shell/msh.c

/* vi: set sw=4 ts=4: */
/*
 * Minix shell port for busybox
 *
 * This version of the Minix shell was adapted for use in busybox
 * by Erik Andersen <andersen@codepoet.org>
 *
 * - backtick expansion did not work properly
 *   Jonas Holmberg <jonas.holmberg@axis.com>
 *   Robert Schwebel <r.schwebel@pengutronix.de>
 *   Erik Andersen <andersen@codepoet.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 *
 * Original copyright notice is retained at the end of this file.
 */

#include <ctype.h>
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <setjmp.h>
#include <signal.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/times.h>
#include <sys/types.h>
#include <sys/wait.h>

#include "cmdedit.h"
#include "busybox.h"


/* -------- sh.h -------- */
/*
 * shell
 */

#define	LINELIM	2100
#define	NPUSH	8	/* limit to input nesting */

#undef NOFILE
#define	NOFILE	20	/* Number of open files */
#define	NUFILE	10	/* Number of user-accessible files */
#define	FDBASE	10	/* First file usable by Shell */

/*
 * values returned by wait
 */
#define	WAITSIG(s) ((s)&0177)
#define	WAITVAL(s) (((s)>>8)&0377)
#define	WAITCORE(s) (((s)&0200)!=0)

/*
 * library and system defintions
 */
typedef void xint;	/* base type of jmp_buf, for not broken compilers */

/*
 * shell components
 */

#define	QUOTE	0200

#define	NOBLOCK	((struct op *)NULL)
#define	NOWORD	((char *)NULL)
#define	NOWORDS	((char **)NULL)
#define	NOPIPE	((int *)NULL)

/*
 * Description of a command or an operation on commands.
 * Might eventually use a union.
 */
struct op {
	int	type;	/* operation type, see below */
	char	**words;	/* arguments to a command */
	struct	ioword	**ioact;	/* IO actions (eg, < > >>) */
	struct op *left;
	struct op *right;
	char	*str;	/* identifier for case and for */
};

#define	TCOM	1	/* command */
#define	TPAREN	2	/* (c-list) */
#define	TPIPE	3	/* a | b */
#define	TLIST	4	/* a [&;] b */
#define	TOR	5	/* || */
#define	TAND	6	/* && */
#define	TFOR	7
#define	TDO	8
#define	TCASE	9
#define	TIF	10
#define	TWHILE	11
#define	TUNTIL	12
#define	TELIF	13
#define	TPAT	14	/* pattern in case */
#define	TBRACE	15	/* {c-list} */
#define	TASYNC	16	/* c & */

/*
 * actions determining the environment of a process
 */
#define	BIT(i)	(1<<(i))
#define	FEXEC	BIT(0)	/* execute without forking */

/*
 * flags to control evaluation of words
 */
#define	DOSUB	1	/* interpret $, `, and quotes */
#define	DOBLANK	2	/* perform blank interpretation */
#define	DOGLOB	4	/* interpret [?* */
#define	DOKEY	8	/* move words with `=' to 2nd arg. list */
#define	DOTRIM	16	/* trim resulting string */

#define	DOALL	(DOSUB|DOBLANK|DOGLOB|DOKEY|DOTRIM)

static	char	**dolv;
static	int	dolc;
static	int	exstat;
static  char	gflg;
static  int	interactive;	/* Is this an interactive shell */
static  int	execflg;
static  int	multiline;	/* \n changed to ; */
static  struct	op	*outtree;	/* result from parser */

static	xint	*failpt;
static	xint	*errpt;
static	struct brkcon	*brklist;
static	int	isbreak;
static int newfile(char *s);
static char *findeq(char *cp);
static char *cclass(char *p, int sub);
static void initarea(void);
extern int msh_main(int argc, char **argv);


struct	brkcon {
	jmp_buf	brkpt;
	struct	brkcon	*nextlev;
} ;

/*
 * redirection
 */
struct ioword {
	short	io_unit;	/* unit affected */
	short	io_flag;	/* action (below) */
	char	*io_name;	/* file name */
};
#define	IOREAD	1	/* < */
#define	IOHERE	2	/* << (here file) */
#define	IOWRITE	4	/* > */
#define	IOCAT	8	/* >> */
#define	IOXHERE	16	/* ${}, ` in << */
#define	IODUP	32	/* >&digit */
#define	IOCLOSE	64	/* >&- */

#define	IODEFAULT (-1)	/* token for default IO unit */

static	struct	wdblock	*wdlist;
static	struct	wdblock	*iolist;

/*
 * parsing & execution environment
 */
static struct	env {
	char	*linep;
	struct	io	*iobase;
	struct	io	*iop;
	xint	*errpt;
	int	iofd;
	struct	env	*oenv;
} e;

/*
 * flags:
 * -e: quit on error
 * -k: look for name=value everywhere on command line
 * -n: no execution
 * -t: exit after reading and executing one command
 * -v: echo as read
 * -x: trace
 * -u: unset variables net diagnostic
 */
static	char	*flag;

static	char	*null;	/* null value for variable */
static	int	intr;	/* interrupt pending */

static	char	*trap[_NSIG+1];
static	char	ourtrap[_NSIG+1];
static	int	trapset;	/* trap pending */

static	int	heedint;	/* heed interrupt signals */

static	int	yynerrs;	/* yacc */

static	char	line[LINELIM];
static	char	*elinep;

/*
 * other functions
 */
static int(*inbuilt(char *s))(struct op *);


static char *rexecve (char *c , char **v, char **envp );
static char *space (int n );
static char *strsave (char *s, int a );
static char *evalstr (char *cp, int f );
static char *putn (int n );
static char *itoa (int n );
static char *unquote (char *as );
static struct var *lookup (char *n );
static int rlookup (char *n );
static struct wdblock *glob (char *cp, struct wdblock *wb );
static int my_getc( int ec);
static int subgetc (int ec, int quoted );
static char **makenv (void);
static char **eval (char **ap, int f );
static int setstatus (int s );
static int waitfor (int lastpid, int canintr );

static void onintr (int s ); /* SIGINT handler */

static int newenv (int f );
static void quitenv (void);
static void err (char *s );
static int anys (char *s1, char *s2 );
static int any (int c, char *s );
static void next (int f );
static void setdash (void);
static void onecommand (void);
static void runtrap (int i );
static int gmatch (char *s, char *p );

