shell/ash.c

/* vi: set sw=4 ts=4: */
/*
 * ash shell port for busybox
 *
 * Copyright (c) 1989, 1991, 1993, 1994
 *      The Regents of the University of California.  All rights reserved.
 *
 * Copyright (c) 1997-2005 Herbert Xu <herbert@gondor.apana.org.au>
 * was re-ported from NetBSD and debianized.
 *
 *
 * This code is derived from software contributed to Berkeley by
 * Kenneth Almquist.
 *
 * Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
 *
 * Original BSD copyright notice is retained at the end of this file.
 */

/*
 * rewrite arith.y to micro stack based cryptic algorithm by
 * Copyright (c) 2001 Aaron Lehmann <aaronl@vitelus.com>
 *
 * Modified by Paul Mundt <lethal@linux-sh.org> (c) 2004 to support
 * dynamic variables.
 *
 * Modified by Vladimir Oleynik <dzo@simtreas.ru> (c) 2001-2005 to be
 * used in busybox and size optimizations,
 * rewrote arith (see notes to this), added locale support,
 * rewrote dynamic variables.
 *
 */

/*
 * The follow should be set to reflect the type of system you have:
 *      JOBS -> 1 if you have Berkeley job control, 0 otherwise.
 *      define SYSV if you are running under System V.
 *      define DEBUG=1 to compile in debugging ('set -o debug' to turn on)
 *      define DEBUG=2 to compile in and turn on debugging.
 *
 * When debugging is on, debugging info will be written to ./trace and
 * a quit signal will generate a core dump.
 */
#define DEBUG 0
#define IFS_BROKEN
#define PROFILE 0
#if ENABLE_ASH_JOB_CONTROL
#define JOBS 1
#else
#define JOBS 0
#endif

#if DEBUG
#define _GNU_SOURCE
#endif
#include "busybox.h" /* for struct bb_applet */
#include <paths.h>
#include <setjmp.h>
#include <fnmatch.h>
#if JOBS || ENABLE_ASH_READ_NCHARS
#include <termios.h>
#endif
extern char **environ;

#if defined(__uClinux__)
#error "Do not even bother, ash will not run on uClinux"
#endif


/* ============ Misc helpers */

#define xbarrier() do { __asm__ __volatile__ ("": : :"memory"); } while (0)

/* C99 say: "char" declaration may be signed or unsigned default */
#define signed_char2int(sc) ((int)((signed char)sc))


/* ============ Shell options */

static const char *const optletters_optnames[] = {
	"e"   "errexit",
	"f"   "noglob",
	"I"   "ignoreeof",
	"i"   "interactive",
	"m"   "monitor",
	"n"   "noexec",
	"s"   "stdin",
	"x"   "xtrace",
	"v"   "verbose",
	"C"   "noclobber",
	"a"   "allexport",
	"b"   "notify",
	"u"   "nounset",
	"\0"  "vi"
#if DEBUG
	,"\0"  "nolog"
	,"\0"  "debug"
#endif
};

#define optletters(n) optletters_optnames[(n)][0]
#define optnames(n) (&optletters_optnames[(n)][1])

enum { NOPTS = ARRAY_SIZE(optletters_optnames) };

static char optlist[NOPTS] ALIGN1;

#define eflag optlist[0]
#define fflag optlist[1]
#define Iflag optlist[2]
#define iflag optlist[3]
#define mflag optlist[4]
#define nflag optlist[5]
#define sflag optlist[6]
#define xflag optlist[7]
#define vflag optlist[8]
#define Cflag optlist[9]
#define aflag optlist[10]
#define bflag optlist[11]
#define uflag optlist[12]
#define viflag optlist[13]
#if DEBUG
#define nolog optlist[14]
#define debug optlist[15]
#endif


/* ============ Misc data */

static char nullstr[1] ALIGN1;  /* zero length string */
static const char homestr[] ALIGN1 = "HOME";
static const char snlfmt[] ALIGN1 = "%s\n";
static const char illnum[] ALIGN1 = "Illegal number: %s";

static char *minusc;  /* argument to -c option */

/* pid of main shell */
static int rootpid;
/* shell level: 0 for the main shell, 1 for its children, and so on */
static int shlvl;
#define rootshell (!shlvl)
/* trap handler commands */
static char *trap[NSIG];
static smallint isloginsh;
/* current value of signal */
static char sigmode[NSIG - 1];
/* indicates specified signal received */
static char gotsig[NSIG - 1];
static char *arg0; /* value of $0 */


/* ============ Interrupts / exceptions */

/*
 * We enclose jmp_buf in a structure so that we can declare pointers to
 * jump locations.  The global variable handler contains the location to
 * jump to when an exception occurs, and the global variable exception
 * contains a code identifying the exception.  To implement nested
 * exception handlers, the user should save the value of handler on entry
 * to an inner scope, set handler to point to a jmploc structure for the
 * inner scope, and restore handler on exit from the scope.
 */
struct jmploc {
	jmp_buf loc;
};
static struct jmploc *exception_handler;
static int exception;
/* exceptions */
#define EXINT 0         /* SIGINT received */
#define EXERROR 1       /* a generic error */
#define EXSHELLPROC 2   /* execute a shell procedure */
#define EXEXEC 3        /* command execution failed */
#define EXEXIT 4        /* exit the shell */
#define EXSIG 5         /* trapped signal in wait(1) */
static volatile int suppressint;
static volatile sig_atomic_t intpending;
/* do we generate EXSIG events */
static int exsig;
/* last pending signal */
static volatile sig_atomic_t pendingsig;

/*
 * Sigmode records the current value of the signal handlers for the various
 * modes.  A value of zero means that the current handler is not known.
 * S_HARD_IGN indicates that the signal was ignored on entry to the shell,
 */

#define S_DFL 1                 /* default signal handling (SIG_DFL) */
#define S_CATCH 2               /* signal is caught */
#define S_IGN 3                 /* signal is ignored (SIG_IGN) */
#define S_HARD_IGN 4            /* signal is ignored permenantly */
#define S_RESET 5               /* temporary - to reset a hard ignored sig */

/*
 * These macros allow the user to suspend the handling of interrupt signals
 * over a period of time.  This is similar to SIGHOLD to or sigblock, but
 * much more efficient and portable.  (But hacking the kernel is so much
 * more fun than worrying about efficiency and portability. :-))
 */
#define INT_OFF \
	do { \
		suppressint++; \
		xbarrier(); \
	} while (0)

/*
 * Called to raise an exception.  Since C doesn't include exceptions, we
 * just do a longjmp to the exception handler.  The type of exception is
 * stored in the global variable "exception".
 */
static void raise_exception(int) ATTRIBUTE_NORETURN;
static void
raise_exception(int e)
{
#if DEBUG
	if (exception_handler == NULL)
		abort();
#endif
	INT_OFF;
	exception = e;
	longjmp(exception_handler->loc, 1);
}

/*
 * Called from trap.c when a SIGINT is received.  (If the user specifies
 * that SIGINT is to be trapped or ignored using the trap builtin, then
 * this routine is not called.)  Suppressint is nonzero when interrupts
 * are held using the INT_OFF macro.  (The test for iflag is just
 * defensive programming.)
 */
static void raise_interrupt(void) ATTRIBUTE_NORETURN;
static void
raise_interrupt(void)
{
	int i;
	sigset_t mask;

	intpending = 0;
	/* Signal is not automatically re-enabled after it is raised,
	 * do it ourself */
	sigemptyset(&mask);
	sigprocmask(SIG_SETMASK, &mask, 0);
	/* pendingsig = 0; - now done in onsig() */

	i = EXSIG;
	if (gotsig[SIGINT - 1] && !trap[SIGINT]) {
		if (!(rootshell && iflag)) {
			signal(SIGINT, SIG_DFL);
			raise(SIGINT);
		}
		i = EXINT;
	}
	raise_exception(i);
	/* NOTREACHED */
}

#if ENABLE_ASH_OPTIMIZE_FOR_SIZE
static void
int_on(void)
{
	if (--suppressint == 0 && intpending) {
		raise_interrupt();
	}
}
#define INT_ON int_on()
static void
force_int_on(void)
{
	suppressint = 0;
	if (intpending)
		raise_interrupt();
}
#define FORCE_INT_ON force_int_on()
#else
#define INT_ON \
	do { \
		xbarrier(); \
		if (--suppressint == 0 && intpending) \
			raise_interrupt(); \
	} while (0)
#define FORCE_INT_ON \
	do { \
		xbarrier(); \
		suppressint = 0; \
		if (intpending) \
			raise_interrupt(); \
	} while (0)
#endif /* ASH_OPTIMIZE_FOR_SIZE */

#define SAVE_INT(v) ((v) = suppressint)

#define RESTORE_INT(v) \
	do { \
		xbarrier(); \
		suppressint = (v); \
		if (suppressint == 0 && intpending) \
			raise_interrupt(); \
	} while (0)

#define EXSIGON \
	do { \
		exsig++; \
		xbarrier(); \
		if (pendingsig) \
			raise_exception(EXSIG); \
	} while (0)
/* EXSIG is turned off by evalbltin(). */

/*
 * Ignore a signal. Only one usage site - in forkchild()
 */
static void
ignoresig(int signo)
{
	if (sigmode[signo - 1] != S_IGN && sigmode[signo - 1] != S_HARD_IGN) {
		signal(signo, SIG_IGN);
	}
	sigmode[signo - 1] = S_HARD_IGN;
}

/*
 * Signal handler. Only one usage site - in setsignal()
 */
static void
onsig(int signo)
{
	gotsig[signo - 1] = 1;
	pendingsig = signo;

	if (exsig || (signo == SIGINT && !trap[SIGINT])) {
		if (!suppressint) {
			pendingsig = 0;
			raise_interrupt();
		}
		intpending = 1;
	}
}


/* ============ Stdout/stderr output */

static void
outstr(const char *p, FILE *file)
{
	INT_OFF;
	fputs(p, file);
	INT_ON;
}

static void
flush_stdout_stderr(void)
{
	INT_OFF;
	fflush(stdout);
	fflush(stderr);
	INT_ON;
}

static void
flush_stderr(void)
{
	INT_OFF;
	fflush(stderr);
	INT_ON;
}

static void
outcslow(int c, FILE *dest)
{
	INT_OFF;
	putc(c, dest);
	fflush(dest);
	INT_ON;
}

static int out1fmt(const char *, ...) __attribute__((__format__(__printf__,1,2)));
static int
out1fmt(const char *fmt, ...)
{
	va_list ap;
	int r;

	INT_OFF;
	va_start(ap, fmt);
	r = vprintf(fmt, ap);
	va_end(ap);
	INT_ON;
	return r;
}

static int fmtstr(char *, size_t, const char *, ...) __attribute__((__format__(__printf__,3,4)));
static int
fmtstr(char *outbuf, size_t length, const char *fmt, ...)
{
	va_list ap;
	int ret;

	va_start(ap, fmt);
	INT_OFF;
	ret = vsnprintf(outbuf, length, fmt, ap);
	va_end(ap);
	INT_ON;
	return ret;
}

static void
out1str(const char *p)
{
	outstr(p, stdout);
}

static void
out2str(const char *p)
{
	outstr(p, stderr);
	flush_stderr();
}


/* ============ Parser structures */

/* control characters in argument strings */
#define CTLESC '\201'           /* escape next character */
#define CTLVAR '\202'           /* variable defn */
#define CTLENDVAR '\203'
#define CTLBACKQ '\204'
#define CTLQUOTE 01             /* ored with CTLBACKQ code if in quotes */
/*      CTLBACKQ | CTLQUOTE == '\205' */
#define CTLARI  '\206'          /* arithmetic expression */
#define CTLENDARI '\207'
#define CTLQUOTEMARK '\210'

/* variable substitution byte (follows CTLVAR) */
#define VSTYPE  0x0f            /* type of variable substitution */
#define VSNUL   0x10            /* colon--treat the empty string as unset */
#define VSQUOTE 0x80            /* inside double quotes--suppress splitting */

