jobs.c

一个开放源代码的 AT&T 的 Korn Shell 的复制品, 支持大多数 ksh89 的特性。

/*
 * Process and job control
 */

/*
 * Reworked/Rewritten version of Eric Gisin's/Ron Natalie's code by
 * Larry Bouzane ([e-mail]) and hacked again by
 * Michael Rendell ([e-mail])
 *
 * The interface to the rest of the shell should probably be changed
 * to allow use of vfork() when available but that would be way too much
 * work :)
 *
 * Notes regarding the copious ifdefs:
 *	- JOB_SIGS is independent of JOBS - it is defined if there are modern
 *	  signal and wait routines available.  This is prefered, even when
 *	  JOBS is not defined, since the shell will not otherwise notice when
 *	  background jobs die until the shell waits for a foreground process
 *	  to die.
 *	- TTY_PGRP defined iff JOBS is defined - defined if there are tty
 *	  process groups
 *	- NEED_PGRP_SYNC defined iff JOBS is defined - see comment below
 */

#include "sh.h"
#include "ksh_stat.h"
#include "ksh_wait.h"
#include "ksh_times.h"
#include "tty.h"

/* Start of system configuration stuff */

/* We keep CHILD_MAX zombie processes around (exact value isn't critical) */
#ifndef CHILD_MAX
# if defined(HAVE_SYSCONF) && defined(_SC_CHILD_MAX)
#  define CHILD_MAX sysconf(_SC_CHILD_MAX)
# else /* _SC_CHILD_MAX */
#  ifdef _POSIX_CHILD_MAX
#   define CHILD_MAX	((_POSIX_CHILD_MAX) * 2)
#  else /* _POSIX_CHILD_MAX */
#   define CHILD_MAX	20
#  endif /* _POSIX_CHILD_MAX */
# endif /* _SC_CHILD_MAX */
#endif /* !CHILD_MAX */

#ifdef JOBS
# if defined(HAVE_TCSETPGRP) || defined(TIOCSPGRP)
#  define TTY_PGRP
# endif
# ifdef BSD_PGRP
#  define setpgid	setpgrp
#  define getpgID()	getpgrp(0)
# else
#  define getpgID()	getpgrp()
# endif
# if defined(TTY_PGRP) && !defined(HAVE_TCSETPGRP)
int tcsetpgrp ARGS((int fd, pid_t grp));
int tcgetpgrp ARGS((int fd));

int
tcsetpgrp(fd, grp)
	int fd;
	pid_t grp;
{
	return ioctl(fd, TIOCSPGRP, &grp);
}

int
tcgetpgrp(fd)
	int	fd;
{
	int r, grp;

	if ((r = ioctl(fd, TIOCGPGRP, &grp)) < 0)
		return r;
	return grp;
}
# endif /* !HAVE_TCSETPGRP && TIOCSPGRP */
#else /* JOBS */
/* These so we can use ifdef xxx instead of if defined(JOBS) && defined(xxx) */
# undef TTY_PGRP
# undef NEED_PGRP_SYNC
#endif /* JOBS */

/* End of system configuration stuff */


/* Order important! */
#define PRUNNING	0
#define PEXITED		1
#define PSIGNALLED	2
#define PSTOPPED	3

typedef struct proc	Proc;
struct proc {
	Proc	*next;		/* next process in pipeline (if any) */
	int	state;
	WAIT_T	status;		/* wait status */
	pid_t	pid;		/* process id */
	char	command[48];	/* process command string */
};

/* Notify/print flag - j_print() argument */
#define JP_NONE		0	/* don't print anything */
#define JP_SHORT	1	/* print signals processes were killed by */
#define JP_MEDIUM	2	/* print [job-num] -/+ command */
#define JP_LONG		3	/* print [job-num] -/+ pid command */
#define JP_PGRP		4	/* print pgrp */

