eval.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。

			 * word is generated if $# is 0 (unless there is
			 * other stuff inside the quotes).
			 */
			type = XBASE;
			if (f&DOBLANK) {
				doblank--;
				/* not really correct: x=; "$x$@" should
				 * generate a null argument and
				 * set A; "${@:+}" shouldn't.
				 */
				if (dp == Xstring(ds, dp))
					word = IFS_WS;
			}
			continue;

		  case XSUB:
			if ((c = *x.str++) == 0) {
				type = XBASE;
				if (f&DOBLANK)
					doblank--;
				continue;
			}
			break;

		  case XARGSEP:
			type = XARG;
			quote = 1;
		  case XARG:
			if ((c = *x.str++) == '\0') {
				/* force null words to be created so
				 * set -- '' 2 ''; foo "$@" will do
				 * the right thing
				 */
				if (quote && x.split)
					word = IFS_WORD;
				if ((x.str = *x.u.strv++) == NULL) {
					type = XBASE;
					if (f&DOBLANK)
						doblank--;
					continue;
				}
				c = ifs0;
				if (c == 0) {
					if (quote && !x.split)
						continue;
					c = ' ';
				}
				if (quote && x.split) {
					/* terminate word for "$@" */
					type = XARGSEP;
					quote = 0;
				}
			}
			break;

		  case XCOM:
			if (newlines) {		/* Spit out saved nl's */
				c = '\n';
				--newlines;
			} else {
				while ((c = shf_getc(x.u.shf)) == 0 || c == '\n')
				    if (c == '\n')
					    newlines++;	/* Save newlines */
				if (newlines && c != EOF) {
					shf_ungetc(c, x.u.shf);
					c = '\n';
					--newlines;
				}
			}
			if (c == EOF) {
				newlines = 0;
				shf_close(x.u.shf);
				if (x.split)
					subst_exstat = waitlast();
				type = XBASE;
				if (f&DOBLANK)
					doblank--;
				continue;
			}
			break;
		}

		/* check for end of word or IFS separation */
		if (c == 0 || (!quote && (f & DOBLANK) && doblank && !make_magic
			       && ctype(c, C_IFS)))
		{
			/* How words are broken up:
			 *		   |       value of c
			 *	  word	   |	ws	nws	0
			 *	-----------------------------------
			 *	IFS_WORD	w/WS	w/NWS	w
			 *	IFS_WS		-/WS	w/NWS	-
			 *	IFS_NWS		-/NWS	w/NWS	w
			 *   (w means generate a word)
			 * Note that IFS_NWS/0 generates a word (at&t ksh
			 * doesn't do this, but POSIX does).
			 */
			if (word == IFS_WORD
			    || (!ctype(c, C_IFSWS) && (c || word == IFS_NWS)))
			{
				char *p;

				*dp++ = '\0';
				p = Xclose(ds, dp);
#ifdef BRACE_EXPAND
				if (fdo & DOBRACE_)
					/* also does globbing */
					alt_expand(wp, p, p,
						   p + Xlength(ds, (dp - 1)),
						   fdo | (f & DOMARKDIRS));
				else
#endif /* BRACE_EXPAND */
				if (fdo & DOGLOB)
					glob(p, wp, f & DOMARKDIRS);
				else if ((f & DOPAT) || !(fdo & DOMAGIC_))
					XPput(*wp, p);
				else
					XPput(*wp, debunk(p, p));
				fdo = 0;
				saw_eq = 0;
				tilde_ok = (f & (DOTILDE|DOASNTILDE)) ? 1 : 0;
				if (c != 0)
					Xinit(ds, dp, 128, ATEMP);
			}
			if (c == 0)
				return;
			if (word != IFS_NWS)
				word = ctype(c, C_IFSWS) ? IFS_WS : IFS_NWS;
		} else {
			/* age tilde_ok info - ~ code tests second bit */
			tilde_ok <<= 1;
			/* mark any special second pass chars */
			if (!quote)
				switch (c) {
				  case '[':
				  case NOT:
				  case '-':
				  case ']':
					/* For character classes - doesn't hurt
					 * to have magic !,-,]'s outside of
					 * [...] expressions.
					 */
					if (f & (DOPAT | DOGLOB)) {
						fdo |= DOMAGIC_;
						if (c == '[')
							fdo |= f & DOGLOB;
						*dp++ = MAGIC;
					}
					break;
				  case '*':
				  case '?':
					if (f & (DOPAT | DOGLOB)) {
						fdo |= DOMAGIC_ | (f & DOGLOB);
						*dp++ = MAGIC;
					}
					break;
#ifdef BRACE_EXPAND
				  case OBRACE:
				  case ',':
				  case CBRACE:
					if ((f & DOBRACE_) && (c == OBRACE
						|| (fdo & DOBRACE_)))
					{
						fdo |= DOBRACE_|DOMAGIC_;
						*dp++ = MAGIC;
					}
					break;
#endif /* BRACE_EXPAND */
				  case '=':
					/* Note first unquoted = for ~ */
					if (!(f & DOTEMP_) && !saw_eq) {
						saw_eq = 1;
						tilde_ok = 1;
					}
					break;
				  case PATHSEP: /* : */
					/* Note unquoted : for ~ */
					if (!(f & DOTEMP_) && (f & DOASNTILDE))
						tilde_ok = 1;
					break;
				  case '~':
					/* tilde_ok is reset whenever
					 * any of ' " $( $(( ${ } are seen.
					 * Note that tilde_ok must be preserved
					 * through the sequence ${A=a=}~
					 */
					if (type == XBASE
					    && (f & (DOTILDE|DOASNTILDE))
					    && (tilde_ok & 2))
					{
						char *p, *dp_x;

