jobs.c

Android 一些工具

	}
#if JOBS
	if (jp->jobctl) {
		if (tcsetpgrp(ttyfd, mypgrp) == -1)
			error("Cannot set tty process group (%s) at %d",
			    strerror(errno), __LINE__);
	}
	if (jp->state == JOBSTOPPED && curjob != jp - jobtab)
		set_curjob(jp, 2);
#endif
	status = jp->ps[jp->nprocs - 1].status;
	/* convert to 8 bits */
	if (WIFEXITED(status))
		st = WEXITSTATUS(status);
#if JOBS
	else if (WIFSTOPPED(status))
		st = WSTOPSIG(status) + 128;
#endif
	else
		st = WTERMSIG(status) + 128;
	TRACE(("waitforjob: job %d, nproc %d, status %x, st %x\n",
		jp - jobtab + 1, jp->nprocs, status, st ));
#if JOBS
	if (jp->jobctl) {
		/*
		 * This is truly gross.
		 * If we're doing job control, then we did a TIOCSPGRP which
		 * caused us (the shell) to no longer be in the controlling
		 * session -- so we wouldn't have seen any ^C/SIGINT.  So, we
		 * intuit from the subprocess exit status whether a SIGINT
		 * occurred, and if so interrupt ourselves.  Yuck.  - mycroft
		 */
		if (WIFSIGNALED(status) && WTERMSIG(status) == SIGINT)
			raise(SIGINT);
	}
#endif
	if (! JOBS || jp->state == JOBDONE)
		freejob(jp);
	INTON;
	return st;
}



/*
 * Wait for a process to terminate.
 */

STATIC int
dowait(int block, struct job *job)
{
	int pid;
	int status;
	struct procstat *sp;
	struct job *jp;
	struct job *thisjob;
	int done;
	int stopped;
	extern volatile char gotsig[];

	TRACE(("dowait(%d) called\n", block));
	do {
		pid = waitproc(block, job, &status);
		TRACE(("wait returns pid %d, status %d\n", pid, status));
	} while (pid == -1 && errno == EINTR && gotsig[SIGINT - 1] == 0);
	if (pid <= 0)
		return pid;
	INTOFF;
	thisjob = NULL;
	for (jp = jobtab ; jp < jobtab + njobs ; jp++) {
		if (jp->used) {
			done = 1;
			stopped = 1;
			for (sp = jp->ps ; sp < jp->ps + jp->nprocs ; sp++) {
				if (sp->pid == -1)
					continue;
				if (sp->pid == pid) {
					TRACE(("Job %d: changing status of proc %d from 0x%x to 0x%x\n", jp - jobtab + 1, pid, sp->status, status));
					sp->status = status;
					thisjob = jp;
				}
				if (sp->status == -1)
					stopped = 0;
				else if (WIFSTOPPED(sp->status))
					done = 0;
			}
			if (stopped) {		/* stopped or done */
				int state = done ? JOBDONE : JOBSTOPPED;
				if (jp->state != state) {
					TRACE(("Job %d: changing state from %d to %d\n", jp - jobtab + 1, jp->state, state));
					jp->state = state;
#if JOBS
					if (done)
						set_curjob(jp, 0);
#endif
				}
			}
		}
	}

	if (thisjob && thisjob->state != JOBRUNNING) {
		int mode = 0;
		if (!rootshell || !iflag)
			mode = SHOW_SIGNALLED;
		if (job == thisjob)
			mode = SHOW_SIGNALLED | SHOW_NO_FREE;
		if (mode)
			showjob(out2, thisjob, mode);
		else {
			TRACE(("Not printing status, rootshell=%d, job=%p\n",
				rootshell, job));
			thisjob->changed = 1;
		}
	}

	INTON;
	return pid;
}



/*
 * Do a wait system call.  If job control is compiled in, we accept
 * stopped processes.  If block is zero, we return a value of zero
 * rather than blocking.
 *
 * System V doesn't have a non-blocking wait system call.  It does
 * have a SIGCLD signal that is sent to a process when one of it's
 * children dies.  The obvious way to use SIGCLD would be to install
 * a handler for SIGCLD which simply bumped a counter when a SIGCLD
 * was received, and have waitproc bump another counter when it got
 * the status of a process.  Waitproc would then know that a wait
 * system call would not block if the two counters were different.
 * This approach doesn't work because if a process has children that
 * have not been waited for, System V will send it a SIGCLD when it
 * installs a signal handler for SIGCLD.  What this means is that when
 * a child exits, the shell will be sent SIGCLD signals continuously
 * until is runs out of stack space, unless it does a wait call before
 * restoring the signal handler.  The code below takes advantage of
 * this (mis)feature by installing a signal handler for SIGCLD and
 * then checking to see whether it was called.  If there are any
 * children to be waited for, it will be.
 *
 * If neither SYSV nor BSD is defined, we don't implement nonblocking
 * waits at all.  In this case, the user will not be informed when
 * a background process until the next time she runs a real program
 * (as opposed to running a builtin command or just typing return),
 * and the jobs command may give out of date information.
 */

