test.c - busybox - Git at Google

 /* vi: set sw=4 ts=4: */
 /*
  * test implementation for busybox
  *
  * Copyright (c) by a whole pile of folks:
  *
  * 	test(1); version 7-like  --  author Erik Baalbergen
  * 	modified by Eric Gisin to be used as built-in.
  * 	modified by Arnold Robbins to add SVR3 compatibility
  * 	(-x -c -b -p -u -g -k) plus Korn's -L -nt -ot -ef and new -S (socket).
  * 	modified by J.T. Conklin for NetBSD.
  * 	modified by Herbert Xu to be used as built-in in ash.
  * 	modified by Erik Andersen <andersee@debian.org> to be used
  * 	in busybox.
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 2 of the License, or
  * (at your option) any later version.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  * General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  *
  * Original copyright notice states:
  * 	"This program is in the Public Domain."
  */

 #include "internal.h"
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <unistd.h>
 #include <ctype.h>
 #include <errno.h>
 #include <stdlib.h>
 #include <string.h>
 #define BB_DECLARE_EXTERN
 #define bb_need_help
 #include "messages.c"

 /* test(1) accepts the following grammar:
 	oexpr	::= aexpr | aexpr "-o" oexpr ;
 	aexpr	::= nexpr | nexpr "-a" aexpr ;
 	nexpr	::= primary | "!" primary
 	primary	::= unary-operator operand
 		| operand binary-operator operand
 		| operand
 		| "(" oexpr ")"
 		;
 	unary-operator ::= "-r"|"-w"|"-x"|"-f"|"-d"|"-c"|"-b"|"-p"|
 		"-u"|"-g"|"-k"|"-s"|"-t"|"-z"|"-n"|"-o"|"-O"|"-G"|"-L"|"-S";

 	binary-operator ::= "="|"!="|"-eq"|"-ne"|"-ge"|"-gt"|"-le"|"-lt"|
 			"-nt"|"-ot"|"-ef";
 	operand ::= <any legal UNIX file name>
 */

 enum token {
 	EOI,
 	FILRD,
 	FILWR,
 	FILEX,
 	FILEXIST,
 	FILREG,
 	FILDIR,
 	FILCDEV,
 	FILBDEV,
 	FILFIFO,
 	FILSOCK,
 	FILSYM,
 	FILGZ,
 	FILTT,
 	FILSUID,
 	FILSGID,
 	FILSTCK,
 	FILNT,
 	FILOT,
 	FILEQ,
 	FILUID,
 	FILGID,
 	STREZ,
 	STRNZ,
 	STREQ,
 	STRNE,
 	STRLT,
 	STRGT,
 	INTEQ,
 	INTNE,
 	INTGE,
 	INTGT,
 	INTLE,
 	INTLT,
 	UNOT,
 	BAND,
 	BOR,
 	LPAREN,
 	RPAREN,
 	OPERAND
 };

 enum token_types {
 	UNOP,
 	BINOP,
 	BUNOP,
 	BBINOP,
 	PAREN
 };