						dp_x = dp;
						p = maybe_expand_tilde(sp,
							&ds, &dp_x,
							f & DOASNTILDE);
						if (p) {
							if (dp != dp_x)
								word = IFS_WORD;
							dp = dp_x;
							sp = p;
							continue;
						}
					}
					break;
				}
			else
				quote &= ~2; /* undo temporary */

			if (make_magic) {
				make_magic = 0;
				fdo |= DOMAGIC_ | (f & DOGLOB);
				*dp++ = MAGIC;
			} else if (ISMAGIC(c)) {
				fdo |= DOMAGIC_;
				*dp++ = MAGIC;
			}
			*dp++ = c; /* save output char */
			word = IFS_WORD;
		}
	}
}

/*
 * Prepare to generate the string returned by ${} substitution.
 */
static int
varsub(xp, sp, word, stypep, slenp)
	Expand *xp;
	char *sp;
	char *word;
	int *stypep;	/* becomes qualifier type */
	int *slenp;	/* " " len (=, :=, etc.) valid iff *stypep != 0 */
{
	int c;
	int state;	/* next state: XBASE, XARG, XSUB, XNULLSUB */
	int stype;	/* substitution type */
	int slen;
	char *p;
	struct tbl *vp;

	if (sp[0] == '\0')	/* Bad variable name */
		return -1;

	xp->var = (struct tbl *) 0;

	/* ${#var}, string length or array size */
	if (sp[0] == '#' && (c = sp[1]) != '\0') {
		int zero_ok = 0;

		/* Can't have any modifiers for ${#...} */
		if (*word != CSUBST)
			return -1;
		sp++;
		/* Check for size of array */
		if ((p=strchr(sp,'[')) && (p[1]=='*'||p[1]=='@') && p[2]==']') {
			int n = 0;
			int max = 0;
			vp = global(arrayname(sp));
			if (vp->flag & (ISSET|ARRAY))
				zero_ok = 1;
			for (; vp; vp = vp->u.array)
				if (vp->flag & ISSET) {
					max = vp->index + 1;
					n++;
				}
			c = n; /* ksh88/ksh93 go for number, not max index */
		} else if (c == '*' || c == '@')
			c = e->loc->argc;
		else {
			p = str_val(global(sp));
			zero_ok = p != null;
			c = strlen(p);
		}
		if (Flag(FNOUNSET) && c == 0 && !zero_ok)
			errorf("%s: parameter not set", sp);
		*stypep = 0; /* unqualified variable/string substitution */
		xp->str = str_save(ulton((unsigned long)c, 10), ATEMP);
		return XSUB;
	}

	/* Check for qualifiers in word part */
	stype = 0;
	c = word[slen = 0] == CHAR ? word[1] : 0;
	if (c == ':') {
		slen += 2;
		stype = 0x80;
		c = word[slen + 0] == CHAR ? word[slen + 1] : 0;
	}
	if (ctype(c, C_SUBOP1)) {
		slen += 2;
		stype |= c;
	} else if (ctype(c, C_SUBOP2)) { /* Note: ksh88 allows :%, :%%, etc */
		slen += 2;
		stype = c;
		if (word[slen + 0] == CHAR && c == word[slen + 1]) {
			stype |= 0x80;
			slen += 2;
		}
	} else if (stype)	/* : is not ok */
		return -1;
	if (!stype && *word != CSUBST)
		return -1;
	*stypep = stype;
	*slenp = slen;

