child));
		}
	}
#ifdef CONFIG_FEATURE_SH_STANDALONE_SHELL
	/* Check if the command matches any busybox internal
	 * commands ("applets") here.  Following discussions from
	 * November 2000 on [e-mail], don't use
	 * bb_get_last_path_component().  This way explicit (with
	 * slashes) filenames will never be interpreted as an
	 * applet, just like with builtins.  This way the user can
	 * override an applet with an explicit filename reference.
	 * The only downside to this change is that an explicit
	 * /bin/foo invocation will fork and exec /bin/foo, even if
	 * /bin/foo is a symlink to busybox.
	 */
	name = child->argv[0];

	{
	    char** argv_l=child->argv;
	    int argc_l;
	    for(argc_l=0;*argv_l!=NULL; argv_l++, argc_l++);
	    optind = 1;
	    run_applet_by_name(name, argc_l, child->argv);
	}
#endif

	execvp(child->argv[0], child->argv);

	/* Do not use bb_perror_msg_and_die() here, since we must not
	 * call exit() but should call _exit() instead */
	fprintf(stderr, "%s: %m\n", child->argv[0]);
	_exit(EXIT_FAILURE);
}

static void insert_job(struct job *newjob, int inbg)
{
	struct job *thejob;
	struct jobset *j_list=newjob->job_list;

	/* find the ID for thejob to use */
	newjob->jobid = 1;
	for (thejob = j_list->head; thejob; thejob = thejob->next)
		if (thejob->jobid >= newjob->jobid)
			newjob->jobid = thejob->jobid + 1;

	/* add thejob to the list of running jobs */
	if (!j_list->head) {
		thejob = j_list->head = xmalloc(sizeof(*thejob));
	} else {
		for (thejob = j_list->head; thejob->next; thejob = thejob->next) /* nothing */;
		thejob->next = xmalloc(sizeof(*thejob));
		thejob = thejob->next;
	}

	*thejob = *newjob;   /* physically copy the struct job */
	thejob->next = NULL;
	thejob->running_progs = thejob->num_progs;
	thejob->stopped_progs = 0;

#ifdef CONFIG_LASH_JOB_CONTROL
	if (inbg) {
		/* we don't wait for background thejobs to return -- append it
		   to the list of backgrounded thejobs and leave it alone */
		printf("[%d] %d\n", thejob->jobid,
			   newjob->progs[newjob->num_progs - 1].pid);
		last_jobid = newjob->jobid;
		last_bg_pid=newjob->progs[newjob->num_progs - 1].pid;
	} else {
		newjob->job_list->fg = thejob;

		/* move the new process group into the foreground */
		/* suppress messages when run from /linuxrc [e-mail] */
		if (tcsetpgrp(shell_terminal, newjob->pgrp) && errno != ENOTTY)
			bb_perror_msg("tcsetpgrp");
	}
#endif
}

static int run_command(struct job *newjob, int inbg, int outpipe[2])
{
	/* struct job *thejob; */
	int i;
	int nextin, nextout;
	int pipefds[2];				/* pipefd[0] is for reading */
	struct built_in_command *x;
	struct child_prog *child;

	nextin = 0, nextout = 1;
	for (i = 0; i < newjob->num_progs; i++) {
		child = & (newjob->progs[i]);

		if ((i + 1) < newjob->num_progs) {
			if (pipe(pipefds)<0) bb_perror_msg_and_die("pipe");
			nextout = pipefds[1];
		} else {
			if (outpipe[1]!=-1) {
				nextout = outpipe[1];
			} else {
				nextout = 1;
			}
		}


		/* Check if the command matches any non-forking builtins,
		 * but only if this is a simple command.
		 * Non-forking builtins within pipes have to fork anyway,
		 * and are handled in pseudo_exec.  "echo foo | read bar"
		 * is doomed to failure, and doesn't work on bash, either.
		 */
		if (newjob->num_progs == 1) {
			for (x = bltins; x->cmd; x++) {
				if (strcmp(child->argv[0], x->cmd) == 0 ) {
					int rcode;
					int squirrel[] = {-1, -1, -1};
					setup_redirects(child, squirrel);
					rcode = x->function(child);
					restore_redirects(squirrel);
					return rcode;
				}
			}
		}

