sh3.c

操作系统源代码

#define Extern extern
#include <sys/types.h>
#include <signal.h>
#include <errno.h>
#include <setjmp.h>
#include <stddef.h>
#include <time.h>
#include <sys/times.h>
#include <sys/stat.h>
#include <sys/wait.h>
#undef NULL
#include "sh.h"

/* -------- exec.c -------- */
/* #include "sh.h" */

/*
 * execute tree
 */

static	char	*signame[] = {
	"Signal 0",
	"Hangup",
	(char *)NULL,	/* interrupt */
	"Quit",
	"Illegal instruction",
	"Trace/BPT trap",
	"Abort",
	"EMT trap",
	"Floating exception",
	"Killed",
	"Bus error",
	"Memory fault",
	"Bad system call",
	(char *)NULL,	/* broken pipe */
	"Alarm clock",
	"Terminated",
};
#define	NSIGNAL (sizeof(signame)/sizeof(signame[0]))


_PROTOTYPE(static int forkexec, (struct op *t, int *pin, int *pout, int act, char **wp, int *pforked ));
_PROTOTYPE(static int parent, (void));
_PROTOTYPE(int iosetup, (struct ioword *iop, int pipein, int pipeout ));
_PROTOTYPE(static void echo, (char **wp ));
_PROTOTYPE(static struct op **find1case, (struct op *t, char *w ));
_PROTOTYPE(static struct op *findcase, (struct op *t, char *w ));
_PROTOTYPE(static void brkset, (struct brkcon *bc ));
_PROTOTYPE(int dolabel, (void));
_PROTOTYPE(int dochdir, (struct op *t ));
_PROTOTYPE(int doshift, (struct op *t ));
_PROTOTYPE(int dologin, (struct op *t ));
_PROTOTYPE(int doumask, (struct op *t ));
_PROTOTYPE(int doexec, (struct op *t ));
_PROTOTYPE(int dodot, (struct op *t ));
_PROTOTYPE(int dowait, (struct op *t ));
_PROTOTYPE(int doread, (struct op *t ));
_PROTOTYPE(int doeval, (struct op *t ));
_PROTOTYPE(int dotrap, (struct op *t ));
_PROTOTYPE(int getsig, (char *s ));
_PROTOTYPE(void setsig, (int n, void (*f)()));
_PROTOTYPE(int getn, (char *as ));
_PROTOTYPE(int dobreak, (struct op *t ));
_PROTOTYPE(int docontinue, (struct op *t ));
_PROTOTYPE(static int brkcontin, (char *cp, int val ));
_PROTOTYPE(int doexit, (struct op *t ));
_PROTOTYPE(int doexport, (struct op *t ));
_PROTOTYPE(int doreadonly, (struct op *t ));
_PROTOTYPE(static void rdexp, (char **wp, void (*f)(), int key));
_PROTOTYPE(static void badid, (char *s ));
_PROTOTYPE(int doset, (struct op *t ));
_PROTOTYPE(void varput, (char *s, int out ));
_PROTOTYPE(int dotimes, (void));

int
execute(t, pin, pout, act)
register struct op *t;
int *pin, *pout;
int act;
{
	register struct op *t1;
	int i, pv[2], rv, child, a;
	char *cp, **wp, **wp2;
	struct var *vp;
	struct brkcon bc;

	if (t == NULL)
		return(0);
	rv = 0;
	a = areanum++;
	wp = (wp2 = t->words) != NULL
	     ? eval(wp2, t->type == TCOM ? DOALL : DOALL & ~DOKEY)
	     : NULL;

	switch(t->type) {
	case TPAREN:
	case TCOM:
		rv = forkexec(t, pin, pout, act, wp, &child);
		if (child) {
			exstat = rv;
			leave();
		}
		break;

	case TPIPE:
		if ((rv = openpipe(pv)) < 0)
			break;
		pv[0] = remap(pv[0]);
		pv[1] = remap(pv[1]);
		(void) execute(t->left, pin, pv, 0);
		rv = execute(t->right, pv, pout, 0);
		break;

	case TLIST:
		(void) execute(t->left, pin, pout, 0);
		rv = execute(t->right, pin, pout, 0);
		break;

	case TASYNC:
		i = parent();
		if (i != 0) {
			if (i != -1) {
				setval(lookup("!"), putn(i));
				if (pin != NULL)
					closepipe(pin);
				if (talking) {
					prs(putn(i));
					prs("\n");
				}
			} else
				rv = -1;
			setstatus(rv);
		} else {
			signal(SIGINT, SIG_IGN);
			signal(SIGQUIT, SIG_IGN);
			if (talking)
				signal(SIGTERM, SIG_DFL);
			talking = 0;
			if (pin == NULL) {
				close(0);
				open("/dev/null", 0);
			}
			exit(execute(t->left, pin, pout, FEXEC));
		}
		break;

	case TOR:
	case TAND:
		rv = execute(t->left, pin, pout, 0);
		if ((t1 = t->right)!=NULL && (rv == 0) == (t->type == TAND))
			rv = execute(t1, pin, pout, 0);
		break;