/*
 * error handling
 */
static void leave (void); /* abort shell (or fail in subshell) */
static void fail (void);	 /* fail but return to process next command */
static void warn (char *s );
static void sig (int i );	 /* default signal handler */



/* -------- area stuff -------- */

#define	REGSIZE		sizeof(struct region)
#define GROWBY		256
//#define	SHRINKBY   64
#undef	SHRINKBY
#define FREE 32767
#define BUSY 0
#define	ALIGN (sizeof(int)-1)


struct region {
	struct	region *next;
	int	area;
};



/* -------- grammar stuff -------- */
typedef union {
	char	*cp;
	char	**wp;
	int	i;
	struct	op *o;
} YYSTYPE;
#define	WORD	256
#define	LOGAND	257
#define	LOGOR	258
#define	BREAK	259
#define	IF	260
#define	THEN	261
#define	ELSE	262
#define	ELIF	263
#define	FI	264
#define	CASE	265
#define	ESAC	266
#define	FOR	267
#define	WHILE	268
#define	UNTIL	269
#define	DO	270
#define	DONE	271
#define	IN	272
#define	YYERRCODE 300

/* flags to yylex */
#define	CONTIN	01	/* skip new lines to complete command */

#define	SYNTAXERR	zzerr()
static struct op *pipeline(int cf );
static struct op *andor(void);
static struct op *c_list(void);
static int synio(int cf );
static void musthave (int c, int cf );
static struct op *simple(void);
static struct op *nested(int type, int mark );
static struct op *command(int cf );
static struct op *dogroup(int onlydone );
static struct op *thenpart(void);
static struct op *elsepart(void);
static struct op *caselist(void);
static struct op *casepart(void);
static char **pattern(void);
static char **wordlist(void);
static struct op *list(struct op *t1, struct op *t2 );
static struct op *block(int type, struct op *t1, struct op *t2, char **wp );
static struct op *newtp(void);
static struct op *namelist(struct op *t );
static char **copyw(void);
static void word(char *cp );
static struct ioword **copyio(void);
static struct ioword *io (int u, int f, char *cp );
static void zzerr(void);
static void yyerror(char *s );
static int yylex(int cf );
static int collect(int c, int c1 );
static int dual(int c );
static void diag(int ec );
static char *tree(unsigned size );

/* -------- var.h -------- */

struct	var {
	char	*value;
	char	*name;
	struct	var	*next;
	char	status;
};
#define	COPYV	1	/* flag to setval, suggesting copy */
#define	RONLY	01	/* variable is read-only */
#define	EXPORT	02	/* variable is to be exported */
#define	GETCELL	04	/* name & value space was got with getcell */

static	struct	var	*vlist;		/* dictionary */

static	struct	var	*homedir;	/* home directory */
static	struct	var	*prompt;	/* main prompt */
static	struct	var	*cprompt;	/* continuation prompt */
static	struct	var	*path;		/* search path for commands */
static	struct	var	*shell;		/* shell to interpret command files */
static	struct	var	*ifs;		/* field separators */

static int yyparse (void);
static struct var *lookup (char *n );
static void setval (struct var *vp, char *val );
static void nameval (struct var *vp, char *val, char *name );
static void export (struct var *vp );
static void ronly (struct var *vp );
static int isassign (char *s );
static int checkname (char *cp );
static int assign (char *s, int cf );
static void putvlist (int f, int out );
static int eqname (char *n1, char *n2 );

static int execute (struct op *t, int *pin, int *pout, int act );

/* -------- io.h -------- */
/* io buffer */
struct iobuf {
  unsigned id;				/* buffer id */
  char buf[512];			/* buffer */
  char *bufp;				/* pointer into buffer */
  char *ebufp;				/* pointer to end of buffer */
};

/* possible arguments to an IO function */
struct ioarg {
	char	*aword;
	char	**awordlist;
	int	afile;		/* file descriptor */
	unsigned afid;		/* buffer id */
	long	afpos;		/* file position */
	struct iobuf *afbuf;	/* buffer for this file */
};
//static struct ioarg ioargstack[NPUSH];
#define AFID_NOBUF	(~0)
#define AFID_ID		0

/* an input generator's state */
struct	io {
	int	(*iofn)(struct  ioarg *, struct io *);
	struct	ioarg	*argp;
	int	peekc;
	char	prev;		/* previous character read by readc() */
	char	nlcount;	/* for `'s */
	char	xchar;		/* for `'s */
	char	task;		/* reason for pushed IO */
};
//static	struct	io	iostack[NPUSH];
#define	XOTHER	0	/* none of the below */
#define	XDOLL	1	/* expanding ${} */
#define	XGRAVE	2	/* expanding `'s */
#define	XIO	3	/* file IO */

/* in substitution */
#define	INSUB()	(e.iop->task == XGRAVE || e.iop->task == XDOLL)

/*
 * input generators for IO structure
 */
static int nlchar (struct ioarg *ap );
static int strchar (struct ioarg *ap );
static int qstrchar (struct ioarg *ap );
static int filechar (struct ioarg *ap );
static int herechar (struct ioarg *ap );
static int linechar (struct ioarg *ap );
static int gravechar (struct ioarg *ap, struct io *iop );
static int qgravechar (struct ioarg *ap, struct io *iop );
static int dolchar (struct ioarg *ap );
static int wdchar (struct ioarg *ap );
static void scraphere (void);
static void freehere (int area );
static void gethere (void);
static void markhere (char *s, struct ioword *iop );
static int herein (char *hname, int xdoll );
static int run (struct ioarg *argp, int (*f)(struct ioarg *));