/* values of VSTYPE field */
#define VSNORMAL        0x1             /* normal variable:  $var or ${var} */
#define VSMINUS         0x2             /* ${var-text} */
#define VSPLUS          0x3             /* ${var+text} */
#define VSQUESTION      0x4             /* ${var?message} */
#define VSASSIGN        0x5             /* ${var=text} */
#define VSTRIMRIGHT     0x6             /* ${var%pattern} */
#define VSTRIMRIGHTMAX  0x7             /* ${var%%pattern} */
#define VSTRIMLEFT      0x8             /* ${var#pattern} */
#define VSTRIMLEFTMAX   0x9             /* ${var##pattern} */
#define VSLENGTH        0xa             /* ${#var} */

static const char dolatstr[] ALIGN1 = {
	CTLVAR, VSNORMAL|VSQUOTE, '@', '=', '\0'
};

#define NCMD 0
#define NPIPE 1
#define NREDIR 2
#define NBACKGND 3
#define NSUBSHELL 4
#define NAND 5
#define NOR 6
#define NSEMI 7
#define NIF 8
#define NWHILE 9
#define NUNTIL 10
#define NFOR 11
#define NCASE 12
#define NCLIST 13
#define NDEFUN 14
#define NARG 15
#define NTO 16
#define NCLOBBER 17
#define NFROM 18
#define NFROMTO 19
#define NAPPEND 20
#define NTOFD 21
#define NFROMFD 22
#define NHERE 23
#define NXHERE 24
#define NNOT 25

union node;

struct ncmd {
	int type;
	union node *assign;
	union node *args;
	union node *redirect;
};

struct npipe {
	int type;
	int backgnd;
	struct nodelist *cmdlist;
};

struct nredir {
	int type;
	union node *n;
	union node *redirect;
};

struct nbinary {
	int type;
	union node *ch1;
	union node *ch2;
};

struct nif {
	int type;
	union node *test;
	union node *ifpart;
	union node *elsepart;
};

struct nfor {
	int type;
	union node *args;
	union node *body;
	char *var;
};

struct ncase {
	int type;
	union node *expr;
	union node *cases;
};

struct nclist {
	int type;
	union node *next;
	union node *pattern;
	union node *body;
};

struct narg {
	int type;
	union node *next;
	char *text;
	struct nodelist *backquote;
};

struct nfile {
	int type;
	union node *next;
	int fd;
	union node *fname;
	char *expfname;
};

struct ndup {
	int type;
	union node *next;
	int fd;
	int dupfd;
	union node *vname;
};

struct nhere {
	int type;
	union node *next;
	int fd;
	union node *doc;
};

struct nnot {
	int type;
	union node *com;
};

union node {
	int type;
	struct ncmd ncmd;
	struct npipe npipe;
	struct nredir nredir;
	struct nbinary nbinary;
	struct nif nif;
	struct nfor nfor;
	struct ncase ncase;
	struct nclist nclist;
	struct narg narg;
	struct nfile nfile;
	struct ndup ndup;
	struct nhere nhere;
	struct nnot nnot;
};

struct nodelist {
	struct nodelist *next;
	union node *n;
};

struct funcnode {
	int count;
	union node n;
};

/*
 * Free a parse tree.
 */
static void
freefunc(struct funcnode *f)
{
	if (f && --f->count < 0)
		free(f);
}


/* ============ Debugging output */

#if DEBUG

static FILE *tracefile;

static void
trace_printf(const char *fmt, ...)
{
	va_list va;

	if (debug != 1)
		return;
	va_start(va, fmt);
	vfprintf(tracefile, fmt, va);
	va_end(va);
}

static void
trace_vprintf(const char *fmt, va_list va)
{
	if (debug != 1)
		return;
	vfprintf(tracefile, fmt, va);
}

static void
trace_puts(const char *s)
{
	if (debug != 1)
		return;
	fputs(s, tracefile);
}

static void
trace_puts_quoted(char *s)
{
	char *p;
	char c;

	if (debug != 1)
		return;
	putc('"', tracefile);
	for (p = s; *p; p++) {
		switch (*p) {
		case '\n':  c = 'n';  goto backslash;
		case '\t':  c = 't';  goto backslash;
		case '\r':  c = 'r';  goto backslash;
		case '"':  c = '"';  goto backslash;
		case '\\':  c = '\\';  goto backslash;
		case CTLESC:  c = 'e';  goto backslash;
		case CTLVAR:  c = 'v';  goto backslash;
		case CTLVAR+CTLQUOTE:  c = 'V'; goto backslash;
		case CTLBACKQ:  c = 'q';  goto backslash;
		case CTLBACKQ+CTLQUOTE:  c = 'Q'; goto backslash;
 backslash:
			putc('\\', tracefile);
			putc(c, tracefile);
			break;
		default:
			if (*p >= ' ' && *p <= '~')
				putc(*p, tracefile);
			else {
				putc('\\', tracefile);
				putc(*p >> 6 & 03, tracefile);
				putc(*p >> 3 & 07, tracefile);
				putc(*p & 07, tracefile);
			}
			break;
		}
	}
	putc('"', tracefile);
}

static void
trace_puts_args(char **ap)
{
	if (debug != 1)
		return;
	if (!*ap)
		return;
	while (1) {
		trace_puts_quoted(*ap);
		if (!*++ap) {
			putc('\n', tracefile);
			break;
		}
		putc(' ', tracefile);
	}
}

static void
opentrace(void)
{
	char s[100];
#ifdef O_APPEND
	int flags;
#endif

	if (debug != 1) {
		if (tracefile)
			fflush(tracefile);
		/* leave open because libedit might be using it */
		return;
	}
	strcpy(s, "./trace");
	if (tracefile) {
		if (!freopen(s, "a", tracefile)) {
			fprintf(stderr, "Can't re-open %s\n", s);
			debug = 0;
			return;
		}
	} else {
		tracefile = fopen(s, "a");
		if (tracefile == NULL) {
			fprintf(stderr, "Can't open %s\n", s);
			debug = 0;
			return;
		}
	}
#ifdef O_APPEND
	flags = fcntl(fileno(tracefile), F_GETFL);
	if (flags >= 0)
		fcntl(fileno(tracefile), F_SETFL, flags | O_APPEND);
#endif
	setlinebuf(tracefile);
	fputs("\nTracing started.\n", tracefile);
}

static void
indent(int amount, char *pfx, FILE *fp)
{
	int i;

	for (i = 0; i < amount; i++) {
		if (pfx && i == amount - 1)
			fputs(pfx, fp);
		putc('\t', fp);
	}
}

/* little circular references here... */
static void shtree(union node *n, int ind, char *pfx, FILE *fp);

static void
sharg(union node *arg, FILE *fp)
{
	char *p;
	struct nodelist *bqlist;
	int subtype;

	if (arg->type != NARG) {
		out1fmt("<node type %d>\n", arg->type);
		abort();
	}
	bqlist = arg->narg.backquote;
	for (p = arg->narg.text; *p; p++) {
		switch (*p) {
		case CTLESC:
			putc(*++p, fp);
			break;
		case CTLVAR:
			putc('$', fp);
			putc('{', fp);
			subtype = *++p;
			if (subtype == VSLENGTH)
				putc('#', fp);

			while (*p != '=')
				putc(*p++, fp);

			if (subtype & VSNUL)
				putc(':', fp);

			switch (subtype & VSTYPE) {
			case VSNORMAL:
				putc('}', fp);
				break;
			case VSMINUS:
				putc('-', fp);
				break;
			case VSPLUS:
				putc('+', fp);
				break;
			case VSQUESTION:
				putc('?', fp);
				break;
			case VSASSIGN:
				putc('=', fp);
				break;
			case VSTRIMLEFT:
				putc('#', fp);
				break;
			case VSTRIMLEFTMAX:
				putc('#', fp);
				putc('#', fp);
				break;
			case VSTRIMRIGHT:
				putc('%', fp);
				break;
			case VSTRIMRIGHTMAX:
				putc('%', fp);
				putc('%', fp);
				break;
			case VSLENGTH:
				break;
			default:
				out1fmt("<subtype %d>", subtype);
			}
			break;
		case CTLENDVAR:
			putc('}', fp);
			break;
		case CTLBACKQ:
		case CTLBACKQ|CTLQUOTE:
			putc('$', fp);
			putc('(', fp);
			shtree(bqlist->n, -1, NULL, fp);
			putc(')', fp);
			break;
		default:
			putc(*p, fp);
			break;
		}
	}
}

static void
shcmd(union node *cmd, FILE *fp)
{
	union node *np;
	int first;
	const char *s;
	int dftfd;

	first = 1;
	for (np = cmd->ncmd.args; np; np = np->narg.next) {
		if (!first)
			putc(' ', fp);
		sharg(np, fp);
		first = 0;
	}
	for (np = cmd->ncmd.redirect; np; np = np->nfile.next) {
		if (!first)
			putc(' ', fp);
		dftfd = 0;
		switch (np->nfile.type) {
		case NTO:      s = ">>"+1; dftfd = 1; break;
		case NCLOBBER: s = ">|"; dftfd = 1; break;
		case NAPPEND:  s = ">>"; dftfd = 1; break;
		case NTOFD:    s = ">&"; dftfd = 1; break;
		case NFROM:    s = "<";  break;
		case NFROMFD:  s = "<&"; break;
		case NFROMTO:  s = "<>"; break;
		default:       s = "*error*"; break;
		}
		if (np->nfile.fd != dftfd)
			fprintf(fp, "%d", np->nfile.fd);
		fputs(s, fp);
		if (np->nfile.type == NTOFD || np->nfile.type == NFROMFD) {
			fprintf(fp, "%d", np->ndup.dupfd);
		} else {
			sharg(np->nfile.fname, fp);
		}
		first = 0;
	}
}

static void
shtree(union node *n, int ind, char *pfx, FILE *fp)
{
	struct nodelist *lp;
	const char *s;

	if (n == NULL)
		return;

	indent(ind, pfx, fp);
	switch (n->type) {
	case NSEMI:
		s = "; ";
		goto binop;
	case NAND:
		s = " && ";
		goto binop;
	case NOR:
		s = " || ";
 binop:
		shtree(n->nbinary.ch1, ind, NULL, fp);
		/* if (ind < 0) */
			fputs(s, fp);
		shtree(n->nbinary.ch2, ind, NULL, fp);
		break;
	case NCMD:
		shcmd(n, fp);
		if (ind >= 0)
			putc('\n', fp);
		break;
	case NPIPE:
		for (lp = n->npipe.cmdlist; lp; lp = lp->next) {
			shcmd(lp->n, fp);
			if (lp->next)
				fputs(" | ", fp);
		}
		if (n->npipe.backgnd)
			fputs(" &", fp);
		if (ind >= 0)
			putc('\n', fp);
		break;
	default:
		fprintf(fp, "<node type %d>", n->type);
		if (ind >= 0)
			putc('\n', fp);
		break;
	}
}

static void
showtree(union node *n)
{
	trace_puts("showtree called\n");
	shtree(n, 1, NULL, stdout);
}

#define TRACE(param)    trace_printf param
#define TRACEV(param)   trace_vprintf param

#else

#define TRACE(param)
#define TRACEV(param)

#endif /* DEBUG */


/* ============ Parser data */

/*
 * ash_vmsg() needs parsefile->fd, hence parsefile definition is moved up.
 */
struct strlist {
	struct strlist *next;
	char *text;
};

#if ENABLE_ASH_ALIAS
struct alias;
#endif

struct strpush {
	struct strpush *prev;   /* preceding string on stack */
	char *prevstring;
	int prevnleft;
#if ENABLE_ASH_ALIAS
	struct alias *ap;       /* if push was associated with an alias */
#endif
	char *string;           /* remember the string since it may change */
};

struct parsefile {
	struct parsefile *prev; /* preceding file on stack */
	int linno;              /* current line */
	int fd;                 /* file descriptor (or -1 if string) */
	int nleft;              /* number of chars left in this line */
	int lleft;              /* number of chars left in this buffer */
	char *nextc;            /* next char in buffer */
	char *buf;              /* input buffer */
	struct strpush *strpush; /* for pushing strings at this level */
	struct strpush basestrpush; /* so pushing one is fast */
};

static struct parsefile basepf;         /* top level input file */
static struct parsefile *parsefile = &basepf;  /* current input file */
static int startlinno;                 /* line # where last token started */
static char *commandname;              /* currently executing command */
static struct strlist *cmdenviron;     /* environment for builtin command */
static int exitstatus;                 /* exit status of last command */


