/* 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 <andersen@codepoet.org> to be used
 *     in busybox.
 *     modified by Bernhard Reutner-Fischer to be useable (i.e. a bit less bloaty).
 *
 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
 *
 * Original copyright notice states:
 *     "This program is in the Public Domain."
 */
//config:config TEST
//config:       bool "test (4.1 kb)"
//config:       default y
//config:       help
//config:       test is used to check file types and compare values,
//config:       returning an appropriate exit code. The bash shell
//config:       has test built in, ash can build it in optionally.
//config:
//config:config TEST1
//config:       bool "test as ["
//config:       default y
//config:       help
//config:       Provide test command in the "[ EXPR ]" form
//config:
//config:config TEST2
//config:       bool "test as [["
//config:       default y
//config:       help
//config:       Provide test command in the "[[ EXPR ]]" form
//config:
//config:config FEATURE_TEST_64
//config:       bool "Extend test to 64 bit"
//config:       default y
//config:       depends on TEST || TEST1 || TEST2 || ASH_TEST || HUSH_TEST
//config:       help
//config:       Enable 64-bit support in test.

//applet:IF_TEST(APPLET_NOFORK(test, test, BB_DIR_USR_BIN, BB_SUID_DROP, test))
//applet:IF_TEST1(APPLET_NOFORK([,   test, BB_DIR_USR_BIN, BB_SUID_DROP, test))
//applet:IF_TEST2(APPLET_NOFORK([[,  test, BB_DIR_USR_BIN, BB_SUID_DROP, test))

//kbuild:lib-$(CONFIG_TEST)  += test.o test_ptr_hack.o
//kbuild:lib-$(CONFIG_TEST1) += test.o test_ptr_hack.o
//kbuild:lib-$(CONFIG_TEST2) += test.o test_ptr_hack.o

//kbuild:lib-$(CONFIG_ASH_TEST)  += test.o test_ptr_hack.o
//kbuild:lib-$(CONFIG_HUSH_TEST) += test.o test_ptr_hack.o

/* "test --help" is special-cased to ignore --help */
//usage:#define test_trivial_usage NOUSAGE_STR
//usage:#define test_full_usage ""
//usage:
//usage:#define test_example_usage
//usage:       "$ test 1 -eq 2\n"
//usage:       "$ echo $?\n"
//usage:       "1\n"
//usage:       "$ test 1 -eq 1\n"
//usage:       "$ echo $?\n"
//usage:       "0\n"
//usage:       "$ [ -d /etc ]\n"
//usage:       "$ echo $?\n"
//usage:       "0\n"
//usage:       "$ [ -d /junk ]\n"
//usage:       "$ echo $?\n"
//usage:       "1\n"

#include "libbb.h"

/* This is a NOFORK applet. Be very careful! */

/* test_main() is called from shells, and we need to be extra careful here.
 * This is true regardless of PREFER_APPLETS and SH_STANDALONE
 * state. */

/* 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>
*/

/* TODO: handle [[ expr ]] bashism bash-compatibly.
 * [[ ]] is meant to be a "better [ ]", with less weird syntax
 * and without the risk of variables and quoted strings misinterpreted
 * as operators.
 * This will require support from shells - we need to know quote status
 * of each parameter (see below).
 *
 * Word splitting and pathname expansion should NOT be performed:
 *      # a="a b"; [[ $a = "a b" ]] && echo YES
 *      YES
 *      # [[ /bin/m* ]] && echo YES
 *      YES
 *
 * =~ should do regexp match
 * = and == should do pattern match against right side:
 *      # [[ *a* == bab ]] && echo YES
 *      # [[ bab == *a* ]] && echo YES
 *      YES
 * != does the negated == (i.e., also with pattern matching).
 * Pattern matching is quotation-sensitive:
 *      # [[ bab == "b"a* ]] && echo YES
 *      YES
 *      # [[ bab == b"a*" ]] && echo YES
 *
 * Conditional operators such as -f must be unquoted literals to be recognized:
 *      # [[ -e /bin ]] && echo YES
 *      YES
 *      # [[ '-e' /bin ]] && echo YES
 *      bash: conditional binary operator expected...
 *      # A='-e'; [[ $A /bin ]] && echo YES
 *      bash: conditional binary operator expected...
 *
 * || and && should work as -o and -a work in [ ]
 * -a and -o aren't recognized (&& and || are to be used instead)
 * ( and ) do not need to be quoted unlike in [ ]:
 *      # [[ ( abc ) && '' ]] && echo YES
 *      # [[ ( abc ) || '' ]] && echo YES
 *      YES
 *      # [[ ( abc ) -o '' ]] && echo YES
 *      bash: syntax error in conditional expression...
 *
 * Apart from the above, [[ expr ]] should work as [ expr ]
 */