/*
 * IO functions
 */
static int eofc (void);
static int readc (void);
static void unget (int c );
static void ioecho (int c );
static void prs (char *s );
static void prn (unsigned u );
static void closef (int i );
static void closeall (void);

/*
 * IO control
 */
static void pushio (struct ioarg *argp, int (*f)(struct ioarg *));
static int remap (int fd );
static int openpipe (int *pv );
static void closepipe (int *pv );
static struct io *setbase (struct io *ip );

static	struct	ioarg	temparg;	/* temporary for PUSHIO */
#define	PUSHIO(what,arg,gen) ((temparg.what = (arg)),pushio(&temparg,(gen)))
#define	RUN(what,arg,gen) ((temparg.what = (arg)), run(&temparg,(gen)))

/* -------- word.h -------- */

#define	NSTART	16	/* default number of words to allow for initially */

struct	wdblock {
	short	w_bsize;
	short	w_nword;
	/* bounds are arbitrary */
	char	*w_words[1];
};

static struct wdblock *addword (char *wd, struct wdblock *wb );
static struct wdblock *newword (int nw );
static char **getwords (struct wdblock *wb );

/* -------- area.h -------- */

/*
 * storage allocation
 */
static char *getcell (unsigned nbytes );
static void garbage (void);
static void setarea (char *cp, int a );
static int getarea (char *cp );
static void freearea (int a );
static void freecell (char *cp );
static	int	areanum;	/* current allocation area */

#define	NEW(type) (type *)getcell(sizeof(type))
#define	DELETE(obj)	freecell((char *)obj)


/* -------- misc stuff -------- */

static int forkexec (struct op *t, int *pin, int *pout, int act, char **wp, int *pforked );
static int iosetup (struct ioword *iop, int pipein, int pipeout );
static void echo(char **wp );
static struct op **find1case (struct op *t, char *w );
static struct op *findcase (struct op *t, char *w );
static void brkset(struct brkcon *bc );
static int dolabel(struct op *t );
static int dohelp(struct op *t );
static int dochdir(struct op *t );
static int doshift(struct op *t );
static int dologin(struct op *t );
static int doumask(struct op *t );
static int doexec(struct op *t );
static int dodot(struct op *t );
static int dowait(struct op *t );
static int doread(struct op *t );
static int doeval(struct op *t );
static int dotrap(struct op *t );
static int getsig(char *s );
static void setsig (int n, sighandler_t f);
static int getn(char *as );
static int dobreak(struct op *t );
static int docontinue(struct op *t );
static int brkcontin (char *cp, int val );
static int doexit(struct op *t );
static int doexport(struct op *t );
static int doreadonly(struct op *t );
static void rdexp (char **wp, void (*f)(struct var *), int key);
static void badid(char *s );
static int doset(struct op *t );
static void varput (char *s, int out );
static int dotimes(struct op *t );
static int expand (char *cp, struct wdblock **wbp, int f );
static char *blank(int f );
static int dollar(int quoted );
static int grave(int quoted );
static void globname (char *we, char *pp );
static char *generate (char *start1, char *end1, char *middle, char *end );
static int anyspcl(struct wdblock *wb );
static int xstrcmp (char *p1, char *p2 );
static void glob0 (char *a0, unsigned int a1, int a2, int (*a3)(char *, char *));
static void glob1 (char *base, char *lim );
static void glob2 (char *i, char *j );
static void glob3 (char *i, char *j, char *k );
static void readhere (char **name, char *s, int ec );
static void pushio (struct ioarg *argp, int (*f)(struct ioarg *));
static int xxchar(struct ioarg *ap );

struct	here {
	char	*h_tag;
	int	h_dosub;
	struct	ioword *h_iop;
	struct	here	*h_next;
};

static	char	*signame[] = {
	"Signal 0",
	"Hangup",
	(char *)NULL,	/* interrupt */
	"Quit",
	"Illegal instruction",
	"Trace/BPT trap",
	"Abort",
	"Bus error",
	"Floating Point Exception",
	"Killed",
	"SIGUSR1",
	"SIGSEGV",
	"SIGUSR2",
	(char *)NULL,	/* broken pipe */
	"Alarm clock",
	"Terminated",
};
#define	NSIGNAL (sizeof(signame)/sizeof(signame[0]))

struct res {
	char *r_name;
	int	  r_val;
};
static struct res restab[] = {
    {"for",		FOR},
    {"case",	CASE},
    {"esac",	ESAC},
    {"while",	WHILE},
    {"do",		DO},
    {"done",	DONE},
    {"if",		IF},
    {"in",		IN},
    {"then",	THEN},
    {"else",	ELSE},
    {"elif",	ELIF},
    {"until",	UNTIL},
    {"fi",		FI},

    {";;",		BREAK},
    {"||",		LOGOR},
    {"&&",		LOGAND},
    {"{",		'{'},
    {"}",		'}'},
    {0,		0},
};


struct builtincmd {
	const char *name;
	int (*builtinfunc)(struct op *t);
};
static const struct	builtincmd	builtincmds[] = {
    {".",		dodot},
    {":",		dolabel},
    {"break",	dobreak},
    {"cd",		dochdir},
    {"continue",docontinue},
    {"eval",	doeval},
    {"exec",	doexec},
    {"exit",	doexit},
    {"export",	doexport},
    {"help",	dohelp},
    {"login",	dologin},
    {"newgrp",	dologin},
    {"read",	doread},
    {"readonly",doreadonly},
    {"set",		doset},
    {"shift",	doshift},
    {"times",	dotimes},
    {"trap",	dotrap},
    {"umask",	doumask},
    {"wait",	dowait},
    {0,0}
};