/* ============ Message printing */

static void
ash_vmsg(const char *msg, va_list ap)
{
	fprintf(stderr, "%s: ", arg0);
	if (commandname) {
		if (strcmp(arg0, commandname))
			fprintf(stderr, "%s: ", commandname);
		if (!iflag || parsefile->fd)
			fprintf(stderr, "line %d: ", startlinno);
	}
	vfprintf(stderr, msg, ap);
	outcslow('\n', stderr);
}

/*
 * Exverror is called to raise the error exception.  If the second argument
 * is not NULL then error prints an error message using printf style
 * formatting.  It then raises the error exception.
 */
static void ash_vmsg_and_raise(int, const char *, va_list) ATTRIBUTE_NORETURN;
static void
ash_vmsg_and_raise(int cond, const char *msg, va_list ap)
{
#if DEBUG
	if (msg) {
		TRACE(("ash_vmsg_and_raise(%d, \"", cond));
		TRACEV((msg, ap));
		TRACE(("\") pid=%d\n", getpid()));
	} else
		TRACE(("ash_vmsg_and_raise(%d, NULL) pid=%d\n", cond, getpid()));
	if (msg)
#endif
		ash_vmsg(msg, ap);

	flush_stdout_stderr();
	raise_exception(cond);
	/* NOTREACHED */
}

static void ash_msg_and_raise_error(const char *, ...) ATTRIBUTE_NORETURN;
static void
ash_msg_and_raise_error(const char *msg, ...)
{
	va_list ap;

	va_start(ap, msg);
	ash_vmsg_and_raise(EXERROR, msg, ap);
	/* NOTREACHED */
	va_end(ap);
}

static void ash_msg_and_raise(int, const char *, ...) ATTRIBUTE_NORETURN;
static void
ash_msg_and_raise(int cond, const char *msg, ...)
{
	va_list ap;

	va_start(ap, msg);
	ash_vmsg_and_raise(cond, msg, ap);
	/* NOTREACHED */
	va_end(ap);
}

/*
 * error/warning routines for external builtins
 */
static void
ash_msg(const char *fmt, ...)
{
	va_list ap;

	va_start(ap, fmt);
	ash_vmsg(fmt, ap);
	va_end(ap);
}

/*
 * Return a string describing an error.  The returned string may be a
 * pointer to a static buffer that will be overwritten on the next call.
 * Action describes the operation that got the error.
 */
static const char *
errmsg(int e, const char *em)
{
	if (e == ENOENT || e == ENOTDIR) {
		return em;
	}
	return strerror(e);
}


/* ============ Memory allocation */

/*
 * It appears that grabstackstr() will barf with such alignments
 * because stalloc() will return a string allocated in a new stackblock.
 */
#define SHELL_ALIGN(nbytes) (((nbytes) + SHELL_SIZE) & ~SHELL_SIZE)
enum {
	/* Most machines require the value returned from malloc to be aligned
	 * in some way.  The following macro will get this right
	 * on many machines.  */
	SHELL_SIZE = sizeof(union {int i; char *cp; double d; }) - 1,
	/* Minimum size of a block */
	MINSIZE  = SHELL_ALIGN(504),
};

struct stack_block {
	struct stack_block *prev;
	char space[MINSIZE];
};

struct stackmark {
	struct stack_block *stackp;
	char *stacknxt;
	size_t stacknleft;
	struct stackmark *marknext;
};

static struct stack_block stackbase;
static struct stack_block *stackp = &stackbase;
static struct stackmark *markp;
static char *stacknxt = stackbase.space;
static size_t stacknleft = MINSIZE;
static char *sstrend = stackbase.space + MINSIZE;
static int herefd = -1;

#define stackblock() ((void *)stacknxt)
#define stackblocksize() stacknleft

static void *
ckrealloc(void * p, size_t nbytes)
{
	p = realloc(p, nbytes);
	if (!p)
		ash_msg_and_raise_error(bb_msg_memory_exhausted);
	return p;
}

static void *
ckmalloc(size_t nbytes)
{
	return ckrealloc(NULL, nbytes);
}

/*
 * Make a copy of a string in safe storage.
 */
static char *
ckstrdup(const char *s)
{
	char *p = strdup(s);
	if (!p)
		ash_msg_and_raise_error(bb_msg_memory_exhausted);
	return p;
}

/*
 * Parse trees for commands are allocated in lifo order, so we use a stack
 * to make this more efficient, and also to avoid all sorts of exception
 * handling code to handle interrupts in the middle of a parse.
 *
 * The size 504 was chosen because the Ultrix malloc handles that size
 * well.
 */
static void *
stalloc(size_t nbytes)
{
	char *p;
	size_t aligned;

	aligned = SHELL_ALIGN(nbytes);
	if (aligned > stacknleft) {
		size_t len;
		size_t blocksize;
		struct stack_block *sp;

		blocksize = aligned;
		if (blocksize < MINSIZE)
			blocksize = MINSIZE;
		len = sizeof(struct stack_block) - MINSIZE + blocksize;
		if (len < blocksize)
			ash_msg_and_raise_error(bb_msg_memory_exhausted);
		INT_OFF;
		sp = ckmalloc(len);
		sp->prev = stackp;
		stacknxt = sp->space;
		stacknleft = blocksize;
		sstrend = stacknxt + blocksize;
		stackp = sp;
		INT_ON;
	}
	p = stacknxt;
	stacknxt += aligned;
	stacknleft -= aligned;
	return p;
}

static void
stunalloc(void *p)
{
#if DEBUG
	if (!p || (stacknxt < (char *)p) || ((char *)p < stackp->space)) {
		write(2, "stunalloc\n", 10);
		abort();
	}
#endif
	stacknleft += stacknxt - (char *)p;
	stacknxt = p;
}

/*
 * Like strdup but works with the ash stack.
 */
static char *
ststrdup(const char *p)
{
	size_t len = strlen(p) + 1;
	return memcpy(stalloc(len), p, len);
}

static void
setstackmark(struct stackmark *mark)
{
	mark->stackp = stackp;
	mark->stacknxt = stacknxt;
	mark->stacknleft = stacknleft;
	mark->marknext = markp;
	markp = mark;
}

static void
popstackmark(struct stackmark *mark)
{
	struct stack_block *sp;

	if (!mark->stackp)
		return;

	INT_OFF;
	markp = mark->marknext;
	while (stackp != mark->stackp) {
		sp = stackp;
		stackp = sp->prev;
		free(sp);
	}
	stacknxt = mark->stacknxt;
	stacknleft = mark->stacknleft;
	sstrend = mark->stacknxt + mark->stacknleft;
	INT_ON;
}

/*
 * When the parser reads in a string, it wants to stick the string on the
 * stack and only adjust the stack pointer when it knows how big the
 * string is.  Stackblock (defined in stack.h) returns a pointer to a block
 * of space on top of the stack and stackblocklen returns the length of
 * this block.  Growstackblock will grow this space by at least one byte,
 * possibly moving it (like realloc).  Grabstackblock actually allocates the
 * part of the block that has been used.
 */
static void
growstackblock(void)
{
	size_t newlen;

	newlen = stacknleft * 2;
	if (newlen < stacknleft)
		ash_msg_and_raise_error(bb_msg_memory_exhausted);
	if (newlen < 128)
		newlen += 128;

	if (stacknxt == stackp->space && stackp != &stackbase) {
		struct stack_block *oldstackp;
		struct stackmark *xmark;
		struct stack_block *sp;
		struct stack_block *prevstackp;
		size_t grosslen;

		INT_OFF;
		oldstackp = stackp;
		sp = stackp;
		prevstackp = sp->prev;
		grosslen = newlen + sizeof(struct stack_block) - MINSIZE;
		sp = ckrealloc(sp, grosslen);
		sp->prev = prevstackp;
		stackp = sp;
		stacknxt = sp->space;
		stacknleft = newlen;
		sstrend = sp->space + newlen;

		/*
		 * Stack marks pointing to the start of the old block
		 * must be relocated to point to the new block
		 */
		xmark = markp;
		while (xmark != NULL && xmark->stackp == oldstackp) {
			xmark->stackp = stackp;
			xmark->stacknxt = stacknxt;
			xmark->stacknleft = stacknleft;
			xmark = xmark->marknext;
		}
		INT_ON;
	} else {
		char *oldspace = stacknxt;
		int oldlen = stacknleft;
		char *p = stalloc(newlen);

		/* free the space we just allocated */
		stacknxt = memcpy(p, oldspace, oldlen);
		stacknleft += newlen;
	}
}

static void
grabstackblock(size_t len)
{
	len = SHELL_ALIGN(len);
	stacknxt += len;
	stacknleft -= len;
}

/*
 * The following routines are somewhat easier to use than the above.
 * The user declares a variable of type STACKSTR, which may be declared
 * to be a register.  The macro STARTSTACKSTR initializes things.  Then
 * the user uses the macro STPUTC to add characters to the string.  In
 * effect, STPUTC(c, p) is the same as *p++ = c except that the stack is
 * grown as necessary.  When the user is done, she can just leave the
 * string there and refer to it using stackblock().  Or she can allocate
 * the space for it using grabstackstr().  If it is necessary to allow
 * someone else to use the stack temporarily and then continue to grow
 * the string, the user should use grabstack to allocate the space, and
 * then call ungrabstr(p) to return to the previous mode of operation.
 *
 * USTPUTC is like STPUTC except that it doesn't check for overflow.
 * CHECKSTACKSPACE can be called before USTPUTC to ensure that there
 * is space for at least one character.
 */
static void *
growstackstr(void)
{
	size_t len = stackblocksize();
	if (herefd >= 0 && len >= 1024) {
		full_write(herefd, stackblock(), len);
		return stackblock();
	}
	growstackblock();
	return stackblock() + len;
}

/*
 * Called from CHECKSTRSPACE.
 */
static char *
makestrspace(size_t newlen, char *p)
{
	size_t len = p - stacknxt;
	size_t size = stackblocksize();

	for (;;) {
		size_t nleft;

		size = stackblocksize();
		nleft = size - len;
		if (nleft >= newlen)
			break;
		growstackblock();
	}
	return stackblock() + len;
}

static char *
stack_nputstr(const char *s, size_t n, char *p)
{
	p = makestrspace(n, p);
	p = memcpy(p, s, n) + n;
	return p;
}

static char *
stack_putstr(const char *s, char *p)
{
	return stack_nputstr(s, strlen(s), p);
}

static char *
_STPUTC(int c, char *p)
{
	if (p == sstrend)
		p = growstackstr();
	*p++ = c;
	return p;
}

#define STARTSTACKSTR(p)        ((p) = stackblock())
#define STPUTC(c, p)            ((p) = _STPUTC((c), (p)))
#define CHECKSTRSPACE(n, p) \
	do { \
		char *q = (p); \
		size_t l = (n); \
		size_t m = sstrend - q; \
		if (l > m) \
			(p) = makestrspace(l, q); \
	} while (0)
#define USTPUTC(c, p)           (*p++ = (c))
#define STACKSTRNUL(p) \
	do { \
		if ((p) == sstrend) \
			p = growstackstr(); \
		*p = '\0'; \
	} while (0)
#define STUNPUTC(p)             (--p)
#define STTOPC(p)               (p[-1])
#define STADJUST(amount, p)     (p += (amount))

#define grabstackstr(p)         stalloc((char *)(p) - (char *)stackblock())
#define ungrabstackstr(s, p)    stunalloc((s))
#define stackstrend()           ((void *)sstrend)


/* ============ String helpers */

/*
 * prefix -- see if pfx is a prefix of string.
 */
static char *
prefix(const char *string, const char *pfx)
{
	while (*pfx) {
		if (*pfx++ != *string++)
			return 0;
	}
	return (char *) string;
}

/*
 * Check for a valid number.  This should be elsewhere.
 */
static int
is_number(const char *p)
{
	do {
		if (!isdigit(*p))
			return 0;
	} while (*++p != '\0');
	return 1;
}

/*
 * Convert a string of digits to an integer, printing an error message on
 * failure.
 */
static int
number(const char *s)
{
	if (!is_number(s))
		ash_msg_and_raise_error(illnum, s);
	return atoi(s);
}

/*
 * Produce a possibly single quoted string suitable as input to the shell.
 * The return string is allocated on the stack.
 */
static char *
single_quote(const char *s)
{
	char *p;

	STARTSTACKSTR(p);

	do {
		char *q;
		size_t len;

		len = strchrnul(s, '\'') - s;

		q = p = makestrspace(len + 3, p);

