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ksh: escape control chars when displaying file name completions.
If there are multiple matches when using autocomplete, the list of
matching file names was output as-is.  However, for a single match,
control characters are escaped before the file name is displayed.
This makes the behavior more consistent by escaping control chars
in the list of matches too.  Discussed with deraadt@, OK op@

/*	$OpenBSD: exec.c,v 1.77 2023/06/21 22:22:08 millert Exp $	*/

/*
 * execute command tree
 */

#include <sys/stat.h>

#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <paths.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "sh.h"
#include "c_test.h"

/* Does ps4 get parameter substitutions done? */
# define PS4_SUBSTITUTE(s)	substitute((s), 0)

static int	comexec(struct op *, struct tbl *volatile, char **,
		    int volatile, volatile int *);
static void	scriptexec(struct op *, char **);
static int	call_builtin(struct tbl *, char **);
static int	iosetup(struct ioword *, struct tbl *);
static int	herein(const char *, int);
static char	*do_selectargs(char **, bool);
static int	dbteste_isa(Test_env *, Test_meta);
static const char *dbteste_getopnd(Test_env *, Test_op, int);
static int	dbteste_eval(Test_env *, Test_op, const char *, const char *,
		    int);
static void	dbteste_error(Test_env *, int, const char *);


/*
 * execute command tree
 */
int
execute(struct op *volatile t,
    volatile int flags,		/* if XEXEC don't fork */
    volatile int *xerrok)	/* inform recursive callers in -e mode that
				 * short-circuit && or || shouldn't be treated
				 * as an error */
{
	int i, dummy = 0, save_xerrok = 0;
	volatile int rv = 0;
	int pv[2];
	char ** volatile ap;
	char *s, *cp;
	struct ioword **iowp;
	struct tbl *tp = NULL;

	if (t == NULL)
		return 0;

	/* Caller doesn't care if XERROK should propagate. */
	if (xerrok == NULL)
		xerrok = &dummy;

	/* Is this the end of a pipeline?  If so, we want to evaluate the
	 * command arguments
	bool eval_done = false;
	if ((flags&XFORK) && !(flags&XEXEC) && (flags&XPCLOSE)) {
		eval_done = true;
		tp = eval_execute_args(t, &ap);
	}
	 */
	if ((flags&XFORK) && !(flags&XEXEC) && t->type != TPIPE)
		return exchild(t, flags & ~XTIME, xerrok, -1); /* run in sub-process */

	newenv(E_EXEC);
	if (trap)
		runtraps(0);

	if (t->type == TCOM) {
		/* Clear subst_exstat before argument expansion.  Used by
		 * null commands (see comexec() and c_eval()) and by c_set().
		 */
		subst_exstat = 0;

		current_lineno = t->lineno;	/* for $LINENO */

		/* POSIX says expand command words first, then redirections,
		 * and assignments last..
		 */
		ap = eval(t->args, t->u.evalflags | DOBLANK | DOGLOB | DOTILDE);
		if (flags & XTIME)
			/* Allow option parsing (bizarre, but POSIX) */
			timex_hook(t, &ap);
		if (Flag(FXTRACE) && ap[0]) {
			shf_fprintf(shl_out, "%s",
				PS4_SUBSTITUTE(str_val(global("PS4"))));
			for (i = 0; ap[i]; i++)
				shf_fprintf(shl_out, "%s%s", ap[i],
				    ap[i + 1] ? " " : "\n");
			shf_flush(shl_out);
		}
		if (ap[0])
			tp = findcom(ap[0], FC_BI|FC_FUNC);
	}
	flags &= ~XTIME;

	if (t->ioact != NULL || t->type == TPIPE || t->type == TCOPROC) {
		genv->savefd = areallocarray(NULL, NUFILE, sizeof(short), ATEMP);
		/* initialize to not redirected */
		memset(genv->savefd, 0, NUFILE * sizeof(short));
	}

	/* do redirection, to be restored in quitenv() */
	if (t->ioact != NULL)
		for (iowp = t->ioact; *iowp != NULL; iowp++) {
			if (iosetup(*iowp, tp) < 0) {
				exstat = rv = 1;
				/* Except in the permanent case (exec 2>afile),
				 * redirection failures for special commands
				 * cause (non-interactive) shell to exit.
				 */
				if (tp && tp->val.f != c_exec &&
				    tp->type == CSHELL &&
				    (tp->flag & SPEC_BI))
					errorf(NULL);
				/* Deal with FERREXIT, quitenv(), etc. */
				goto Break;
			}
		}

	switch (t->type) {
	case TCOM:
		rv = comexec(t, tp, ap, flags, xerrok);
		break;

	case TPAREN:
		rv = execute(t->left, flags|XFORK, xerrok);
		break;

	case TPIPE:
		flags |= XFORK;
		flags &= ~XEXEC;
		genv->savefd[0] = savefd(0);
		genv->savefd[1] = savefd(1);
		while (t->type == TPIPE) {
			openpipe(pv);
			(void) ksh_dup2(pv[1], 1, false); /* stdout of curr */
			/* Let exchild() close pv[0] in child
			 * (if this isn't done, commands like
			 *    (: ; cat /etc/termcap) | sleep 1
			 *  will hang forever).
			 */
			exchild(t->left, flags|XPIPEO|XCCLOSE, NULL, pv[0]);
			(void) ksh_dup2(pv[0], 0, false); /* stdin of next */
			closepipe(pv);
			flags |= XPIPEI;
			t = t->right;
		}
		restfd(1, genv->savefd[1]); /* stdout of last */
		genv->savefd[1] = 0; /* no need to re-restore this */
		/* Let exchild() close 0 in parent, after fork, before wait */
		i = exchild(t, flags|XPCLOSE, xerrok, 0);
		if (!(flags&XBGND) && !(flags&XXCOM))
			rv = i;
		break;

	case TLIST:
		while (t->type == TLIST) {
			execute(t->left, flags & XERROK, NULL);
			t = t->right;
		}
		rv = execute(t, flags & XERROK, xerrok);
		break;

	case TCOPROC:
	    {
		sigset_t	omask;