 struct t_op {
 	const char *op_text;
 	short op_num, op_type;
 } const ops [] = {
 	{"-r",	FILRD,	UNOP},
 	{"-w",	FILWR,	UNOP},
 	{"-x",	FILEX,	UNOP},
 	{"-e",	FILEXIST,UNOP},
 	{"-f",	FILREG,	UNOP},
 	{"-d",	FILDIR,	UNOP},
 	{"-c",	FILCDEV,UNOP},
 	{"-b",	FILBDEV,UNOP},
 	{"-p",	FILFIFO,UNOP},
 	{"-u",	FILSUID,UNOP},
 	{"-g",	FILSGID,UNOP},
 	{"-k",	FILSTCK,UNOP},
 	{"-s",	FILGZ,	UNOP},
 	{"-t",	FILTT,	UNOP},
 	{"-z",	STREZ,	UNOP},
 	{"-n",	STRNZ,	UNOP},
 	{"-h",	FILSYM,	UNOP},		/* for backwards compat */
 	{"-O",	FILUID,	UNOP},
 	{"-G",	FILGID,	UNOP},
 	{"-L",	FILSYM,	UNOP},
 	{"-S",	FILSOCK,UNOP},
 	{"=",	STREQ,	BINOP},
 	{"!=",	STRNE,	BINOP},
 	{"<",	STRLT,	BINOP},
 	{">",	STRGT,	BINOP},
 	{"-eq",	INTEQ,	BINOP},
 	{"-ne",	INTNE,	BINOP},
 	{"-ge",	INTGE,	BINOP},
 	{"-gt",	INTGT,	BINOP},
 	{"-le",	INTLE,	BINOP},
 	{"-lt",	INTLT,	BINOP},
 	{"-nt",	FILNT,	BINOP},
 	{"-ot",	FILOT,	BINOP},
 	{"-ef",	FILEQ,	BINOP},
 	{"!",	UNOT,	BUNOP},
 	{"-a",	BAND,	BBINOP},
 	{"-o",	BOR,	BBINOP},
 	{"(",	LPAREN,	PAREN},
 	{")",	RPAREN,	PAREN},
 	{0,	0,	0}
 };

 char **t_wp;
 struct t_op const *t_wp_op;
 static gid_t *group_array = NULL;
 static int ngroups;

 static enum token t_lex();
 static int oexpr();
 static int aexpr();
 static int nexpr();
 static int binop();
 static int primary();
 static int filstat();
 static int getn();
 static int newerf();
 static int olderf();
 static int equalf();
 static void syntax();
 static int test_eaccess();
 static int is_a_group_member();
 static void initialize_group_array();

 extern int
 test_main(int argc, char** argv)
 {
 	int	res;

 	if (strcmp(argv[0], "[") == 0) {
 		if (strcmp(argv[--argc], "]"))
 			fatalError("missing ]\n");
 		argv[argc] = NULL;
 	}
 	if (strcmp(argv[1], dash_dash_help) == 0) {
 		usage("test EXPRESSION\n"
 			  "or   [ EXPRESSION ]\n"
 #ifndef BB_FEATURE_TRIVIAL_HELP
 				"\nChecks file types and compares values returning an exit\n"
 				"code determined by the value of EXPRESSION.\n"
 #endif
 				);
 	}

 	/* Implement special cases from POSIX.2, section 4.62.4 */
 	switch (argc) {
 	case 1:
 		exit( 1);
 	case 2:
 		exit (*argv[1] == '\0');
 	case 3:
 		if (argv[1][0] == '!' && argv[1][1] == '\0') {
 			exit (!(*argv[2] == '\0'));
 		}
 		break;
 	case 4:
 		if (argv[1][0] != '!' || argv[1][1] != '\0') {
 			if (t_lex(argv[2]),
 			    t_wp_op && t_wp_op->op_type == BINOP) {
 				t_wp = &argv[1];
 				exit (binop() == 0);
 			}
 		}
 		break;
 	case 5:
 		if (argv[1][0] == '!' && argv[1][1] == '\0') {
 			if (t_lex(argv[3]),
 			    t_wp_op && t_wp_op->op_type == BINOP) {
 				t_wp = &argv[2];
 				exit (!(binop() == 0));
 			}
 		}
 		break;
 	}

 	t_wp = &argv[1];
 	res = !oexpr(t_lex(*t_wp));

 	if (*t_wp != NULL && *++t_wp != NULL)
 		syntax(*t_wp, "unknown operand");

 	return( res);
 }

 static void
 syntax(op, msg)
 	char	*op;
 	char	*msg;
 {
 	if (op && *op)
 		fatalError("%s: %s\n", op, msg);
 	else
 		fatalError("%s\n", msg);
 }

 static int
 oexpr(n)
 	enum token n;
 {
 	int res;

 	res = aexpr(n);
 	if (t_lex(*++t_wp) == BOR)
 		return oexpr(t_lex(*++t_wp)) || res;
 	t_wp--;
 	return res;
 }