		*q++ = '\'';
		q = memcpy(q, s, len) + len;
		*q++ = '\'';
		s += len;

		STADJUST(q - p, p);

		len = strspn(s, "'");
		if (!len)
			break;

		q = p = makestrspace(len + 3, p);

		*q++ = '"';
		q = memcpy(q, s, len) + len;
		*q++ = '"';
		s += len;

		STADJUST(q - p, p);
	} while (*s);

	USTPUTC(0, p);

	return stackblock();
}


/* ============ nextopt */

static char **argptr;                  /* argument list for builtin commands */
static char *optionarg;                /* set by nextopt (like getopt) */
static char *optptr;                   /* used by nextopt */

/*
 * XXX - should get rid of.  have all builtins use getopt(3).  the
 * library getopt must have the BSD extension static variable "optreset"
 * otherwise it can't be used within the shell safely.
 *
 * Standard option processing (a la getopt) for builtin routines.  The
 * only argument that is passed to nextopt is the option string; the
 * other arguments are unnecessary.  It return the character, or '\0' on
 * end of input.
 */
static int
nextopt(const char *optstring)
{
	char *p;
	const char *q;
	char c;

	p = optptr;
	if (p == NULL || *p == '\0') {
		p = *argptr;
		if (p == NULL || *p != '-' || *++p == '\0')
			return '\0';
		argptr++;
		if (LONE_DASH(p))        /* check for "--" */
			return '\0';
	}
	c = *p++;
	for (q = optstring; *q != c; ) {
		if (*q == '\0')
			ash_msg_and_raise_error("illegal option -%c", c);
		if (*++q == ':')
			q++;
	}
	if (*++q == ':') {
		if (*p == '\0' && (p = *argptr++) == NULL)
			ash_msg_and_raise_error("no arg for -%c option", c);
		optionarg = p;
		p = NULL;
	}
	optptr = p;
	return c;
}


/* ============ Math support definitions */

#if ENABLE_ASH_MATH_SUPPORT_64
typedef int64_t arith_t;
#define arith_t_type long long
#else
typedef long arith_t;
#define arith_t_type long
#endif

#if ENABLE_ASH_MATH_SUPPORT
static arith_t dash_arith(const char *);
static arith_t arith(const char *expr, int *perrcode);
#endif

#if ENABLE_ASH_RANDOM_SUPPORT
static unsigned long rseed;
#ifndef DYNAMIC_VAR
#define DYNAMIC_VAR
#endif
#endif


/* ============ Shell variables */

/* flags */
#define VEXPORT         0x01    /* variable is exported */
#define VREADONLY       0x02    /* variable cannot be modified */
#define VSTRFIXED       0x04    /* variable struct is statically allocated */
#define VTEXTFIXED      0x08    /* text is statically allocated */
#define VSTACK          0x10    /* text is allocated on the stack */
#define VUNSET          0x20    /* the variable is not set */
#define VNOFUNC         0x40    /* don't call the callback function */
#define VNOSET          0x80    /* do not set variable - just readonly test */
#define VNOSAVE         0x100   /* when text is on the heap before setvareq */
#ifdef DYNAMIC_VAR
# define VDYNAMIC       0x200   /* dynamic variable */
#else
# define VDYNAMIC       0
#endif

#ifdef IFS_BROKEN
static const char defifsvar[] ALIGN1 = "IFS= \t\n";
#define defifs (defifsvar + 4)
#else
static const char defifs[] ALIGN1 = " \t\n";
#endif

struct shparam {
	int nparam;             /* # of positional parameters (without $0) */
	unsigned char malloc;   /* if parameter list dynamically allocated */
	char **p;               /* parameter list */
#if ENABLE_ASH_GETOPTS
	int optind;             /* next parameter to be processed by getopts */
	int optoff;             /* used by getopts */
#endif
};

static struct shparam shellparam;      /* $@ current positional parameters */

/*
 * Free the list of positional parameters.
 */
static void
freeparam(volatile struct shparam *param)
{
	char **ap;

	if (param->malloc) {
		for (ap = param->p; *ap; ap++)
			free(*ap);
		free(param->p);
	}
}

#if ENABLE_ASH_GETOPTS
static void
getoptsreset(const char *value)
{
	shellparam.optind = number(value);
	shellparam.optoff = -1;
}
#endif

struct var {
	struct var *next;               /* next entry in hash list */
	int flags;                      /* flags are defined above */
	const char *text;               /* name=value */
	void (*func)(const char *);     /* function to be called when  */
					/* the variable gets set/unset */
};

struct localvar {
	struct localvar *next;          /* next local variable in list */
	struct var *vp;                 /* the variable that was made local */
	int flags;                      /* saved flags */
	const char *text;               /* saved text */
};

/* Forward decls for varinit[] */
#if ENABLE_LOCALE_SUPPORT
static void
change_lc_all(const char *value)
{
	if (value && *value != '\0')
		setlocale(LC_ALL, value);
}
static void
change_lc_ctype(const char *value)
{
	if (value && *value != '\0')
		setlocale(LC_CTYPE, value);
}
#endif
#if ENABLE_ASH_MAIL
static void chkmail(void);
static void changemail(const char *);
#endif
static void changepath(const char *);
#if ENABLE_ASH_RANDOM_SUPPORT
static void change_random(const char *);
#endif

static struct var varinit[] = {
#ifdef IFS_BROKEN
	{ NULL, VSTRFIXED|VTEXTFIXED,           defifsvar,      NULL },
#else
	{ NULL, VSTRFIXED|VTEXTFIXED|VUNSET,    "IFS\0",        NULL },
#endif
#if ENABLE_ASH_MAIL
	{ NULL, VSTRFIXED|VTEXTFIXED|VUNSET,    "MAIL\0",       changemail },
	{ NULL, VSTRFIXED|VTEXTFIXED|VUNSET,    "MAILPATH\0",   changemail },
#endif
	{ NULL, VSTRFIXED|VTEXTFIXED,           bb_PATH_root_path, changepath },
	{ NULL, VSTRFIXED|VTEXTFIXED,           "PS1=$ ",       NULL },
	{ NULL, VSTRFIXED|VTEXTFIXED,           "PS2=> ",       NULL },
	{ NULL, VSTRFIXED|VTEXTFIXED,           "PS4=+ ",       NULL },
#if ENABLE_ASH_GETOPTS
	{ NULL, VSTRFIXED|VTEXTFIXED,           "OPTIND=1",     getoptsreset },
#endif
#if ENABLE_ASH_RANDOM_SUPPORT
	{ NULL, VSTRFIXED|VTEXTFIXED|VUNSET|VDYNAMIC, "RANDOM\0", change_random },
#endif
#if ENABLE_LOCALE_SUPPORT
	{ NULL, VSTRFIXED | VTEXTFIXED | VUNSET, "LC_ALL\0",    change_lc_all },
	{ NULL, VSTRFIXED | VTEXTFIXED | VUNSET, "LC_CTYPE\0",  change_lc_ctype },
#endif
#if ENABLE_FEATURE_EDITING_SAVEHISTORY
	{ NULL, VSTRFIXED | VTEXTFIXED | VUNSET, "HISTFILE\0",  NULL },
#endif
};

#define vifs varinit[0]
#if ENABLE_ASH_MAIL
#define vmail (&vifs)[1]
#define vmpath (&vmail)[1]
#else
#define vmpath vifs
#endif
#define vpath (&vmpath)[1]
#define vps1 (&vpath)[1]
#define vps2 (&vps1)[1]
#define vps4 (&vps2)[1]
#define voptind (&vps4)[1]
#if ENABLE_ASH_GETOPTS
#define vrandom (&voptind)[1]
#else
#define vrandom (&vps4)[1]
#endif

/*
 * The following macros access the values of the above variables.
 * They have to skip over the name.  They return the null string
 * for unset variables.
 */
#define ifsval()        (vifs.text + 4)
#define ifsset()        ((vifs.flags & VUNSET) == 0)
#define mailval()       (vmail.text + 5)
#define mpathval()      (vmpath.text + 9)
#define pathval()       (vpath.text + 5)
#define ps1val()        (vps1.text + 4)
#define ps2val()        (vps2.text + 4)
#define ps4val()        (vps4.text + 4)
#define optindval()     (voptind.text + 7)

#define mpathset()      ((vmpath.flags & VUNSET) == 0)

/*
 * The parsefile structure pointed to by the global variable parsefile
 * contains information about the current file being read.
 */
struct redirtab {
	struct redirtab *next;
	int renamed[10];
	int nullredirs;
};

static struct redirtab *redirlist;
static int nullredirs;
static int preverrout_fd;   /* save fd2 before print debug if xflag is set. */

#define VTABSIZE 39

static struct var *vartab[VTABSIZE];

#define is_name(c)      ((c) == '_' || isalpha((unsigned char)(c)))
#define is_in_name(c)   ((c) == '_' || isalnum((unsigned char)(c)))

/*
 * Return of a legal variable name (a letter or underscore followed by zero or
 * more letters, underscores, and digits).
 */
static char *
endofname(const char *name)
{
	char *p;

	p = (char *) name;
	if (!is_name(*p))
		return p;
	while (*++p) {
		if (!is_in_name(*p))
			break;
	}
	return p;
}

/*
 * Compares two strings up to the first = or '\0'.  The first
 * string must be terminated by '='; the second may be terminated by
 * either '=' or '\0'.
 */
static int
varcmp(const char *p, const char *q)
{
	int c, d;

	while ((c = *p) == (d = *q)) {
		if (!c || c == '=')
			goto out;
		p++;
		q++;
	}
	if (c == '=')
		c = '\0';
	if (d == '=')
		d = '\0';
 out:
	return c - d;
}

static int
varequal(const char *a, const char *b)
{
	return !varcmp(a, b);
}

/*
 * Find the appropriate entry in the hash table from the name.
 */
static struct var **
hashvar(const char *p)
{
	unsigned hashval;

	hashval = ((unsigned char) *p) << 4;
	while (*p && *p != '=')
		hashval += (unsigned char) *p++;
	return &vartab[hashval % VTABSIZE];
}

static int
vpcmp(const void *a, const void *b)
{
	return varcmp(*(const char **)a, *(const char **)b);
}

/*
 * This routine initializes the builtin variables.
 */
static void
initvar(void)
{
	struct var *vp;
	struct var *end;
	struct var **vpp;

	/*
	 * PS1 depends on uid
	 */
#if ENABLE_FEATURE_EDITING && ENABLE_FEATURE_EDITING_FANCY_PROMPT
	vps1.text = "PS1=\\w \\$ ";
#else
	if (!geteuid())
		vps1.text = "PS1=# ";
#endif
	vp = varinit;
	end = vp + ARRAY_SIZE(varinit);
	do {
		vpp = hashvar(vp->text);
		vp->next = *vpp;
		*vpp = vp;
	} while (++vp < end);
}

static struct var **
findvar(struct var **vpp, const char *name)
{
	for (; *vpp; vpp = &(*vpp)->next) {
		if (varequal((*vpp)->text, name)) {
			break;
		}
	}
	return vpp;
}

/*
 * Find the value of a variable.  Returns NULL if not set.
 */
static char *
lookupvar(const char *name)
{
	struct var *v;

	v = *findvar(hashvar(name), name);
	if (v) {
#ifdef DYNAMIC_VAR
	/*
	 * Dynamic variables are implemented roughly the same way they are
	 * in bash. Namely, they're "special" so long as they aren't unset.
	 * As soon as they're unset, they're no longer dynamic, and dynamic
	 * lookup will no longer happen at that point. -- PFM.
	 */
		if ((v->flags & VDYNAMIC))
			(*v->func)(NULL);
#endif
		if (!(v->flags & VUNSET))
			return strchrnul(v->text, '=') + 1;
	}
	return NULL;
}

/*
 * Search the environment of a builtin command.
 */
static char *
bltinlookup(const char *name)
{
	struct strlist *sp;

	for (sp = cmdenviron; sp; sp = sp->next) {
		if (varequal(sp->text, name))
			return strchrnul(sp->text, '=') + 1;
	}
	return lookupvar(name);
}