		/* Block sigchild as we are using things changed in the
		 * signal handler
		 */
		sigprocmask(SIG_BLOCK, &sm_sigchld, &omask);
		genv->type = E_ERRH;
		i = sigsetjmp(genv->jbuf, 0);
		if (i) {
			sigprocmask(SIG_SETMASK, &omask, NULL);
			quitenv(NULL);
			unwind(i);
			/* NOTREACHED */
		}
		/* Already have a (live) co-process? */
		if (coproc.job && coproc.write >= 0)
			errorf("coprocess already exists");

		/* Can we re-use the existing co-process pipe? */
		coproc_cleanup(true);

		/* do this before opening pipes, in case these fail */
		genv->savefd[0] = savefd(0);
		genv->savefd[1] = savefd(1);

		openpipe(pv);
		if (pv[0] != 0) {
			ksh_dup2(pv[0], 0, false);
			close(pv[0]);
		}
		coproc.write = pv[1];
		coproc.job = NULL;

		if (coproc.readw >= 0)
			ksh_dup2(coproc.readw, 1, false);
		else {
			openpipe(pv);
			coproc.read = pv[0];
			ksh_dup2(pv[1], 1, false);
			coproc.readw = pv[1];	 /* closed before first read */
			coproc.njobs = 0;
			/* create new coprocess id */
			++coproc.id;
		}
		sigprocmask(SIG_SETMASK, &omask, NULL);
		genv->type = E_EXEC; /* no more need for error handler */

		/* exchild() closes coproc.* in child after fork,
		 * will also increment coproc.njobs when the
		 * job is actually created.
		 */
		flags &= ~XEXEC;
		exchild(t->left, flags|XBGND|XFORK|XCOPROC|XCCLOSE,
		    NULL, coproc.readw);
		break;
	    }

	case TASYNC:
		/* XXX non-optimal, I think - "(foo &)", forks for (),
		 * forks again for async...  parent should optimize
		 * this to "foo &"...
		 */
		rv = execute(t->left, (flags&~XEXEC)|XBGND|XFORK, xerrok);
		break;

	case TOR:
	case TAND:
		rv = execute(t->left, XERROK, xerrok);
		if ((rv == 0) == (t->type == TAND))
			rv = execute(t->right, flags & XERROK, xerrok);
		else {
			flags |= XERROK;
			*xerrok = 1;
		}
		break;

	case TBANG:
		rv = !execute(t->right, XERROK, xerrok);
		flags |= XERROK;
		*xerrok = 1;
		break;

	case TDBRACKET:
	    {
		Test_env te;

		te.flags = TEF_DBRACKET;
		te.pos.wp = t->args;
		te.isa = dbteste_isa;
		te.getopnd = dbteste_getopnd;
		te.eval = dbteste_eval;
		te.error = dbteste_error;

		rv = test_parse(&te);
		break;
	    }

	case TFOR:
	case TSELECT:
	    {
		volatile bool is_first = true;
		ap = (t->vars != NULL) ? eval(t->vars, DOBLANK|DOGLOB|DOTILDE) :
		    genv->loc->argv + 1;
		genv->type = E_LOOP;
		while (1) {
			i = sigsetjmp(genv->jbuf, 0);
			if (!i)
				break;
			if ((genv->flags&EF_BRKCONT_PASS) ||
			    (i != LBREAK && i != LCONTIN)) {
				quitenv(NULL);
				unwind(i);
			} else if (i == LBREAK) {
				rv = 0;
				goto Break;
			}
		}
		rv = 0; /* in case of a continue */
		if (t->type == TFOR) {
			save_xerrok = *xerrok;
			while (*ap != NULL) {
				setstr(global(t->str), *ap++, KSH_UNWIND_ERROR);
				/* undo xerrok in all iterations except the
				 * last */
				*xerrok = save_xerrok;
				rv = execute(t->left, flags & XERROK, xerrok);
			}
			/* ripple xerrok set at final iteration */
		} else { /* TSELECT */
			for (;;) {
				if (!(cp = do_selectargs(ap, is_first))) {
					rv = 1;
					break;
				}
				is_first = false;
				setstr(global(t->str), cp, KSH_UNWIND_ERROR);
				rv = execute(t->left, flags & XERROK, xerrok);
			}
		}
	    }
		break;

	case TWHILE:
	case TUNTIL:
		genv->type = E_LOOP;
		while (1) {
			i = sigsetjmp(genv->jbuf, 0);
			if (!i)
				break;
			if ((genv->flags&EF_BRKCONT_PASS) ||
			    (i != LBREAK && i != LCONTIN)) {
				quitenv(NULL);
				unwind(i);
			} else if (i == LBREAK) {
				rv = 0;
				goto Break;
			}
		}
		rv = 0; /* in case of a continue */
		while ((execute(t->left, XERROK, NULL) == 0) == (t->type == TWHILE))
			rv = execute(t->right, flags & XERROK, xerrok);
		break;