/* Globals */
extern	char	**environ;	/* environment pointer */
static char	**dolv;
static int	dolc;
static int	exstat;
static char	gflg;
static int	interactive;	/* Is this an interactive shell */
static int	execflg;
static int	multiline;	/* \n changed to ; */
static struct	op	*outtree;	/* result from parser */
static xint	*failpt;
static xint	*errpt;
static struct	brkcon	*brklist;
static int	isbreak;
static struct	wdblock	*wdlist;
static struct	wdblock	*iolist;
static char	*trap[_NSIG+1];
static char	ourtrap[_NSIG+1];
static int	trapset;	/* trap pending */
static int	yynerrs;	/* yacc */
static char	line[LINELIM];
static struct	var	*vlist;		/* dictionary */
static struct	var	*homedir;	/* home directory */
static struct	var	*prompt;	/* main prompt */
static struct	var	*cprompt;	/* continuation prompt */
static struct	var	*path;		/* search path for commands */
static struct	var	*shell;		/* shell to interpret command files */
static struct	var	*ifs;		/* field separators */
static struct	ioarg ioargstack[NPUSH];
static struct	io	iostack[NPUSH];
static int	areanum;	/* current allocation area */
static int	intr;
static int	inparse;
static char	flags['z'-'a'+1];
static char	*flag = flags-'a';
static char	*elinep = line+sizeof(line)-5;
static char	*null	= "";
static int	heedint =1;
static struct env e ={line, iostack, iostack-1, (xint *)NULL, FDBASE, (struct env *)NULL};
static void (*qflag)(int) = SIG_IGN;
static	int	startl;
static	int	peeksym;
static	int	nlseen;
static	int	iounit = IODEFAULT;
static	YYSTYPE	yylval;
static struct iobuf sharedbuf = {AFID_NOBUF};
static struct iobuf mainbuf = {AFID_NOBUF};
static unsigned bufid = AFID_ID;	/* buffer id counter */
static struct ioarg temparg = {0, 0, 0, AFID_NOBUF, 0};
static	struct here *inhere;		/* list of hear docs while parsing */
static	struct here *acthere;		/* list of active here documents */
static	struct region *areabot;		/* bottom of area */
static	struct region *areatop;		/* top of area */
static	struct region *areanxt;		/* starting point of scan */
static void * brktop;
static void * brkaddr;


#ifdef CONFIG_FEATURE_COMMAND_EDITING
static char * current_prompt;
#endif

/* -------- sh.c -------- */
/*
 * shell
 */


extern int msh_main(int argc, char **argv)
{
	register int f;
	register char *s;
	int cflag;
	char *name, **ap;
	int (*iof)(struct ioarg *);

	initarea();
	if ((ap = environ) != NULL) {
		while (*ap)
			assign(*ap++, !COPYV);
		for (ap = environ; *ap;)
			export(lookup(*ap++));
	}
	closeall();
	areanum = 1;

	shell = lookup("SHELL");
	if (shell->value == null)
		setval(shell, DEFAULT_SHELL);
	export(shell);

	homedir = lookup("HOME");
	if (homedir->value == null)
		setval(homedir, "/");
	export(homedir);

	setval(lookup("$"), putn(getpid()));

	path = lookup("PATH");
	if (path->value == null) {
		if (geteuid() == 0)
			setval(path, "/sbin:/bin:/usr/sbin:/usr/bin");
		else
			setval(path, "/bin:/usr/bin");
	}
	export(path);

	ifs = lookup("IFS");
	if (ifs->value == null)
		setval(ifs, " \t\n");

	prompt = lookup("PS1");
#ifdef CONFIG_FEATURE_SH_FANCY_PROMPT
	if (prompt->value == null)
#endif
		setval(prompt, "$ ");
	if (geteuid() == 0) {
		setval(prompt, "# ");
		prompt->status &= ~EXPORT;
	}
	cprompt = lookup("PS2");
#ifdef CONFIG_FEATURE_SH_FANCY_PROMPT
	if (cprompt->value == null)
#endif
		setval(cprompt, "> ");

	iof = filechar;
	cflag = 0;
	name = *argv++;
	if (--argc >= 1) {
		if(argv[0][0] == '-' && argv[0][1] != '\0') {
			for (s = argv[0]+1; *s; s++)
				switch (*s) {
				case 'c':
					prompt->status &= ~EXPORT;
					cprompt->status &= ~EXPORT;
					setval(prompt, "");
					setval(cprompt, "");
					cflag = 1;
					if (--argc > 0)
						PUSHIO(aword, *++argv, iof = nlchar);
					break;

				case 'q':
					qflag = SIG_DFL;
					break;

				case 's':
					/* standard input */
					break;

				case 't':
					prompt->status &= ~EXPORT;
					setval(prompt, "");
					iof = linechar;
					break;

				case 'i':
					interactive++;
				default:
					if (*s>='a' && *s<='z')
						flag[(int)*s]++;
				}
		} else {
			argv--;
			argc++;
		}
		if (iof == filechar && --argc > 0) {
			setval(prompt, "");
			setval(cprompt, "");
			prompt->status &= ~EXPORT;
			cprompt->status &= ~EXPORT;
			if (newfile(name = *++argv))
				exit(1);
		}
	}
	setdash();
	if (e.iop < iostack) {
		PUSHIO(afile, 0, iof);
		if (isatty(0) && isatty(1) && !cflag) {
			interactive++;
#ifndef CONFIG_FEATURE_SH_EXTRA_QUIET
			printf( "\n\n" BB_BANNER " Built-in shell (msh)\n");
			printf( "Enter 'help' for a list of built-in commands.\n\n");
#endif
		}
	}
	signal(SIGQUIT, qflag);
	if (name && name[0] == '-') {
		interactive++;
		if ((f = open(".profile", 0)) >= 0)
			next(remap(f));
		if ((f = open("/etc/profile", 0)) >= 0)
			next(remap(f));
	}
	if (interactive)
		signal(SIGTERM, sig);
	if (signal(SIGINT, SIG_IGN) != SIG_IGN)
		signal(SIGINT, onintr);
	dolv = argv;
	dolc = argc;
	dolv[0] = name;
	if (dolc > 1) {
		for (ap = ++argv; --argc > 0;) {
			if (assign(*ap = *argv++, !COPYV)) {
				dolc--;	/* keyword */
			} else {
				ap++;
			}
		}
	}
	setval(lookup("#"), putn((--dolc < 0) ? (dolc = 0) : dolc));

