hush.c

uboot详细解读可用启动引导LINUX2.6内核

			pi->progs[prognum].pid = 0;

			if (!pi->running_progs) {
				printf(JOB_STATUS_FORMAT, pi->jobid, "Done", pi->text);
				remove_bg_job(pi);
			}
		} else {
			/* child stopped */
			pi->stopped_progs++;
			pi->progs[prognum].is_stopped = 1;

#if 0
			/* Printing this stuff is a pain, since it tends to
			 * overwrite the prompt an inconveinient moments.  So
			 * don't do that.  */
			if (pi->stopped_progs == pi->num_progs) {
				printf("\n"JOB_STATUS_FORMAT, pi->jobid, "Stopped", pi->text);
			}
#endif
		}
	}

	if (childpid == -1 && errno != ECHILD)
		perror_msg("waitpid");

	/* move the shell to the foreground */
	/*if (interactive && tcsetpgrp(shell_terminal, getpgid(0))) */
	/*	perror_msg("tcsetpgrp-2"); */
	return -1;
}

/* Figure out our controlling tty, checking in order stderr,
 * stdin, and stdout.  If check_pgrp is set, also check that
 * we belong to the foreground process group associated with
 * that tty.  The value of shell_terminal is needed in order to call
 * tcsetpgrp(shell_terminal, ...); */
void controlling_tty(int check_pgrp)
{
	pid_t curpgrp;

	if ((curpgrp = tcgetpgrp(shell_terminal = 2)) < 0
			&& (curpgrp = tcgetpgrp(shell_terminal = 0)) < 0
			&& (curpgrp = tcgetpgrp(shell_terminal = 1)) < 0)
		goto shell_terminal_error;

	if (check_pgrp && curpgrp != getpgid(0))
		goto shell_terminal_error;

	return;

shell_terminal_error:
		shell_terminal = -1;
		return;
}
#endif

/* run_pipe_real() starts all the jobs, but doesn't wait for anything
 * to finish.  See checkjobs().
 *
 * return code is normally -1, when the caller has to wait for children
 * to finish to determine the exit status of the pipe.  If the pipe
 * is a simple builtin command, however, the action is done by the
 * time run_pipe_real returns, and the exit code is provided as the
 * return value.
 *
 * The input of the pipe is always stdin, the output is always
 * stdout.  The outpipe[] mechanism in BusyBox-0.48 lash is bogus,
 * because it tries to avoid running the command substitution in
 * subshell, when that is in fact necessary.  The subshell process
 * now has its stdout directed to the input of the appropriate pipe,
 * so this routine is noticeably simpler.
 */
static int run_pipe_real(struct pipe *pi)
{
	int i;
#ifndef __U_BOOT__
	int nextin, nextout;
	int pipefds[2];				/* pipefds[0] is for reading */
	struct child_prog *child;
	struct built_in_command *x;
	char *p;
# if __GNUC__
	/* Avoid longjmp clobbering */
	(void) &i;
	(void) &nextin;
	(void) &nextout;
	(void) &child;
# endif
#else
	int nextin;
	int flag = do_repeat ? CMD_FLAG_REPEAT : 0;
	struct child_prog *child;
	cmd_tbl_t *cmdtp;
	char *p;
# if __GNUC__
	/* Avoid longjmp clobbering */
	(void) &i;
	(void) &nextin;
	(void) &child;
# endif
#endif	/* __U_BOOT__ */