#ifdef SYSV
STATIC int gotsigchild;

STATIC int onsigchild() {
	gotsigchild = 1;
}
#endif


STATIC int
waitproc(int block, struct job *jp, int *status)
{
#ifdef BSD
	int flags = 0;

#if JOBS
	if (jp != NULL && jp->jobctl)
		flags |= WUNTRACED;
#endif
	if (block == 0)
		flags |= WNOHANG;
	return wait3(status, flags, (struct rusage *)NULL);
#else
#ifdef SYSV
	int (*save)();

	if (block == 0) {
		gotsigchild = 0;
		save = signal(SIGCLD, onsigchild);
		signal(SIGCLD, save);
		if (gotsigchild == 0)
			return 0;
	}
	return wait(status);
#else
	if (block == 0)
		return 0;
	return wait(status);
#endif
#endif
}

/*
 * return 1 if there are stopped jobs, otherwise 0
 */
int job_warning = 0;
int
stoppedjobs(void)
{
	int jobno;
	struct job *jp;

	if (job_warning || jobs_invalid)
		return (0);
	for (jobno = 1, jp = jobtab; jobno <= njobs; jobno++, jp++) {
		if (jp->used == 0)
			continue;
		if (jp->state == JOBSTOPPED) {
			out2str("You have stopped jobs.\n");
			job_warning = 2;
			return (1);
		}
	}

	return (0);
}

/*
 * Return a string identifying a command (to be printed by the
 * jobs command).
 */

STATIC char *cmdnextc;
STATIC int cmdnleft;

void
commandtext(struct procstat *ps, union node *n)
{
	int len;

	cmdnextc = ps->cmd;
	if (iflag || mflag || sizeof ps->cmd < 100)
		len = sizeof(ps->cmd);
	else
		len = sizeof(ps->cmd) / 10;
	cmdnleft = len;
	cmdtxt(n);
	if (cmdnleft <= 0) {
		char *p = ps->cmd + len - 4;
		p[0] = '.';
		p[1] = '.';
		p[2] = '.';
		p[3] = 0;
	} else
		*cmdnextc = '\0';
	TRACE(("commandtext: ps->cmd %x, end %x, left %d\n\t\"%s\"\n",
		ps->cmd, cmdnextc, cmdnleft, ps->cmd));
}


STATIC void
cmdtxt(union node *n)
{
	union node *np;
	struct nodelist *lp;
	const char *p;
	int i;
	char s[2];

