msh.c

shell-HHARM9200.rar 华恒 AT91rm9200 中Busybox shell的源代码

	while ((int)sbrk(0) & ALIGN)
		sbrk(1);
	areabot = (struct region *)sbrk(REGSIZE);

	areabot->next = areabot;
	areabot->area = BUSY;
	areatop = areabot;
	areanxt = areabot;
}

char *
getcell(nbytes)
unsigned nbytes;
{
	register int nregio;
	register struct region *p, *q;
	register int i;

	if (nbytes == 0) {
		puts("getcell(0)");
		abort();
	}	/* silly and defeats the algorithm */
	/*
	 * round upwards and add administration area
	 */
	nregio = (nbytes+(REGSIZE-1))/REGSIZE + 1;
	for (p = areanxt;;) {
		if (p->area > areanum) {
			/*
			 * merge free cells
			 */
			while ((q = p->next)->area > areanum && q != areanxt)
				p->next = q->next;
			/*
			 * exit loop if cell big enough
			 */
			if (q >= p + nregio)
				goto found;
		}
		p = p->next;
		if (p == areanxt)
			break;
	}
	i = nregio >= GROWBY ? nregio : GROWBY;
	p = (struct region *)sbrk(i * REGSIZE);
	if (p == (struct region *)-1)
		return((char *)NULL);
	p--;
	if (p != areatop) {
		puts("not contig");
		abort();	/* allocated areas are contiguous */
	}
	q = p + i;
	p->next = q;
	p->area = FREE;
	q->next = areabot;
	q->area = BUSY;
	areatop = q;
found:
	/*
	 * we found a FREE area big enough, pointed to by 'p', and up to 'q'
	 */
	areanxt = p + nregio;
	if (areanxt < q) {
		/*
		 * split into requested area and rest
		 */
		if (areanxt+1 > q) {
			puts("OOM");
			abort();	/* insufficient space left for admin */
		}
		areanxt->next = q;
		areanxt->area = FREE;
		p->next = areanxt;
	}
	p->area = areanum;
	return((char *)(p+1));
}

static void
freecell(cp)
char *cp;
{
	register struct region *p;

	if ((p = (struct region *)cp) != NULL) {
		p--;
		if (p < areanxt)
			areanxt = p;
		p->area = FREE;
	}
}

static void
freearea(a)
register int a;
{
	register struct region *p, *top;

	top = areatop;
	for (p = areabot; p != top; p = p->next)
		if (p->area >= a)
			p->area = FREE;
}

static void
setarea(cp,a)
char *cp;
int a;
{
	register struct region *p;

	if ((p = (struct region *)cp) != NULL)
		(p-1)->area = a;
}

int
getarea(cp)
char *cp;
{
	return ((struct region*)cp-1)->area;
}

static void
garbage()
{
	register struct region *p, *q, *top;

	top = areatop;
	for (p = areabot; p != top; p = p->next) {
		if (p->area > areanum) {
			while ((q = p->next)->area > areanum)
				p->next = q->next;
			areanxt = p;
		}
	}
#ifdef SHRINKBY
	if (areatop >= q + SHRINKBY && q->area > areanum) {
		brk((char *)(q+1));
		q->next = areabot;
		q->area = BUSY;
		areatop = q;
	}
#endif
}

/* -------- csyn.c -------- */
/*
 * shell: syntax (C version)
 */


int
yyparse()
{
	startl  = 1;
	peeksym = 0;
	yynerrs = 0;
	outtree = c_list();
	musthave('\n', 0);
	return(yynerrs!=0);
}

static struct op *
pipeline(cf)
int cf;
{
	register struct op *t, *p;
	register int c;

	t = command(cf);
	if (t != NULL) {
		while ((c = yylex(0)) == '|') {
			if ((p = command(CONTIN)) == NULL)
				SYNTAXERR;
			if (t->type != TPAREN && t->type != TCOM) {
				/* shell statement */
				t = block(TPAREN, t, NOBLOCK, NOWORDS);
			}
			t = block(TPIPE, t, p, NOWORDS);
		}
		peeksym = c;
	}
	return(t);
}

static struct op *
andor()
{
	register struct op *t, *p;
	register int c;

	t = pipeline(0);
	if (t != NULL) {
		while ((c = yylex(0)) == LOGAND || c == LOGOR) {
			if ((p = pipeline(CONTIN)) == NULL)
				SYNTAXERR;
			t = block(c == LOGAND? TAND: TOR, t, p, NOWORDS);
		}
		peeksym = c;
	}
	return(t);
}

static struct op *
c_list()
{
	register struct op *t, *p;
	register int c;