#define TEST_DEBUG 0

enum token {
        EOI,

        FILRD, /* file access */
        FILWR,
        FILEX,

        FILEXIST,

        FILREG, /* file type */
        FILDIR,
        FILCDEV,
        FILBDEV,
        FILFIFO,
        FILSOCK,

        FILSYM,
        FILGZ,
        FILTT,

        FILSUID, /* file bit */
        FILSGID,
        FILSTCK,

        FILNT, /* file ops */
        FILOT,
        FILEQ,

        FILUID,
        FILGID,

        STREZ, /* str ops */
        STRNZ,
        STREQ,
        STRNE,
        STRLT,
        STRGT,

        INTEQ, /* int ops */
        INTNE,
        INTGE,
        INTGT,
        INTLE,
        INTLT,

        UNOT,
        BAND,
        BOR,
        LPAREN,
        RPAREN,
        OPERAND
};
#define is_int_op(a)      (((unsigned char)((a) - INTEQ)) <= 5)
#define is_str_op(a)      (((unsigned char)((a) - STREZ)) <= 5)
#define is_file_op(a)     (((unsigned char)((a) - FILNT)) <= 2)
#define is_file_access(a) (((unsigned char)((a) - FILRD)) <= 2)
#define is_file_type(a)   (((unsigned char)((a) - FILREG)) <= 5)
#define is_file_bit(a)    (((unsigned char)((a) - FILSUID)) <= 2)

#if TEST_DEBUG
int depth;
#define nest_msg(...) do { \
        depth++; \
        fprintf(stderr, "%*s", depth*2, ""); \
        fprintf(stderr, __VA_ARGS__); \
} while (0)
#define unnest_msg(...) do { \
        fprintf(stderr, "%*s", depth*2, ""); \
        fprintf(stderr, __VA_ARGS__); \
        depth--; \
} while (0)
#define dbg_msg(...) do { \
        fprintf(stderr, "%*s", depth*2, ""); \
        fprintf(stderr, __VA_ARGS__); \
} while (0)
#define unnest_msg_and_return(expr, ...) do { \
        number_t __res = (expr); \
        fprintf(stderr, "%*s", depth*2, ""); \
        fprintf(stderr, __VA_ARGS__, res); \
        depth--; \
        return __res; \
} while (0)
static const char *const TOKSTR[] = {
        "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"
};
#else
#define nest_msg(...)   ((void)0)
#define unnest_msg(...) ((void)0)
#define dbg_msg(...)    ((void)0)
#define unnest_msg_and_return(expr, ...) return expr
#endif

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

struct operator_t {
        unsigned char op_num, op_type;
};

static const struct operator_t ops_table[] = {
        { /* "-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  },
        /* "==" is bashism, http://pubs.opengroup.org/onlinepubs/9699919799/utilities/test.html
         * lists only "=" as comparison operator.
         */
        { /* "==" */ 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  },
};
/* Please keep these two tables in sync */
static const char ops_texts[] ALIGN1 =
        "-r"  "\0"
        "-w"  "\0"
        "-x"  "\0"
        "-e"  "\0"
        "-f"  "\0"
        "-d"  "\0"
        "-c"  "\0"
        "-b"  "\0"
        "-p"  "\0"
        "-u"  "\0"
        "-g"  "\0"
        "-k"  "\0"
        "-s"  "\0"
        "-t"  "\0"
        "-z"  "\0"
        "-n"  "\0"
        "-h"  "\0"