/* put_job() flags */
#define PJ_ON_FRONT	0	/* at very front */
#define PJ_PAST_STOPPED	1	/* just past any stopped jobs */

/* Job.flags values */
#define JF_STARTED	0x001	/* set when all processes in job are started */
#define JF_WAITING	0x002	/* set if j_waitj() is waiting on job */
#define JF_W_ASYNCNOTIFY 0x004	/* set if waiting and async notification ok */
#define JF_XXCOM	0x008	/* set for `command` jobs */
#define JF_FG		0x010	/* running in foreground (also has tty pgrp) */
#define JF_SAVEDTTY	0x020	/* j->ttystate is valid */
#define JF_CHANGED	0x040	/* process has changed state */
#define JF_KNOWN	0x080	/* $! referenced */
#define JF_ZOMBIE	0x100	/* known, unwaited process */
#define JF_REMOVE	0x200	/* flaged for removal (j_jobs()/j_noityf()) */
#define JF_USETTYMODE	0x400	/* tty mode saved if process exits normally */
#define JF_SAVEDTTYPGRP	0x800	/* j->saved_ttypgrp is valid */

typedef struct job Job;
struct job {
	Job	*next;		/* next job in list */
	int	job;		/* job number: %n */
	int	flags;		/* see JF_* */
	int	state;		/* job state */
	int	status;		/* exit status of last process */
	pid_t	pgrp;		/* process group of job */
	pid_t	ppid;		/* pid of process that forked job */
	INT32	age;		/* number of jobs started */
	clock_t	systime;	/* system time used by job */
	clock_t	usrtime;	/* user time used by job */
	Proc	*proc_list;	/* process list */
	Proc	*last_proc;	/* last process in list */
#ifdef KSH
	Coproc_id coproc_id;	/* 0 or id of coprocess output pipe */
#endif /* KSH */
#ifdef TTY_PGRP
	TTY_state ttystate;	/* saved tty state for stopped jobs */
	pid_t	saved_ttypgrp;	/* saved tty process group for stopped jobs */
#endif /* TTY_PGRP */
};

/* Flags for j_waitj() */
#define JW_NONE		0x00
#define JW_INTERRUPT	0x01	/* ^C will stop the wait */
#define JW_ASYNCNOTIFY	0x02	/* asynchronous notification during wait ok */
#define JW_STOPPEDWAIT	0x04	/* wait even if job stopped */

/* Error codes for j_lookup() */
#define JL_OK		0
#define JL_NOSUCH	1	/* no such job */
#define JL_AMBIG	2	/* %foo or %?foo is ambiguous */
#define JL_INVALID	3	/* non-pid, non-% job id */

static const char	*const lookup_msgs[] = {
				null,
				"no such job",
				"ambiguous",
				"argument must be %job or process id",
				(char *) 0
			    };
clock_t	j_systime, j_usrtime;	/* user and system time of last j_waitjed job */

static Job		*job_list;	/* job list */
static Job		*last_job;
static Job		*async_job;
static pid_t		async_pid;

static int		nzombie;	/* # of zombies owned by this process */
static INT32		njobs;		/* # of jobs started */
static int		child_max;	/* CHILD_MAX */


#ifdef JOB_SIGS
/* held_sigchld is set if sigchld occurs before a job is completely started */
static int		held_sigchld;
#endif /* JOB_SIGS */

#ifdef JOBS
static struct shf	*shl_j;
#endif /* JOBS */

#ifdef NEED_PGRP_SYNC
/* On some systems, the kernel doesn't count zombie processes when checking
 * if a process group is valid, which can cause problems in creating the
 * pipeline "cmd1 | cmd2": if cmd1 can die (and go into the zombie state)
 * before cmd2 is started, the kernel doesn't allow the setpgid() for cmd2
 * to succeed.  Solution is to create a pipe between the parent and the first
 * process; the first process doesn't do anything until the pipe is closed
 * and the parent doesn't close the pipe until all the processes are started.
 */
static int		j_sync_pipe[2];
static int		j_sync_open;
#endif /* NEED_PGRP_SYNC */