/*
 * Same as setvar except that the variable and value are passed in
 * the first argument as name=value.  Since the first argument will
 * be actually stored in the table, it should not be a string that
 * will go away.
 * Called with interrupts off.
 */
static void
setvareq(char *s, int flags)
{
	struct var *vp, **vpp;

	vpp = hashvar(s);
	flags |= (VEXPORT & (((unsigned) (1 - aflag)) - 1));
	vp = *findvar(vpp, s);
	if (vp) {
		if ((vp->flags & (VREADONLY|VDYNAMIC)) == VREADONLY) {
			const char *n;

			if (flags & VNOSAVE)
				free(s);
			n = vp->text;
			ash_msg_and_raise_error("%.*s: is read only", strchrnul(n, '=') - n, n);
		}

		if (flags & VNOSET)
			return;

		if (vp->func && (flags & VNOFUNC) == 0)
			(*vp->func)(strchrnul(s, '=') + 1);

		if ((vp->flags & (VTEXTFIXED|VSTACK)) == 0)
			free((char*)vp->text);

		flags |= vp->flags & ~(VTEXTFIXED|VSTACK|VNOSAVE|VUNSET);
	} else {
		if (flags & VNOSET)
			return;
		/* not found */
		vp = ckmalloc(sizeof(*vp));
		vp->next = *vpp;
		vp->func = NULL;
		*vpp = vp;
	}
	if (!(flags & (VTEXTFIXED|VSTACK|VNOSAVE)))
		s = ckstrdup(s);
	vp->text = s;
	vp->flags = flags;
}

/*
 * Set the value of a variable.  The flags argument is ored with the
 * flags of the variable.  If val is NULL, the variable is unset.
 */
static void
setvar(const char *name, const char *val, int flags)
{
	char *p, *q;
	size_t namelen;
	char *nameeq;
	size_t vallen;

	q = endofname(name);
	p = strchrnul(q, '=');
	namelen = p - name;
	if (!namelen || p != q)
		ash_msg_and_raise_error("%.*s: bad variable name", namelen, name);
	vallen = 0;
	if (val == NULL) {
		flags |= VUNSET;
	} else {
		vallen = strlen(val);
	}
	INT_OFF;
	nameeq = ckmalloc(namelen + vallen + 2);
	p = memcpy(nameeq, name, namelen) + namelen;
	if (val) {
		*p++ = '=';
		p = memcpy(p, val, vallen) + vallen;
	}
	*p = '\0';
	setvareq(nameeq, flags | VNOSAVE);
	INT_ON;
}

#if ENABLE_ASH_GETOPTS
/*
 * Safe version of setvar, returns 1 on success 0 on failure.
 */
static int
setvarsafe(const char *name, const char *val, int flags)
{
	int err;
	volatile int saveint;
	struct jmploc *volatile savehandler = exception_handler;
	struct jmploc jmploc;

	SAVE_INT(saveint);
	if (setjmp(jmploc.loc))
		err = 1;
	else {
		exception_handler = &jmploc;
		setvar(name, val, flags);
		err = 0;
	}
	exception_handler = savehandler;
	RESTORE_INT(saveint);
	return err;
}
#endif

/*
 * Unset the specified variable.
 */
static int
unsetvar(const char *s)
{
	struct var **vpp;
	struct var *vp;
	int retval;

	vpp = findvar(hashvar(s), s);
	vp = *vpp;
	retval = 2;
	if (vp) {
		int flags = vp->flags;

		retval = 1;
		if (flags & VREADONLY)
			goto out;
#ifdef DYNAMIC_VAR
		vp->flags &= ~VDYNAMIC;
#endif
		if (flags & VUNSET)
			goto ok;
		if ((flags & VSTRFIXED) == 0) {
			INT_OFF;
			if ((flags & (VTEXTFIXED|VSTACK)) == 0)
				free((char*)vp->text);
			*vpp = vp->next;
			free(vp);
			INT_ON;
		} else {
			setvar(s, 0, 0);
			vp->flags &= ~VEXPORT;
		}
 ok:
		retval = 0;
	}
 out:
	return retval;
}

/*
 * Process a linked list of variable assignments.
 */
static void
listsetvar(struct strlist *list_set_var, int flags)
{
	struct strlist *lp = list_set_var;

	if (!lp)
		return;
	INT_OFF;
	do {
		setvareq(lp->text, flags);
		lp = lp->next;
	} while (lp);
	INT_ON;
}

/*
 * Generate a list of variables satisfying the given conditions.
 */
static char **
listvars(int on, int off, char ***end)
{
	struct var **vpp;
	struct var *vp;
	char **ep;
	int mask;

	STARTSTACKSTR(ep);
	vpp = vartab;
	mask = on | off;
	do {
		for (vp = *vpp; vp; vp = vp->next) {
			if ((vp->flags & mask) == on) {
				if (ep == stackstrend())
					ep = growstackstr();
				*ep++ = (char *) vp->text;
			}
		}
	} while (++vpp < vartab + VTABSIZE);
	if (ep == stackstrend())
		ep = growstackstr();
	if (end)
		*end = ep;
	*ep++ = NULL;
	return grabstackstr(ep);
}


/* ============ Path search helper
 *
 * The variable path (passed by reference) should be set to the start
 * of the path before the first call; padvance will update
 * this value as it proceeds.  Successive calls to padvance will return
 * the possible path expansions in sequence.  If an option (indicated by
 * a percent sign) appears in the path entry then the global variable
 * pathopt will be set to point to it; otherwise pathopt will be set to
 * NULL.
 */
static const char *pathopt;     /* set by padvance */

static char *
padvance(const char **path, const char *name)
{
	const char *p;
	char *q;
	const char *start;
	size_t len;

	if (*path == NULL)
		return NULL;
	start = *path;
	for (p = start; *p && *p != ':' && *p != '%'; p++);
	len = p - start + strlen(name) + 2;     /* "2" is for '/' and '\0' */
	while (stackblocksize() < len)
		growstackblock();
	q = stackblock();
	if (p != start) {
		memcpy(q, start, p - start);
		q += p - start;
		*q++ = '/';
	}
	strcpy(q, name);
	pathopt = NULL;
	if (*p == '%') {
		pathopt = ++p;
		while (*p && *p != ':') p++;
	}
	if (*p == ':')
		*path = p + 1;
	else
		*path = NULL;
	return stalloc(len);
}


/* ============ Prompt */

static smallint doprompt;                   /* if set, prompt the user */
static smallint needprompt;                 /* true if interactive and at start of line */

#if ENABLE_FEATURE_EDITING
static line_input_t *line_input_state;
static const char *cmdedit_prompt;
static void
putprompt(const char *s)
{
	if (ENABLE_ASH_EXPAND_PRMT) {
		free((char*)cmdedit_prompt);
		cmdedit_prompt = ckstrdup(s);
		return;
	}
	cmdedit_prompt = s;
}
#else
static void
putprompt(const char *s)
{
	out2str(s);
}
#endif

#if ENABLE_ASH_EXPAND_PRMT
/* expandstr() needs parsing machinery, so it is far away ahead... */
static const char *expandstr(const char *ps);
#else
#define expandstr(s) s
#endif

static void
setprompt(int whichprompt)
{
	const char *prompt;
#if ENABLE_ASH_EXPAND_PRMT
	struct stackmark smark;
#endif

	needprompt = 0;

	switch (whichprompt) {
	case 1:
		prompt = ps1val();
		break;
	case 2:
		prompt = ps2val();
		break;
	default:                        /* 0 */
		prompt = nullstr;
	}
#if ENABLE_ASH_EXPAND_PRMT
	setstackmark(&smark);
	stalloc(stackblocksize());
#endif
	putprompt(expandstr(prompt));
#if ENABLE_ASH_EXPAND_PRMT
	popstackmark(&smark);
#endif
}


/* ============ The cd and pwd commands */

#define CD_PHYSICAL 1
#define CD_PRINT 2

static int docd(const char *, int);

static char *curdir = nullstr;          /* current working directory */
static char *physdir = nullstr;         /* physical working directory */

static int
cdopt(void)
{
	int flags = 0;
	int i, j;

	j = 'L';
	while ((i = nextopt("LP"))) {
		if (i != j) {
			flags ^= CD_PHYSICAL;
			j = i;
		}
	}

	return flags;
}

/*
 * Update curdir (the name of the current directory) in response to a
 * cd command.
 */
static const char *
updatepwd(const char *dir)
{
	char *new;
	char *p;
	char *cdcomppath;
	const char *lim;

	cdcomppath = ststrdup(dir);
	STARTSTACKSTR(new);
	if (*dir != '/') {
		if (curdir == nullstr)
			return 0;
		new = stack_putstr(curdir, new);
	}
	new = makestrspace(strlen(dir) + 2, new);
	lim = stackblock() + 1;
	if (*dir != '/') {
		if (new[-1] != '/')
			USTPUTC('/', new);
		if (new > lim && *lim == '/')
			lim++;
	} else {
		USTPUTC('/', new);
		cdcomppath++;
		if (dir[1] == '/' && dir[2] != '/') {
			USTPUTC('/', new);
			cdcomppath++;
			lim++;
		}
	}
	p = strtok(cdcomppath, "/");
	while (p) {
		switch (*p) {
		case '.':
			if (p[1] == '.' && p[2] == '\0') {
				while (new > lim) {
					STUNPUTC(new);
					if (new[-1] == '/')
						break;
				}
				break;
			}
			if (p[1] == '\0')
				break;
			/* fall through */
		default:
			new = stack_putstr(p, new);
			USTPUTC('/', new);
		}
		p = strtok(0, "/");
	}
	if (new > lim)
		STUNPUTC(new);
	*new = 0;
	return stackblock();
}

/*
 * Find out what the current directory is. If we already know the current
 * directory, this routine returns immediately.
 */
static char *
getpwd(void)
{
	char *dir = getcwd(0, 0);
	return dir ? dir : nullstr;
}

static void
setpwd(const char *val, int setold)
{
	char *oldcur, *dir;

	oldcur = dir = curdir;

	if (setold) {
		setvar("OLDPWD", oldcur, VEXPORT);
	}
	INT_OFF;
	if (physdir != nullstr) {
		if (physdir != oldcur)
			free(physdir);
		physdir = nullstr;
	}
	if (oldcur == val || !val) {
		char *s = getpwd();
		physdir = s;
		if (!val)
			dir = s;
	} else
		dir = ckstrdup(val);
	if (oldcur != dir && oldcur != nullstr) {
		free(oldcur);
	}
	curdir = dir;
	INT_ON;
	setvar("PWD", dir, VEXPORT);
}

static void hashcd(void);

/*
 * Actually do the chdir.  We also call hashcd to let the routines in exec.c
 * know that the current directory has changed.
 */
static int
docd(const char *dest, int flags)
{
	const char *dir = 0;
	int err;

	TRACE(("docd(\"%s\", %d) called\n", dest, flags));

	INT_OFF;
	if (!(flags & CD_PHYSICAL)) {
		dir = updatepwd(dest);
		if (dir)
			dest = dir;
	}
	err = chdir(dest);
	if (err)
		goto out;
	setpwd(dir, 1);
	hashcd();
 out:
	INT_ON;
	return err;
}

static int
cdcmd(int argc, char **argv)
{
	const char *dest;
	const char *path;
	const char *p;
	char c;
	struct stat statb;
	int flags;

	flags = cdopt();
	dest = *argptr;
	if (!dest)
		dest = bltinlookup(homestr);
	else if (LONE_DASH(dest)) {
		dest = bltinlookup("OLDPWD");
		flags |= CD_PRINT;
	}
	if (!dest)
		dest = nullstr;
	if (*dest == '/')
		goto step7;
	if (*dest == '.') {
		c = dest[1];
 dotdot:
		switch (c) {
		case '\0':
		case '/':
			goto step6;
		case '.':
			c = dest[2];
			if (c != '.')
				goto dotdot;
		}
	}
	if (!*dest)
		dest = ".";
	path = bltinlookup("CDPATH");
	if (!path) {
 step6:
 step7:
		p = dest;
		goto docd;
	}
	do {
		c = *path;
		p = padvance(&path, dest);
		if (stat(p, &statb) >= 0 && S_ISDIR(statb.st_mode)) {
			if (c && c != ':')
				flags |= CD_PRINT;
 docd:
			if (!docd(p, flags))
				goto out;
			break;
		}
	} while (path);
	ash_msg_and_raise_error("can't cd to %s", dest);
	/* NOTREACHED */
 out:
	if (flags & CD_PRINT)
		out1fmt(snlfmt, curdir);
	return 0;
}

static int
pwdcmd(int argc, char **argv)
{
	int flags;
	const char *dir = curdir;

	flags = cdopt();
	if (flags) {
		if (physdir == nullstr)
			setpwd(dir, 0);
		dir = physdir;
	}
	out1fmt(snlfmt, dir);
	return 0;
}