 static int
 aexpr(n)
 	enum token n;
 {
 	int res;

 	res = nexpr(n);
 	if (t_lex(*++t_wp) == BAND)
 		return aexpr(t_lex(*++t_wp)) && res;
 	t_wp--;
 	return res;
 }

 static int
 nexpr(n)
 	enum token n;			/* token */
 {
 	if (n == UNOT)
 		return !nexpr(t_lex(*++t_wp));
 	return primary(n);
 }

 static int
 primary(n)
 	enum token n;
 {
 	int res;

 	if (n == EOI)
 		syntax(NULL, "argument expected");
 	if (n == LPAREN) {
 		res = oexpr(t_lex(*++t_wp));
 		if (t_lex(*++t_wp) != RPAREN)
 			syntax(NULL, "closing paren expected");
 		return res;
 	}
 	if (t_wp_op && t_wp_op->op_type == UNOP) {
 		/* unary expression */
 		if (*++t_wp == NULL)
 			syntax(t_wp_op->op_text, "argument expected");
 		switch (n) {
 		case STREZ:
 			return strlen(*t_wp) == 0;
 		case STRNZ:
 			return strlen(*t_wp) != 0;
 		case FILTT:
 			return isatty(getn(*t_wp));
 		default:
 			return filstat(*t_wp, n);
 		}
 	}

 	if (t_lex(t_wp[1]), t_wp_op && t_wp_op->op_type == BINOP) {
 		return binop();
 	}

 	return strlen(*t_wp) > 0;
 }

 static int
 binop()
 {
 	const char *opnd1, *opnd2;
 	struct t_op const *op;

 	opnd1 = *t_wp;
 	(void) t_lex(*++t_wp);
 	op = t_wp_op;

 	if ((opnd2 = *++t_wp) == (char *)0)
 		syntax(op->op_text, "argument expected");

 	switch (op->op_num) {
 	case STREQ:
 		return strcmp(opnd1, opnd2) == 0;
 	case STRNE:
 		return strcmp(opnd1, opnd2) != 0;
 	case STRLT:
 		return strcmp(opnd1, opnd2) < 0;
 	case STRGT:
 		return strcmp(opnd1, opnd2) > 0;
 	case INTEQ:
 		return getn(opnd1) == getn(opnd2);
 	case INTNE:
 		return getn(opnd1) != getn(opnd2);
 	case INTGE:
 		return getn(opnd1) >= getn(opnd2);
 	case INTGT:
 		return getn(opnd1) > getn(opnd2);
 	case INTLE:
 		return getn(opnd1) <= getn(opnd2);
 	case INTLT:
 		return getn(opnd1) < getn(opnd2);
 	case FILNT:
 		return newerf (opnd1, opnd2);
 	case FILOT:
 		return olderf (opnd1, opnd2);
 	case FILEQ:
 		return equalf (opnd1, opnd2);
 	}
 	/* NOTREACHED */
 	return 1;
 }

 static int
 filstat(nm, mode)
 	char *nm;
 	enum token mode;
 {
 	struct stat s;
 	int i;

 	if (mode == FILSYM) {
 #ifdef S_IFLNK
 		if (lstat(nm, &s) == 0) {
 			i = S_IFLNK;
 			goto filetype;
 		}
 #endif
 		return 0;
 	}

 	if (stat(nm, &s) != 0)
 		return 0;