	case TIF:
	case TELIF:
		if (t->right == NULL)
			break;	/* should be error */
		rv = execute(t->left, XERROK, NULL) == 0 ?
		    execute(t->right->left, flags & XERROK, xerrok) :
		    execute(t->right->right, flags & XERROK, xerrok);
		break;

	case TCASE:
		cp = evalstr(t->str, DOTILDE);
		for (t = t->left; t != NULL && t->type == TPAT; t = t->right) {
			for (ap = t->vars; *ap; ap++) {
				if ((s = evalstr(*ap, DOTILDE|DOPAT)) &&
				    gmatch(cp, s, false))
					goto Found;
			}
		}
		break;
	  Found:
		rv = execute(t->left, flags & XERROK, xerrok);
		break;

	case TBRACE:
		rv = execute(t->left, flags & XERROK, xerrok);
		break;

	case TFUNCT:
		rv = define(t->str, t);
		break;

	case TTIME:
		/* Clear XEXEC so nested execute() call doesn't exit
		 * (allows "ls -l | time grep foo").
		 */
		rv = timex(t, flags & ~XEXEC, xerrok);
		break;

	case TEXEC:		/* an eval'd TCOM */
		s = t->args[0];
		ap = makenv();
		restoresigs();
		cleanup_proc_env();
		execve(t->str, t->args, ap);
		if (errno == ENOEXEC)
			scriptexec(t, ap);
		else
			errorf("%s: %s", s, strerror(errno));
	}
    Break:
	exstat = rv;

	quitenv(NULL);		/* restores IO */
	if ((flags&XEXEC))
		unwind(LEXIT);	/* exit child */
	if (rv != 0 && !(flags & XERROK) && !*xerrok) {
		trapsig(SIGERR_);
		if (Flag(FERREXIT))
			unwind(LERROR);
	}
	return rv;
}

/*
 * execute simple command
 */

static int
comexec(struct op *t, struct tbl *volatile tp, char **ap, volatile int flags,
    volatile int *xerrok)
{
	int i;
	volatile int rv = 0;
	char *cp;
	char **lastp;
	struct op texec;
	int type_flags;
	int keepasn_ok;
	int fcflags = FC_BI|FC_FUNC|FC_PATH;
	int bourne_function_call = 0;

	/* snag the last argument for $_ XXX not the same as at&t ksh,
	 * which only seems to set $_ after a newline (but not in
	 * functions/dot scripts, but in interactive and script) -
	 * perhaps save last arg here and set it in shell()?.
	 */
	if (!Flag(FSH) && Flag(FTALKING) && *(lastp = ap)) {
		while (*++lastp)
			;
		/* setstr() can't fail here */
		setstr(typeset("_", LOCAL, 0, INTEGER, 0), *--lastp,
		    KSH_RETURN_ERROR);
	}

	/* Deal with the shell builtins builtin, exec and command since
	 * they can be followed by other commands.  This must be done before
	 * we know if we should create a local block, which must be done
	 * before we can do a path search (in case the assignments change
	 * PATH).
	 * Odd cases:
	 *   FOO=bar exec > /dev/null		FOO is kept but not exported
	 *   FOO=bar exec foobar		FOO is exported
	 *   FOO=bar command exec > /dev/null	FOO is neither kept nor exported
	 *   FOO=bar command			FOO is neither kept nor exported
	 *   PATH=... foobar			use new PATH in foobar search
	 */
	keepasn_ok = 1;
	while (tp && tp->type == CSHELL) {
		fcflags = FC_BI|FC_FUNC|FC_PATH;/* undo effects of command */
		if (tp->val.f == c_builtin) {
			if ((cp = *++ap) == NULL) {
				tp = NULL;
				break;
			}
			tp = findcom(cp, FC_BI);
			if (tp == NULL)
				errorf("builtin: %s: not a builtin", cp);
			continue;
		} else if (tp->val.f == c_exec) {
			if (ap[1] == NULL)
				break;
			ap++;
			flags |= XEXEC;
		} else if (tp->val.f == c_command) {
			int optc, saw_p = 0;

			/* Ugly dealing with options in two places (here and
			 * in c_command(), but such is life)
			 */
			ksh_getopt_reset(&builtin_opt, 0);
			while ((optc = ksh_getopt(ap, &builtin_opt, ":p")) == 'p')
				saw_p = 1;
			if (optc != EOF)
				break;	/* command -vV or something */
			/* don't look for functions */
			fcflags = FC_BI|FC_PATH;
			if (saw_p) {
				if (Flag(FRESTRICTED)) {
					warningf(true,
					    "command -p: restricted");
					rv = 1;
					goto Leave;
				}
				fcflags |= FC_DEFPATH;
			}
			ap += builtin_opt.optind;
			/* POSIX says special builtins lose their status
			 * if accessed using command.
			 */
			keepasn_ok = 0;
			if (!ap[0]) {
				/* ensure command with no args exits with 0 */
				subst_exstat = 0;
				break;
			}
		} else
			break;
		tp = findcom(ap[0], fcflags & (FC_BI|FC_FUNC));
	}
	if (keepasn_ok && (!ap[0] || (tp && (tp->flag & KEEPASN))))
		type_flags = 0;
	else {
		/* create new variable/function block */
		newblock();
		/* ksh functions don't keep assignments, POSIX functions do. */
		if (keepasn_ok && tp && tp->type == CFUNC &&
		    !(tp->flag & FKSH)) {
			bourne_function_call = 1;
			type_flags = 0;
		} else
			type_flags = LOCAL|LOCAL_COPY|EXPORT;
	}
	if (Flag(FEXPORT))
		type_flags |= EXPORT;
	for (i = 0; t->vars[i]; i++) {
		cp = evalstr(t->vars[i], DOASNTILDE);
		if (Flag(FXTRACE)) {
			if (i == 0)
				shf_fprintf(shl_out, "%s",
				    PS4_SUBSTITUTE(str_val(global("PS4"))));
			shf_fprintf(shl_out, "%s%s", cp,
			    t->vars[i + 1] ? " " : "\n");
			if (!t->vars[i + 1])
				shf_flush(shl_out);
		}
		typeset(cp, type_flags, 0, 0, 0);
		if (bourne_function_call && !(type_flags & EXPORT))
			typeset(cp, LOCAL|LOCAL_COPY|EXPORT, 0, 0, 0);
	}

