source: MondoRescue/branches/2.2.9/mindi-busybox/coreutils/test.c@ 2725

/* 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."
 */

//kbuild:lib-$(CONFIG_TEST)      += test.o test_ptr_hack.o
//kbuild:lib-$(CONFIG_ASH)       += test.o test_ptr_hack.o
//kbuild:lib-$(CONFIG_HUSH)      += test.o test_ptr_hack.o

//config:config TEST
//config:   bool "test"
//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 FEATURE_TEST_64
//config:   bool "Extend test to 64 bit"
//config:   default y
//config:   depends on TEST || ASH_BUILTIN_TEST || HUSH
//config:   help
//config:     Enable 64-bit support in test.

#include "libbb.h"
#include <setjmp.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 STANDALONE_SHELL
 * 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  },
    { /* "==" */ 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"
    "=="  "\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(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)
{
    int n;

    /* getgroups may be expensive, try to use it only once */
    ngroups = 32;
    do {
        /* FIXME: ash tries so hard to not die on OOM,
         * and we spoil it with just one xrealloc here */
        /* We realloc, because test_main can be entered repeatedly by shell.
         * Testcase (ash): 'while true; do test -x some_file; done'
         * and watch top. (some_file must have owner != you) */
        n = ngroups;
        group_array = xrealloc(group_array, n * sizeof(gid_t));
        ngroups = getgroups(n, group_array);
    } while (ngroups > n);
}


/* 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(char *path, int mode)
{
    struct stat st;
    unsigned 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 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(nm, 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 */
            unnest_msg("<nexpr:1 (!EOI)\n");
            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\n", res, args[1]);
    if (check_operator(*++args) == BAND) {
        dbg_msg("aexpr: arg is AND, next args:%s\n", args[1]);
        res = aexpr(check_operator(*++args)) && res;
        unnest_msg("<aexpr:%lld\n", res);
        return res;
    }
    args--;
    unnest_msg("<aexpr:%lld, args:%s\n", res, 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\n", res, args[1]);
    if (check_operator(*++args) == BOR) {
        dbg_msg("oexpr: next arg is OR, next args:%s\n", args[1]);
        res = oexpr(check_operator(*++args)) || res;
        unnest_msg("<oexpr:%lld\n", res);
        return res;
    }
    args--;
    unnest_msg("<oexpr:%lld, args:%s\n", res, 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;
//  bool negate = 0;

    arg0 = bb_basename(argv[0]);
    if (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;
    }

    /* 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() */

    //argc--;
    argv++;

    /* Implement special cases from POSIX.2, section 4.62.4 */
    if (!argv[0]) { /* "test" */
        res = 1;
        goto ret;
    }
#if 0
// Now it's fixed in the parser and should not be needed
    if (LONE_CHAR(argv[0], '!') && argv[1]) {
        negate = 1;
        //argc--;
        argv++;
    }
    if (!argv[1]) { /* "test [!] arg" */
        res = (*argv[0] == '\0');
        goto ret;
    }
    if (argv[2] && !argv[3]) {
        check_operator(argv[1]);
        if (last_operator->op_type == BINOP) {
            /* "test [!] arg1 <binary_op> arg2" */
            args = argv;
            res = (binop() == 0);
            goto ret;
        }
    }

    /* Some complex expression. Undo '!' removal */
    if (negate) {
        negate = 0;
        //argc++;
        argv--;
    }
#endif
    args = argv;
    res = !oexpr(check_operator(*args));

    if (*args != NULL && *++args != NULL) {
        /* TODO: example when this happens? */
        bb_error_msg("%s: unknown operand", *args);
        res = 2;
    }
 ret:
    DEINIT_S();
//  return negate ? !res : res;
    return res;
}