hush.c

uboot详细解读可用启动引导LINUX2.6内核

#ifndef CONFIG_FEATURE_SH_FANCY_PROMPT
	/* Set up the prompt */
	if (promptmode == 1) {
		free(PS1);
		PS1=xmalloc(strlen(cwd)+4);
		sprintf(PS1, "%s %s", cwd, ( geteuid() != 0 ) ?  "$ ":"# ");
		*prompt_str = PS1;
	} else {
		*prompt_str = PS2;
	}
#else
	*prompt_str = (promptmode==1)? PS1 : PS2;
#endif
	debug_printf("result %s\n",*prompt_str);
}
#endif

static void get_user_input(struct in_str *i)
{
#ifndef __U_BOOT__
	char *prompt_str;
	static char the_command[BUFSIZ];

	setup_prompt_string(i->promptmode, &prompt_str);
#ifdef CONFIG_FEATURE_COMMAND_EDITING
	/*
	 ** enable command line editing only while a command line
	 ** is actually being read; otherwise, we'll end up bequeathing
	 ** atexit() handlers and other unwanted stuff to our
	 ** child processes ([e-mail])
	 */
	cmdedit_read_input(prompt_str, the_command);
#else
	fputs(prompt_str, stdout);
	fflush(stdout);
	the_command[0]=fgetc(i->file);
	the_command[1]='\0';
#endif
	fflush(stdout);
	i->p = the_command;
#else
	extern char console_buffer[CFG_CBSIZE];
	int n;
	static char the_command[CFG_CBSIZE];

#ifdef CONFIG_BOOT_RETRY_TIME
#  ifdef CONFIG_RESET_TO_RETRY
	extern int do_reset (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[]);
#  else
#	error "This currently only works with CONFIG_RESET_TO_RETRY enabled"
#  endif
	reset_cmd_timeout();
#endif
	i->__promptme = 1;
	if (i->promptmode == 1) {
		n = readline(CFG_PROMPT);
	} else {
		n = readline(CFG_PROMPT_HUSH_PS2);
	}
#ifdef CONFIG_BOOT_RETRY_TIME
	if (n == -2) {
	  puts("\nTimeout waiting for command\n");
#  ifdef CONFIG_RESET_TO_RETRY
	  do_reset(NULL, 0, 0, NULL);
#  else
#	error "This currently only works with CONFIG_RESET_TO_RETRY enabled"
#  endif
	}
#endif
	if (n == -1 ) {
		flag_repeat = 0;
		i->__promptme = 0;
	}
	n = strlen(console_buffer);
	console_buffer[n] = '\n';
	console_buffer[n+1]= '\0';
	if (had_ctrlc()) flag_repeat = 0;
	clear_ctrlc();
	do_repeat = 0;
	if (i->promptmode == 1) {
		if (console_buffer[0] == '\n'&& flag_repeat == 0) {
			strcpy(the_command,console_buffer);
		}
		else {
			if (console_buffer[0] != '\n') {
				strcpy(the_command,console_buffer);
				flag_repeat = 1;
			}
			else {
				do_repeat = 1;
			}
		}
		i->p = the_command;
	}
	else {
		if (console_buffer[0] != '\n') {
			if (strlen(the_command) + strlen(console_buffer)
			    < CFG_CBSIZE) {
				n = strlen(the_command);
				the_command[n-1] = ' ';
				strcpy(&the_command[n],console_buffer);
			}
			else {
				the_command[0] = '\n';
				the_command[1] = '\0';
				flag_repeat = 0;
			}
		}
		if (i->__promptme == 0) {
			the_command[0] = '\n';
			the_command[1] = '\0';
		}
		i->p = console_buffer;
	}
#endif
}

/* This is the magic location that prints prompts
 * and gets data back from the user */
static int file_get(struct in_str *i)
{
	int ch;

	ch = 0;
	/* If there is data waiting, eat it up */
	if (i->p && *i->p) {
		ch = *i->p++;
	} else {
		/* need to double check i->file because we might be doing something
		 * more complicated by now, like sourcing or substituting. */
#ifndef __U_BOOT__
		if (i->__promptme && interactive && i->file == stdin) {
			while(! i->p || (interactive && strlen(i->p)==0) ) {
#else
			while(! i->p  || strlen(i->p)==0 ) {
#endif
				get_user_input(i);
			}
			i->promptmode=2;
#ifndef __U_BOOT__
			i->__promptme = 0;
#endif
			if (i->p && *i->p) {
				ch = *i->p++;
			}
#ifndef __U_BOOT__
		} else {
			ch = fgetc(i->file);
		}

#endif
		debug_printf("b_getch: got a %d\n", ch);
	}
#ifndef __U_BOOT__
	if (ch == '\n') i->__promptme=1;
#endif
	return ch;
}