	t = andor();
	if (t != NULL) {
		if((peeksym = yylex(0)) == '&')
			t = block(TASYNC, t, NOBLOCK, NOWORDS);
		while ((c = yylex(0)) == ';' || c == '&' || (multiline && c == '\n')) {
			if ((p = andor()) == NULL)
				return(t);
			if((peeksym = yylex(0)) == '&')
				p = block(TASYNC, p, NOBLOCK, NOWORDS);
			t = list(t, p);
		}
		peeksym = c;
	}
	return(t);
}


static int
synio(cf)
int cf;
{
	register struct ioword *iop;
	register int i;
	register int c;

	if ((c = yylex(cf)) != '<' && c != '>') {
		peeksym = c;
		return(0);
	}
	i = yylval.i;
	musthave(WORD, 0);
	iop = io(iounit, i, yylval.cp);
	iounit = IODEFAULT;
	if (i & IOHERE)
		markhere(yylval.cp, iop);
	return(1);
}

static void
musthave(c, cf)
int c, cf;
{
	if ((peeksym = yylex(cf)) != c)
		SYNTAXERR;
	peeksym = 0;
}

static struct op *
simple()
{
	register struct op *t;

	t = NULL;
	for (;;) {
		switch (peeksym = yylex(0)) {
		case '<':
		case '>':
			(void) synio(0);
			break;

		case WORD:
			if (t == NULL) {
				t = newtp();
				t->type = TCOM;
			}
			peeksym = 0;
			word(yylval.cp);
			break;

		default:
			return(t);
		}
	}
}

static struct op *
nested(type, mark)
int type, mark;
{
	register struct op *t;

	multiline++;
	t = c_list();
	musthave(mark, 0);
	multiline--;
	return(block(type, t, NOBLOCK, NOWORDS));
}

static struct op *
command(cf)
int cf;
{
	register struct op *t;
	struct wdblock *iosave;
	register int c;

	iosave = iolist;
	iolist = NULL;
	if (multiline)
		cf |= CONTIN;
	while (synio(cf))
		cf = 0;
	switch (c = yylex(cf)) {
	default:
		peeksym = c;
		if ((t = simple()) == NULL) {
			if (iolist == NULL)
				return((struct op *)NULL);
			t = newtp();
			t->type = TCOM;
		}
		break;

	case '(':
		t = nested(TPAREN, ')');
		break;

	case '{':
		t = nested(TBRACE, '}');
		break;

	case FOR:
		t = newtp();
		t->type = TFOR;
		musthave(WORD, 0);
		startl = 1;
		t->str = yylval.cp;
		multiline++;
		t->words = wordlist();
		if ((c = yylex(0)) != '\n' && c != ';')
			peeksym = c;
		t->left = dogroup(0);
		multiline--;
		break;

	case WHILE:
	case UNTIL:
		multiline++;
		t = newtp();
		t->type = c == WHILE? TWHILE: TUNTIL;
		t->left = c_list();
		t->right = dogroup(1);
		t->words = NULL;
		multiline--;
		break;

	case CASE:
		t = newtp();
		t->type = TCASE;
		musthave(WORD, 0);
		t->str = yylval.cp;
		startl++;
		multiline++;
		musthave(IN, CONTIN);
		startl++;
		t->left = caselist();
		musthave(ESAC, 0);
		multiline--;
		break;

	case IF:
		multiline++;
		t = newtp();
		t->type = TIF;
		t->left = c_list();
		t->right = thenpart();
		musthave(FI, 0);
		multiline--;
		break;
	}
	while (synio(0))
		;
	t = namelist(t);
	iolist = iosave;
	return(t);
}

static struct op *
dogroup(onlydone)
int onlydone;
{
	register int c;
	register struct op *mylist;

	c = yylex(CONTIN);
	if (c == DONE && onlydone)
		return((struct op *)NULL);
	if (c != DO)
		SYNTAXERR;
	mylist = c_list();
	musthave(DONE, 0);
	return(mylist);
}

static struct op *
thenpart()
{
	register int c;
	register struct op *t;

	if ((c = yylex(0)) != THEN) {
		peeksym = c;
		return((struct op *)NULL);
	}
	t = newtp();
	t->type = 0;
	t->left = c_list();
	if (t->left == NULL)
		SYNTAXERR;
	t->right = elsepart();
	return(t);
}

static struct op *
elsepart()
{
	register int c;
	register struct op *t;

	switch (c = yylex(0)) {
	case ELSE:
		if ((t = c_list()) == NULL)
			SYNTAXERR;
		return(t);

	case ELIF:
		t = newtp();
		t->type = TELIF;
		t->left = c_list();
		t->right = thenpart();
		return(t);

	default:
		peeksym = c;
		return((struct op *)NULL);
	}
}

static struct op *
caselist()
{
	register struct op *t;

	t = NULL;
	while ((peeksym = yylex(CONTIN)) != ESAC)
		t = list(t, casepart());
	return(t);
}

static struct op *
casepart()
{
	register struct op *t;