	if ((cp = *ap) == NULL) {
		rv = subst_exstat;
		goto Leave;
	} else if (!tp) {
		if (Flag(FRESTRICTED) && strchr(cp, '/')) {
			warningf(true, "%s: restricted", cp);
			rv = 1;
			goto Leave;
		}
		tp = findcom(cp, fcflags);
	}

	switch (tp->type) {
	case CSHELL:			/* shell built-in */
		rv = call_builtin(tp, ap);
		break;

	case CFUNC:			/* function call */
	    {
		volatile int old_xflag, old_inuse;
		const char *volatile old_kshname;

		if (!(tp->flag & ISSET)) {
			struct tbl *ftp;

			if (!tp->u.fpath) {
				if (tp->u2.errno_) {
					warningf(true,
					    "%s: can't find function "
					    "definition file - %s",
					    cp, strerror(tp->u2.errno_));
					rv = 126;
				} else {
					warningf(true,
					    "%s: can't find function "
					    "definition file", cp);
					rv = 127;
				}
				break;
			}
			if (include(tp->u.fpath, 0, NULL, 0) < 0) {
				warningf(true,
				    "%s: can't open function definition file %s - %s",
				    cp, tp->u.fpath, strerror(errno));
				rv = 127;
				break;
			}
			if (!(ftp = findfunc(cp, hash(cp), false)) ||
			    !(ftp->flag & ISSET)) {
				warningf(true,
				    "%s: function not defined by %s",
				    cp, tp->u.fpath);
				rv = 127;
				break;
			}
			tp = ftp;
		}

		/* ksh functions set $0 to function name, POSIX functions leave
		 * $0 unchanged.
		 */
		old_kshname = kshname;
		if (tp->flag & FKSH)
			kshname = ap[0];
		else
			ap[0] = (char *) kshname;
		genv->loc->argv = ap;
		for (i = 0; *ap++ != NULL; i++)
			;
		genv->loc->argc = i - 1;
		/* ksh-style functions handle getopts sanely,
		 * bourne/posix functions are insane...
		 */
		if (tp->flag & FKSH) {
			genv->loc->flags |= BF_DOGETOPTS;
			genv->loc->getopts_state = user_opt;
			getopts_reset(1);
		}

		old_xflag = Flag(FXTRACE);
		Flag(FXTRACE) = tp->flag & TRACE ? true : false;

		old_inuse = tp->flag & FINUSE;
		tp->flag |= FINUSE;

		genv->type = E_FUNC;
		i = sigsetjmp(genv->jbuf, 0);
		if (i == 0) {
			/* seems odd to pass XERROK here, but at&t ksh does */
			exstat = execute(tp->val.t, flags & XERROK, xerrok);
			i = LRETURN;
		}
		kshname = old_kshname;
		Flag(FXTRACE) = old_xflag;
		tp->flag = (tp->flag & ~FINUSE) | old_inuse;
		/* Were we deleted while executing?  If so, free the execution
		 * tree.  todo: Unfortunately, the table entry is never re-used
		 * until the lookup table is expanded.
		 */
		if ((tp->flag & (FDELETE|FINUSE)) == FDELETE) {
			if (tp->flag & ALLOC) {
				tp->flag &= ~ALLOC;
				tfree(tp->val.t, tp->areap);
			}
			tp->flag = 0;
		}
		switch (i) {
		case LRETURN:
		case LERROR:
			rv = exstat;
			break;
		case LINTR:
		case LEXIT:
		case LLEAVE:
		case LSHELL:
			quitenv(NULL);
			unwind(i);
			/* NOTREACHED */
		default:
			quitenv(NULL);
			internal_errorf("CFUNC %d", i);
		}
		break;
	    }

	case CEXEC:		/* executable command */
	case CTALIAS:		/* tracked alias */
		if (!(tp->flag&ISSET)) {
			/* errno_ will be set if the named command was found
			 * but could not be executed (permissions, no execute
			 * bit, directory, etc).  Print out a (hopefully)
			 * useful error message and set the exit status to 126.
			 */
			if (tp->u2.errno_) {
				warningf(true, "%s: cannot execute - %s", cp,
				    strerror(tp->u2.errno_));
				rv = 126;	/* POSIX */
			} else {
				warningf(true, "%s: not found", cp);
				rv = 127;
			}
			break;
		}

		if (!Flag(FSH)) {
			/* set $_ to program's full path */
			/* setstr() can't fail here */
			setstr(typeset("_", LOCAL|EXPORT, 0, INTEGER, 0),
			    tp->val.s, KSH_RETURN_ERROR);
		}

		if (flags&XEXEC) {
			j_exit();
			if (!(flags&XBGND) || Flag(FMONITOR)) {
				setexecsig(&sigtraps[SIGINT], SS_RESTORE_ORIG);
				setexecsig(&sigtraps[SIGQUIT], SS_RESTORE_ORIG);
			}
		}