#if !defined(__UCLIBC__) || defined(__ARCH_HAS_MMU__)
		if (!(child->pid = fork()))
#else
		if (!(child->pid = vfork()))
#endif
		{
			/* Set the handling for job control signals back to the default.  */
			signal(SIGINT, SIG_DFL);
			signal(SIGQUIT, SIG_DFL);
			signal(SIGTSTP, SIG_DFL);
			signal(SIGTTIN, SIG_DFL);
			signal(SIGTTOU, SIG_DFL);
			signal(SIGCHLD, SIG_DFL);

			close_all();

			if (outpipe[1]!=-1) {
				close(outpipe[0]);
			}
			if (nextin != 0) {
				dup2(nextin, 0);
				close(nextin);
			}

			if (nextout != 1) {
				dup2(nextout, 1);
				dup2(nextout, 2);  /* Really? */
				close(nextout);
				close(pipefds[0]);
			}

			/* explicit redirects override pipes */
			setup_redirects(child,NULL);

			pseudo_exec(child);
		}
		if (outpipe[1]!=-1) {
			close(outpipe[1]);
		}

		/* put our child in the process group whose leader is the
		   first process in this pipe */
		setpgid(child->pid, newjob->progs[0].pid);
		if (nextin != 0)
			close(nextin);
		if (nextout != 1)
			close(nextout);

		/* If there isn't another process, nextin is garbage
		   but it doesn't matter */
		nextin = pipefds[0];
	}

	newjob->pgrp = newjob->progs[0].pid;

	insert_job(newjob, inbg);

	return 0;
}

static int busy_loop(FILE * input)
{
	char *command;
	char *next_command = NULL;
	struct job newjob;
	int i;
	int inbg;
	int status;
#ifdef CONFIG_LASH_JOB_CONTROL
	pid_t  parent_pgrp;
	/* save current owner of TTY so we can restore it on exit */
	parent_pgrp = tcgetpgrp(shell_terminal);
#endif
	newjob.job_list = &job_list;
	newjob.job_context = DEFAULT_CONTEXT;

	command = (char *) xcalloc(BUFSIZ, sizeof(char));

	while (1) {
		if (!job_list.fg) {
			/* no job is in the foreground */

			/* see if any background processes have exited */
			checkjobs(&job_list);

			if (!next_command) {
				if (get_command(input, command))
					break;
				next_command = command;
			}

			if (! expand_arguments(next_command)) {
				free(command);
				command = (char *) xcalloc(BUFSIZ, sizeof(char));
				next_command = NULL;
				continue;
			}

			if (!parse_command(&next_command, &newjob, &inbg) &&
				newjob.num_progs) {
				int pipefds[2] = {-1,-1};
				debug_printf( "job=%p fed to run_command by busy_loop()'\n",
						&newjob);
				run_command(&newjob, inbg, pipefds);
			}
			else {
				free(command);
				command = (char *) xcalloc(BUFSIZ, sizeof(char));
				next_command = NULL;
			}
		} else {
			/* a job is running in the foreground; wait for it */
			i = 0;
			while (!job_list.fg->progs[i].pid ||
				   job_list.fg->progs[i].is_stopped == 1) i++;

			if (waitpid(job_list.fg->progs[i].pid, &status, WUNTRACED)<0) {
				if (errno != ECHILD) {
					bb_perror_msg_and_die("waitpid(%d)",job_list.fg->progs[i].pid);
				}
			}

			if (WIFEXITED(status) || WIFSIGNALED(status)) {
				/* the child exited */
				job_list.fg->running_progs--;
				job_list.fg->progs[i].pid = 0;

				last_return_code=WEXITSTATUS(status);

				if (!job_list.fg->running_progs) {
					/* child exited */
					remove_job(&job_list, job_list.fg);
					job_list.fg = NULL;
				}
			}
#ifdef CONFIG_LASH_JOB_CONTROL
			else {
				/* the child was stopped */
				job_list.fg->stopped_progs++;
				job_list.fg->progs[i].is_stopped = 1;

				if (job_list.fg->stopped_progs == job_list.fg->running_progs) {
					printf("\n" JOB_STATUS_FORMAT, job_list.fg->jobid,
						   "Stopped", job_list.fg->text);
					job_list.fg = NULL;
				}
			}

			if (!job_list.fg) {
				/* move the shell to the foreground */
				/* suppress messages when run from /linuxrc [e-mail] */
				if (tcsetpgrp(shell_terminal, getpgrp()) && errno != ENOTTY)
					bb_perror_msg("tcsetpgrp");
			}
#endif
		}
	}
	free(command);

#ifdef CONFIG_LASH_JOB_CONTROL
	/* return controlling TTY back to parent process group before exiting */
	if (tcsetpgrp(shell_terminal, parent_pgrp) && errno != ENOTTY)
		bb_perror_msg("tcsetpgrp");
#endif