	for (;;) {
		if (interactive && e.iop <= iostack) {
#ifdef CONFIG_FEATURE_COMMAND_EDITING
			current_prompt=prompt->value;
#else
			prs(prompt->value);
#endif
		}
		onecommand();
		/* Ensure that getenv("PATH") stays current */
		setenv("PATH", path->value, 1);
	}
}

static void
setdash()
{
	register char *cp;
	register int c;
	char m['z'-'a'+1];

	cp = m;
	for (c='a'; c<='z'; c++)
		if (flag[(int)c])
			*cp++ = c;
	*cp = 0;
	setval(lookup("-"), m);
}

static int
newfile(s)
register char *s;
{
	register int f;

	if (strcmp(s, "-") != 0) {
		f = open(s, 0);
		if (f < 0) {
			prs(s);
			err(": cannot open");
			return(1);
		}
	} else
		f = 0;
	next(remap(f));
	return(0);
}

static void
onecommand()
{
	register int i;
	jmp_buf m1;

	while (e.oenv)
		quitenv();
	areanum = 1;
	freehere(areanum);
	freearea(areanum);
	garbage();
	wdlist = 0;
	iolist = 0;
	e.errpt = 0;
	e.linep = line;
	yynerrs = 0;
	multiline = 0;
	inparse = 1;
	intr = 0;
	execflg = 0;
	setjmp(failpt = m1);	/* Bruce Evans' fix */
	if (setjmp(failpt = m1) || yyparse() || intr) {
		while (e.oenv)
			quitenv();
		scraphere();
		if (!interactive && intr)
			leave();
		inparse = 0;
		intr = 0;
		return;
	}
	inparse = 0;
	brklist = 0;
	intr = 0;
	execflg = 0;
	if (!flag['n'])
		execute(outtree, NOPIPE, NOPIPE, 0);
	if (!interactive && intr) {
		execflg = 0;
		leave();
	}
	if ((i = trapset) != 0) {
		trapset = 0;
		runtrap(i);
	}
}

static void
fail()
{
	longjmp(failpt, 1);
	/* NOTREACHED */
}

static void
leave()
{
	if (execflg)
		fail();
	scraphere();
	freehere(1);
	runtrap(0);
	exit(exstat);
	/* NOTREACHED */
}

static void
warn(s)
register char *s;
{
	if(*s) {
		prs(s);
		exstat = -1;
	}
	prs("\n");
	if (flag['e'])
		leave();
}

static void
err(s)
char *s;
{
	warn(s);
	if (flag['n'])
		return;
	if (!interactive)
		leave();
	if (e.errpt)
		longjmp(e.errpt, 1);
	closeall();
	e.iop = e.iobase = iostack;
}

static int
newenv(f)
int f;
{
	register struct env *ep;

	if (f) {
		quitenv();
		return(1);
	}
	ep = (struct env *) space(sizeof(*ep));
	if (ep == NULL) {
		while (e.oenv)
			quitenv();
		fail();
	}
	*ep = e;
	e.oenv = ep;
	e.errpt = errpt;
	return(0);
}

static void
quitenv()
{
	register struct env *ep;
	register int fd;

	if ((ep = e.oenv) != NULL) {
		fd = e.iofd;
		e = *ep;
		/* should close `'d files */
		DELETE(ep);
		while (--fd >= e.iofd)
			close(fd);
	}
}

/*
 * Is any character from s1 in s2?
 */
static int
anys(s1, s2)
register char *s1, *s2;
{
	while (*s1)
		if (any(*s1++, s2))
			return(1);
	return(0);
}

/*
 * Is character c in s?
 */
static int
any(c, s)
register int c;
register char *s;
{
	while (*s)
		if (*s++ == c)
			return(1);
	return(0);
}

static char *
putn(n)
register int n;
{
	return(itoa(n));
}

static char *
itoa(n)
register int n;
{
	static char s[20];
	snprintf(s, sizeof(s), "%u", n);
	return(s);
}

static void
next(int f)
{
	PUSHIO(afile, f, filechar);
}

static void
onintr(s)
int s;				/* ANSI C requires a parameter */
{
	signal(SIGINT, onintr);
	intr = 1;
	if (interactive) {
		if (inparse) {
			prs("\n");
			fail();
		}
	}
	else if (heedint) {
		execflg = 0;
		leave();
	}
}

static char *
space(n)
int n;
{
	register char *cp;

	if ((cp = getcell(n)) == 0)
		err("out of string space");
	return(cp);
}

static char *
strsave(s, a)
register char *s;
int a;
{
	register char *cp, *xp;

	if ((cp = space(strlen(s)+1)) != NULL) {
		setarea((char *)cp, a);
		for (xp = cp; (*xp++ = *s++) != '\0';)
			;
		return(cp);
	}
	return("");
}

/*
 * trap handling
 */
static void
sig(i)
register int i;
{
	trapset = i;
	signal(i, sig);
}

static void runtrap(i)
int i;
{
	char *trapstr;

	if ((trapstr = trap[i]) == NULL)
		return;
	if (i == 0)
		trap[i] = 0;
	RUN(aword, trapstr, nlchar);
}