/* ============ ... */

#define IBUFSIZ COMMON_BUFSIZE
#define basebuf bb_common_bufsiz1       /* buffer for top level input file */

/* Syntax classes */
#define CWORD 0                 /* character is nothing special */
#define CNL 1                   /* newline character */
#define CBACK 2                 /* a backslash character */
#define CSQUOTE 3               /* single quote */
#define CDQUOTE 4               /* double quote */
#define CENDQUOTE 5             /* a terminating quote */
#define CBQUOTE 6               /* backwards single quote */
#define CVAR 7                  /* a dollar sign */
#define CENDVAR 8               /* a '}' character */
#define CLP 9                   /* a left paren in arithmetic */
#define CRP 10                  /* a right paren in arithmetic */
#define CENDFILE 11             /* end of file */
#define CCTL 12                 /* like CWORD, except it must be escaped */
#define CSPCL 13                /* these terminate a word */
#define CIGN 14                 /* character should be ignored */

#if ENABLE_ASH_ALIAS
#define SYNBASE 130
#define PEOF -130
#define PEOA -129
#define PEOA_OR_PEOF PEOA
#else
#define SYNBASE 129
#define PEOF -129
#define PEOA_OR_PEOF PEOF
#endif

/* number syntax index */
#define BASESYNTAX 0    /* not in quotes */
#define DQSYNTAX   1    /* in double quotes */
#define SQSYNTAX   2    /* in single quotes */
#define ARISYNTAX  3    /* in arithmetic */
#define PSSYNTAX   4    /* prompt */

#if ENABLE_ASH_OPTIMIZE_FOR_SIZE
#define USE_SIT_FUNCTION
#endif

#if ENABLE_ASH_MATH_SUPPORT
static const char S_I_T[][4] = {
#if ENABLE_ASH_ALIAS
	{ CSPCL, CIGN, CIGN, CIGN },            /* 0, PEOA */
#endif
	{ CSPCL, CWORD, CWORD, CWORD },         /* 1, ' ' */
	{ CNL, CNL, CNL, CNL },                 /* 2, \n */
	{ CWORD, CCTL, CCTL, CWORD },           /* 3, !*-/:=?[]~ */
	{ CDQUOTE, CENDQUOTE, CWORD, CWORD },   /* 4, '"' */
	{ CVAR, CVAR, CWORD, CVAR },            /* 5, $ */
	{ CSQUOTE, CWORD, CENDQUOTE, CWORD },   /* 6, "'" */
	{ CSPCL, CWORD, CWORD, CLP },           /* 7, ( */
	{ CSPCL, CWORD, CWORD, CRP },           /* 8, ) */
	{ CBACK, CBACK, CCTL, CBACK },          /* 9, \ */
	{ CBQUOTE, CBQUOTE, CWORD, CBQUOTE },   /* 10, ` */
	{ CENDVAR, CENDVAR, CWORD, CENDVAR },   /* 11, } */
#ifndef USE_SIT_FUNCTION
	{ CENDFILE, CENDFILE, CENDFILE, CENDFILE }, /* 12, PEOF */
	{ CWORD, CWORD, CWORD, CWORD },         /* 13, 0-9A-Za-z */
	{ CCTL, CCTL, CCTL, CCTL }              /* 14, CTLESC ... */
#endif
};
#else
static const char S_I_T[][3] = {
#if ENABLE_ASH_ALIAS
	{ CSPCL, CIGN, CIGN },                  /* 0, PEOA */
#endif
	{ CSPCL, CWORD, CWORD },                /* 1, ' ' */
	{ CNL, CNL, CNL },                      /* 2, \n */
	{ CWORD, CCTL, CCTL },                  /* 3, !*-/:=?[]~ */
	{ CDQUOTE, CENDQUOTE, CWORD },          /* 4, '"' */
	{ CVAR, CVAR, CWORD },                  /* 5, $ */
	{ CSQUOTE, CWORD, CENDQUOTE },          /* 6, "'" */
	{ CSPCL, CWORD, CWORD },                /* 7, ( */
	{ CSPCL, CWORD, CWORD },                /* 8, ) */
	{ CBACK, CBACK, CCTL },                 /* 9, \ */
	{ CBQUOTE, CBQUOTE, CWORD },            /* 10, ` */
	{ CENDVAR, CENDVAR, CWORD },            /* 11, } */
#ifndef USE_SIT_FUNCTION
	{ CENDFILE, CENDFILE, CENDFILE },       /* 12, PEOF */
	{ CWORD, CWORD, CWORD },                /* 13, 0-9A-Za-z */
	{ CCTL, CCTL, CCTL }                    /* 14, CTLESC ... */
#endif
};
#endif /* ASH_MATH_SUPPORT */

#ifdef USE_SIT_FUNCTION

static int
SIT(int c, int syntax)
{
	static const char spec_symbls[] ALIGN1 = "\t\n !\"$&'()*-/:;<=>?[\\]`|}~";
#if ENABLE_ASH_ALIAS
	static const char syntax_index_table[] ALIGN1 = {
		1, 2, 1, 3, 4, 5, 1, 6,         /* "\t\n !\"$&'" */
		7, 8, 3, 3, 3, 3, 1, 1,         /* "()*-/:;<" */
		3, 1, 3, 3, 9, 3, 10, 1,        /* "=>?[\\]`|" */
		11, 3                           /* "}~" */
	};
#else
	static const char syntax_index_table[] ALIGN1 = {
		0, 1, 0, 2, 3, 4, 0, 5,         /* "\t\n !\"$&'" */
		6, 7, 2, 2, 2, 2, 0, 0,         /* "()*-/:;<" */
		2, 0, 2, 2, 8, 2, 9, 0,         /* "=>?[\\]`|" */
		10, 2                           /* "}~" */
	};
#endif
	const char *s;
	int indx;

	if (c == PEOF)          /* 2^8+2 */
		return CENDFILE;
#if ENABLE_ASH_ALIAS
	if (c == PEOA)          /* 2^8+1 */
		indx = 0;
	else
#endif
#define U_C(c) ((unsigned char)(c))

	if ((unsigned char)c >= (unsigned char)(CTLESC)
	 && (unsigned char)c <= (unsigned char)(CTLQUOTEMARK)
	) {
		return CCTL;
	} else {
		s = strchr(spec_symbls, c);
		if (s == NULL || *s == '\0')
			return CWORD;
		indx = syntax_index_table[(s - spec_symbls)];
	}
	return S_I_T[indx][syntax];
}

#else   /* !USE_SIT_FUNCTION */

#if ENABLE_ASH_ALIAS
#define CSPCL_CIGN_CIGN_CIGN                     0
#define CSPCL_CWORD_CWORD_CWORD                  1
#define CNL_CNL_CNL_CNL                          2
#define CWORD_CCTL_CCTL_CWORD                    3
#define CDQUOTE_CENDQUOTE_CWORD_CWORD            4
#define CVAR_CVAR_CWORD_CVAR                     5
#define CSQUOTE_CWORD_CENDQUOTE_CWORD            6
#define CSPCL_CWORD_CWORD_CLP                    7
#define CSPCL_CWORD_CWORD_CRP                    8
#define CBACK_CBACK_CCTL_CBACK                   9
#define CBQUOTE_CBQUOTE_CWORD_CBQUOTE           10
#define CENDVAR_CENDVAR_CWORD_CENDVAR           11
#define CENDFILE_CENDFILE_CENDFILE_CENDFILE     12
#define CWORD_CWORD_CWORD_CWORD                 13
#define CCTL_CCTL_CCTL_CCTL                     14
#else
#define CSPCL_CWORD_CWORD_CWORD                  0
#define CNL_CNL_CNL_CNL                          1
#define CWORD_CCTL_CCTL_CWORD                    2
#define CDQUOTE_CENDQUOTE_CWORD_CWORD            3
#define CVAR_CVAR_CWORD_CVAR                     4
#define CSQUOTE_CWORD_CENDQUOTE_CWORD            5
#define CSPCL_CWORD_CWORD_CLP                    6
#define CSPCL_CWORD_CWORD_CRP                    7
#define CBACK_CBACK_CCTL_CBACK                   8
#define CBQUOTE_CBQUOTE_CWORD_CBQUOTE            9
#define CENDVAR_CENDVAR_CWORD_CENDVAR           10
#define CENDFILE_CENDFILE_CENDFILE_CENDFILE     11
#define CWORD_CWORD_CWORD_CWORD                 12
#define CCTL_CCTL_CCTL_CCTL                     13
#endif