	t = newtp();
	t->type = TPAT;
	t->words = pattern();
	musthave(')', 0);
	t->left = c_list();
	if ((peeksym = yylex(CONTIN)) != ESAC)
		musthave(BREAK, CONTIN);
	return(t);
}

static char **
pattern()
{
	register int c, cf;

	cf = CONTIN;
	do {
		musthave(WORD, cf);
		word(yylval.cp);
		cf = 0;
	} while ((c = yylex(0)) == '|');
	peeksym = c;
	word(NOWORD);
	return(copyw());
}

static char **
wordlist()
{
	register int c;

	if ((c = yylex(0)) != IN) {
		peeksym = c;
		return((char **)NULL);
	}
	startl = 0;
	while ((c = yylex(0)) == WORD)
		word(yylval.cp);
	word(NOWORD);
	peeksym = c;
	return(copyw());
}

/*
 * supporting functions
 */
static struct op *
list(t1, t2)
register struct op *t1, *t2;
{
	if (t1 == NULL)
		return(t2);
	if (t2 == NULL)
		return(t1);
	return(block(TLIST, t1, t2, NOWORDS));
}

static struct op *
block(type, t1, t2, wp)
int type;
struct op *t1, *t2;
char **wp;
{
	register struct op *t;

	t = newtp();
	t->type = type;
	t->left = t1;
	t->right = t2;
	t->words = wp;
	return(t);
}

static int
rlookup(n)
register char *n;
{
	register struct res *rp;

	for (rp = restab; rp->r_name; rp++)
		if (strcmp(rp->r_name, n) == 0)
			return(rp->r_val);
	return(0);
}

static struct op *
newtp()
{
	register struct op *t;

	t = (struct op *)tree(sizeof(*t));
	t->type = 0;
	t->words = NULL;
	t->ioact = NULL;
	t->left = NULL;
	t->right = NULL;
	t->str = NULL;
	return(t);
}

static struct op *
namelist(t)
register struct op *t;
{
	if (iolist) {
		iolist = addword((char *)NULL, iolist);
		t->ioact = copyio();
	} else
		t->ioact = NULL;
	if (t->type != TCOM) {
		if (t->type != TPAREN && t->ioact != NULL) {
			t = block(TPAREN, t, NOBLOCK, NOWORDS);
			t->ioact = t->left->ioact;
			t->left->ioact = NULL;
		}
		return(t);
	}
	word(NOWORD);
	t->words = copyw();
	return(t);
}

static char **
copyw()
{
	register char **wd;

	wd = getwords(wdlist);
	wdlist = 0;
	return(wd);
}

static void
word(cp)
char *cp;
{
	wdlist = addword(cp, wdlist);
}

static struct ioword **
copyio()
{
	register struct ioword **iop;

	iop = (struct ioword **) getwords(iolist);
	iolist = 0;
	return(iop);
}

static struct ioword *
io(u, f, cp)
int u;
int f;
char *cp;
{
	register struct ioword *iop;

	iop = (struct ioword *) tree(sizeof(*iop));
	iop->io_unit = u;
	iop->io_flag = f;
	iop->io_name = cp;
	iolist = addword((char *)iop, iolist);
	return(iop);
}

static void
zzerr()
{
	yyerror("syntax error");
}

static void
yyerror(s)
char *s;
{
	yynerrs++;
	if (interactive && e.iop <= iostack) {
		multiline = 0;
		while (eofc() == 0 && yylex(0) != '\n')
			;
	}
	err(s);
	fail();
}

static int
yylex(cf)
int cf;
{
	register int c, c1;
	int atstart;

	if ((c = peeksym) > 0) {
		peeksym = 0;
		if (c == '\n')
			startl = 1;
		return(c);
	}
	nlseen = 0;
	e.linep = line;
	atstart = startl;
	startl = 0;
	yylval.i = 0;

loop:
	while ((c = my_getc(0)) == ' ' || c == '\t')
		;
	switch (c) {
	default:
		if (any(c, "0123456789")) {
			unget(c1 = my_getc(0));
			if (c1 == '<' || c1 == '>') {
				iounit = c - '0';
				goto loop;
			}
			*e.linep++ = c;
			c = c1;
		}
		break;

	case '#':
		while ((c = my_getc(0)) != 0 && c != '\n')
			;
		unget(c);
		goto loop;

	case 0:
		return(c);

	case '$':
		*e.linep++ = c;
		if ((c = my_getc(0)) == '{') {
			if ((c = collect(c, '}')) != '\0')
				return(c);
			goto pack;
		}
		break;

	case '`':
	case '\'':
	case '"':
		if ((c = collect(c, c)) != '\0')
			return(c);
		goto pack;

	case '|':
	case '&':
	case ';':
		if ((c1 = dual(c)) != '\0') {
			startl = 1;
			return(c1);
		}
		startl = 1;