 	switch (mode) {
 	case FILRD:
 		return test_eaccess(nm, R_OK) == 0;
 	case FILWR:
 		return test_eaccess(nm, W_OK) == 0;
 	case FILEX:
 		return test_eaccess(nm, X_OK) == 0;
 	case FILEXIST:
 		return 1;
 	case FILREG:
 		i = S_IFREG;
 		goto filetype;
 	case FILDIR:
 		i = S_IFDIR;
 		goto filetype;
 	case FILCDEV:
 		i = S_IFCHR;
 		goto filetype;
 	case FILBDEV:
 		i = S_IFBLK;
 		goto filetype;
 	case FILFIFO:
 #ifdef S_IFIFO
 		i = S_IFIFO;
 		goto filetype;
 #else
 		return 0;
 #endif
 	case FILSOCK:
 #ifdef S_IFSOCK
 		i = S_IFSOCK;
 		goto filetype;
 #else
 		return 0;
 #endif
 	case FILSUID:
 		i = S_ISUID;
 		goto filebit;
 	case FILSGID:
 		i = S_ISGID;
 		goto filebit;
 	case FILSTCK:
 		i = S_ISVTX;
 		goto filebit;
 	case FILGZ:
 		return s.st_size > 0L;
 	case FILUID:
 		return s.st_uid == geteuid();
 	case FILGID:
 		return s.st_gid == getegid();
 	default:
 		return 1;
 	}

 filetype:
 	return ((s.st_mode & S_IFMT) == i);

 filebit:
 	return ((s.st_mode & i) != 0);
 }

 static enum token
 t_lex(s)
 	char *s;
 {
 	struct t_op const *op = ops;

 	if (s == 0) {
 		t_wp_op = (struct t_op *)0;
 		return EOI;
 	}
 	while (op->op_text) {
 		if (strcmp(s, op->op_text) == 0) {
 			t_wp_op = op;
 			return op->op_num;
 		}
 		op++;
 	}
 	t_wp_op = (struct t_op *)0;
 	return OPERAND;
 }

 /* atoi with error detection */
 static int
 getn(s)
 	char *s;
 {
 	char *p;
 	long r;

 	errno = 0;
 	r = strtol(s, &p, 10);

 	if (errno != 0)
 	  fatalError("%s: out of range\n", s);

 	while (isspace(*p))
 	  p++;

 	if (*p)
 	  fatalError("%s: bad number\n", s);

 	return (int) r;
 }

 static int
 newerf (f1, f2)
 char *f1, *f2;
 {
 	struct stat b1, b2;

 	return (stat (f1, &b1) == 0 &&
 		stat (f2, &b2) == 0 &&
 		b1.st_mtime > b2.st_mtime);
 }

 static int
 olderf (f1, f2)
 char *f1, *f2;
 {
 	struct stat b1, b2;

 	return (stat (f1, &b1) == 0 &&
 		stat (f2, &b2) == 0 &&
 		b1.st_mtime < b2.st_mtime);
 }

 static int
 equalf (f1, f2)
 char *f1, *f2;
 {
 	struct stat b1, b2;

 	return (stat (f1, &b1) == 0 &&
 		stat (f2, &b2) == 0 &&
 		b1.st_dev == b2.st_dev &&
 		b1.st_ino == b2.st_ino);
 }

 /* Do the same thing access(2) does, but use the effective uid and gid,
    and don't make the mistake of telling root that any file is
    executable. */
 static int
 test_eaccess (path, mode)
 char *path;
 int mode;
 {
 	struct stat st;
 	int euid = geteuid();

 	if (stat (path, &st) < 0)
 		return (-1);

 	if (euid == 0) {
 		/* Root can read or write any file. */
 		if (mode != X_OK)
 		return (0);

 		/* Root can execute any file that has any one of the execute
 		   bits set. */
 		if (st.st_mode & (S_IXUSR | S_IXGRP | S_IXOTH))
 			return (0);
 	}

 	if (st.st_uid == euid)		/* owner */
 		mode <<= 6;
 	else if (is_a_group_member (st.st_gid))
 		mode <<= 3;

 	if (st.st_mode & mode)
 		return (0);

 	return (-1);
 }

 static void
 initialize_group_array ()
 {
 	ngroups = getgroups(0, NULL);
 	if ((group_array = realloc(group_array, ngroups * sizeof(gid_t))) == NULL)
 		fatalError("Out of space\n");

 	getgroups(ngroups, group_array);
 }

 /* Return non-zero if GID is one that we have in our groups list. */
 static int
 is_a_group_member (gid)
 gid_t gid;
 {
 	register int i;