	case TFOR:
		if (wp == NULL) {
			wp = dolv+1;
			if ((i = dolc) < 0)
				i = 0;
		} else {
			i = -1;
			while (*wp++ != NULL)
				;			
		}
		vp = lookup(t->str);
		while (setjmp(bc.brkpt))
			if (isbreak)
				goto broken;
		brkset(&bc);
		for (t1 = t->left; i-- && *wp != NULL;) {
			setval(vp, *wp++);
			rv = execute(t1, pin, pout, 0);
		}
		brklist = brklist->nextlev;
		break;

	case TWHILE:
	case TUNTIL:
		while (setjmp(bc.brkpt))
			if (isbreak)
				goto broken;
		brkset(&bc);
		t1 = t->left;
		while ((execute(t1, pin, pout, 0) == 0) == (t->type == TWHILE))
			rv = execute(t->right, pin, pout, 0);
		brklist = brklist->nextlev;
		break;

	case TIF:
	case TELIF:
	 	if (t->right != NULL) {
		rv = !execute(t->left, pin, pout, 0) ?
			execute(t->right->left, pin, pout, 0):
			execute(t->right->right, pin, pout, 0);
		}
		break;

	case TCASE:
		if ((cp = evalstr(t->str, DOSUB|DOTRIM)) == 0)
			cp = "";
		if ((t1 = findcase(t->left, cp)) != NULL)
			rv = execute(t1, pin, pout, 0);
		break;

	case TBRACE:
/*
		if (iopp = t->ioact)
			while (*iopp)
				if (iosetup(*iopp++, pin!=NULL, pout!=NULL)) {
					rv = -1;
					break;
				}
*/
		if (rv >= 0 && (t1 = t->left))
			rv = execute(t1, pin, pout, 0);
		break;
	}

broken:
	t->words = wp2;
	isbreak = 0;
	freehere(areanum);
	freearea(areanum);
	areanum = a;
	if (talking && intr) {
		closeall();
		fail();
	}
	if ((i = trapset) != 0) {
		trapset = 0;
		runtrap(i);
	}
	return(rv);
}

static int
forkexec(t, pin, pout, act, wp, pforked)
register struct op *t;
int *pin, *pout;
int act;
char **wp;
int *pforked;
{
	int i, rv, (*shcom)();
	register int f;
	char *cp;
	struct ioword **iopp;
	int resetsig;
	char **owp;

	owp = wp;
	resetsig = 0;
	*pforked = 0;
	shcom = NULL;
	rv = -1;	/* system-detected error */
	if (t->type == TCOM) {
		while ((cp = *wp++) != NULL)
			;
		cp = *wp;

		/* strip all initial assignments */
		/* not correct wrt PATH=yyy command  etc */
		if (flag['x'])
			echo (cp ? wp: owp);
		if (cp == NULL && t->ioact == NULL) {
			while ((cp = *owp++) != NULL && assign(cp, COPYV))
				;
			return(setstatus(0));
		}
		else if (cp != NULL)
			shcom = inbuilt(cp);
	}
	t->words = wp;
	f = act;
	if (shcom == NULL && (f & FEXEC) == 0) {
		i = parent();
		if (i != 0) {
			if (i == -1)
				return(rv);
			if (pin != NULL)
				closepipe(pin);
			return(pout==NULL? setstatus(waitfor(i,0)): 0);
		}
		if (talking) {
			signal(SIGINT, SIG_IGN);
			signal(SIGQUIT, SIG_IGN);
			resetsig = 1;
		}
		talking = 0;
		intr = 0;
		(*pforked)++;
		brklist = 0;
		execflg = 0;
	}
	if (owp != NULL)
		while ((cp = *owp++) != NULL && assign(cp, COPYV))
			if (shcom == NULL)
				export(lookup(cp));
#ifdef COMPIPE
	if ((pin != NULL || pout != NULL) && shcom != NULL && shcom != doexec) {
		err("piping to/from shell builtins not yet done");
		return(-1);
	}
#endif
	if (pin != NULL) {
		dup2(pin[0], 0);
		closepipe(pin);
	}
	if (pout != NULL) {
		dup2(pout[1], 1);
		closepipe(pout);
	}
	if ((iopp = t->ioact) != NULL) {
		if (shcom != NULL && shcom != doexec) {
			prs(cp);
			err(": cannot redirect shell command");
			return(-1);
		}
		while (*iopp)
			if (iosetup(*iopp++, pin!=NULL, pout!=NULL))
				return(rv);
	}
	if (shcom)
		return(setstatus((*shcom)(t)));
	/* should use FIOCEXCL */
	for (i=FDBASE; i<NOFILE; i++)
		close(i);
	if (resetsig) {
		signal(SIGINT, SIG_DFL);
		signal(SIGQUIT, SIG_DFL);
	}
	if (t->type == TPAREN)
		exit(execute(t->left, NOPIPE, NOPIPE, FEXEC));
	if (wp[0] == NULL)
		exit(0);
	cp = rexecve(wp[0], wp, makenv());
	prs(wp[0]); prs(": "); warn(cp);
	if (!execflg)
		trap[0] = NULL;
	leave();
	/* NOTREACHED */
}