/* All the callers guarantee this routine will never be
 * used right after a newline, so prompting is not needed.
 */
static int file_peek(struct in_str *i)
{
#ifndef __U_BOOT__
	if (i->p && *i->p) {
#endif
		return *i->p;
#ifndef __U_BOOT__
	} else {
		i->peek_buf[0] = fgetc(i->file);
		i->peek_buf[1] = '\0';
		i->p = i->peek_buf;
		debug_printf("b_peek: got a %d\n", *i->p);
		return *i->p;
	}
#endif
}

#ifndef __U_BOOT__
static void setup_file_in_str(struct in_str *i, FILE *f)
#else
static void setup_file_in_str(struct in_str *i)
#endif
{
	i->peek = file_peek;
	i->get = file_get;
	i->__promptme=1;
	i->promptmode=1;
#ifndef __U_BOOT__
	i->file = f;
#endif
	i->p = NULL;
}

static void setup_string_in_str(struct in_str *i, const char *s)
{
	i->peek = static_peek;
	i->get = static_get;
	i->__promptme=1;
	i->promptmode=1;
	i->p = s;
}

#ifndef __U_BOOT__
static void mark_open(int fd)
{
	struct close_me *new = xmalloc(sizeof(struct close_me));
	new->fd = fd;
	new->next = close_me_head;
	close_me_head = new;
}

static void mark_closed(int fd)
{
	struct close_me *tmp;
	if (close_me_head == NULL || close_me_head->fd != fd)
		error_msg_and_die("corrupt close_me");
	tmp = close_me_head;
	close_me_head = close_me_head->next;
	free(tmp);
}

static void close_all(void)
{
	struct close_me *c;
	for (c=close_me_head; c; c=c->next) {
		close(c->fd);
	}
	close_me_head = NULL;
}

/* squirrel != NULL means we squirrel away copies of stdin, stdout,
 * and stderr if they are redirected. */
static int setup_redirects(struct child_prog *prog, int squirrel[])
{
	int openfd, mode;
	struct redir_struct *redir;

	for (redir=prog->redirects; redir; redir=redir->next) {
		if (redir->dup == -1 && redir->word.gl_pathv == NULL) {
			/* something went wrong in the parse.  Pretend it didn't happen */
			continue;
		}
		if (redir->dup == -1) {
			mode=redir_table[redir->type].mode;
			openfd = open(redir->word.gl_pathv[0], mode, 0666);
			if (openfd < 0) {
			/* this could get lost if stderr has been redirected, but
			   bash and ash both lose it as well (though zsh doesn't!) */
				perror_msg("error opening %s", redir->word.gl_pathv[0]);
				return 1;
			}
		} else {
			openfd = redir->dup;
		}

		if (openfd != redir->fd) {
			if (squirrel && redir->fd < 3) {
				squirrel[redir->fd] = dup(redir->fd);
			}
			if (openfd == -3) {
				close(openfd);
			} else {
				dup2(openfd, redir->fd);
				if (redir->dup == -1)
					close (openfd);
			}
		}
	}
	return 0;
}

static void restore_redirects(int squirrel[])
{
	int i, fd;
	for (i=0; i<3; i++) {
		fd = squirrel[i];
		if (fd != -1) {
			/* No error checking.  I sure wouldn't know what
			 * to do with an error if I found one! */
			dup2(fd, i);
			close(fd);
		}
	}
}

/* never returns */
/* XXX no exit() here.  If you don't exec, use _exit instead.
 * The at_exit handlers apparently confuse the calling process,
 * in particular stdin handling.  Not sure why? */
static void pseudo_exec(struct child_prog *child)
{
	int i, rcode;
	char *p;
	struct built_in_command *x;
	if (child->argv) {
		for (i=0; is_assignment(child->argv[i]); i++) {
			debug_printf("pid %d environment modification: %s\n",getpid(),child->argv[i]);
			p = insert_var_value(child->argv[i]);
			putenv(strdup(p));
			if (p != child->argv[i]) free(p);
		}
		child->argv+=i;  /* XXX this hack isn't so horrible, since we are about
					to exit, and therefore don't need to keep data
					structures consistent for free() use. */
		/* If a variable is assigned in a forest, and nobody listens,
		 * was it ever really set?
		 */
		if (child->argv[0] == NULL) {
			_exit(EXIT_SUCCESS);
		}

		/*
		 * Check if the command matches any of the 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 ) {
				debug_printf("builtin exec %s\n", child->argv[0]);
				rcode = x->function(child);
				fflush(stdout);
				_exit(rcode);
			}
		}

		/* Check if the command matches any busybox internal commands
		 * ("applets") here.
		 * FIXME: This feature is not 100% safe, since
		 * BusyBox is not fully reentrant, so we have no guarantee the things
		 * from the .bss are still zeroed, or that things from .data are still
		 * at their defaults.  We could exec ourself from /proc/self/exe, but I
		 * really dislike relying on /proc for things.  We could exec ourself
		 * from global_argv[0], but if we are in a chroot, we may not be able
		 * to find ourself... */
#ifdef CONFIG_FEATURE_SH_STANDALONE_SHELL
		{
			int argc_l;
			char** argv_l=child->argv;
			char *name = child->argv[0];