		/* to fork we set up a TEXEC node and call execute */
		memset(&texec, 0, sizeof(texec));
		texec.type = TEXEC;
		texec.left = t;	/* for tprint */
		texec.str = tp->val.s;
		texec.args = ap;
		rv = exchild(&texec, flags, xerrok, -1);
		break;
	}
  Leave:
	if (flags & XEXEC) {
		exstat = rv;
		unwind(LLEAVE);
	}
	return rv;
}

static void
scriptexec(struct op *tp, char **ap)
{
	char *shell;

	shell = str_val(global("EXECSHELL"));
	if (shell && *shell)
		shell = search(shell, search_path, X_OK, NULL);
	if (!shell || !*shell)
		shell = _PATH_BSHELL;

	*tp->args-- = tp->str;
	*tp->args = shell;

	execve(tp->args[0], tp->args, ap);

	/* report both the program that was run and the bogus shell */
	errorf("%s: %s: %s", tp->str, shell, strerror(errno));
}

int
shcomexec(char **wp)
{
	struct tbl *tp;

	tp = ktsearch(&builtins, *wp, hash(*wp));
	if (tp == NULL)
		internal_errorf("%s: %s", __func__, *wp);
	return call_builtin(tp, wp);
}

/*
 * Search function tables for a function.  If create set, a table entry
 * is created if none is found.
 */
struct tbl *
findfunc(const char *name, unsigned int h, int create)
{
	struct block *l;
	struct tbl *tp = NULL;

	for (l = genv->loc; l; l = l->next) {
		tp = ktsearch(&l->funs, name, h);
		if (tp)
			break;
		if (!l->next && create) {
			tp = ktenter(&l->funs, name, h);
			tp->flag = DEFINED;
			tp->type = CFUNC;
			tp->val.t = NULL;
			break;
		}
	}
	return tp;
}

/*
 * define function.  Returns 1 if function is being undefined (t == 0) and
 * function did not exist, returns 0 otherwise.
 */
int
define(const char *name, struct op *t)
{
	struct tbl *tp;
	int was_set = 0;

	while (1) {
		tp = findfunc(name, hash(name), true);

		if (tp->flag & ISSET)
			was_set = 1;
		/* If this function is currently being executed, we zap this
		 * table entry so findfunc() won't see it
		 */
		if (tp->flag & FINUSE) {
			tp->name[0] = '\0';
			tp->flag &= ~DEFINED; /* ensure it won't be found */
			tp->flag |= FDELETE;
		} else
			break;
	}

	if (tp->flag & ALLOC) {
		tp->flag &= ~(ISSET|ALLOC);
		tfree(tp->val.t, tp->areap);
	}

	if (t == NULL) {		/* undefine */
		ktdelete(tp);
		return was_set ? 0 : 1;
	}

	tp->val.t = tcopy(t->left, tp->areap);
	tp->flag |= (ISSET|ALLOC);
	if (t->u.ksh_func)
		tp->flag |= FKSH;

	return 0;
}

/*
 * add builtin
 */
void
builtin(const char *name, int (*func) (char **))
{
	struct tbl *tp;
	int flag;

	/* see if any flags should be set for this builtin */
	for (flag = 0; ; name++) {
		if (*name == '=')	/* command does variable assignment */
			flag |= KEEPASN;
		else if (*name == '*')	/* POSIX special builtin */
			flag |= SPEC_BI;
		else if (*name == '+')	/* POSIX regular builtin */
			flag |= REG_BI;
		else
			break;
	}

	tp = ktenter(&builtins, name, hash(name));
	tp->flag = DEFINED | flag;
	tp->type = CSHELL;
	tp->val.f = func;
}

/*
 * find command
 * either function, hashed command, or built-in (in that order)
 */
struct tbl *
findcom(const char *name, int flags)
{
	static struct tbl temp;
	unsigned int h = hash(name);
	struct tbl *tp = NULL, *tbi;
	int insert = Flag(FTRACKALL);	/* insert if not found */
	char *fpath;			/* for function autoloading */
	char *npath;

	if (strchr(name, '/') != NULL) {
		insert = 0;
		/* prevent FPATH search below */
		flags &= ~FC_FUNC;
		goto Search;
	}
	tbi = (flags & FC_BI) ? ktsearch(&builtins, name, h) : NULL;
	/* POSIX says special builtins first, then functions, then
	 * POSIX regular builtins, then search path...
	 */
	if ((flags & FC_SPECBI) && tbi && (tbi->flag & SPEC_BI))
		tp = tbi;
	if (!tp && (flags & FC_FUNC)) {
		tp = findfunc(name, h, false);
		if (tp && !(tp->flag & ISSET)) {
			if ((fpath = str_val(global("FPATH"))) == null) {
				tp->u.fpath = NULL;
				tp->u2.errno_ = 0;
			} else
				tp->u.fpath = search(name, fpath, R_OK,
				    &tp->u2.errno_);
		}
	}
	if (!tp && (flags & FC_REGBI) && tbi && (tbi->flag & REG_BI))
		tp = tbi;
	/* todo: posix says non-special/non-regular builtins must
	 * be triggered by some user-controllable means like a
	 * special directory in PATH.  Requires modifications to
	 * the search() function.  Tracked aliases should be
	 * modified to allow tracking of builtin commands.
	 * This should be under control of the FPOSIX flag.
	 * If this is changed, also change c_whence...
	 */
	if (!tp && (flags & FC_UNREGBI) && tbi)
		tp = tbi;
	if (!tp && (flags & FC_PATH) && !(flags & FC_DEFPATH)) {
		tp = ktsearch(&taliases, name, h);
		if (tp && (tp->flag & ISSET) && access(tp->val.s, X_OK) != 0) {
			if (tp->flag & ALLOC) {
				tp->flag &= ~ALLOC;
				afree(tp->val.s, APERM);
			}
			tp->flag &= ~ISSET;
		}
	}