/* -------- var.c -------- */

/*
 * Find the given name in the dictionary
 * and return its value.  If the name was
 * not previously there, enter it now and
 * return a null value.
 */
static struct var *
lookup(n)
register char *n;
{
	register struct var *vp;
	register char *cp;
	register int c;
	static struct var dummy;

	if (isdigit(*n)) {
		dummy.name = n;
		for (c = 0; isdigit(*n) && c < 1000; n++)
			c = c*10 + *n-'0';
		dummy.status = RONLY;
		dummy.value = c <= dolc? dolv[c]: null;
		return(&dummy);
	}
	for (vp = vlist; vp; vp = vp->next)
		if (eqname(vp->name, n))
			return(vp);
	cp = findeq(n);
	vp = (struct var *)space(sizeof(*vp));
	if (vp == 0 || (vp->name = space((int)(cp-n)+2)) == 0) {
		dummy.name = dummy.value = "";
		return(&dummy);
	}
	for (cp = vp->name; (*cp = *n++) && *cp != '='; cp++)
		;
	if (*cp == 0)
		*cp = '=';
	*++cp = 0;
	setarea((char *)vp, 0);
	setarea((char *)vp->name, 0);
	vp->value = null;
	vp->next = vlist;
	vp->status = GETCELL;
	vlist = vp;
	return(vp);
}

/*
 * give variable at `vp' the value `val'.
 */
static void
setval(vp, val)
struct var *vp;
char *val;
{
	nameval(vp, val, (char *)NULL);
}

/*
 * if name is not NULL, it must be
 * a prefix of the space `val',
 * and end with `='.
 * this is all so that exporting
 * values is reasonably painless.
 */
static void
nameval(vp, val, name)
register struct var *vp;
char *val, *name;
{
	register char *cp, *xp;
	char *nv;
	int fl;

	if (vp->status & RONLY) {
		for (xp = vp->name; *xp && *xp != '=';)
			putc(*xp++, stderr);
		err(" is read-only");
		return;
	}
	fl = 0;
	if (name == NULL) {
		xp = space(strlen(vp->name)+strlen(val)+2);
		if (xp == 0)
			return;
		/* make string:  name=value */
		setarea((char *)xp, 0);
		name = xp;
		for (cp = vp->name; (*xp = *cp++) && *xp!='='; xp++)
			;
		if (*xp++ == 0)
			xp[-1] = '=';
		nv = xp;
		for (cp = val; (*xp++ = *cp++) != '\0';)
			;
		val = nv;
		fl = GETCELL;
	}
	if (vp->status & GETCELL)
		freecell(vp->name);    /* form new string `name=value' */
	vp->name = name;
	vp->value = val;
	vp->status |= fl;
}

static void
export(vp)
struct var *vp;
{
	vp->status |= EXPORT;
}

static void
ronly(vp)
struct var *vp;
{
	if (isalpha(vp->name[0]) || vp->name[0] == '_')	/* not an internal symbol */
		vp->status |= RONLY;
}

static int
isassign(s)
register char *s;
{
	if (!isalpha((int)*s) && *s != '_')
		return(0);
	for (; *s != '='; s++)
		if (*s == 0 || (!isalnum(*s) && *s != '_'))
			return(0);
	return(1);
}

static int
assign(s, cf)
register char *s;
int cf;
{
	register char *cp;
	struct var *vp;

	if (!isalpha(*s) && *s != '_')
		return(0);
	for (cp = s; *cp != '='; cp++)
		if (*cp == 0 || (!isalnum(*cp) && *cp != '_'))
			return(0);
	vp = lookup(s);
	nameval(vp, ++cp, cf == COPYV? (char *)NULL: s);
	if (cf != COPYV)
		vp->status &= ~GETCELL;
	return(1);
}

static int
checkname(cp)
register char *cp;
{
	if (!isalpha(*cp++) && *(cp-1) != '_')
		return(0);
	while (*cp)
		if (!isalnum(*cp++) && *(cp-1) != '_')
			return(0);
	return(1);
}

static void
putvlist(f, out)
register int f, out;
{
	register struct var *vp;

	for (vp = vlist; vp; vp = vp->next)
		if (vp->status & f && (isalpha(*vp->name) || *vp->name == '_')) {
			if (vp->status & EXPORT)
				write(out, "export ", 7);
			if (vp->status & RONLY)
				write(out, "readonly ", 9);
			write(out, vp->name, (int)(findeq(vp->name) - vp->name));
			write(out, "\n", 1);
		}
}

static int
eqname(n1, n2)
register char *n1, *n2;
{
	for (; *n1 != '=' && *n1 != 0; n1++)
		if (*n2++ != *n1)
			return(0);
	return(*n2 == 0 || *n2 == '=');
}

static char *
findeq(cp)
register char *cp;
{
	while (*cp != '\0' && *cp != '=')
		cp++;
	return(cp);
}

/* -------- gmatch.c -------- */
/*
 * int gmatch(string, pattern)
 * char *string, *pattern;
 *
 * Match a pattern as in sh(1).
 */

#define	CMASK	0377
#define	QUOTE	0200
#define	QMASK	(CMASK&~QUOTE)
#define	NOT	'!'	/* might use ^ */

static int
gmatch(s, p)
register char *s, *p;
{
	register int sc, pc;

	if (s == NULL || p == NULL)
		return(0);
	while ((pc = *p++ & CMASK) != '\0') {
		sc = *s++ & QMASK;
		switch (pc) {
		case '[':
			if ((p = cclass(p, sc)) == NULL)
				return(0);
			break;

		case '?':
			if (sc == 0)
				return(0);
			break;

		case '*':
			s--;
			do {
				if (*p == '\0' || gmatch(s, p))
					return(1);
			} while (*s++ != '\0');
			return(0);

		default:
			if (sc != (pc&~QUOTE))
				return(0);
		}
	}
	return(*s == 0);
}

static char *
cclass(p, sub)
register char *p;
register int sub;
{
	register int c, d, not, found;

	if ((not = *p == NOT) != 0)
		p++;
	found = not;
	do {
		if (*p == '\0')
			return((char *)NULL);
		c = *p & CMASK;
		if (p[1] == '-' && p[2] != ']') {
			d = p[2] & CMASK;
			p++;
		} else
			d = c;
		if (c == sub || (c <= sub && sub <= d))
			found = !not;
	} while (*++p != ']');
	return(found? p+1: (char *)NULL);
}