#ifdef TTY_PGRP
static int		ttypgrp_ok;	/* set if can use tty pgrps */
static pid_t		restore_ttypgrp = -1;
static pid_t		our_pgrp;
static int const	tt_sigs[] = { SIGTSTP, SIGTTIN, SIGTTOU };
#endif /* TTY_PGRP */

static void		j_set_async ARGS((Job *j));
static void		j_startjob ARGS((Job *j));
static int		j_waitj ARGS((Job *j, int flags, const char *where));
static RETSIGTYPE	j_sigchld ARGS((int sig));
static void		j_print ARGS((Job *j, int how, struct shf *shf));
static Job		*j_lookup ARGS((const char *cp, int *ecodep));
static Job		*new_job ARGS((void));
static Proc		*new_proc ARGS((void));
static void		check_job ARGS((Job *j));
static void		put_job ARGS((Job *j, int where));
static void		remove_job ARGS((Job *j, const char *where));
static void		kill_job ARGS((Job *j));
static void	 	fill_command ARGS((char *c, int len, struct op *t));

/* initialize job control */
void
j_init(mflagset)
	int mflagset;
{
	child_max = CHILD_MAX; /* so syscon() isn't always being called */

#ifdef JOB_SIGS
	sigemptyset(&sm_default);
	sigprocmask(SIG_SETMASK, &sm_default, (sigset_t *) 0);

	sigemptyset(&sm_sigchld);
	sigaddset(&sm_sigchld, SIGCHLD);

	setsig(&sigtraps[SIGCHLD], j_sigchld,
		SS_RESTORE_ORIG|SS_FORCE|SS_SHTRAP);
#else /* JOB_SIGS */
	/* Make sure SIGCHLD isn't ignored - can do odd things under SYSV */
	setsig(&sigtraps[SIGCHLD], SIG_DFL, SS_RESTORE_ORIG|SS_FORCE);
#endif /* JOB_SIGS */

#ifdef JOBS
	if (!mflagset && Flag(FTALKING))
		Flag(FMONITOR) = 1;

	/* shl_j is used to do asynchronous notification (used in
	 * an interrupt handler, so need a distinct shf)
	 */
	shl_j = shf_fdopen(2, SHF_WR, (struct shf *) 0);

# ifdef TTY_PGRP
	if (Flag(FMONITOR) || Flag(FTALKING)) {
		int i;

		/* the TF_SHELL_USES test is a kludge that lets us know if
		 * if the signals have been changed by the shell.
		 */
		for (i = NELEM(tt_sigs); --i >= 0; ) {
			sigtraps[tt_sigs[i]].flags |= TF_SHELL_USES;
			/* j_change() sets this to SS_RESTORE_DFL if FMONITOR */
			setsig(&sigtraps[tt_sigs[i]], SIG_IGN,
				SS_RESTORE_IGN|SS_FORCE);
		}
	}
# endif /* TTY_PGRP */

	/* j_change() calls tty_init() */
	if (Flag(FMONITOR))
		j_change();
	else
#endif /* JOBS */
	  if (Flag(FTALKING))
		tty_init(TRUE);
}

/* job cleanup before shell exit */
void
j_exit()
{
	/* kill stopped, and possibly running, jobs */
	Job	*j;
	int	killed = 0;

	for (j = job_list; j != (Job *) 0; j = j->next) {
		if (j->ppid == procpid
		    && (j->state == PSTOPPED
			|| (j->state == PRUNNING
			    && ((j->flags & JF_FG)
				|| (Flag(FLOGIN) && !Flag(FNOHUP)
				    && procpid == kshpid)))))
		{
			killed = 1;
			killpg(j->pgrp, SIGHUP);
#ifdef JOBS
			if (j->state == PSTOPPED)
				killpg(j->pgrp, SIGCONT);
#endif /* JOBS */
		}
	}
	if (killed)
		sleep(1);
	j_notify();