  Search:
	if ((!tp || (tp->type == CTALIAS && !(tp->flag&ISSET))) &&
	    (flags & FC_PATH)) {
		if (!tp) {
			if (insert && !(flags & FC_DEFPATH)) {
				tp = ktenter(&taliases, name, h);
				tp->type = CTALIAS;
			} else {
				tp = &temp;
				tp->type = CEXEC;
			}
			tp->flag = DEFINED;	/* make ~ISSET */
		}
		npath = search(name, flags & FC_DEFPATH ? def_path :
		    search_path, X_OK, &tp->u2.errno_);
		if (npath) {
			if (tp == &temp) {
				tp->val.s = npath;
			} else {
				tp->val.s = str_save(npath, APERM);
				if (npath != name)
					afree(npath, ATEMP);
			}
			tp->flag |= ISSET|ALLOC;
		} else if ((flags & FC_FUNC) &&
		    (fpath = str_val(global("FPATH"))) != null &&
		    (npath = search(name, fpath, R_OK,
		    &tp->u2.errno_)) != NULL) {
			/* An undocumented feature of at&t ksh is that it
			 * searches FPATH if a command is not found, even
			 * if the command hasn't been set up as an autoloaded
			 * function (ie, no typeset -uf).
			 */
			tp = &temp;
			tp->type = CFUNC;
			tp->flag = DEFINED; /* make ~ISSET */
			tp->u.fpath = npath;
		}
	}
	return tp;
}

/*
 * flush executable commands with relative paths
 */
void
flushcom(int all)	/* just relative or all */
{
	struct tbl *tp;
	struct tstate ts;

	for (ktwalk(&ts, &taliases); (tp = ktnext(&ts)) != NULL; )
		if ((tp->flag&ISSET) && (all || tp->val.s[0] != '/')) {
			if (tp->flag&ALLOC) {
				tp->flag &= ~(ALLOC|ISSET);
				afree(tp->val.s, APERM);
			}
			tp->flag &= ~ISSET;
		}
}

/* Check if path is something we want to find.  Returns -1 for failure. */
int
search_access(const char *path, int mode,
    int *errnop)	/* set if candidate found, but not suitable */
{
	int ret, err = 0;
	struct stat statb;

	if (stat(path, &statb) == -1)
		return -1;
	ret = access(path, mode);
	if (ret == -1)
		err = errno; /* File exists, but we can't access it */
	else if (mode == X_OK && (!S_ISREG(statb.st_mode) ||
	    !(statb.st_mode & (S_IXUSR|S_IXGRP|S_IXOTH)))) {
	    /* This 'cause access() says root can execute everything */
		ret = -1;
		err = S_ISDIR(statb.st_mode) ? EISDIR : EACCES;
	}
	if (err && errnop && !*errnop)
		*errnop = err;
	return ret;
}

/*
 * search for command with PATH
 */
char *
search(const char *name, const char *path,
    int mode,		/* R_OK or X_OK */
    int *errnop)	/* set if candidate found, but not suitable */
{
	const char *sp, *p;
	char *xp;
	XString xs;
	int namelen;

	if (errnop)
		*errnop = 0;
	if (strchr(name, '/')) {
		if (search_access(name, mode, errnop) == 0)
			return (char *) name;
		return NULL;
	}

	namelen = strlen(name) + 1;
	Xinit(xs, xp, 128, ATEMP);

	sp = path;
	while (sp != NULL) {
		xp = Xstring(xs, xp);
		if (!(p = strchr(sp, ':')))
			p = sp + strlen(sp);
		if (p != sp) {
			XcheckN(xs, xp, p - sp);
			memcpy(xp, sp, p - sp);
			xp += p - sp;
			*xp++ = '/';
		}
		sp = p;
		XcheckN(xs, xp, namelen);
		memcpy(xp, name, namelen);
		if (search_access(Xstring(xs, xp), mode, errnop) == 0)
			return Xclose(xs, xp + namelen);
		if (*sp++ == '\0')
			sp = NULL;
	}
	Xfree(xs, xp);
	return NULL;
}

static int
call_builtin(struct tbl *tp, char **wp)
{
	int rv;

	builtin_argv0 = wp[0];
	builtin_flag = tp->flag;
	shf_reopen(1, SHF_WR, shl_stdout);
	shl_stdout_ok = 1;
	ksh_getopt_reset(&builtin_opt, GF_ERROR);
	rv = (*tp->val.f)(wp);
	shf_flush(shl_stdout);
	shl_stdout_ok = 0;
	builtin_flag = 0;
	builtin_argv0 = NULL;
	return rv;
}