        "-O"  "\0"
        "-G"  "\0"
        "-L"  "\0"
        "-S"  "\0"
        "="   "\0"
        /* "==" is bashism */
        "=="  "\0"
        "!="  "\0"
        "<"   "\0"
        ">"   "\0"
        "-eq" "\0"
        "-ne" "\0"
        "-ge" "\0"
        "-gt" "\0"
        "-le" "\0"
        "-lt" "\0"
        "-nt" "\0"
        "-ot" "\0"
        "-ef" "\0"
        "!"   "\0"
        "-a"  "\0"
        "-o"  "\0"
        "("   "\0"
        ")"   "\0"
;


#if ENABLE_FEATURE_TEST_64
typedef int64_t number_t;
#else
typedef int number_t;
#endif


/* We try to minimize both static and stack usage. */
struct test_statics {
        char **args;
        /* set only by check_operator(), either to bogus struct
         * or points to matching operator_t struct. Never NULL. */
        const struct operator_t *last_operator;
        gid_t *group_array;
        int ngroups;
        jmp_buf leaving;
};

/* See test_ptr_hack.c */
extern struct test_statics *const test_ptr_to_statics;

#define S (*test_ptr_to_statics)
#define args            (S.args         )
#define last_operator   (S.last_operator)
#define group_array     (S.group_array  )
#define ngroups         (S.ngroups      )
#define leaving         (S.leaving      )

#define INIT_S() do { \
        (*(struct test_statics**)&test_ptr_to_statics) = xzalloc(sizeof(S)); \
        barrier(); \
} while (0)
#define DEINIT_S() do { \
        free(group_array); \
        free(test_ptr_to_statics); \
} while (0)

static number_t primary(enum token n);

static void syntax(const char *op, const char *msg) NORETURN;
static void syntax(const char *op, const char *msg)
{
        if (op && *op) {
                bb_error_msg("%s: %s", op, msg);
        } else {
                bb_error_msg("%s: %s"+4, msg);
        }
        longjmp(leaving, 2);
}

/* atoi with error detection */
//XXX: FIXME: duplicate of existing libbb function?
static number_t getn(const char *s)
{
        char *p;
#if ENABLE_FEATURE_TEST_64
        long long r;
#else
        long r;
#endif

        errno = 0;
#if ENABLE_FEATURE_TEST_64
        r = strtoll(s, &p, 10);
#else
        r = strtol(s, &p, 10);
#endif

        if (errno != 0)
                syntax(s, "out of range");

        if (p == s || *(skip_whitespace(p)) != '\0')
                syntax(s, "bad number");

        return r;
}

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

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

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

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

static int equalf(const char *f1, const char *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);
}
*/


static enum token check_operator(const char *s)
{
        static const struct operator_t no_op = {
                .op_num = -1,
                .op_type = -1
        };
        int n;

        last_operator = &no_op;
        if (s == NULL)
                return EOI;
        n = index_in_strings(ops_texts, s);
        if (n < 0)
                return OPERAND;
        last_operator = &ops_table[n];
        return ops_table[n].op_num;
}


static int binop(void)
{
        const char *opnd1, *opnd2;
        const struct operator_t *op;
        number_t val1, val2;

        opnd1 = *args;
        check_operator(*++args);
        op = last_operator;

        opnd2 = *++args;
        if (opnd2 == NULL)
                syntax(args[-1], "argument expected");