static const char syntax_index_table[258] = {
	/* BASESYNTAX_DQSYNTAX_SQSYNTAX_ARISYNTAX */
	/*   0  PEOF */      CENDFILE_CENDFILE_CENDFILE_CENDFILE,
#if ENABLE_ASH_ALIAS
	/*   1  PEOA */      CSPCL_CIGN_CIGN_CIGN,
#endif
	/*   2  -128 0x80 */ CWORD_CWORD_CWORD_CWORD,
	/*   3  -127 CTLESC       */ CCTL_CCTL_CCTL_CCTL,
	/*   4  -126 CTLVAR       */ CCTL_CCTL_CCTL_CCTL,
	/*   5  -125 CTLENDVAR    */ CCTL_CCTL_CCTL_CCTL,
	/*   6  -124 CTLBACKQ     */ CCTL_CCTL_CCTL_CCTL,
	/*   7  -123 CTLQUOTE     */ CCTL_CCTL_CCTL_CCTL,
	/*   8  -122 CTLARI       */ CCTL_CCTL_CCTL_CCTL,
	/*   9  -121 CTLENDARI    */ CCTL_CCTL_CCTL_CCTL,
	/*  10  -120 CTLQUOTEMARK */ CCTL_CCTL_CCTL_CCTL,
	/*  11  -119      */ CWORD_CWORD_CWORD_CWORD,
	/*  12  -118      */ CWORD_CWORD_CWORD_CWORD,
	/*  13  -117      */ CWORD_CWORD_CWORD_CWORD,
	/*  14  -116      */ CWORD_CWORD_CWORD_CWORD,
	/*  15  -115      */ CWORD_CWORD_CWORD_CWORD,
	/*  16  -114      */ CWORD_CWORD_CWORD_CWORD,
	/*  17  -113      */ CWORD_CWORD_CWORD_CWORD,
	/*  18  -112      */ CWORD_CWORD_CWORD_CWORD,
	/*  19  -111      */ CWORD_CWORD_CWORD_CWORD,
	/*  20  -110      */ CWORD_CWORD_CWORD_CWORD,
	/*  21  -109      */ CWORD_CWORD_CWORD_CWORD,
	/*  22  -108      */ CWORD_CWORD_CWORD_CWORD,
	/*  23  -107      */ CWORD_CWORD_CWORD_CWORD,
	/*  24  -106      */ CWORD_CWORD_CWORD_CWORD,
	/*  25  -105      */ CWORD_CWORD_CWORD_CWORD,
	/*  26  -104      */ CWORD_CWORD_CWORD_CWORD,
	/*  27  -103      */ CWORD_CWORD_CWORD_CWORD,
	/*  28  -102      */ CWORD_CWORD_CWORD_CWORD,
	/*  29  -101      */ CWORD_CWORD_CWORD_CWORD,
	/*  30  -100      */ CWORD_CWORD_CWORD_CWORD,
	/*  31   -99      */ CWORD_CWORD_CWORD_CWORD,
	/*  32   -98      */ CWORD_CWORD_CWORD_CWORD,
	/*  33   -97      */ CWORD_CWORD_CWORD_CWORD,
	/*  34   -96      */ CWORD_CWORD_CWORD_CWORD,
	/*  35   -95      */ CWORD_CWORD_CWORD_CWORD,
	/*  36   -94      */ CWORD_CWORD_CWORD_CWORD,
	/*  37   -93      */ CWORD_CWORD_CWORD_CWORD,
	/*  38   -92      */ CWORD_CWORD_CWORD_CWORD,
	/*  39   -91      */ CWORD_CWORD_CWORD_CWORD,
	/*  40   -90      */ CWORD_CWORD_CWORD_CWORD,
	/*  41   -89      */ CWORD_CWORD_CWORD_CWORD,
	/*  42   -88      */ CWORD_CWORD_CWORD_CWORD,
	/*  43   -87      */ CWORD_CWORD_CWORD_CWORD,
	/*  44   -86      */ CWORD_CWORD_CWORD_CWORD,
	/*  45   -85      */ CWORD_CWORD_CWORD_CWORD,
	/*  46   -84      */ CWORD_CWORD_CWORD_CWORD,
	/*  47   -83      */ CWORD_CWORD_CWORD_CWORD,
	/*  48   -82      */ CWORD_CWORD_CWORD_CWORD,
	/*  49   -81      */ CWORD_CWORD_CWORD_CWORD,
	/*  50   -80      */ CWORD_CWORD_CWORD_CWORD,
	/*  51   -79      */ CWORD_CWORD_CWORD_CWORD,
	/*  52   -78      */ CWORD_CWORD_CWORD_CWORD,
	/*  53   -77      */ CWORD_CWORD_CWORD_CWORD,
	/*  54   -76      */ CWORD_CWORD_CWORD_CWORD,
	/*  55   -75      */ CWORD_CWORD_CWORD_CWORD,
	/*  56   -74      */ CWORD_CWORD_CWORD_CWORD,
	/*  57   -73      */ CWORD_CWORD_CWORD_CWORD,
	/*  58   -72      */ CWORD_CWORD_CWORD_CWORD,
	/*  59   -71      */ CWORD_CWORD_CWORD_CWORD,
	/*  60   -70      */ CWORD_CWORD_CWORD_CWORD,
	/*  61   -69      */ CWORD_CWORD_CWORD_CWORD,
	/*  62   -68      */ CWORD_CWORD_CWORD_CWORD,
	/*  63   -67      */ CWORD_CWORD_CWORD_CWORD,
	/*  64   -66      */ CWORD_CWORD_CWORD_CWORD,
	/*  65   -65      */ CWORD_CWORD_CWORD_CWORD,
	/*  66   -64      */ CWORD_CWORD_CWORD_CWORD,
	/*  67   -63      */ CWORD_CWORD_CWORD_CWORD,
	/*  68   -62      */ CWORD_CWORD_CWORD_CWORD,
	/*  69   -61      */ CWORD_CWORD_CWORD_CWORD,
	/*  70   -60      */ CWORD_CWORD_CWORD_CWORD,
	/*  71   -59      */ CWORD_CWORD_CWORD_CWORD,
	/*  72   -58      */ CWORD_CWORD_CWORD_CWORD,
	/*  73   -57      */ CWORD_CWORD_CWORD_CWORD,
	/*  74   -56      */ CWORD_CWORD_CWORD_CWORD,
	/*  75   -55      */ CWORD_CWORD_CWORD_CWORD,
	/*  76   -54      */ CWORD_CWORD_CWORD_CWORD,
	/*  77   -53      */ CWORD_CWORD_CWORD_CWORD,
	/*  78   -52      */ CWORD_CWORD_CWORD_CWORD,
	/*  79   -51      */ CWORD_CWORD_CWORD_CWORD,
	/*  80   -50      */ CWORD_CWORD_CWORD_CWORD,
	/*  81   -49      */ CWORD_CWORD_CWORD_CWORD,
	/*  82   -48      */ CWORD_CWORD_CWORD_CWORD,
	/*  83   -47      */ CWORD_CWORD_CWORD_CWORD,
	/*  84   -46      */ CWORD_CWORD_CWORD_CWORD,
	/*  85   -45      */ CWORD_CWORD_CWORD_CWORD,
	/*  86   -44      */ CWORD_CWORD_CWORD_CWORD,
	/*  87   -43      */ CWORD_CWORD_CWORD_CWORD,
	/*  88   -42      */ CWORD_CWORD_CWORD_CWORD,
	/*  89   -41      */ CWORD_CWORD_CWORD_CWORD,
	/*  90   -40      */ CWORD_CWORD_CWORD_CWORD,
	/*  91   -39      */ CWORD_CWORD_CWORD_CWORD,
	/*  92   -38      */ CWORD_CWORD_CWORD_CWORD,
	/*  93   -37      */ CWORD_CWORD_CWORD_CWORD,
	/*  94   -36      */ CWORD_CWORD_CWORD_CWORD,
	/*  95   -35      */ CWORD_CWORD_CWORD_CWORD,
	/*  96   -34      */ CWORD_CWORD_CWORD_CWORD,
	/*  97   -33      */ CWORD_CWORD_CWORD_CWORD,
	/*  98   -32      */ CWORD_CWORD_CWORD_CWORD,
	/*  99   -31      */ CWORD_CWORD_CWORD_CWORD,
	/* 100   -30      */ CWORD_CWORD_CWORD_CWORD,
	/* 101   -29      */ CWORD_CWORD_CWORD_CWORD,
	/* 102   -28      */ CWORD_CWORD_CWORD_CWORD,
	/* 103   -27      */ CWORD_CWORD_CWORD_CWORD,
	/* 104   -26      */ CWORD_CWORD_CWORD_CWORD,
	/* 105   -25      */ CWORD_CWORD_CWORD_CWORD,
	/* 106   -24      */ CWORD_CWORD_CWORD_CWORD,
	/* 107   -23      */ CWORD_CWORD_CWORD_CWORD,
	/* 108   -22      */ CWORD_CWORD_CWORD_CWORD,
	/* 109   -21      */ CWORD_CWORD_CWORD_CWORD,
	/* 110   -20      */ CWORD_CWORD_CWORD_CWORD,
	/* 111   -19      */ CWORD_CWORD_CWORD_CWORD,
	/* 112   -18      */ CWORD_CWORD_CWORD_CWORD,
	/* 113   -17      */ CWORD_CWORD_CWORD_CWORD,
	/* 114   -16      */ CWORD_CWORD_CWORD_CWORD,
	/* 115   -15      */ CWORD_CWORD_CWORD_CWORD,
	/* 116   -14      */ CWORD_CWORD_CWORD_CWORD,
	/* 117   -13      */ CWORD_CWORD_CWORD_CWORD,
	/* 118   -12      */ CWORD_CWORD_CWORD_CWORD,
	/* 119   -11      */ CWORD_CWORD_CWORD_CWORD,
	/* 120   -10      */ CWORD_CWORD_CWORD_CWORD,
	/* 121    -9      */ CWORD_CWORD_CWORD_CWORD,
	/* 122    -8      */ CWORD_CWORD_CWORD_CWORD,
	/* 123    -7      */ CWORD_CWORD_CWORD_CWORD,
	/* 124    -6      */ CWORD_CWORD_CWORD_CWORD,
	/* 125    -5      */ CWORD_CWORD_CWORD_CWORD,
	/* 126    -4      */ CWORD_CWORD_CWORD_CWORD,
	/* 127    -3      */ CWORD_CWORD_CWORD_CWORD,
	/* 128    -2      */ CWORD_CWORD_CWORD_CWORD,
	/* 129    -1      */ CWORD_CWORD_CWORD_CWORD,
	/* 130     0      */ CWORD_CWORD_CWORD_CWORD,
	/* 131     1      */ CWORD_CWORD_CWORD_CWORD,
	/* 132     2      */ CWORD_CWORD_CWORD_CWORD,
	/* 133     3      */ CWORD_CWORD_CWORD_CWORD,
	/* 134     4      */ CWORD_CWORD_CWORD_CWORD,
	/* 135     5      */ CWORD_CWORD_CWORD_CWORD,
	/* 136     6      */ CWORD_CWORD_CWORD_CWORD,
	/* 137     7      */ CWORD_CWORD_CWORD_CWORD,
	/* 138     8      */ CWORD_CWORD_CWORD_CWORD,
	/* 139     9 "\t" */ CSPCL_CWORD_CWORD_CWORD,
	/* 140    10 "\n" */ CNL_CNL_CNL_CNL,
	/* 141    11      */ CWORD_CWORD_CWORD_CWORD,
	/* 142    12      */ CWORD_CWORD_CWORD_CWORD,
	/* 143    13      */ CWORD_CWORD_CWORD_CWORD,
	/* 144    14      */ CWORD_CWORD_CWORD_CWORD,
	/* 145    15      */ CWORD_CWORD_CWORD_CWORD,
	/* 146    16      */ CWORD_CWORD_CWORD_CWORD,
	/* 147    17      */ CWORD_CWORD_CWORD_CWORD,
	/* 148    18      */ CWORD_CWORD_CWORD_CWORD,
	/* 149    19      */ CWORD_CWORD_CWORD_CWORD,
	/* 150    20      */ CWORD_CWORD_CWORD_CWORD,
	/* 151    21      */ CWORD_CWORD_CWORD_CWORD,
	/* 152    22      */ CWORD_CWORD_CWORD_CWORD,
	/* 153    23      */ CWORD_CWORD_CWORD_CWORD,
	/* 154    24      */ CWORD_CWORD_CWORD_CWORD,
	/* 155    25      */ CWORD_CWORD_CWORD_CWORD,
	/* 156    26      */ CWORD_CWORD_CWORD_CWORD,
	/* 157    27      */ CWORD_CWORD_CWORD_CWORD,
	/* 158    28      */ CWORD_CWORD_CWORD_CWORD,
	/* 159    29      */ CWORD_CWORD_CWORD_CWORD,
	/* 160    30      */ CWORD_CWORD_CWORD_CWORD,
	/* 161    31      */ CWORD_CWORD_CWORD_CWORD,
	/* 162    32  " " */ CSPCL_CWORD_CWORD_CWORD,
	/* 163    33  "!" */ CWORD_CCTL_CCTL_CWORD,
	/* 164    34  """ */ CDQUOTE_CENDQUOTE_CWORD_CWORD,
	/* 165    35  "#" */ CWORD_CWORD_CWORD_CWORD,
	/* 166    36  "$" */ CVAR_CVAR_CWORD_CVAR,
	/* 167    37  "%" */ CWORD_CWORD_CWORD_CWORD,
	/* 168    38  "&" */ CSPCL_CWORD_CWORD_CWORD,
	/* 169    39  "'" */ CSQUOTE_CWORD_CENDQUOTE_CWORD,
	/* 170    40  "(" */ CSPCL_CWORD_CWORD_CLP,
	/* 171    41  ")" */ CSPCL_CWORD_CWORD_CRP,
	/* 172    42  "*" */ CWORD_CCTL_CCTL_CWORD,
	/* 173    43  "+" */ CWORD_CWORD_CWORD_CWORD,
	/* 174    44  "," */ CWORD_CWORD_CWORD_CWORD,
	/* 175    45  "-" */ CWORD_CCTL_CCTL_CWORD,
	/* 176    46  "." */ CWORD_CWORD_CWORD_CWORD,
	/* 177    47  "/" */ CWORD_CCTL_CCTL_CWORD,
	/* 178    48  "0" */ CWORD_CWORD_CWORD_CWORD,
	/* 179    49  "1" */ CWORD_CWORD_CWORD_CWORD,
	/* 180    50  "2" */ CWORD_CWORD_CWORD_CWORD,
	/* 181    51  "3" */ CWORD_CWORD_CWORD_CWORD,
	/* 182    52  "4" */ CWORD_CWORD_CWORD_CWORD,
	/* 183    53  "5" */ CWORD_CWORD_CWORD_CWORD,
	/* 184    54  "6" */ CWORD_CWORD_CWORD_CWORD,
	/* 185    55  "7" */ CWORD_CWORD_CWORD_CWORD,
	/* 186    56  "8" */ CWORD_CWORD_CWORD_CWORD,
	/* 187    57  "9" */ CWORD_CWORD_CWORD_CWORD,
	/* 188    58  ":" */ CWORD_CCTL_CCTL_CWORD,
	/* 189    59  ";" */ CSPCL_CWORD_CWORD_CWORD,
	/* 190    60  "<" */ CSPCL_CWORD_CWORD_CWORD,
	/* 191    61  "=" */ CWORD_CCTL_CCTL_CWORD,
	/* 192    62  ">" */ CSPCL_CWORD_CWORD_CWORD,
	/* 193    63  "?" */ CWORD_CCTL_CCTL_CWORD,
	/* 194    64  "@" */ CWORD_CWORD_CWORD_CWORD,
	/* 195    65  "A" */ CWORD_CWORD_CWORD_CWORD,
	/* 196    66  "B" */ CWORD_CWORD_CWORD_CWORD,
	/* 197    67  "C" */ CWORD_CWORD_CWORD_CWORD,
	/* 198    68  "D" */ CWORD_CWORD_CWORD_CWORD,
	/* 199    69  "E" */ CWORD_CWORD_CWORD_CWORD,
	/* 200    70  "F" */ CWORD_CWORD_CWORD_CWORD,
	/* 201    71  "G" */ CWORD_CWORD_CWORD_CWORD,
	/* 202    72  "H" */ CWORD_CWORD_CWORD_CWORD,
	/* 203    73  "I" */ CWORD_CWORD_CWORD_CWORD,
	/* 204    74  "J" */ CWORD_CWORD_CWORD_CWORD,
	/* 205    75  "K" */ CWORD_CWORD_CWORD_CWORD,
	/* 206    76  "L" */ CWORD_CWORD_CWORD_CWORD,
	/* 207    77  "M" */ CWORD_CWORD_CWORD_CWORD,
	/* 208    78  "N" */ CWORD_CWORD_CWORD_CWORD,
	/* 209    79  "O" */ CWORD_CWORD_CWORD_CWORD,
	/* 210    80  "P" */ CWORD_CWORD_CWORD_CWORD,
	/* 211    81  "Q" */ CWORD_CWORD_CWORD_CWORD,
	/* 212    82  "R" */ CWORD_CWORD_CWORD_CWORD,
	/* 213    83  "S" */ CWORD_CWORD_CWORD_CWORD,
	/* 214    84  "T" */ CWORD_CWORD_CWORD_CWORD,
	/* 215    85  "U" */ CWORD_CWORD_CWORD_CWORD,
	/* 216    86  "V" */ CWORD_CWORD_CWORD_CWORD,
	/* 217    87  "W" */ CWORD_CWORD_CWORD_CWORD,
	/* 218    88  "X" */ CWORD_CWORD_CWORD_CWORD,
	/* 219    89  "Y" */ CWORD_CWORD_CWORD_CWORD,
	/* 220    90  "Z" */ CWORD_CWORD_CWORD_CWORD,
	/* 221    91  "[" */ CWORD_CCTL_CCTL_CWORD,
	/* 222    92  "\" */ CBACK_CBACK_CCTL_CBACK,
	/* 223    93  "]" */ CWORD_CCTL_CCTL_CWORD,
	/* 224    94  "^" */ CWORD_CWORD_CWORD_CWORD,
	/* 225    95  "_" */ CWORD_CWORD_CWORD_CWORD,
	/* 226    96  "`" */ CBQUOTE_CBQUOTE_CWORD_CBQUOTE,
	/* 227    97  "a" */ CWORD_CWORD_CWORD_CWORD,
	/* 228    98  "b" */ CWORD_CWORD_CWORD_CWORD,
	/* 229    99  "c" */ CWORD_CWORD_CWORD_CWORD,
	/* 230   100  "d" */ CWORD_CWORD_CWORD_CWORD,
	/* 231   101  "e" */ CWORD_CWORD_CWORD_CWORD,
	/* 232   102  "f" */ CWORD_CWORD_CWORD_CWORD,
	/* 233   103  "g" */ CWORD_CWORD_CWORD_CWORD,
	/* 234   104  "h" */ CWORD_CWORD_CWORD_CWORD,
	/* 235   105  "i" */ CWORD_CWORD_CWORD_CWORD,
	/* 236   106  "j" */ CWORD_CWORD_CWORD_CWORD,
	/* 237   107  "k" */ CWORD_CWORD_CWORD_CWORD,
	/* 238   108  "l" */ CWORD_CWORD_CWORD_CWORD,
	/* 239   109  "m" */ CWORD_CWORD_CWORD_CWORD,
	/* 240   110  "n" */ CWORD_CWORD_CWORD_CWORD,
	/* 241   111  "o" */ CWORD_CWORD_CWORD_CWORD,
	/* 242   112  "p" */ CWORD_CWORD_CWORD_CWORD,
	/* 243   113  "q" */ CWORD_CWORD_CWORD_CWORD,
	/* 244   114  "r" */ CWORD_CWORD_CWORD_CWORD,
	/* 245   115  "s" */ CWORD_CWORD_CWORD_CWORD,
	/* 246   116  "t" */ CWORD_CWORD_CWORD_CWORD,
	/* 247   117  "u" */ CWORD_CWORD_CWORD_CWORD,
	/* 248   118  "v" */ CWORD_CWORD_CWORD_CWORD,
	/* 249   119  "w" */ CWORD_CWORD_CWORD_CWORD,
	/* 250   120  "x" */ CWORD_CWORD_CWORD_CWORD,
	/* 251   121  "y" */ CWORD_CWORD_CWORD_CWORD,
	/* 252   122  "z" */ CWORD_CWORD_CWORD_CWORD,
	/* 253   123  "{" */ CWORD_CWORD_CWORD_CWORD,
	/* 254   124  "|" */ CSPCL_CWORD_CWORD_CWORD,
	/* 255   125  "}" */ CENDVAR_CENDVAR_CWORD_CENDVAR,
	/* 256   126  "~" */ CWORD_CCTL_CCTL_CWORD,
	/* 257   127      */ CWORD_CWORD_CWORD_CWORD,
};