/*
 * set up redirection, saving old fd's in e->savefd
 */
static int
iosetup(struct ioword *iop, struct tbl *tp)
{
	int u = -1;
	char *cp = iop->name;
	int iotype = iop->flag & IOTYPE;
	int do_open = 1, do_close = 0, flags = 0;
	struct ioword iotmp;
	struct stat statb;

	if (iotype != IOHERE)
		cp = evalonestr(cp, DOTILDE|(Flag(FTALKING_I) ? DOGLOB : 0));

	/* Used for tracing and error messages to print expanded cp */
	iotmp = *iop;
	iotmp.name = (iotype == IOHERE) ? NULL : cp;
	iotmp.flag |= IONAMEXP;

	if (Flag(FXTRACE))
		shellf("%s%s\n",
		    PS4_SUBSTITUTE(str_val(global("PS4"))),
		    snptreef(NULL, 32, "%R", &iotmp));

	switch (iotype) {
	case IOREAD:
		flags = O_RDONLY;
		break;

	case IOCAT:
		flags = O_WRONLY | O_APPEND | O_CREAT;
		break;

	case IOWRITE:
		flags = O_WRONLY | O_CREAT | O_TRUNC;
		/* The stat() is here to allow redirections to
		 * things like /dev/null without error.
		 */
		if (Flag(FNOCLOBBER) && !(iop->flag & IOCLOB) &&
		    (stat(cp, &statb) == -1 || S_ISREG(statb.st_mode)))
			flags |= O_EXCL;
		break;

	case IORDWR:
		flags = O_RDWR | O_CREAT;
		break;

	case IOHERE:
		do_open = 0;
		/* herein() returns -2 if error has been printed */
		u = herein(iop->heredoc, iop->flag & IOEVAL);
		/* cp may have wrong name */
		break;

	case IODUP:
	    {
		const char *emsg;

		do_open = 0;
		if (*cp == '-' && !cp[1]) {
			u = 1009;	 /* prevent error return below */
			do_close = 1;
		} else if ((u = check_fd(cp,
		    X_OK | ((iop->flag & IORDUP) ? R_OK : W_OK),
		    &emsg)) < 0) {
			warningf(true, "%s: %s",
			    snptreef(NULL, 32, "%R", &iotmp), emsg);
			return -1;
		}
		if (u == iop->unit)
			return 0;		/* "dup from" == "dup to" */
		break;
	    }
	}

	if (do_open) {
		if (Flag(FRESTRICTED) && (flags & O_CREAT)) {
			warningf(true, "%s: restricted", cp);
			return -1;
		}
		u = open(cp, flags, 0666);
	}
	if (u < 0) {
		/* herein() may already have printed message */
		if (u == -1)
			warningf(true, "cannot %s %s: %s",
			    iotype == IODUP ? "dup" :
			    (iotype == IOREAD || iotype == IOHERE) ?
			    "open" : "create", cp, strerror(errno));
		return -1;
	}
	/* Do not save if it has already been redirected (i.e. "cat >x >y"). */
	if (genv->savefd[iop->unit] == 0) {
		/* If these are the same, it means unit was previously closed */
		if (u == iop->unit)
			genv->savefd[iop->unit] = -1;
		else
			/* c_exec() assumes e->savefd[fd] set for any
			 * redirections.  Ask savefd() not to close iop->unit;
			 * this allows error messages to be seen if iop->unit
			 * is 2; also means we can't lose the fd (eg, both
			 * dup2 below and dup2 in restfd() failing).
			 */
			genv->savefd[iop->unit] = savefd(iop->unit);
	}

	if (do_close)
		close(iop->unit);
	else if (u != iop->unit) {
		if (ksh_dup2(u, iop->unit, true) < 0) {
			warningf(true,
			    "could not finish (dup) redirection %s: %s",
			    snptreef(NULL, 32, "%R", &iotmp),
			    strerror(errno));
			if (iotype != IODUP)
				close(u);
			return -1;
		}
		if (iotype != IODUP)
			close(u);
		/* Touching any co-process fd in an empty exec
		 * causes the shell to close its copies
		 */
		else if (tp && tp->type == CSHELL && tp->val.f == c_exec) {
			if (iop->flag & IORDUP)	/* possible exec <&p */
				coproc_read_close(u);
			else			/* possible exec >&p */
				coproc_write_close(u);
		}
	}
	if (u == 2) /* Clear any write errors */
		shf_reopen(2, SHF_WR, shl_out);
	return 0;
}

/*
 * open here document temp file.
 * if unquoted here, expand here temp file into second temp file.
 */
static int
herein(const char *content, int sub)
{
	volatile int fd = -1;
	struct source *s, *volatile osource;
	struct shf *volatile shf;
	struct temp *h;
	int i;

	/* ksh -c 'cat << EOF' can cause this... */
	if (content == NULL) {
		warningf(true, "here document missing");
		return -2; /* special to iosetup(): don't print error */
	}

