parser.c

来自「Android 一些工具」· C语言 代码 · 共 1,652 行 · 第 1/3 页

/*	$NetBSD: parser.c,v 1.57 2004/06/27 10:27:57 dsl Exp $	*/

/*-
 * Copyright (c) 1991, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Kenneth Almquist.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/cdefs.h>
#ifndef lint
#if 0
static char sccsid[] = "@(#)parser.c	8.7 (Berkeley) 5/16/95";
#else
__RCSID("$NetBSD: parser.c,v 1.57 2004/06/27 10:27:57 dsl Exp $");
#endif
#endif /* not lint */

#include <stdlib.h>

#include "shell.h"
#include "parser.h"
#include "nodes.h"
#include "expand.h"	/* defines rmescapes() */
#include "eval.h"	/* defines commandname */
#include "redir.h"	/* defines copyfd() */
#include "syntax.h"
#include "options.h"
#include "input.h"
#include "output.h"
#include "var.h"
#include "error.h"
#include "memalloc.h"
#include "mystring.h"
#include "alias.h"
#include "show.h"
#ifndef SMALL
#include "myhistedit.h"
#endif

/*
 * Shell command parser.
 */

#define EOFMARKLEN 79

/* values returned by readtoken */
#include "token.h"

#define OPENBRACE '{'
#define CLOSEBRACE '}'


struct heredoc {
	struct heredoc *next;	/* next here document in list */
	union node *here;		/* redirection node */
	char *eofmark;		/* string indicating end of input */
	int striptabs;		/* if set, strip leading tabs */
};



static int noalias = 0;		/* when set, don't handle aliases */
struct heredoc *heredoclist;	/* list of here documents to read */
int parsebackquote;		/* nonzero if we are inside backquotes */
int doprompt;			/* if set, prompt the user */
int needprompt;			/* true if interactive and at start of line */
int lasttoken;			/* last token read */
MKINIT int tokpushback;		/* last token pushed back */
char *wordtext;			/* text of last word returned by readtoken */
MKINIT int checkkwd;            /* 1 == check for kwds, 2 == also eat newlines */
struct nodelist *backquotelist;
union node *redirnode;
struct heredoc *heredoc;
int quoteflag;			/* set if (part of) last token was quoted */
int startlinno;			/* line # where last token started */


STATIC union node *list(int);
STATIC union node *andor(void);
STATIC union node *pipeline(void);
STATIC union node *command(void);
STATIC union node *simplecmd(union node **, union node *);
STATIC union node *makename(void);
STATIC void parsefname(void);
STATIC void parseheredoc(void);
STATIC int peektoken(void);
STATIC int readtoken(void);
STATIC int xxreadtoken(void);
STATIC int readtoken1(int, char const *, char *, int);
STATIC int noexpand(char *);
STATIC void synexpect(int) __attribute__((__noreturn__));
STATIC void synerror(const char *) __attribute__((__noreturn__));
STATIC void setprompt(int);


/*
 * Read and parse a command.  Returns NEOF on end of file.  (NULL is a
 * valid parse tree indicating a blank line.)
 */

union node *
parsecmd(int interact)
{
	int t;

	tokpushback = 0;
	doprompt = interact;
	if (doprompt)
		setprompt(1);
	else
		setprompt(0);
	needprompt = 0;
	t = readtoken();
	if (t == TEOF)
		return NEOF;
	if (t == TNL)
		return NULL;
	tokpushback++;
	return list(1);
}


STATIC union node *
list(int nlflag)
{
	union node *n1, *n2, *n3;
	int tok;

	checkkwd = 2;
	if (nlflag == 0 && tokendlist[peektoken()])
		return NULL;
	n1 = NULL;
	for (;;) {
		n2 = andor();
		tok = readtoken();
		if (tok == TBACKGND) {
			if (n2->type == NCMD || n2->type == NPIPE) {
				n2->ncmd.backgnd = 1;
			} else if (n2->type == NREDIR) {
				n2->type = NBACKGND;
			} else {
				n3 = (union node *)stalloc(sizeof (struct nredir));
				n3->type = NBACKGND;
				n3->nredir.n = n2;
				n3->nredir.redirect = NULL;
				n2 = n3;
			}
		}
		if (n1 == NULL) {
			n1 = n2;
		}
		else {
			n3 = (union node *)stalloc(sizeof (struct nbinary));
			n3->type = NSEMI;
			n3->nbinary.ch1 = n1;
			n3->nbinary.ch2 = n2;
			n1 = n3;
		}
		switch (tok) {
		case TBACKGND:
		case TSEMI:
			tok = readtoken();
			/* fall through */
		case TNL:
			if (tok == TNL) {
				parseheredoc();
				if (nlflag)
					return n1;
			} else {
				tokpushback++;
			}
			checkkwd = 2;
			if (tokendlist[peektoken()])
				return n1;
			break;
		case TEOF:
			if (heredoclist)
				parseheredoc();
			else
				pungetc();		/* push back EOF on input */
			return n1;
		default:
			if (nlflag)
				synexpect(-1);
			tokpushback++;
			return n1;
		}
	}
}