	if (n == NULL || cmdnleft <= 0)
		return;
	switch (n->type) {
	case NSEMI:
		cmdtxt(n->nbinary.ch1);
		cmdputs("; ");
		cmdtxt(n->nbinary.ch2);
		break;
	case NAND:
		cmdtxt(n->nbinary.ch1);
		cmdputs(" && ");
		cmdtxt(n->nbinary.ch2);
		break;
	case NOR:
		cmdtxt(n->nbinary.ch1);
		cmdputs(" || ");
		cmdtxt(n->nbinary.ch2);
		break;
	case NPIPE:
		for (lp = n->npipe.cmdlist ; lp ; lp = lp->next) {
			cmdtxt(lp->n);
			if (lp->next)
				cmdputs(" | ");
		}
		break;
	case NSUBSHELL:
		cmdputs("(");
		cmdtxt(n->nredir.n);
		cmdputs(")");
		break;
	case NREDIR:
	case NBACKGND:
		cmdtxt(n->nredir.n);
		break;
	case NIF:
		cmdputs("if ");
		cmdtxt(n->nif.test);
		cmdputs("; then ");
		cmdtxt(n->nif.ifpart);
		if (n->nif.elsepart) {
			cmdputs("; else ");
			cmdtxt(n->nif.elsepart);
		}
		cmdputs("; fi");
		break;
	case NWHILE:
		cmdputs("while ");
		goto until;
	case NUNTIL:
		cmdputs("until ");
until:
		cmdtxt(n->nbinary.ch1);
		cmdputs("; do ");
		cmdtxt(n->nbinary.ch2);
		cmdputs("; done");
		break;
	case NFOR:
		cmdputs("for ");
		cmdputs(n->nfor.var);
		cmdputs(" in ");
		cmdlist(n->nfor.args, 1);
		cmdputs("; do ");
		cmdtxt(n->nfor.body);
		cmdputs("; done");
		break;
	case NCASE:
		cmdputs("case ");
		cmdputs(n->ncase.expr->narg.text);
		cmdputs(" in ");
		for (np = n->ncase.cases; np; np = np->nclist.next) {
			cmdtxt(np->nclist.pattern);
			cmdputs(") ");
			cmdtxt(np->nclist.body);
			cmdputs(";; ");
		}
		cmdputs("esac");
		break;
	case NDEFUN:
		cmdputs(n->narg.text);
		cmdputs("() { ... }");
		break;
	case NCMD:
		cmdlist(n->ncmd.args, 1);
		cmdlist(n->ncmd.redirect, 0);
		break;
	case NARG:
		cmdputs(n->narg.text);
		break;
	case NTO:
		p = ">";  i = 1;  goto redir;
	case NCLOBBER:
		p = ">|";  i = 1;  goto redir;
	case NAPPEND:
		p = ">>";  i = 1;  goto redir;
	case NTOFD:
		p = ">&";  i = 1;  goto redir;
	case NFROM:
		p = "<";  i = 0;  goto redir;
	case NFROMFD:
		p = "<&";  i = 0;  goto redir;
	case NFROMTO:
		p = "<>";  i = 0;  goto redir;
redir:
		if (n->nfile.fd != i) {
			s[0] = n->nfile.fd + '0';
			s[1] = '\0';
			cmdputs(s);
		}
		cmdputs(p);
		if (n->type == NTOFD || n->type == NFROMFD) {
			s[0] = n->ndup.dupfd + '0';
			s[1] = '\0';
			cmdputs(s);
		} else {
			cmdtxt(n->nfile.fname);
		}
		break;
	case NHERE:
	case NXHERE:
		cmdputs("<<...");
		break;
	default:
		cmdputs("???");
		break;
	}
}

STATIC void
cmdlist(union node *np, int sep)
{
	for (; np; np = np->narg.next) {
		if (!sep)
			cmdputs(" ");
		cmdtxt(np);
		if (sep && np->narg.next)
			cmdputs(" ");
	}
}


STATIC void
cmdputs(const char *s)
{
	const char *p, *str = 0;
	char c, cc[2] = " ";
	char *nextc;
	int nleft;
	int subtype = 0;
	int quoted = 0;
	static char vstype[16][4] = { "", "}", "-", "+", "?", "=",
					"#", "##", "%", "%%" };

	p = s;
	nextc = cmdnextc;
	nleft = cmdnleft;
	while (nleft > 0 && (c = *p++) != 0) {
		switch (c) {
		case CTLESC:
			c = *p++;
			break;
		case CTLVAR:
			subtype = *p++;
			if ((subtype & VSTYPE) == VSLENGTH)
				str = "${#";
			else
				str = "${";
			if (!(subtype & VSQUOTE) != !(quoted & 1)) {
				quoted ^= 1;
				c = '"';
			} else
				c = *str++;
			break;
		case CTLENDVAR:
			if (quoted & 1) {
				c = '"';
				str = "}";
			} else
				c = '}';
			quoted >>= 1;
			subtype = 0;
			break;
		case CTLBACKQ:
			c = '$';
			str = "(...)";
			break;
		case CTLBACKQ+CTLQUOTE:
			c = '"';
			str = "$(...)\"";
			break;
		case CTLARI:
			c = '$';
			str = "((";
			break;
		case CTLENDARI:
			c = ')';
			str = ")";
			break;
		case CTLQUOTEMARK:
			quoted ^= 1;
			c = '"';
			break;
		case '=':
			if (subtype == 0)
				break;
			str = vstype[subtype & VSTYPE];
			if (subtype & VSNUL)
				c = ':';
			else
				c = *str++;
			if (c != '}')
				quoted <<= 1;
			break;
		case '\'':
		case '\\':
		case '"':
		case '$':
			/* These can only happen inside quotes */
			cc[0] = c;
			str = cc;
			c = '\\';
			break;
		default:
			break;
		}
		do {
			*nextc++ = c;
		} while (--nleft > 0 && str && (c = *str++));
		str = 0;
	}
	if ((quoted & 1) && nleft) {
		*nextc++ = '"';
		nleft--;
	}
	cmdnleft = nleft;
	cmdnextc = nextc;
}