#ifdef JOBS
# ifdef TTY_PGRP
	if (kshpid == procpid && restore_ttypgrp >= 0) {
		/* Need to restore the tty pgrp to what it was when the
		 * shell started up, so that the process that started us
		 * will be able to access the tty when we are done.
		 * Also need to restore our process group in case we are
		 * about to do an exec so that both our parent and the
		 * process we are to become will be able to access the tty.
		 */
		tcsetpgrp(tty_fd, restore_ttypgrp);
		setpgid(0, restore_ttypgrp);
	}
# endif /* TTY_PGRP */
	if (Flag(FMONITOR)) {
		Flag(FMONITOR) = 0;
		j_change();
	}
#endif /* JOBS */
}

#ifdef JOBS
/* turn job control on or off according to Flag(FMONITOR) */
void
j_change()
{
	int i;

	if (Flag(FMONITOR)) {
		/* Don't call get_tty() 'til we own the tty process group */
		tty_init(FALSE);

# ifdef TTY_PGRP
		/* no controlling tty, no SIGT* */
		ttypgrp_ok = tty_fd >= 0 && tty_devtty;

		if (ttypgrp_ok && (our_pgrp = getpgID()) < 0) {
			warningf(FALSE, "j_init: getpgrp() failed: %s",
				strerror(errno));
			ttypgrp_ok = 0;
		}
		if (ttypgrp_ok) {
			setsig(&sigtraps[SIGTTIN], SIG_DFL,
				SS_RESTORE_ORIG|SS_FORCE);
			/* wait to be given tty (POSIX.1, B.2, job control) */
			while (1) {
				pid_t ttypgrp;

				if ((ttypgrp = tcgetpgrp(tty_fd)) < 0) {
					warningf(FALSE,
					"j_init: tcgetpgrp() failed: %s",
						strerror(errno));
					ttypgrp_ok = 0;
					break;
				}
				if (ttypgrp == our_pgrp)
					break;
				kill(0, SIGTTIN);
			}
		}
		for (i = NELEM(tt_sigs); --i >= 0; )
			setsig(&sigtraps[tt_sigs[i]], SIG_IGN,
				SS_RESTORE_DFL|SS_FORCE);
		if (ttypgrp_ok && our_pgrp != kshpid) {
			if (setpgid(0, kshpid) < 0) {
				warningf(FALSE,
					"j_init: setpgid() failed: %s",
					strerror(errno));
				ttypgrp_ok = 0;
			} else {
				if (tcsetpgrp(tty_fd, kshpid) < 0) {
					warningf(FALSE,
					"j_init: tcsetpgrp() failed: %s",
						strerror(errno));
					ttypgrp_ok = 0;
				} else
					restore_ttypgrp = our_pgrp;
				our_pgrp = kshpid;
			}
		}
#  if defined(NTTYDISC) && defined(TIOCSETD) && !defined(HAVE_TERMIOS_H) && !defined(HAVE_TERMIO_H)
		if (ttypgrp_ok) {
			int ldisc = NTTYDISC;

			if (ioctl(tty_fd, TIOCSETD, &ldisc) < 0)
				warningf(FALSE,
				"j_init: can't set new line discipline: %s",
					strerror(errno));
		}
#  endif /* NTTYDISC && TIOCSETD */
		if (!ttypgrp_ok)
			warningf(FALSE, "warning: won't have full job control");
# endif /* TTY_PGRP */
		if (tty_fd >= 0)
			get_tty(tty_fd, &tty_state);
	} else {
# ifdef TTY_PGRP
		ttypgrp_ok = 0;
		if (Flag(FTALKING))
			for (i = NELEM(tt_sigs); --i >= 0; )
				setsig(&sigtraps[tt_sigs[i]], SIG_IGN,
					SS_RESTORE_IGN|SS_FORCE);
		else
			for (i = NELEM(tt_sigs); --i >= 0; ) {
				if (sigtraps[tt_sigs[i]].flags & (TF_ORIG_IGN
							          |TF_ORIG_DFL))
					setsig(&sigtraps[tt_sigs[i]],
						(sigtraps[tt_sigs[i]].flags & TF_ORIG_IGN) ? SIG_IGN : SIG_DFL,
						SS_RESTORE_ORIG|SS_FORCE);
			}
# endif /* TTY_PGRP */
		if (!Flag(FTALKING))
			tty_close();
	}
}
#endif /* JOBS */