STATIC union node *
andor(void)
{
	union node *n1, *n2, *n3;
	int t;

	n1 = pipeline();
	for (;;) {
		if ((t = readtoken()) == TAND) {
			t = NAND;
		} else if (t == TOR) {
			t = NOR;
		} else {
			tokpushback++;
			return n1;
		}
		n2 = pipeline();
		n3 = (union node *)stalloc(sizeof (struct nbinary));
		n3->type = t;
		n3->nbinary.ch1 = n1;
		n3->nbinary.ch2 = n2;
		n1 = n3;
	}
}



STATIC union node *
pipeline(void)
{
	union node *n1, *n2, *pipenode;
	struct nodelist *lp, *prev;
	int negate;

	negate = 0;
	TRACE(("pipeline: entered\n"));
	while (readtoken() == TNOT)
		negate = !negate;
	tokpushback++;
	n1 = command();
	if (readtoken() == TPIPE) {
		pipenode = (union node *)stalloc(sizeof (struct npipe));
		pipenode->type = NPIPE;
		pipenode->npipe.backgnd = 0;
		lp = (struct nodelist *)stalloc(sizeof (struct nodelist));
		pipenode->npipe.cmdlist = lp;
		lp->n = n1;
		do {
			prev = lp;
			lp = (struct nodelist *)stalloc(sizeof (struct nodelist));
			lp->n = command();
			prev->next = lp;
		} while (readtoken() == TPIPE);
		lp->next = NULL;
		n1 = pipenode;
	}
	tokpushback++;
	if (negate) {
		n2 = (union node *)stalloc(sizeof (struct nnot));
		n2->type = NNOT;
		n2->nnot.com = n1;
		return n2;
	} else
		return n1;
}



STATIC union node *
command(void)
{
	union node *n1, *n2;
	union node *ap, **app;
	union node *cp, **cpp;
	union node *redir, **rpp;
	int t, negate = 0;

	checkkwd = 2;
	redir = NULL;
	n1 = NULL;
	rpp = &redir;

	/* Check for redirection which may precede command */
	while (readtoken() == TREDIR) {
		*rpp = n2 = redirnode;
		rpp = &n2->nfile.next;
		parsefname();
	}
	tokpushback++;

	while (readtoken() == TNOT) {
		TRACE(("command: TNOT recognized\n"));
		negate = !negate;
	}
	tokpushback++;

	switch (readtoken()) {
	case TIF:
		n1 = (union node *)stalloc(sizeof (struct nif));
		n1->type = NIF;
		n1->nif.test = list(0);
		if (readtoken() != TTHEN)
			synexpect(TTHEN);
		n1->nif.ifpart = list(0);
		n2 = n1;
		while (readtoken() == TELIF) {
			n2->nif.elsepart = (union node *)stalloc(sizeof (struct nif));
			n2 = n2->nif.elsepart;
			n2->type = NIF;
			n2->nif.test = list(0);
			if (readtoken() != TTHEN)
				synexpect(TTHEN);
			n2->nif.ifpart = list(0);
		}
		if (lasttoken == TELSE)
			n2->nif.elsepart = list(0);
		else {
			n2->nif.elsepart = NULL;
			tokpushback++;
		}
		if (readtoken() != TFI)
			synexpect(TFI);
		checkkwd = 1;
		break;
	case TWHILE:
	case TUNTIL: {
		int got;
		n1 = (union node *)stalloc(sizeof (struct nbinary));
		n1->type = (lasttoken == TWHILE)? NWHILE : NUNTIL;
		n1->nbinary.ch1 = list(0);
		if ((got=readtoken()) != TDO) {
TRACE(("expecting DO got %s %s\n", tokname[got], got == TWORD ? wordtext : ""));
			synexpect(TDO);
		}
		n1->nbinary.ch2 = list(0);
		if (readtoken() != TDONE)
			synexpect(TDONE);
		checkkwd = 1;
		break;
	}
	case TFOR:
		if (readtoken() != TWORD || quoteflag || ! goodname(wordtext))
			synerror("Bad for loop variable");
		n1 = (union node *)stalloc(sizeof (struct nfor));
		n1->type = NFOR;
		n1->nfor.var = wordtext;
		if (readtoken() == TWORD && ! quoteflag && equal(wordtext, "in")) {
			app = &ap;
			while (readtoken() == TWORD) {
				n2 = (union node *)stalloc(sizeof (struct narg));
				n2->type = NARG;
				n2->narg.text = wordtext;
				n2->narg.backquote = backquotelist;
				*app = n2;
				app = &n2->narg.next;
			}
			*app = NULL;
			n1->nfor.args = ap;
			if (lasttoken != TNL && lasttoken != TSEMI)
				synexpect(-1);
		} else {
			static char argvars[5] = {CTLVAR, VSNORMAL|VSQUOTE,
								   '@', '=', '\0'};
			n2 = (union node *)stalloc(sizeof (struct narg));
			n2->type = NARG;
			n2->narg.text = argvars;
			n2->narg.backquote = NULL;
			n2->narg.next = NULL;
			n1->nfor.args = n2;
			/*
			 * Newline or semicolon here is optional (but note
			 * that the original Bourne shell only allowed NL).
			 */
			if (lasttoken != TNL && lasttoken != TSEMI)
				tokpushback++;
		}
		checkkwd = 2;
		if ((t = readtoken()) == TDO)
			t = TDONE;
		else if (t == TBEGIN)
			t = TEND;
		else
			synexpect(-1);
		n1->nfor.body = list(0);
		if (readtoken() != t)
			synexpect(t);
		checkkwd = 1;
		break;
	case TCASE:
		n1 = (union node *)stalloc(sizeof (struct ncase));
		n1->type = NCASE;
		if (readtoken() != TWORD)
			synexpect(TWORD);
		n1->ncase.expr = n2 = (union node *)stalloc(sizeof (struct narg));
		n2->type = NARG;
		n2->narg.text = wordtext;
		n2->narg.backquote = backquotelist;
		n2->narg.next = NULL;
		while (readtoken() == TNL);
		if (lasttoken != TWORD || ! equal(wordtext, "in"))
			synerror("expecting \"in\"");
		cpp = &n1->ncase.cases;
		noalias = 1;
		checkkwd = 2, readtoken();
		do {
			*cpp = cp = (union node *)stalloc(sizeof (struct nclist));
			cp->type = NCLIST;
			app = &cp->nclist.pattern;
			for (;;) {
				*app = ap = (union node *)stalloc(sizeof (struct narg));
				ap->type = NARG;
				ap->narg.text = wordtext;
				ap->narg.backquote = backquotelist;
				if (checkkwd = 2, readtoken() != TPIPE)
					break;
				app = &ap->narg.next;
				readtoken();
			}
			ap->narg.next = NULL;
			noalias = 0;
			if (lasttoken != TRP) {
				synexpect(TRP);
			}
			cp->nclist.body = list(0);