 	/* Short-circuit if possible, maybe saving a call to getgroups(). */
 	if (gid == getgid() || gid == getegid())
 		return (1);

 	if (ngroups == 0)
 		initialize_group_array ();

 	/* Search through the list looking for GID. */
 	for (i = 0; i < ngroups; i++)
 		if (gid == group_array[i])
 			return (1);

 	return (0);
 }
	/* vi: set sw=4 ts=4: */
	/*
	* test implementation for busybox
	*
	* Copyright (c) by a whole pile of folks:
	*
	* test(1); version 7-like -- author Erik Baalbergen
	* modified by Eric Gisin to be used as built-in.
	* modified by Arnold Robbins to add SVR3 compatibility
	* (-x -c -b -p -u -g -k) plus Korn's -L -nt -ot -ef and new -S (socket).
	* modified by J.T. Conklin for NetBSD.
	* modified by Herbert Xu to be used as built-in in ash.
	* modified by Erik Andersen <andersee@debian.org> to be used
	* in busybox.
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation; either version 2 of the License, or
	* (at your option) any later version.
	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	* General Public License for more details.
	*
	* You should have received a copy of the GNU General Public License
	* along with this program; if not, write to the Free Software
	* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
	*
	* Original copyright notice states:
	* "This program is in the Public Domain."
	*/

	#include "internal.h"
	#include <sys/types.h>
	#include <sys/stat.h>
	#include <unistd.h>
	#include <ctype.h>
	#include <errno.h>
	#include <stdlib.h>
	#include <string.h>
	#define BB_DECLARE_EXTERN
	#define bb_need_help
	#include "messages.c"

	/* test(1) accepts the following grammar:
	oexpr ::= aexpr \| aexpr "-o" oexpr ;
	aexpr ::= nexpr \| nexpr "-a" aexpr ;
	nexpr ::= primary \| "!" primary
	primary ::= unary-operator operand
	\| operand binary-operator operand
	\| operand
	\| "(" oexpr ")"
	;
	unary-operator ::= "-r"\|"-w"\|"-x"\|"-f"\|"-d"\|"-c"\|"-b"\|"-p"\|
	"-u"\|"-g"\|"-k"\|"-s"\|"-t"\|"-z"\|"-n"\|"-o"\|"-O"\|"-G"\|"-L"\|"-S";

	binary-operator ::= "="\|"!="\|"-eq"\|"-ne"\|"-ge"\|"-gt"\|"-le"\|"-lt"\|
	"-nt"\|"-ot"\|"-ef";
	operand ::= <any legal UNIX file name>
	*/

	enum token {
	EOI,
	FILRD,
	FILWR,
	FILEX,
	FILEXIST,
	FILREG,
	FILDIR,
	FILCDEV,
	FILBDEV,
	FILFIFO,
	FILSOCK,
	FILSYM,
	FILGZ,
	FILTT,
	FILSUID,
	FILSGID,
	FILSTCK,
	FILNT,
	FILOT,
	FILEQ,
	FILUID,
	FILGID,
	STREZ,
	STRNZ,
	STREQ,
	STRNE,
	STRLT,
	STRGT,
	INTEQ,
	INTNE,
	INTGE,
	INTGT,
	INTLE,
	INTLT,
	UNOT,
	BAND,
	BOR,
	LPAREN,
	RPAREN,
	OPERAND
	};

	enum token_types {
	UNOP,
	BINOP,
	BUNOP,
	BBINOP,
	PAREN
	};