	nextin = 0;
#ifndef __U_BOOT__
	pi->pgrp = -1;
#endif

	/* Check if this is a simple builtin (not part of a pipe).
	 * Builtins within pipes have to fork anyway, and are handled in
	 * pseudo_exec.  "echo foo | read bar" doesn't work on bash, either.
	 */
	if (pi->num_progs == 1) child = & (pi->progs[0]);
#ifndef __U_BOOT__
	if (pi->num_progs == 1 && child->group && child->subshell == 0) {
		int squirrel[] = {-1, -1, -1};
		int rcode;
		debug_printf("non-subshell grouping\n");
		setup_redirects(child, squirrel);
		/* XXX could we merge code with following builtin case,
		 * by creating a pseudo builtin that calls run_list_real? */
		rcode = run_list_real(child->group);
		restore_redirects(squirrel);
#else
		if (pi->num_progs == 1 && child->group) {
		int rcode;
		debug_printf("non-subshell grouping\n");
		rcode = run_list_real(child->group);
#endif
		return rcode;
	} else if (pi->num_progs == 1 && pi->progs[0].argv != NULL) {
		for (i=0; is_assignment(child->argv[i]); i++) { /* nothing */ }
		if (i!=0 && child->argv[i]==NULL) {
			/* assignments, but no command: set the local environment */
			for (i=0; child->argv[i]!=NULL; i++) {

				/* Ok, this case is tricky.  We have to decide if this is a
				 * local variable, or an already exported variable.  If it is
				 * already exported, we have to export the new value.  If it is
				 * not exported, we need only set this as a local variable.
				 * This junk is all to decide whether or not to export this
				 * variable. */
				int export_me=0;
				char *name, *value;
				name = xstrdup(child->argv[i]);
				debug_printf("Local environment set: %s\n", name);
				value = strchr(name, '=');
				if (value)
					*value=0;
#ifndef __U_BOOT__
				if ( get_local_var(name)) {
					export_me=1;
				}
#endif
				free(name);
				p = insert_var_value(child->argv[i]);
				set_local_var(p, export_me);
				if (p != child->argv[i]) free(p);
			}
			return EXIT_SUCCESS;   /* don't worry about errors in set_local_var() yet */
		}
		for (i = 0; is_assignment(child->argv[i]); i++) {
			p = insert_var_value(child->argv[i]);
#ifndef __U_BOOT__
			putenv(strdup(p));
#else
			set_local_var(p, 0);
#endif
			if (p != child->argv[i]) {
				child->sp--;
				free(p);
			}
		}
		if (child->sp) {
			char * str = NULL;

			str = make_string((child->argv + i));
			parse_string_outer(str, FLAG_EXIT_FROM_LOOP | FLAG_REPARSING);
			free(str);
			return last_return_code;
		}
#ifndef __U_BOOT__
		for (x = bltins; x->cmd; x++) {
			if (strcmp(child->argv[i], x->cmd) == 0 ) {
				int squirrel[] = {-1, -1, -1};
				int rcode;
				if (x->function == builtin_exec && child->argv[i+1]==NULL) {
					debug_printf("magic exec\n");
					setup_redirects(child,NULL);
					return EXIT_SUCCESS;
				}
				debug_printf("builtin inline %s\n", child->argv[0]);
				/* XXX setup_redirects acts on file descriptors, not FILEs.
				 * This is perfect for work that comes after exec().
				 * Is it really safe for inline use?  Experimentally,
				 * things seem to work with glibc. */
				setup_redirects(child, squirrel);
#else
			/* check ";", because ,example , argv consist from
			 * "help;flinfo" must not execute
			 */
			if (strchr(child->argv[i], ';')) {
				printf ("Unknown command '%s' - try 'help' or use 'run' command\n",
					child->argv[i]);
				return -1;
			}
			/* Look up command in command table */


			if ((cmdtp = find_cmd(child->argv[i])) == NULL) {
				printf ("Unknown command '%s' - try 'help'\n", child->argv[i]);
				return -1;	/* give up after bad command */
			} else {
				int rcode;
#if defined(CONFIG_CMD_BOOTD)
	    extern int do_bootd (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[]);

				/* avoid "bootd" recursion */
				if (cmdtp->cmd == do_bootd) {
					if (flag & CMD_FLAG_BOOTD) {
						printf ("'bootd' recursion detected\n");
						return -1;
					}
				else
					flag |= CMD_FLAG_BOOTD;
				}
#endif
				/* found - check max args */
				if ((child->argc - i) > cmdtp->maxargs) {
					printf ("Usage:\n%s\n", cmdtp->usage);
					return -1;
				}
#endif
				child->argv+=i;  /* XXX horrible hack */
#ifndef __U_BOOT__
				rcode = x->function(child);
#else
				/* OK - call function to do the command */

				rcode = (cmdtp->cmd)
(cmdtp, flag,child->argc-i,&child->argv[i]);
				if ( !cmdtp->repeatable )
					flag_repeat = 0;