#define SIT(c, syntax) (S_I_T[(int)syntax_index_table[((int)c)+SYNBASE]][syntax])

#endif  /* USE_SIT_FUNCTION */


/* ============ Alias handling */

#if ENABLE_ASH_ALIAS

#define ALIASINUSE 1
#define ALIASDEAD  2

#define ATABSIZE 39

struct alias {
	struct alias *next;
	char *name;
	char *val;
	int flag;
};

static struct alias *atab[ATABSIZE];

static struct alias **
__lookupalias(const char *name) {
	unsigned int hashval;
	struct alias **app;
	const char *p;
	unsigned int ch;

	p = name;

	ch = (unsigned char)*p;
	hashval = ch << 4;
	while (ch) {
		hashval += ch;
		ch = (unsigned char)*++p;
	}
	app = &atab[hashval % ATABSIZE];

	for (; *app; app = &(*app)->next) {
		if (strcmp(name, (*app)->name) == 0) {
			break;
		}
	}

	return app;
}

static struct alias *
lookupalias(const char *name, int check)
{
	struct alias *ap = *__lookupalias(name);

	if (check && ap && (ap->flag & ALIASINUSE))
		return NULL;
	return ap;
}

static struct alias *
freealias(struct alias *ap)
{
	struct alias *next;

	if (ap->flag & ALIASINUSE) {
		ap->flag |= ALIASDEAD;
		return ap;
	}

	next = ap->next;
	free(ap->name);
	free(ap->val);
	free(ap);
	return next;
}

static void
setalias(const char *name, const char *val)
{
	struct alias *ap, **app;

	app = __lookupalias(name);
	ap = *app;
	INT_OFF;
	if (ap) {
		if (!(ap->flag & ALIASINUSE)) {
			free(ap->val);
		}
		ap->val = ckstrdup(val);
		ap->flag &= ~ALIASDEAD;
	} else {
		/* not found */
		ap = ckmalloc(sizeof(struct alias));
		ap->name = ckstrdup(name);
		ap->val = ckstrdup(val);
		ap->flag = 0;
		ap->next = 0;
		*app = ap;
	}
	INT_ON;
}

static int
unalias(const char *name)
{
	struct alias **app;

	app = __lookupalias(name);

	if (*app) {
		INT_OFF;
		*app = freealias(*app);
		INT_ON;
		return 0;
	}

	return 1;
}

static void
rmaliases(void)
{
	struct alias *ap, **app;
	int i;

	INT_OFF;
	for (i = 0; i < ATABSIZE; i++) {
		app = &atab[i];
		for (ap = *app; ap; ap = *app) {
			*app = freealias(*app);
			if (ap == *app) {
				app = &ap->next;
			}
		}
	}
	INT_ON;
}

static void
printalias(const struct alias *ap)
{
	out1fmt("%s=%s\n", ap->name, single_quote(ap->val));
}

/*
 * TODO - sort output
 */
static int
aliascmd(int argc, char **argv)
{
	char *n, *v;
	int ret = 0;
	struct alias *ap;

	if (argc == 1) {
		int i;

		for (i = 0; i < ATABSIZE; i++)
			for (ap = atab[i]; ap; ap = ap->next) {
				printalias(ap);
			}
		return 0;
	}
	while ((n = *++argv) != NULL) {
		v = strchr(n+1, '=');
		if (v == NULL) { /* n+1: funny ksh stuff */
			ap = *__lookupalias(n);
			if (ap == NULL) {
				fprintf(stderr, "%s: %s not found\n", "alias", n);
				ret = 1;
			} else
				printalias(ap);
		} else {
			*v++ = '\0';
			setalias(n, v);
		}
	}

	return ret;
}

static int
unaliascmd(int argc, char **argv)
{
	int i;

	while ((i = nextopt("a")) != '\0') {
		if (i == 'a') {
			rmaliases();
			return 0;
		}
	}
	for (i = 0; *argptr; argptr++) {
		if (unalias(*argptr)) {
			fprintf(stderr, "%s: %s not found\n", "unalias", *argptr);
			i = 1;
		}
	}

	return i;
}

#endif /* ASH_ALIAS */


/* ============ jobs.c */

/* Mode argument to forkshell.  Don't change FORK_FG or FORK_BG. */
#define FORK_FG 0
#define FORK_BG 1
#define FORK_NOJOB 2

/* mode flags for showjob(s) */
#define SHOW_PGID       0x01    /* only show pgid - for jobs -p */
#define SHOW_PID        0x04    /* include process pid */
#define SHOW_CHANGED    0x08    /* only jobs whose state has changed */

/*
 * A job structure contains information about a job.  A job is either a
 * single process or a set of processes contained in a pipeline.  In the
 * latter case, pidlist will be non-NULL, and will point to a -1 terminated
 * array of pids.
 */

struct procstat {
	pid_t   pid;            /* process id */
	int     status;         /* last process status from wait() */
	char    *cmd;           /* text of command being run */
};

struct job {
	struct procstat ps0;    /* status of process */
	struct procstat *ps;    /* status or processes when more than one */
#if JOBS
	int stopstatus;         /* status of a stopped job */
#endif
	uint32_t
		nprocs: 16,     /* number of processes */
		state: 8,
#define JOBRUNNING      0       /* at least one proc running */
#define JOBSTOPPED      1       /* all procs are stopped */
#define JOBDONE         2       /* all procs are completed */
#if JOBS
		sigint: 1,      /* job was killed by SIGINT */
		jobctl: 1,      /* job running under job control */
#endif
		waited: 1,      /* true if this entry has been waited for */
		used: 1,        /* true if this entry is in used */
		changed: 1;     /* true if status has changed */
	struct job *prev_job;   /* previous job */
};

static pid_t backgndpid;        /* pid of last background process */
static smallint job_warning;    /* user was warned about stopped jobs (can be 2, 1 or 0). */

static struct job *makejob(union node *, int);
static int forkshell(struct job *, union node *, int);
static int waitforjob(struct job *);

#if !JOBS
enum { jobctl = 0 };
#define setjobctl(on) do {} while (0)
#else
static smallint jobctl;              /* true if doing job control */
static void setjobctl(int);
#endif

/*
 * Set the signal handler for the specified signal.  The routine figures
 * out what it should be set to.
 */
static void
setsignal(int signo)
{
	int action;
	char *t, tsig;
	struct sigaction act;

	t = trap[signo];
	if (t == NULL)
		action = S_DFL;
	else if (*t != '\0')
		action = S_CATCH;
	else
		action = S_IGN;
	if (rootshell && action == S_DFL) {
		switch (signo) {
		case SIGINT:
			if (iflag || minusc || sflag == 0)
				action = S_CATCH;
			break;
		case SIGQUIT:
#if DEBUG
			if (debug)
				break;
#endif
			/* FALLTHROUGH */
		case SIGTERM:
			if (iflag)
				action = S_IGN;
			break;
#if JOBS
		case SIGTSTP:
		case SIGTTOU:
			if (mflag)
				action = S_IGN;
			break;
#endif
		}
	}

	t = &sigmode[signo -