/*
 * common actions when creating a new child
 */
static int
parent()
{
	register int i;

	i = fork();
	if (i != 0) {
		if (i == -1)
			warn("try again");
	}
	return(i);
}

/*
 * 0< 1> are ignored as required
 * within pipelines.
 */
int
iosetup(iop, pipein, pipeout)
register struct ioword *iop;
int pipein, pipeout;
{
	register u;
	char *cp, *msg;

	if (iop->io_unit == IODEFAULT)	/* take default */
		iop->io_unit = iop->io_flag&(IOREAD|IOHERE)? 0: 1;
	if (pipein && iop->io_unit == 0)
		return(0);
	if (pipeout && iop->io_unit == 1)
		return(0);
	msg = iop->io_flag&(IOREAD|IOHERE)? "open": "create";
	if ((iop->io_flag & IOHERE) == 0) {
		cp = iop->io_name;
		if ((cp = evalstr(cp, DOSUB|DOTRIM)) == NULL)
			return(1);
	}
	if (iop->io_flag & IODUP) {
		if (cp[1] || (!digit(*cp) && *cp != '-')) {
			prs(cp);
			err(": illegal >& argument");
			return(1);
		}
		if (*cp == '-')
			iop->io_flag = IOCLOSE;
		iop->io_flag &= ~(IOREAD|IOWRITE);
	}
	switch (iop->io_flag) {
	case IOREAD:
		u = open(cp, 0);
		break;

	case IOHERE:
	case IOHERE|IOXHERE:
		u = herein(iop->io_name, iop->io_flag&IOXHERE);
		cp = "here file";
		break;

	case IOWRITE|IOCAT:
		if ((u = open(cp, 1)) >= 0) {
			lseek(u, (long)0, 2);
			break;
		}
	case IOWRITE:
		u = creat(cp, 0666);
		break;

	case IODUP:
		u = dup2(*cp-'0', iop->io_unit);
		break;

	case IOCLOSE:
		close(iop->io_unit);
		return(0);
	}
	if (u < 0) {
		prs(cp);
		prs(": cannot ");
		warn(msg);
		return(1);
	} else {
		if (u != iop->io_unit) {
			dup2(u, iop->io_unit);
			close(u);
		}
	}
	return(0);
}

static void
echo(wp)
register char **wp;
{
	register i;

	prs("+");
	for (i=0; wp[i]; i++) {
		if (i)
			prs(" ");
		prs(wp[i]);
	}
	prs("\n");
}

static struct op **
find1case(t, w)
struct op *t;
char *w;
{
	register struct op *t1;
	struct op **tp;
	register char **wp, *cp;

	if (t == NULL)
		return((struct op **)NULL);
	if (t->type == TLIST) {
		if ((tp = find1case(t->left, w)) != NULL)
			return(tp);
		t1 = t->right;	/* TPAT */
	} else
		t1 = t;
	for (wp = t1->words; *wp;)
		if ((cp = evalstr(*wp++, DOSUB)) && gmatch(w, cp))
			return(&t1->left);
	return((struct op **)NULL);
}

static struct op *
findcase(t, w)
struct op *t;
char *w;
{
	register struct op **tp;

	return((tp = find1case(t, w)) != NULL? *tp: (struct op *)NULL);
}

/*
 * Enter a new loop level (marked for break/continue).
 */
static void
brkset(bc)
struct brkcon *bc;
{
	bc->nextlev = brklist;
	brklist = bc;
}

/*
 * Wait for the last process created.
 * Print a message for each process found
 * that was killed by a signal.
 * Ignore interrupt signals while waiting
 * unless `canintr' is true.
 */
int
waitfor(lastpid, canintr)
register int lastpid;
int canintr;
{
	register int pid, rv;
	int s;
	int oheedint = heedint;

	heedint = 0;
	rv = 0;
	do {
		pid = wait(&s);
		if (pid == -1) {
			if (errno != EINTR || canintr)
				break;
		} else {
			if ((rv = WAITSIG(s)) != 0) {
				if (rv < NSIGNAL) {
					if (signame[rv] != NULL) {
						if (pid != lastpid) {
							prn(pid);
							prs(": ");
						}
						prs(signame[rv]);
					}
				} else {
					if (pid != lastpid) {
						prn(pid);
						prs(": ");
					}
					prs("Signal "); prn(rv); prs(" ");
				}
				if (WAITCORE(s))
					prs(" - core dumped");
				if (rv >= NSIGNAL || signame[rv])
					prs("\n");
				rv = -1;
			} else
				rv = WAITVAL(s);
		}
	} while (pid != lastpid);
	heedint = oheedint;
	if (intr)
		if (talking) {
			if (canintr)
				intr = 0;
		} else {
			if (exstat == 0) exstat = rv;
			onintr(0);
		}
	return(rv);
}

int
setstatus(s)
register int s;
{
	exstat = s;
	setval(lookup("?"), putn(s));
	return(s);
}

/*
 * PATH-searching interface to execve.
 * If getenv("PATH") were kept up-to-date,
 * execvp might be used.
 */
char *
rexecve(c, v, envp)
char *c, **v, **envp;
{