        if (is_int_op(op->op_num)) {
                val1 = getn(opnd1);
                val2 = getn(opnd2);
                if (op->op_num == INTEQ)
                        return val1 == val2;
                if (op->op_num == INTNE)
                        return val1 != val2;
                if (op->op_num == INTGE)
                        return val1 >= val2;
                if (op->op_num == INTGT)
                        return val1 >  val2;
                if (op->op_num == INTLE)
                        return val1 <= val2;
                /*if (op->op_num == INTLT)*/
                return val1 <  val2;
        }
        if (is_str_op(op->op_num)) {
                val1 = strcmp(opnd1, opnd2);
                if (op->op_num == STREQ)
                        return val1 == 0;
                if (op->op_num == STRNE)
                        return val1 != 0;
                if (op->op_num == STRLT)
                        return val1 < 0;
                /*if (op->op_num == STRGT)*/
                return val1 > 0;
        }
        /* We are sure that these three are by now the only binops we didn't check
         * yet, so we do not check if the class is correct:
         */
/*      if (is_file_op(op->op_num)) */
        {
                struct stat b1, b2;

                if (stat(opnd1, &b1) || stat(opnd2, &b2))
                        return 0; /* false, since at least one stat failed */
                if (op->op_num == FILNT)
                        return b1.st_mtime > b2.st_mtime;
                if (op->op_num == FILOT)
                        return b1.st_mtime < b2.st_mtime;
                /*if (op->op_num == FILEQ)*/
                return b1.st_dev == b2.st_dev && b1.st_ino == b2.st_ino;
        }
        /*return 1; - NOTREACHED */
}

static void initialize_group_array(void)
{
        group_array = bb_getgroups(&ngroups, NULL);
}

/* Return non-zero if GID is one that we have in our groups list. */
//XXX: FIXME: duplicate of existing libbb function?
// see toplevel TODO file:
// possible code duplication ingroup() and is_a_group_member()
static int is_a_group_member(gid_t gid)
{
        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;
}


/* 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(struct stat *st, int mode)
{
        unsigned int euid = geteuid();

        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 int filstat(char *nm, enum token mode)
{
        struct stat s;
        unsigned i = i; /* gcc 3.x thinks it can be used uninitialized */

        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;
        if (mode == FILEXIST)
                return 1;
        if (is_file_access(mode)) {
                if (mode == FILRD)
                        i = R_OK;
                if (mode == FILWR)
                        i = W_OK;
                if (mode == FILEX)
                        i = X_OK;
                return test_eaccess(&s, i) == 0;
        }
        if (is_file_type(mode)) {
                if (mode == FILREG)
                        i = S_IFREG;
                if (mode == FILDIR)
                        i = S_IFDIR;
                if (mode == FILCDEV)
                        i = S_IFCHR;
                if (mode == FILBDEV)
                        i = S_IFBLK;
                if (mode == FILFIFO) {
#ifdef S_IFIFO
                        i = S_IFIFO;
#else
                        return 0;
#endif
                }
                if (mode == FILSOCK) {
#ifdef S_IFSOCK
                        i = S_IFSOCK;
#else
                        return 0;
#endif
                }
 filetype:
                return ((s.st_mode & S_IFMT) == i);
        }
        if (is_file_bit(mode)) {
                if (mode == FILSUID)
                        i = S_ISUID;
                if (mode == FILSGID)
                        i = S_ISGID;
                if (mode == FILSTCK)
                        i = S_ISVTX;
                return ((s.st_mode & i) != 0);
        }
        if (mode == FILGZ)
                return s.st_size > 0L;
        if (mode == FILUID)
                return s.st_uid == geteuid();
        if (mode == FILGID)
                return s.st_gid == getegid();
        return 1; /* NOTREACHED */
}


static number_t nexpr(enum token n)
{
        number_t res;

        nest_msg(">nexpr(%s)\n", TOKSTR[n]);
        if (n == UNOT) {
                n = check_operator(*++args);
                if (n == EOI) {
                        /* special case: [ ! ], [ a -a ! ] are valid */
                        /* IOW, "! ARG" may miss ARG */
                        args--;
                        unnest_msg("<nexpr:1 (!EOI), args:%s(%p)\n", args[0], &args[0]);
                        return 1;
                }
                res = !nexpr(n);
                unnest_msg("<nexpr:%lld\n", res);
                return res;
        }
        res = primary(n);
        unnest_msg("<nexpr:%lld\n", res);
        return res;
}