	struct t_op {
	const char *op_text;
	short op_num, op_type;
	} const ops [] = {
	{"-r", FILRD, UNOP},
	{"-w", FILWR, UNOP},
	{"-x", FILEX, UNOP},
	{"-e", FILEXIST,UNOP},
	{"-f", FILREG, UNOP},
	{"-d", FILDIR, UNOP},
	{"-c", FILCDEV,UNOP},
	{"-b", FILBDEV,UNOP},
	{"-p", FILFIFO,UNOP},
	{"-u", FILSUID,UNOP},
	{"-g", FILSGID,UNOP},
	{"-k", FILSTCK,UNOP},
	{"-s", FILGZ, UNOP},
	{"-t", FILTT, UNOP},
	{"-z", STREZ, UNOP},
	{"-n", STRNZ, UNOP},
	{"-h", FILSYM, UNOP}, /* for backwards compat */
	{"-O", FILUID, UNOP},
	{"-G", FILGID, UNOP},
	{"-L", FILSYM, UNOP},
	{"-S", FILSOCK,UNOP},
	{"=", STREQ, BINOP},
	{"!=", STRNE, BINOP},
	{"<", STRLT, BINOP},
	{">", STRGT, BINOP},
	{"-eq", INTEQ, BINOP},
	{"-ne", INTNE, BINOP},
	{"-ge", INTGE, BINOP},
	{"-gt", INTGT, BINOP},
	{"-le", INTLE, BINOP},
	{"-lt", INTLT, BINOP},
	{"-nt", FILNT, BINOP},
	{"-ot", FILOT, BINOP},
	{"-ef", FILEQ, BINOP},
	{"!", UNOT, BUNOP},
	{"-a", BAND, BBINOP},
	{"-o", BOR, BBINOP},
	{"(", LPAREN, PAREN},
	{")", RPAREN, PAREN},
	{0, 0, 0}
	};

	char **t_wp;
	struct t_op const *t_wp_op;
	static gid_t *group_array = NULL;
	static int ngroups;

	static enum token t_lex();
	static int oexpr();
	static int aexpr();
	static int nexpr();
	static int binop();
	static int primary();
	static int filstat();
	static int getn();
	static int newerf();
	static int olderf();
	static int equalf();
	static void syntax();
	static int test_eaccess();
	static int is_a_group_member();
	static void initialize_group_array();

	extern int
	test_main(int argc, char** argv)
	{
	int res;

	if (strcmp(argv[0], "[") == 0) {
	if (strcmp(argv[--argc], "]"))
	fatalError("missing ]\n");
	argv[argc] = NULL;
	}
	if (strcmp(argv[1], dash_dash_help) == 0) {
	usage("test EXPRESSION\n"
	"or [ EXPRESSION ]\n"
	#ifndef BB_FEATURE_TRIVIAL_HELP
	"\nChecks file types and compares values returning an exit\n"
	"code determined by the value of EXPRESSION.\n"
	#endif
	);
	}

	/* Implement special cases from POSIX.2, section 4.62.4 */
	switch (argc) {
	case 1:
	exit( 1);
	case 2:
	exit (*argv[1] == '\0');
	case 3:
	if (argv[1][0] == '!' && argv[1][1] == '\0') {
	exit (!(*argv[2] == '\0'));
	}
	break;
	case 4:
	if (argv[1][0] != '!' \|\| argv[1][1] != '\0') {
	if (t_lex(argv[2]),
	t_wp_op && t_wp_op->op_type == BINOP) {
	t_wp = &argv[1];
	exit (binop() == 0);
	}
	}
	break;
	case 5:
	if (argv[1][0] == '!' && argv[1][1] == '\0') {
	if (t_lex(argv[3]),
	t_wp_op && t_wp_op->op_type == BINOP) {
	t_wp = &argv[2];
	exit (!(binop() == 0));
	}
	}
	break;
	}

	t_wp = &argv[1];
	res = !oexpr(t_lex(*t_wp));

	if (t_wp != NULL && ++t_wp != NULL)
	syntax(*t_wp, "unknown operand");

	return( res);
	}

	static void
	syntax(op, msg)
	char *op;
	char *msg;
	{
	if (op && *op)
	fatalError("%s: %s\n", op, msg);
	else
	fatalError("%s\n", msg);
	}

	static int
	oexpr(n)
	enum token n;
	{
	int res;