	/* return exit status if called with "-c" */
	if (input == NULL && WIFEXITED(status))
		return WEXITSTATUS(status);

	return 0;
}

#ifdef CONFIG_FEATURE_CLEAN_UP
void free_memory(void)
{
	if (cwd && cwd!=bb_msg_unknown) {
		free((char*)cwd);
	}
	if (local_pending_command)
		free(local_pending_command);

	if (job_list.fg && !job_list.fg->running_progs) {
		remove_job(&job_list, job_list.fg);
	}
}
#endif

#ifdef CONFIG_LASH_JOB_CONTROL
/* Make sure we have a controlling tty.  If we get started under a job
 * aware app (like bash for example), make sure we are now in charge so
 * we don't fight over who gets the foreground */
static void setup_job_control(void)
{
	int status;
	pid_t shell_pgrp;

	/* Loop until we are in the foreground.  */
	while ((status = tcgetpgrp (shell_terminal)) >= 0) {
		if (status == (shell_pgrp = getpgrp ())) {
			break;
		}
		kill (- shell_pgrp, SIGTTIN);
	}

	/* Ignore interactive and job-control signals.  */
	signal(SIGINT, SIG_IGN);
	signal(SIGQUIT, SIG_IGN);
	signal(SIGTSTP, SIG_IGN);
	signal(SIGTTIN, SIG_IGN);
	signal(SIGTTOU, SIG_IGN);
	signal(SIGCHLD, SIG_IGN);

	/* Put ourselves in our own process group.  */
	setsid();
	shell_pgrp = getpid ();
	setpgid (shell_pgrp, shell_pgrp);

	/* Grab control of the terminal.  */
	tcsetpgrp(shell_terminal, shell_pgrp);
}
#else
static inline void setup_job_control(void)
{
}
#endif

int lash_main(int argc_l, char **argv_l)
{
	int opt, interactive=FALSE;
	FILE *input = stdin;
	argc = argc_l;
	argv = argv_l;

	/* These variables need re-initializing when recursing */
	last_jobid = 0;
	local_pending_command = NULL;
	close_me_head = NULL;
	job_list.head = NULL;
	job_list.fg = NULL;
	last_return_code=1;

	if (argv[0] && argv[0][0] == '-') {
		FILE *prof_input;
		prof_input = fopen("/etc/profile", "r");
		if (prof_input) {
			int tmp_fd = fileno(prof_input);
			mark_open(tmp_fd);
			/* Now run the file */
			busy_loop(prof_input);
			fclose(prof_input);
			mark_closed(tmp_fd);
		}
	}

	while ((opt = getopt(argc_l, argv_l, "cxi")) > 0) {
		switch (opt) {
			case 'c':
				input = NULL;
				if (local_pending_command != 0)
					bb_error_msg_and_die("multiple -c arguments");
				local_pending_command = bb_xstrdup(argv[optind]);
				optind++;
				argv = argv+optind;
				break;
			case 'i':
				interactive = TRUE;
				break;
			default:
				bb_show_usage();
		}
	}
	/* A shell is interactive if the `-i' flag was given, or if all of
	 * the following conditions are met:
	 *	  no -c command
	 *    no arguments remaining or the -s flag given
	 *    standard input is a terminal
	 *    standard output is a terminal
	 *    Refer to Posix.2, the description of the `sh' utility. */
	if (argv[optind]==NULL && input==stdin &&
			isatty(STDIN_FILENO) && isatty(STDOUT_FILENO)) {
		interactive=TRUE;
	}
	setup_job_control();
	if (interactive==TRUE) {
		//printf( "optind=%d  argv[optind]='%s'\n", optind, argv[optind]);
		/* Looks like they want an interactive shell */
#ifndef CONFIG_FEATURE_SH_EXTRA_QUIET
		printf( "\n\n" BB_BANNER " Built-in shell (lash)\n");
		printf( "Enter 'help' for a list of built-in commands.\n\n");
#endif
	} else if (local_pending_command==NULL) {
		//printf( "optind=%d  argv[optind]='%s'\n", optind, argv[optind]);
		input = bb_xfopen(argv[optind], "r");
		mark_open(fileno(input));  /* be lazy, never mark this closed */
	}

	/* initialize the cwd -- this is never freed...*/
	cwd = xgetcwd(0);
	if (!cwd)
		cwd = bb_msg_unknown;

#ifdef CONFIG_FEATURE_CLEAN_UP
	atexit(free_memory);
#endif

#ifdef CONFIG_FEATURE_COMMAND_EDITING
	cmdedit_set_initial_prompt();
#else
	PS1 = NULL;
#endif

	return (busy_loop(input));
}