#ifdef CONFIG_FEATURE_SH_APPLETS_ALWAYS_WIN
			/* Following discussions from November 2000 on the busybox mailing
			 * list, the default configuration, (without
			 * get_last_path_component()) lets the user force use of an
			 * external command by specifying the full (with slashes) filename.
			 * If you enable CONFIG_FEATURE_SH_APPLETS_ALWAYS_WIN then applets
			 * _aways_ override external commands, so if you want to run
			 * /bin/cat, it will use BusyBox cat even if /bin/cat exists on the
			 * filesystem and is _not_ busybox.  Some systems may want this,
			 * most do not.  */
			name = get_last_path_component(name);
#endif
			/* Count argc for use in a second... */
			for(argc_l=0;*argv_l!=NULL; argv_l++, argc_l++);
			optind = 1;
			debug_printf("running applet %s\n", name);
			run_applet_by_name(name, argc_l, child->argv);
		}
#endif
		debug_printf("exec of %s\n",child->argv[0]);
		execvp(child->argv[0],child->argv);
		perror_msg("couldn't exec: %s",child->argv[0]);
		_exit(1);
	} else if (child->group) {
		debug_printf("runtime nesting to group\n");
		interactive=0;    /* crucial!!!! */
		rcode = run_list_real(child->group);
		/* OK to leak memory by not calling free_pipe_list,
		 * since this process is about to exit */
		_exit(rcode);
	} else {
		/* Can happen.  See what bash does with ">foo" by itself. */
		debug_printf("trying to pseudo_exec null command\n");
		_exit(EXIT_SUCCESS);
	}
}

static void insert_bg_job(struct pipe *pi)
{
	struct pipe *thejob;

	/* Linear search for the ID of the job to use */
	pi->jobid = 1;
	for (thejob = job_list; thejob; thejob = thejob->next)
		if (thejob->jobid >= pi->jobid)
			pi->jobid = thejob->jobid + 1;

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

	/* physically copy the struct job */
	memcpy(thejob, pi, sizeof(struct pipe));
	thejob->next = NULL;
	thejob->running_progs = thejob->num_progs;
	thejob->stopped_progs = 0;
	thejob->text = xmalloc(BUFSIZ); /* cmdedit buffer size */

	/*if (pi->progs[0] && pi->progs[0].argv && pi->progs[0].argv[0]) */
	{
		char *bar=thejob->text;
		char **foo=pi->progs[0].argv;
		while(foo && *foo) {
			bar += sprintf(bar, "%s ", *foo++);
		}
	}

	/* 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, thejob->progs[0].pid);
	last_bg_pid = thejob->progs[0].pid;
	last_jobid = thejob->jobid;
}

/* remove a backgrounded job */
static void remove_bg_job(struct pipe *pi)
{
	struct pipe *prev_pipe;

	if (pi == job_list) {
		job_list = pi->next;
	} else {
		prev_pipe = job_list;
		while (prev_pipe->next != pi)
			prev_pipe = prev_pipe->next;
		prev_pipe->next = pi->next;
	}
	if (job_list)
		last_jobid = job_list->jobid;
	else
		last_jobid = 0;

	pi->stopped_progs = 0;
	free_pipe(pi, 0);
	free(pi);
}

/* Checks to see if any processes have exited -- if they
   have, figure out why and see if a job has completed */
static int checkjobs(struct pipe* fg_pipe)
{
	int attributes;
	int status;
	int prognum = 0;
	struct pipe *pi;
	pid_t childpid;

	attributes = WUNTRACED;
	if (fg_pipe==NULL) {
		attributes |= WNOHANG;
	}

	while ((childpid = waitpid(-1, &status, attributes)) > 0) {
		if (fg_pipe) {
			int i, rcode = 0;
			for (i=0; i < fg_pipe->num_progs; i++) {
				if (fg_pipe->progs[i].pid == childpid) {
					if (i==fg_pipe->num_progs-1)
						rcode=WEXITSTATUS(status);
					(fg_pipe->num_progs)--;
					return(rcode);
				}
			}
		}

		for (pi = job_list; pi; pi = pi->next) {
			prognum = 0;
			while (prognum < pi->num_progs && pi->progs[prognum].pid != childpid) {
				prognum++;
			}
			if (prognum < pi->num_progs)
				break;
		}

		if(pi==NULL) {
			debug_printf("checkjobs: pid %d was not in our list!\n", childpid);
			continue;
		}

		if (WIFEXITED(status) || WIFSIGNALED(status)) {
			/* child exited */
			pi->running_progs--;