			checkkwd = 2;
			if ((t = readtoken()) != TESAC) {
				if (t != TENDCASE) {
					noalias = 0;
					synexpect(TENDCASE);
				} else {
					noalias = 1;
					checkkwd = 2;
					readtoken();
				}
			}
			cpp = &cp->nclist.next;
		} while(lasttoken != TESAC);
		noalias = 0;
		*cpp = NULL;
		checkkwd = 1;
		break;
	case TLP:
		n1 = (union node *)stalloc(sizeof (struct nredir));
		n1->type = NSUBSHELL;
		n1->nredir.n = list(0);
		n1->nredir.redirect = NULL;
		if (readtoken() != TRP)
			synexpect(TRP);
		checkkwd = 1;
		break;
	case TBEGIN:
		n1 = list(0);
		if (readtoken() != TEND)
			synexpect(TEND);
		checkkwd = 1;
		break;
	/* Handle an empty command like other simple commands.  */
	case TSEMI:
		/*
		 * An empty command before a ; doesn't make much sense, and
		 * should certainly be disallowed in the case of `if ;'.
		 */
		if (!redir)
			synexpect(-1);
	case TAND:
	case TOR:
	case TNL:
	case TEOF:
	case TWORD:
	case TRP:
		tokpushback++;
		n1 = simplecmd(rpp, redir);
		goto checkneg;
	default:
		synexpect(-1);
		/* NOTREACHED */
	}

	/* Now check for redirection which may follow command */
	while (readtoken() == TREDIR) {
		*rpp = n2 = redirnode;
		rpp = &n2->nfile.next;
		parsefname();
	}
	tokpushback++;
	*rpp = NULL;
	if (redir) {
		if (n1->type != NSUBSHELL) {
			n2 = (union node *)stalloc(sizeof (struct nredir));
			n2->type = NREDIR;
			n2->nredir.n = n1;
			n1 = n2;
		}
		n1->nredir.redirect = redir;
	}

checkneg:
	if (negate) {
		n2 = (union node *)stalloc(sizeof (struct nnot));
		n2->type = NNOT;
		n2->nnot.com = n1;
		return n2;
	}
	else
		return n1;
}


STATIC union node *
simplecmd(union node **rpp, union node *redir)
{
	union node *args, **app;
	union node **orig_rpp = rpp;
	union node *n = NULL, *n2;
	int negate = 0;

	/* If we don't have any redirections already, then we must reset */
	/* rpp to be the address of the local redir variable.  */
	if (redir == 0)
		rpp = &redir;

	args = NULL;
	app = &args;
	/*
	 * We save the incoming value, because we need this for shell
	 * functions.  There can not be a redirect or an argument between
	 * the function name and the open parenthesis.
	 */
	orig_rpp = rpp;

	while (readtoken() == TNOT) {
		TRACE(("command: TNOT recognized\n"));