#endif
				child->argv-=i;  /* XXX restore hack so free() can work right */
#ifndef __U_BOOT__

				restore_redirects(squirrel);
#endif

				return rcode;
			}
		}
#ifndef __U_BOOT__
	}

	for (i = 0; i < pi->num_progs; i++) {
		child = & (pi->progs[i]);

		/* pipes are inserted between pairs of commands */
		if ((i + 1) < pi->num_progs) {
			if (pipe(pipefds)<0) perror_msg_and_die("pipe");
			nextout = pipefds[1];
		} else {
			nextout=1;
			pipefds[0] = -1;
		}

		/* XXX test for failed fork()? */
		if (!(child->pid = fork())) {
			/* Set the handling for job control signals back to the default.  */
			signal(SIGINT, SIG_DFL);
			signal(SIGQUIT, SIG_DFL);
			signal(SIGTERM, SIG_DFL);
			signal(SIGTSTP, SIG_DFL);
			signal(SIGTTIN, SIG_DFL);
			signal(SIGTTOU, SIG_DFL);
			signal(SIGCHLD, SIG_DFL);

			close_all();

			if (nextin != 0) {
				dup2(nextin, 0);
				close(nextin);
			}
			if (nextout != 1) {
				dup2(nextout, 1);
				close(nextout);
			}
			if (pipefds[0]!=-1) {
				close(pipefds[0]);  /* opposite end of our output pipe */
			}

			/* Like bash, explicit redirects override pipes,
			 * and the pipe fd is available for dup'ing. */
			setup_redirects(child,NULL);

			if (interactive && pi->followup!=PIPE_BG) {
				/* If we (the child) win the race, put ourselves in the process
				 * group whose leader is the first process in this pipe. */
				if (pi->pgrp < 0) {
					pi->pgrp = getpid();
				}
				if (setpgid(0, pi->pgrp) == 0) {
					tcsetpgrp(2, pi->pgrp);
				}
			}

			pseudo_exec(child);
		}


		/* put our child in the process group whose leader is the
		   first process in this pipe */
		if (pi->pgrp < 0) {
			pi->pgrp = child->pid;
		}
		/* Don't check for errors.  The child may be dead already,
		 * in which case setpgid returns error code EACCES. */
		setpgid(child->pid, pi->pgrp);