/* -------- area.c -------- */

/*
 * All memory between (char *)areabot and (char *)(areatop+1) is
 * exclusively administered by the area management routines.
 * It is assumed that sbrk() and brk() manipulate the high end.
 */

#define sbrk(X) ({ void * __q = (void *)-1; if (brkaddr + (int)(X) < brktop) { __q = brkaddr; brkaddr+=(int)(X); } __q;})

static void
initarea()
{
	brkaddr = malloc(65000);
	brktop = brkaddr + 65000;

	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;
		return(c);
	case '^':
		startl = 1;
		return('|');
	case '>':
	case '<':
		diag(c);
		return(c);

	case '\n':
		nlseen++;
		gethere();
		startl = 1;
		if (multiline || cf & CONTIN) {
			if (interactive && e.iop <= iostack) {
#ifdef CONFIG_FEATURE_COMMAND_EDITING
			current_prompt=cprompt->value;
#else
			prs(cprompt->value);
#endif
			}
			if (cf & CONTIN)
				goto loop;
		}
		return(c);

	case '(':
	case ')':
		startl = 1;
		return(c);
	}

	unget(c);

pack:
	while ((c = my_getc(0)) != 0 && !any(c, "`$ '\"\t;&<>()|^\n"))
		if (e.linep >= elinep)
			err("word too long");
		else
			*e.linep++ = c;
	unget(c);
	if(any(c, "\"'`$"))
		goto loop;
	*e.linep++ = '\0';
	if (atstart && (c = rlookup(line))!=0) {
		startl = 1;
		return(c);
	}
	yylval.cp = strsave(line, areanum);
	return(WORD);
}

static int
collect(c, c1)
register int c, c1;
{
	char s[2];

	*e.linep++ = c;
	while ((c = my_getc(c1)) != c1) {
		if (c == 0) {
			unget(c);
			s[0] = c1;
			s[1] = 0;
			prs("no closing "); yyerror(s);
			return(YYERRCODE);
		}
		if (interactive && c == '\n' && e.iop <= iostack) {
#ifdef CONFIG_FEATURE_COMMAND_EDITING
		    current_prompt=cprompt->value;
#else
		    prs(cprompt->value);
#endif
		}
		*e.linep++ = c;
	}
	*e.linep++ = c;
	return(0);
}

static int
dual(c)
register int c;
{
	char s[3];
	register char *cp = s;

	*cp++ = c;
	*cp++ = my_getc(0);
	*cp = 0;
	if ((c = rlookup(s)) == 0)
		unget(*--cp);
	return(c);
}

static void
diag(ec)
register int ec;
{
	register int c;

	c = my_getc(0);
	if (c == '>' || c == '<') {
		if (c != ec)
			zzerr();
		yylval.i = ec == '>'? IOWRITE|IOCAT: IOHERE;
		c = my_getc(0);
	} else
		yylval.i = ec == '>'? IOWRITE: IOREAD;
	if (c != '&' || yylval.i == IOHERE)
		unget(c);
	else
		yylval.i |= IODUP;
}

static char *
tree(size)
unsigned size;
{
	register char *t;

	if ((t = getcell(size)) == NULL) {
		prs("command line too complicated\n");
		fail();
		/* NOTREACHED */
	}
	return(t);
}

/* VARARGS1 */
/* ARGSUSED */

/* -------- exec.c -------- */

/*
 * execute tree
 */


static int
execute(t, pin, pout, act)
register struct op *t;
int *pin, *pout;
int act;
{
	register struct op *t1;
	volatile int i, rv, a;
	char *cp, **wp, **wp2;
	struct var *vp;
	struct brkcon bc;

#if __GNUC__
	/* Avoid longjmp clobbering */
	(void) &wp;
#endif


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

	case TCOM:
		{
			int child;
			rv = forkexec(t, pin, pout, act, wp, &child);
			if (child) {
				exstat = rv;
				leave();
			}
		}
		break;

	case TPIPE:
		{
		    int pv[2];
		    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:
	{
		int hinteractive = interactive;

		i = vfork();
		if (i != 0) {
			interactive = hinteractive;
			if (i != -1) {
				setval(lookup("!"), putn(i));
				if (pin != NULL)
					closepipe(pin);
				if (interactive) {
					prs(putn(i));
					prs("\n");
				}
			} else
				rv = -1;
			setstatus(rv);
		} else {
			signal(SIGINT, SIG_IGN);
			signal(SIGQUIT, SIG_IGN);
			if (interactive)
				signal(SIGTERM, SIG_DFL);
			interactive = 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 (interactive && intr) {
		closeall();
		fail();
	}
	if ((i = trapset) != 0) {
		trapset = 0;
		runtrap(i);
	}
	return(rv);
}

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

	int *hpin = pin;
	int *hpout = pout;
	int hforked;
	char *hwp;
	int hinteractive;
	int hintr;
	struct brkcon * hbrklist;
	int hexecflg;

#if __GNUC__
	/* Avoid longjmp clobbering */
	(void) &pin;
	(void) &pout;
	(void) &wp;
	(void) &shcom;
	(void) &cp;
	(void) &resetsig;
	(void) &owp;
#endif

	owp = wp;
	resetsig = 0;
	*pforked = 0;
	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) {

		hpin = pin;
		hpout = pout;
		hforked = *pforked;
		hwp = *wp;
		hinteractive = interactive;
		hintr = intr;
		hbrklist = brklist;
		hexecflg = execflg;

		i = vfork();
		if (i != 0) {
                	/* who wrote this crappy non vfork safe shit? */
			pin = hpin;
			pout = hpout;
			*pforked = hforked;
			*wp = hwp;
			interactive = hinteractive;
			intr = hintr;
			brklist = hbrklist;
			execflg = hexecflg;