	res = aexpr(n);
	if (t_lex(*++t_wp) == BOR)
	return oexpr(t_lex(*++t_wp)) \|\| res;
	t_wp--;
	return res;
	}

	static int
	aexpr(n)
	enum token n;
	{
	int res;

	res = nexpr(n);
	if (t_lex(*++t_wp) == BAND)
	return aexpr(t_lex(*++t_wp)) && res;
	t_wp--;
	return res;
	}

	static int
	nexpr(n)
	enum token n; /* token */
	{
	if (n == UNOT)
	return !nexpr(t_lex(*++t_wp));
	return primary(n);
	}

	static int
	primary(n)
	enum token n;
	{
	int res;

	if (n == EOI)
	syntax(NULL, "argument expected");
	if (n == LPAREN) {
	res = oexpr(t_lex(*++t_wp));
	if (t_lex(*++t_wp) != RPAREN)
	syntax(NULL, "closing paren expected");
	return res;
	}
	if (t_wp_op && t_wp_op->op_type == UNOP) {
	/* unary expression */
	if (*++t_wp == NULL)
	syntax(t_wp_op->op_text, "argument expected");
	switch (n) {
	case STREZ:
	return strlen(*t_wp) == 0;
	case STRNZ:
	return strlen(*t_wp) != 0;
	case FILTT:
	return isatty(getn(*t_wp));
	default:
	return filstat(*t_wp, n);
	}
	}

	if (t_lex(t_wp[1]), t_wp_op && t_wp_op->op_type == BINOP) {
	return binop();
	}

	return strlen(*t_wp) > 0;
	}

	static int
	binop()
	{
	const char opnd1, opnd2;
	struct t_op const *op;

	opnd1 = *t_wp;
	(void) t_lex(*++t_wp);
	op = t_wp_op;

	if ((opnd2 = ++t_wp) == (char )0)
	syntax(op->op_text, "argument expected");

	switch (op->op_num) {
	case STREQ:
	return strcmp(opnd1, opnd2) == 0;
	case STRNE:
	return strcmp(opnd1, opnd2) != 0;
	case STRLT:
	return strcmp(opnd1, opnd2) < 0;
	case STRGT:
	return strcmp(opnd1, opnd2) > 0;
	case INTEQ:
	return getn(opnd1) == getn(opnd2);
	case INTNE:
	return getn(opnd1) != getn(opnd2);
	case INTGE:
	return getn(opnd1) >= getn(opnd2);
	case INTGT:
	return getn(opnd1) > getn(opnd2);
	case INTLE:
	return getn(opnd1) <= getn(opnd2);
	case INTLT:
	return getn(opnd1) < getn(opnd2);
	case FILNT:
	return newerf (opnd1, opnd2);
	case FILOT:
	return olderf (opnd1, opnd2);
	case FILEQ:
	return equalf (opnd1, opnd2);
	}
	/* NOTREACHED */
	return 1;
	}

	static int
	filstat(nm, mode)
	char *nm;
	enum token mode;
	{
	struct stat s;
	int i;

	if (mode == FILSYM) {
	#ifdef S_IFLNK
	if (lstat(nm, &s) == 0) {
	i = S_IFLNK;
	goto filetype;
	}
	#endif
	return 0;
	}

	if (stat(nm, &s) != 0)
	return 0;

	switch (mode) {
	case FILRD:
	return test_eaccess(nm, R_OK) == 0;
	case FILWR:
	return test_eaccess(nm, W_OK) == 0;
	case FILEX:
	return test_eaccess(nm, X_OK) == 0;
	case FILEXIST:
	return 1;
	case FILREG:
	i = S_IFREG;
	goto filetype;
	case FILDIR:
	i = S_IFDIR;
	goto filetype;
	case FILCDEV:
	i = S_IFCHR;
	goto filetype;
	case FILBDEV:
	i = S_IFBLK;
	goto filetype;
	case FILFIFO:
	#ifdef S_IFIFO
	i = S_IFIFO;
	goto filetype;
	#else
	return 0;
	#endif
	case FILSOCK:
	#ifdef S_IFSOCK
	i = S_IFSOCK;
	goto filetype;
	#else
	return 0;
	#endif
	case FILSUID:
	i = S_ISUID;
	goto filebit;
	case FILSGID:
	i = S_ISGID;
	goto filebit;
	case FILSTCK:
	i = S_ISVTX;
	goto filebit;
	case FILGZ:
	return s.st_size > 0L;
	case FILUID:
	return s.st_uid == geteuid();
	case FILGID:
	return s.st_gid == getegid();
	default:
	return 1;
	}