	/* Create temp file to hold content (done before newenv so temp
	 * doesn't get removed too soon).
	 */
	h = maketemp(ATEMP, TT_HEREDOC_EXP, &genv->temps);
	if (!(shf = h->shf) || (fd = open(h->name, O_RDONLY)) == -1) {
		warningf(true, "can't %s temporary file %s: %s",
		    !shf ? "create" : "open",
		    h->name, strerror(errno));
		if (shf)
			shf_close(shf);
		return -2 /* special to iosetup(): don't print error */;
	}

	osource = source;
	newenv(E_ERRH);
	i = sigsetjmp(genv->jbuf, 0);
	if (i) {
		source = osource;
		quitenv(shf);
		close(fd);
		return -2; /* special to iosetup(): don't print error */
	}
	if (sub) {
		/* Do substitutions on the content of heredoc */
		s = pushs(SSTRING, ATEMP);
		s->start = s->str = content;
		source = s;
		if (yylex(ONEWORD|HEREDOC) != LWORD)
			internal_errorf("%s: yylex", __func__);
		source = osource;
		shf_puts(evalstr(yylval.cp, 0), shf);
	} else
		shf_puts(content, shf);

	quitenv(NULL);

	if (shf_close(shf) == EOF) {
		close(fd);
		warningf(true, "error writing %s: %s", h->name,
		    strerror(errno));
		return -2; /* special to iosetup(): don't print error */
	}

	return fd;
}

/*
 *	ksh special - the select command processing section
 *	print the args in column form - assuming that we can
 */
static char *
do_selectargs(char **ap, bool print_menu)
{
	static const char *const read_args[] = {
		"read", "-r", "REPLY", NULL
	};
	const char *errstr;
	char *s;
	int i, argct;

	for (argct = 0; ap[argct]; argct++)
		;
	while (1) {
		/* Menu is printed if
		 *	- this is the first time around the select loop
		 *	- the user enters a blank line
		 *	- the REPLY parameter is empty
		 */
		if (print_menu || !*str_val(global("REPLY")))
			pr_menu(ap);
		shellf("%s", str_val(global("PS3")));
		if (call_builtin(findcom("read", FC_BI), (char **) read_args))
			return NULL;
		s = str_val(global("REPLY"));
		if (*s) {
			i = strtonum(s, 1, argct, &errstr);
			if (errstr)
				return null;
			return ap[i - 1];
		}
		print_menu = 1;
	}
}

struct select_menu_info {
	char	*const *args;
	int	arg_width;
	int	num_width;
};

static char *select_fmt_entry(void *arg, int i, char *buf, int buflen);

/* format a single select menu item */
static char *
select_fmt_entry(void *arg, int i, char *buf, int buflen)
{
	struct select_menu_info *smi = (struct select_menu_info *) arg;

	shf_snprintf(buf, buflen, "%*d) %s",
	    smi->num_width, i + 1, smi->args[i]);
	return buf;
}

/*
 *	print a select style menu
 */
int
pr_menu(char *const *ap)
{
	struct select_menu_info smi;
	char *const *pp;
	int nwidth, dwidth;
	int i, n;

	/* Width/column calculations were done once and saved, but this
	 * means select can't be used recursively so we re-calculate each
	 * time (could save in a structure that is returned, but its probably
	 * not worth the bother).
	 */

	/*
	 * get dimensions of the list
	 */
	for (n = 0, nwidth = 0, pp = ap; *pp; n++, pp++) {
		i = strlen(*pp);
		nwidth = (i > nwidth) ? i : nwidth;
	}
	/*
	 * we will print an index of the form
	 *	%d)
	 * in front of each entry
	 * get the max width of this
	 */
	for (i = n, dwidth = 1; i >= 10; i /= 10)
		dwidth++;

	smi.args = ap;
	smi.arg_width = nwidth;
	smi.num_width = dwidth;
	print_columns(shl_out, n, select_fmt_entry, (void *) &smi,
	    dwidth + nwidth + 2, 1);

	return n;
}

/*
 *	[[ ... ]] evaluation routines
 */

extern const char *const dbtest_tokens[];
extern const char db_close[];

/* Test if the current token is a whatever.  Accepts the current token if
 * it is.  Returns 0 if it is not, non-zero if it is (in the case of
 * TM_UNOP and TM_BINOP, the returned value is a Test_op).
 */
static int
dbteste_isa(Test_env *te, Test_meta meta)
{
	int ret = 0;
	int uqword;
	char *p;

	if (!*te->pos.wp)
		return meta == TM_END;

	/* unquoted word? */
	for (p = *te->pos.wp; *p == CHAR; p += 2)
		;
	uqword = *p == EOS;

	if (meta == TM_UNOP || meta == TM_BINOP) {
		if (uqword) {
			char buf[8];	/* longer than the longest operator */
			char *q = buf;
			for (p = *te->pos.wp;
			    *p == CHAR && q < &buf[sizeof(buf) - 1]; p += 2)
				*q++ = p[1];
			*q = '\0';
			ret = (int) test_isop(te, meta, buf);
		}
	} else if (meta == TM_END)
		ret = 0;
	else
		ret = uqword &&
		    strcmp(*te->pos.wp, dbtest_tokens[(int) meta]) == 0;

	/* Accept the token? */
	if (ret)
		te->pos.wp++;

	return ret;
}

static const char *
dbteste_getopnd(Test_env *te, Test_op op, int do_eval)
{
	char *s = *te->pos.wp;

	if (!s)
		return NULL;

	te->pos.wp++;

	if (!do_eval)
		return null;

	if (op == TO_STEQL || op == TO_STNEQ)
		s = evalstr(s, DOTILDE | DOPAT);
	else
		s = evalstr(s, DOTILDE);

	return s;
}

static int
dbteste_eval(Test_env *te, Test_op op, const char *opnd1, const char *opnd2,
    int do_eval)
{
	return test_eval(te, op, opnd1, opnd2, do_eval);
}

static void
dbteste_error(Test_env *te, int offset, const char *msg)
{
	te->flags |= TEF_ERROR;
	internal_warningf("%s: %s (offset %d)", __func__, msg, offset);
}