			*pforked = 0;
			if (i == -1)
				return(rv);
			if (pin != NULL)
				closepipe(pin);
			return(pout==NULL? setstatus(waitfor(i,0)): 0);
		}

		if (interactive) {
			signal(SIGINT, SIG_IGN);
			signal(SIGQUIT, SIG_IGN);
			resetsig = 1;
		}
		interactive = 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 */
	exit(1);
}

/*
 * 0< 1> are ignored as required
 * within pipelines.
 */
static int
iosetup(iop, pipein, pipeout)
register struct ioword *iop;
int pipein, pipeout;
{
	register int u = -1;
	char *cp=NULL, *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] || (!isdigit(*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 int 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.
 */
static 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 (interactive) {
			if (canintr)
				intr = 0;
		} else {
			if (exstat == 0) exstat = rv;
			onintr(0);
		}
	}
	return(rv);
}

static 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.
 */
static char *
rexecve(c, v, envp)
char *c, **v, **envp;
{
	register int i;
	register char *sp, *tp;
	int eacces = 0, asis = 0;

#ifdef CONFIG_FEATURE_SH_STANDALONE_SHELL
	char *name = c;
	optind = 1;
	if (find_applet_by_name(name)) {
		/* We have to exec here since we vforked.  Running
		 * run_applet_by_name() won't work and bad things
		 * will happen. */
		execve("/proc/self/exe", v, envp);
		execve("busybox", v, envp);
	}
#endif

	sp = any('/', c)? "": path->value;
	asis = *sp == '\0';
	while (asis || *sp != '\0') {
		asis = 0;
		tp = e.linep;
		for (; *sp != '\0'; tp++)
			if ((*tp = *sp++) == ':') {
				asis = *sp == '\0';
				break;
			}
		if (tp != e.linep)
			*tp++ = '/';
		for (i = 0; (*tp++ = c[i++]) != '\0';)
			;

		execve(e.linep, v, envp);
		switch (errno) {
		case ENOEXEC:
			*v = e.linep;
			tp = *--v;
			*v = e.linep;
			execve(DEFAULT_SHELL, v, envp);
			*v = tp;
			return("no Shell");

		case ENOMEM:
			return((char*)bb_msg_memory_exhausted);

		case E2BIG:
			return("argument list too long");

		case EACCES:
			eacces++;
			break;
		}
	}
	return(errno==ENOENT ? "not found" : "cannot execute");
}

/*
 * Run the command produced by generator `f'
 * applied to stream `arg'.
 */
static int
run(struct ioarg *argp, int (*f)(struct ioarg *))
{
	struct op *otree;
	struct wdblock *swdlist;
	struct wdblock *siolist;
	jmp_buf ev, rt;
	xint *ofail;
	int rv;

#if __GNUC__
	/* Avoid longjmp clobbering */
	(void) &rv;
#endif

	areanum++;
	swdlist = wdlist;
	siolist = iolist;
	otree = outtree;
	ofail = failpt;
	rv = -1;
	if (newenv(setjmp(errpt = ev)) == 0) {
		wdlist = 0;
		iolist = 0;
		pushio(argp, f);
		e.iobase = e.iop;
		yynerrs = 0;
		if (setjmp(failpt = rt) == 0 && yyparse() == 0)
			rv = execute(outtree, NOPIPE, NOPIPE, 0);
		quitenv();
	}
	wdlist = swdlist;
	iolist = siolist;
	failpt = ofail;
	outtree = otree;
	freearea(areanum--);
	return(rv);
}

/* -------- do.c -------- */

/*
 * built-in commands: doX
 */

static int dohelp(struct op *t )
{
	int col;
	const struct builtincmd *x;

	printf("\nBuilt-in commands:\n");
	printf("-------------------\n");

	for (col=0, x = builtincmds; x->builtinfunc != NULL; x++) {
		if (!x->name)
			continue;
		col += printf("%s%s", ((col == 0) ? "\t" : " "), x->name);
		if (col > 60) {
			printf("\n");
			col = 0;
		}
	}
#ifdef CONFIG_FEATURE_SH_STANDALONE_SHELL
	{
		int i;
		const struct BB_applet *applet;
		extern const struct BB_applet applets[];
		extern const size_t NUM_APPLETS;

		for (i=0, applet = applets; i < NUM_APPLETS; applet++, i++) {
			if (!applet->name)
				continue;

			col += printf("%s%s", ((col == 0) ? "\t" : " "),
					applet->name);
			if (col > 60) {
				printf("\n");
				col = 0;
			}
		}
	}
#endif
	printf("\n\n");
	return EXIT_SUCCESS;
}



static int dolabel(struct op *t )
{
	return(0);
}

static int
dochdir(t)
register struct op *t;
{
	register char *cp, *er;

	if ((cp = t->words[1]) == NULL && (cp = homedir->value) == NULL)
		er = ": no home directory";
	else if(chdir(cp) < 0)
		er = ": bad directory";
	else
		return(0);
	prs(cp != NULL? cp: "cd");
	err(er);
	return(1);
}

static int
doshift(t)
register struct op *t;
{
	register int n;

	n = t->words[1]? getn(t->words[1]): 1;
	if(dolc < n) {
		err("nothing to shift");
		return(1);
	}
	dolv[n] = dolv[0];
	dolv += n;
	dolc -= n;
	setval(lookup("#"), putn(dolc));
	return(0);
}

/*
 * execute login and newgrp directly
 */
static int
dologin(t)
struct op *t;
{
	register char *cp;

	if (interactive) {
		signal(SIGINT, SIG_DFL);
		signal(SIGQUIT, SIG_DFL);
	}
	cp = rexecve(t->words[0], t->words, makenv());
	prs(t->words[0]); prs(": "); err(cp);
	return(1);
}

static int