	filetype:
	return ((s.st_mode & S_IFMT) == i);

	filebit:
	return ((s.st_mode & i) != 0);
	}

	static enum token
	t_lex(s)
	char *s;
	{
	struct t_op const *op = ops;

	if (s == 0) {
	t_wp_op = (struct t_op *)0;
	return EOI;
	}
	while (op->op_text) {
	if (strcmp(s, op->op_text) == 0) {
	t_wp_op = op;
	return op->op_num;
	}
	op++;
	}
	t_wp_op = (struct t_op *)0;
	return OPERAND;
	}

	/* atoi with error detection */
	static int
	getn(s)
	char *s;
	{
	char *p;
	long r;

	errno = 0;
	r = strtol(s, &p, 10);

	if (errno != 0)
	fatalError("%s: out of range\n", s);

	while (isspace(*p))
	p++;

	if (*p)
	fatalError("%s: bad number\n", s);

	return (int) r;
	}

	static int
	newerf (f1, f2)
	char f1, f2;
	{
	struct stat b1, b2;

	return (stat (f1, &b1) == 0 &&
	stat (f2, &b2) == 0 &&
	b1.st_mtime > b2.st_mtime);
	}

	static int
	olderf (f1, f2)
	char f1, f2;
	{
	struct stat b1, b2;

	return (stat (f1, &b1) == 0 &&
	stat (f2, &b2) == 0 &&
	b1.st_mtime < b2.st_mtime);
	}

	static int
	equalf (f1, f2)
	char f1, f2;
	{
	struct stat b1, b2;

	return (stat (f1, &b1) == 0 &&
	stat (f2, &b2) == 0 &&
	b1.st_dev == b2.st_dev &&
	b1.st_ino == b2.st_ino);
	}

	/* Do the same thing access(2) does, but use the effective uid and gid,
	and don't make the mistake of telling root that any file is
	executable. */
	static int
	test_eaccess (path, mode)
	char *path;
	int mode;
	{
	struct stat st;
	int euid = geteuid();

	if (stat (path, &st) < 0)
	return (-1);

	if (euid == 0) {
	/* Root can read or write any file. */
	if (mode != X_OK)
	return (0);

	/* Root can execute any file that has any one of the execute
	bits set. */
	if (st.st_mode & (S_IXUSR \| S_IXGRP \| S_IXOTH))
	return (0);
	}

	if (st.st_uid == euid) /* owner */
	mode <<= 6;
	else if (is_a_group_member (st.st_gid))
	mode <<= 3;

	if (st.st_mode & mode)
	return (0);

	return (-1);
	}

	static void
	initialize_group_array ()
	{
	ngroups = getgroups(0, NULL);
	if ((group_array = realloc(group_array, ngroups * sizeof(gid_t))) == NULL)
	fatalError("Out of space\n");

	getgroups(ngroups, group_array);
	}

	/* Return non-zero if GID is one that we have in our groups list. */
	static int
	is_a_group_member (gid)
	gid_t gid;
	{
	register int i;

	/* Short-circuit if possible, maybe saving a call to getgroups(). */
	if (gid == getgid() \|\| gid == getegid())
	return (1);

	if (ngroups == 0)
	initialize_group_array ();

	/* Search through the list looking for GID. */
	for (i = 0; i < ngroups; i++)
	if (gid == group_array[i])
	return (1);

	return (0);
	}