/* execute tree in child subprocess */
int
exchild(t, flags, close_fd)
	struct op	*t;
	int		flags;
	int		close_fd;	/* used if XPCLOSE or XCCLOSE */
{
	static Proc	*last_proc;	/* for pipelines */

	int		i;
#ifdef JOB_SIGS
	sigset_t	omask;
#endif /* JOB_SIGS */
	Proc		*p;
	Job		*j;
	int		rv = 0;
	int		forksleep;
	int		ischild;

	if (flags & XEXEC)
		/* Clear XFORK|XPCLOSE|XCCLOSE|XCOPROC|XPIPEO|XPIPEI|XXCOM|XBGND
		 * (also done in another execute() below)
		 */
		return execute(t, flags & (XEXEC | XERROK));

#ifdef JOB_SIGS
	/* no SIGCHLD's while messing with job and process lists */
	sigprocmask(SIG_BLOCK, &sm_sigchld, &omask);
#endif /* JOB_SIGS */

	p = new_proc();
	p->next = (Proc *) 0;
	p->state = PRUNNING;
	WSTATUS(p->status) = 0;
	p->pid = 0;

	/* link process into jobs list */
	if (flags&XPIPEI) {	/* continuing with a pipe */
		if (!last_job)
			internal_errorf(1, "exchild: XPIPEI and no last_job - pid %d", (int) procpid);
		j = last_job;
		last_proc->next = p;
		last_proc = p;
	} else {
#ifdef NEED_PGRP_SYNC
		if (j_sync_open) {	/* should never happen */
			j_sync_open = 0;
			closepipe(j_sync_pipe);
		}
		/* don't do the sync pipe business if there is no pipeline */
		if (flags & XPIPEO) {
			openpipe(j_sync_pipe);
			j_sync_open = 1;
		}
#endif /* NEED_PGRP_SYNC */
		j = new_job(); /* fills in j->job */
		/* we don't consider XXCOM's foreground since they don't get
		 * tty process group and we don't save or restore tty modes.
		 */
		j->flags = (flags & XXCOM) ? JF_XXCOM
			: ((flags & XBGND) ? 0 : (JF_FG|JF_USETTYMODE));
		j->usrtime = j->systime = 0;
		j->state = PRUNNING;
		j->pgrp = 0;
		j->ppid = procpid;
		j->age = ++njobs;
		j->proc_list = p;
#ifdef KSH
		j->coproc_id = 0;
#endif /* KSH */
		last_job = j;
		last_proc = p;
		put_job(j, PJ_PAST_STOPPED);
	}

	fill_command(p->command, sizeof(p->command), t);

	/* create child process */
	forksleep = 1;
	while ((i = fork()) < 0 && errno == EAGAIN && forksleep < 32) {
		if (intrsig)	 /* allow user to ^C out... */
			break;
		sleep(forksleep);
		forksleep <<= 1;
	}
	if (i < 0) {
		kill_job(j);
		remove_job(j, "fork failed");
#ifdef NEED_PGRP_SYNC
		if (j_sync_open) {
			closepipe(j_sync_pipe);
			j_sync_open = 0;
		}
#endif /* NEED_PGRP_SYNC */
#ifdef JOB_SIGS
		sigprocmask(SIG_SETMASK, &omask, (sigset_t *) 0);
#endif /* JOB_SIGS */
		errorf("cannot fork - try again");
	}
	ischild = i == 0;
	if (ischild)
		p->pid = procpid = getpid();
	else
		p->pid = i;