	c = sp[0];
	if (c == '*' || c == '@') {
		switch (stype & 0x7f) {
		  case '=':	/* can't assign to a vector */
		  case '%':	/* can't trim a vector (yet) */
		  case '#':
			return -1;
		}
		if (e->loc->argc == 0) {
			xp->str = null;
			state = c == '@' ? XNULLSUB : XSUB;
		} else {
			xp->u.strv = (const char **) e->loc->argv + 1;
			xp->str = *xp->u.strv++;
			xp->split = c == '@'; /* $@ */
			state = XARG;
		}
	} else {
		if ((p=strchr(sp,'[')) && (p[1]=='*'||p[1]=='@') && p[2]==']') {
			XPtrV wv;

			switch (stype & 0x7f) {
			  case '=':	/* can't assign to a vector */
			  case '%':	/* can't trim a vector (yet) */
			  case '#':
				return -1;
			}
			XPinit(wv, 32);
			vp = global(arrayname(sp));
			for (; vp; vp = vp->u.array) {
				if (!(vp->flag&ISSET))
					continue;
				XPput(wv, str_val(vp));
			}
			if (XPsize(wv) == 0) {
				xp->str = null;
				state = p[1] == '@' ? XNULLSUB : XSUB;
				XPfree(wv);
			} else {
				XPput(wv, 0);
				xp->u.strv = (const char **) XPptrv(wv);
				xp->str = *xp->u.strv++;
				xp->split = p[1] == '@'; /* ${foo[@]} */
				state = XARG;
			}
		} else {
			/* Can't assign things like $! or $1 */
			if ((stype & 0x7f) == '='
			    && (ctype(*sp, C_VAR1) || digit(*sp)))
				return -1;
			xp->var = global(sp);
			xp->str = str_val(xp->var);
			state = XSUB;
		}
	}

	c = stype&0x7f;
	/* test the compiler's code generator */
	if (ctype(c, C_SUBOP2) ||
	    (((stype&0x80) ? *xp->str=='\0' : xp->str==null) ? /* undef? */
	     c == '=' || c == '-' || c == '?' : c == '+'))
		state = XBASE;	/* expand word instead of variable value */
	if (Flag(FNOUNSET) && xp->str == null
	    && (ctype(c, C_SUBOP2) || (state != XBASE && c != '+')))
		errorf("%s: parameter not set", sp);
	return state;
}

/*
 * Run the command in $(...) and read its output.
 */
static int
comsub(xp, cp)
	register Expand *xp;
	char *cp;
{
	Source *s, *sold;
	register struct op *t;
	struct shf *shf;

	s = pushs(SSTRING, ATEMP);
	s->start = s->str = cp;
	sold = source;
	t = compile(s);
	source = sold;

	if (t == NULL)
		return XBASE;

	if (t != NULL && t->type == TCOM && /* $(<file) */
	    *t->args == NULL && *t->vars == NULL && t->ioact != NULL) {
		register struct ioword *io = *t->ioact;
		char *name;

		if ((io->flag&IOTYPE) != IOREAD)
			errorf("funny $() command: %s",
				snptreef((char *) 0, 32, "%R", io));
		shf = shf_open(name = evalstr(io->name, DOTILDE), O_RDONLY, 0,
			SHF_MAPHI|SHF_CLEXEC);
		if (shf == NULL)
			errorf("%s: cannot open $() input", name);
		xp->split = 0;	/* no waitlast() */
	} else {
		int ofd1, pv[2];
		openpipe(pv);
		shf = shf_fdopen(pv[0], SHF_RD, (struct shf *) 0);
		ofd1 = savefd(1, 0);	/* fd 1 may be closed... */
		ksh_dup2(pv[1], 1, FALSE);
		close(pv[1]);
		execute(t, XFORK|XXCOM|XPIPEO);
		restfd(1, ofd1);
		startlast();
		xp->split = 1;	/* waitlast() */
	}

	xp->u.shf = shf;
	return XCOM;
}

/*
 * perform #pattern and %pattern substitution in ${}
 */

static char *
trimsub(str, pat, how)
	register char *str;
	char *pat;
	int how;
{
	register char *end = strchr(str, 0);
	register char *p, c;

	switch (how&0xff) {	/* UCHAR_MAX maybe? */
	  case '#':		/* shortest at begining */
		for (p = str; p <= end; p++) {
			c = *p; *p = '\0';
			if (gmatch(str, pat, FALSE)) {
				*p = c;
				return p;
			}
			*p = c;
		}
		break;
	  case '#'|0x80:	/* longest match at begining */
		for (p = end; p >= str; p--) {
			c = *p; *p = '\0';
			if (gmatch(str, pat, FALSE)) {
				*p = c;
				return p;
			}
			*p = c;
		}
		break;