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

        nest_msg(">aexpr(%s)\n", TOKSTR[n]);
        res = nexpr(n);
        dbg_msg("aexpr: nexpr:%lld, next args:%s(%p)\n", res, args[1], &args[1]);
        if (check_operator(*++args) == BAND) {
                dbg_msg("aexpr: arg is AND, next args:%s(%p)\n", args[1], &args[1]);
                res = aexpr(check_operator(*++args)) && res;
                unnest_msg("<aexpr:%lld\n", res);
                return res;
        }
        args--;
        unnest_msg("<aexpr:%lld, args:%s(%p)\n", res, args[0], &args[0]);
        return res;
}


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

        nest_msg(">oexpr(%s)\n", TOKSTR[n]);
        res = aexpr(n);
        dbg_msg("oexpr: aexpr:%lld, next args:%s(%p)\n", res, args[1], &args[1]);
        if (check_operator(*++args) == BOR) {
                dbg_msg("oexpr: next arg is OR, next args:%s(%p)\n", args[1], &args[1]);
                res = oexpr(check_operator(*++args)) || res;
                unnest_msg("<oexpr:%lld\n", res);
                return res;
        }
        args--;
        unnest_msg("<oexpr:%lld, args:%s(%p)\n", res, args[0], &args[0]);
        return res;
}


static number_t primary(enum token n)
{
#if TEST_DEBUG
        number_t res = res; /* for compiler */
#else
        number_t res;
#endif
        const struct operator_t *args0_op;

        nest_msg(">primary(%s)\n", TOKSTR[n]);
        if (n == EOI) {
                syntax(NULL, "argument expected");
        }
        if (n == LPAREN) {
                res = oexpr(check_operator(*++args));
                if (check_operator(*++args) != RPAREN)
                        syntax(NULL, "closing paren expected");
                unnest_msg("<primary:%lld\n", res);
                return res;
        }

        /* coreutils 6.9 checks "is args[1] binop and args[2] exist?" first,
         * do the same */
        args0_op = last_operator;
        /* last_operator = operator at args[1] */
        if (check_operator(args[1]) != EOI) { /* if args[1] != NULL */
                if (args[2]) {
                        // coreutils also does this:
                        // if (args[3] && args[0]="-l" && args[2] is BINOP)
                        //      return binop(1 /* prepended by -l */);
                        if (last_operator->op_type == BINOP)
                                unnest_msg_and_return(binop(), "<primary: binop:%lld\n");
                }
        }
        /* check "is args[0] unop?" second */
        if (args0_op->op_type == UNOP) {
                /* unary expression */
                if (args[1] == NULL)
//                      syntax(args0_op->op_text, "argument expected");
                        goto check_emptiness;
                args++;
                if (n == STREZ)
                        unnest_msg_and_return(args[0][0] == '\0', "<primary:%lld\n");
                if (n == STRNZ)
                        unnest_msg_and_return(args[0][0] != '\0', "<primary:%lld\n");
                if (n == FILTT)
                        unnest_msg_and_return(isatty(getn(*args)), "<primary: isatty(%s)%lld\n", *args);
                unnest_msg_and_return(filstat(*args, n), "<primary: filstat(%s):%lld\n", *args);
        }