		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];
	}
#endif
	return -1;
}

static int run_list_real(struct pipe *pi)
{
	char *save_name = NULL;
	char **list = NULL;
	char **save_list = NULL;
	struct pipe *rpipe;
	int flag_rep = 0;
#ifndef __U_BOOT__
	int save_num_progs;
#endif
	int rcode=0, flag_skip=1;
	int flag_restore = 0;
	int if_code=0, next_if_code=0;  /* need double-buffer to handle elif */
	reserved_style rmode, skip_more_in_this_rmode=RES_XXXX;
	/* check syntax for "for" */
	for (rpipe = pi; rpipe; rpipe = rpipe->next) {
		if ((rpipe->r_mode == RES_IN ||
		    rpipe->r_mode == RES_FOR) &&
		    (rpipe->next == NULL)) {
				syntax();
#ifdef __U_BOOT__
				flag_repeat = 0;
#endif
				return 1;
		}
		if ((rpipe->r_mode == RES_IN &&
			(rpipe->next->r_mode == RES_IN &&
			rpipe->next->progs->argv != NULL))||
			(rpipe->r_mode == RES_FOR &&
			rpipe->next->r_mode != RES_IN)) {
				syntax();
#ifdef __U_BOOT__
				flag_repeat = 0;
#endif
				return 1;
		}
	}
	for (; pi; pi = (flag_restore != 0) ? rpipe : pi->next) {
		if (pi->r_mode == RES_WHILE || pi->r_mode == RES_UNTIL ||
			pi->r_mode == RES_FOR) {
#ifdef __U_BOOT__
				/* check Ctrl-C */
				ctrlc();
				if ((had_ctrlc())) {
					return 1;
				}
#endif
				flag_restore = 0;
				if (!rpipe) {
					flag_rep = 0;
					rpipe = pi;
				}
		}
		rmode = pi->r_mode;
		debug_printf("rmode=%d  if_code=%d  next_if_code=%d skip_more=%d\n", rmode, if_code, next_if_code, skip_more_in_this_rmode);
		if (rmode == skip_more_in_this_rmode && flag_skip) {
			if (pi->followup == PIPE_SEQ) flag_skip=0;
			continue;
		}
		flag_skip = 1;
		skip_more_in_this_rmode = RES_XXXX;
		if (rmode == RES_THEN || rmode == RES_ELSE) if_code = next_if_code;
		if (rmode == RES_THEN &&  if_code) continue;
		if (rmode == RES_ELSE && !if_code) continue;
		if (rmode == RES_ELIF && !if_code) break;
		if (rmode == RES_FOR && pi->num_progs) {
			if (!list) {
				/* if no variable values after "in" we skip "for" */
				if (!pi->next->progs->argv) continue;
				/* create list of variable values */
				list = make_list_in(pi->next->progs->argv,
					pi->progs->argv[0]);
				save_list = list;
				save_name = pi->progs->argv[0];
				pi->progs->argv[0] = NULL;
				flag_rep = 1;
			}
			if (!(*list)) {
				free(pi->progs->argv[0]);
				free(save_list);
				list = NULL;
				flag_rep = 0;
				pi->progs->argv[0] = save_name;
#ifndef __U_BOOT__
				pi->progs->glob_result.gl_pathv[0] =
					pi->progs->argv[0];
#endif
				continue;
			} else {
				/* insert new value from list for variable */
				if (pi->progs->argv[0])
					free(pi->progs->argv[0]);
				pi->progs->argv[0] = *list++;
#ifndef __U_BOOT__
				pi->progs->glob_result.gl_pathv[0] =
					pi->progs->argv[0];
#endif
			}
		}
		if (rmode == RES_IN) continue;
		if (rmode == RES_DO) {
			if (!flag_rep) continue;
		}
		if ((rmode == RES_DONE)) {
			if (flag_rep) {
				flag_restore = 1;
			} else {
				rpipe = NULL;
			}
		}
		if (pi->num_progs == 0) continue;
#ifndef __U_BOOT__
		save_num_progs = pi->num_progs; /* save number of programs */
#endif
		rcode = run_pipe_real(pi);
		debug_printf("run_pipe_real returned %d\n",rcode);
#ifndef __U_BOOT__
		if (rcode!=-1) {
			/* We only ran a builtin: rcode was set by the return value
			 * of run_pipe_real(), and we don't need to wait for anything. */
		} else if (pi->followup==PIPE_BG) {
			/* XXX check bash's behavior with nontrivial pipes */
			/* XXX compute jobid */
			/* XXX what does bash do with attempts to background builtins? */
			insert_bg_job(pi);
			rcode = EXIT_SUCCESS;
		} else {
			if (interactive) {
				/* move the new process group into the foreground */
				if (tcsetpgrp(shell_terminal, pi->pgrp) && errno != ENOTTY)
					perror_msg("tcsetpgrp-3");
				rcode = checkjobs(pi);
				/* move the shell to the foreground */
				if (tcsetpgrp(shell_terminal, getpgid(0)) && errno != ENOTTY)
					perror_msg("tcsetpgrp-4");
			} else {
				rcode = checkjobs(pi);
			}
			debug_printf("checkjobs returned %d\n",rcode);
		}
		last_return_code=rcode;
#else
		if (rcode < -1) {
			last_return_code = -rcode - 2;
			return -2;	/* exit */
		}
		last_return_code=(rcode == 0) ? 0 : 1;
#endif
#ifndef __U_BOOT__
		pi->num_progs = save_num_progs; /* restore number of programs */
#endif
		if ( rmode == RES_IF || rmode == RES_ELIF )
			next_if_code=rcode;  /* can be overwritten a number of times */
		if (rmode == RES_WHILE)
			flag_rep = !last_return_code;