#ifdef JOBS
	/* job control set up */
	if (Flag(FMONITOR) && !(flags&XXCOM)) {
		int	dotty = 0;
# ifdef NEED_PGRP_SYNC
		int	first_child_sync = 0;
# endif /* NEED_PGRP_SYNC */

# ifdef NEED_PGRP_SYNC
		if (j_sync_open) {
			/*
			 * The Parent closes 0, keeps 1 open 'til the whole
			 * pipeline is started.  The First child closes 1,
			 * keeps 0 open (reads from it).  The remaining
			 * children just have to close 1 (parent has already
			 * closeed 0).
			 */
			if (j->pgrp == 0) { /* First process */
				close(j_sync_pipe[ischild]);
				j_sync_pipe[ischild] = -1;
				first_child_sync = ischild;
			} else if (ischild) {
				j_sync_open = 0;
				closepipe(j_sync_pipe);
			}
		}
# endif /* NEED_PGRP_SYNC */
		if (j->pgrp == 0) {	/* First process */
			j->pgrp = p->pid;
			dotty = 1;
		}

		/* set pgrp in both parent and child to deal with race
		 * condition
		 */
		setpgid(p->pid, j->pgrp);
# ifdef TTY_PGRP
		/* YYY: should this be
		   if (ttypgrp_ok && ischild && !(flags&XBGND))
			tcsetpgrp(tty_fd, j->pgrp);
		   instead? (see also YYY below)
		 */
		if (ttypgrp_ok && dotty && !(flags & XBGND))
			tcsetpgrp(tty_fd, j->pgrp);
# endif /* TTY_PGRP */
# ifdef NEED_PGRP_SYNC
		if (first_child_sync) {
			char c;
			while (read(j_sync_pipe[0], &c, 1) == -1
			       && errno == EINTR)
				;
			close(j_sync_pipe[0]);
			j_sync_open = 0;
		}
# endif /* NEED_PGRP_SYNC */
	}
#endif /* JOBS */

	/* used to close pipe input fd */
	if (close_fd >= 0 && (((flags & XPCLOSE) && !ischild)
			      || ((flags & XCCLOSE) && ischild)))
		close(close_fd);
	if (ischild) {		/* child */
#ifdef KSH
		/* Do this before restoring signal */
		if (flags & XCOPROC)
			coproc_cleanup(FALSE);
#endif /* KSH */
#ifdef JOB_SIGS
		sigprocmask(SIG_SETMASK, &omask, (sigset_t *) 0);
#endif /* JOB_SIGS */
		cleanup_parents_env();
#ifdef TTY_PGRP
		/* If FMONITOR or FTALKING is set, these signals are ignored,
		 * if neither FMONITOR nor FTALKING are set, the signals have
		 * their inherited values.
		 */
		if (Flag(FMONITOR) && !(flags & XXCOM)) {
			for (i = NELEM(tt_sigs); --i >= 0; )
				setsig(&sigtraps[tt_sigs[i]], SIG_DFL,
					SS_RESTORE_DFL|SS_FORCE);
		}
#endif /* TTY_PGRP */
#ifdef HAVE_NICE
		if (Flag(FBGNICE) && (flags & XBGND))
			nice(4);
#endif /* HAVE_NICE */
		if ((flags & XBGND) && !Flag(FMONITOR)) {
			setsig(&sigtraps[SIGINT], SIG_IGN,
				SS_RESTORE_IGN|SS_FORCE);
			setsig(&sigtraps[SIGQUIT], SIG_IGN,
				SS_RESTORE_IGN|SS_FORCE);
			if (!(flags & (XPIPEI | XCOPROC))) {
				int fd = open("/dev/null", 0);
				(void) ksh_dup2(fd, 0, TRUE);
				close(fd);