        /*check_operator(args[1]); - already done */
        if (last_operator->op_type == BINOP) {
                /* args[2] is known to be NULL, isn't it bound to fail? */
                unnest_msg_and_return(binop(), "<primary:%lld\n");
        }
 check_emptiness:
        unnest_msg_and_return(args[0][0] != '\0', "<primary:%lld\n");
}


int test_main(int argc, char **argv)
{
        int res;
        const char *arg0;

        arg0 = bb_basename(argv[0]);
        if ((ENABLE_TEST1 || ENABLE_TEST2 || ENABLE_ASH_TEST || ENABLE_HUSH_TEST)
         && (arg0[0] == '[')
        ) {
                --argc;
                if (!arg0[1]) { /* "[" ? */
                        if (NOT_LONE_CHAR(argv[argc], ']')) {
                                bb_error_msg("missing ]");
                                return 2;
                        }
                } else { /* assuming "[[" */
                        if (strcmp(argv[argc], "]]") != 0) {
                                bb_error_msg("missing ]]");
                                return 2;
                        }
                }
                argv[argc] = NULL;
        }
        /* argc is unused after this point */

        /* We must do DEINIT_S() prior to returning */
        INIT_S();

        res = setjmp(leaving);
        if (res)
                goto ret;

        /* resetting ngroups is probably unnecessary.  it will
         * force a new call to getgroups(), which prevents using
         * group data fetched during a previous call.  but the
         * only way the group data could be stale is if there's
         * been an intervening call to setgroups(), and this
         * isn't likely in the case of a shell.  paranoia
         * prevails...
         */
        /*ngroups = 0; - done by INIT_S() */

        argv++;
        args = argv;

        /* Implement special cases from POSIX.2, section 4.62.4.
         * Testcase: "test '(' = '('"
         * The general parser would misinterpret '(' as group start.
         */
        if (1) {
                int negate = 0;
 again:
                if (!argv[0]) {
                        /* "test" */
                        res = 1;
                        goto ret_special;
                }
                if (!argv[1]) {
                        /* "test [!] arg" */
                        res = (argv[0][0] == '\0');
                        goto ret_special;
                }
                if (argv[2]) {
                        if (!argv[3]) {
                                /*
                                 * http://pubs.opengroup.org/onlinepubs/009695399/utilities/test.html
                                 * """ 3 arguments:
                                 * If $2 is a binary primary, perform the binary test of $1 and $3.
                                 * """
                                 */
                                check_operator(argv[1]);
                                if (last_operator->op_type == BINOP) {
                                        /* "test [!] arg1 <binary_op> arg2" */
                                        args = argv;
                                        res = (binop() == 0);
 ret_special:
                                        /* If there was leading "!" op... */
                                        res ^= negate;
                                        goto ret;
                                }
                                /* """If $1 is '(' and $3 is ')', perform the unary test of $2."""
                                 * Looks like this works without additional coding.
                                 */
                                goto check_negate;
                        }
                        /* argv[3] exists (at least 4 args), is it exactly 4 args? */
                        if (!argv[4]) {
                                /*
                                 * """ 4 arguments:
                                 * If $1 is '!', negate the three-argument test of $2, $3, and $4.
                                 * If $1 is '(' and $4 is ')', perform the two-argument test of $2 and $3.
                                 * """
                                 * Example why code below is necessary: test '(' ! -e ')'
                                 */
                                if (LONE_CHAR(argv[0], '(')
                                 && LONE_CHAR(argv[3], ')')
                                ) {
                                        /* "test [!] ( x y )" */
                                        argv[3] = NULL;
                                        argv++;
                                }
                        }
                }
 check_negate:
                if (LONE_CHAR(argv[0], '!')) {
                        argv++;
                        negate ^= 1;
                        goto again;
                }
        }

        res = !oexpr(check_operator(*args));

        if (*args != NULL && *++args != NULL) {
                /* Examples:
                 * test 3 -lt 5 6
                 * test -t 1 2
                 */
                bb_error_msg("%s: unknown operand", *args);
                res = 2;
        }
 ret:
        DEINIT_S();
        return res;
}